Monsoon Updates

El Niño is a climate cycle in the Pacific Ocean with a global impact on weather patterns. Keep up with the latest updates and a comprehensive report on how it affects Indian monsoon.

Monsoon Updates

How Asian desert dust enhances Indian summer monsoon?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Indian Monsson : Onset and Withdrawal

Mains level : Determinants of Indian Monsoon

A new study has revealed how dust coming from the deserts in West, Central and East Asia plays an important role in the Indian Summer Monsoon.

Try this PYQ:

With reference to ‘Indian Ocean Dipole (IOD)’, sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?

  1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
  2. An IOD phenomenon can influence an El Nino’s impact on the monsoon.

Select the correct Option using the code given below:

(a) Only 1

(b) Only 2

(c) Both 1 and 2

(d) Neither 1 nor 2

Why study dust?

  • Many studies have shown that the dust emission scheme is extremely sensitive to climate change.
  • Understanding these mechanisms and effects of dust will help us understand our monsoon systems in the face of global climate change.

Impact of dust on Indian Monsoon

  • Dust swarms from the desert when lifted by strong winds can absorb solar radiation and become hot.
  • This can cause heating of the atmosphere, change the air pressure, wind circulation patterns, influence moisture transport and increase precipitation and rainfall.
  • A strong monsoon can also transport air to West Asia and again pick up a lot of dust.
  • The researchers say this is a positive feedback loop.

Role of the Iranian plateau

  • Not just the dust from the Middle East, the Iranian Plateau also influences the Indian Summer Monsoon.
  • The hot air over the Iranian Plateau can heat the atmosphere over the plateau, strengthen the circulation over the deserts of the Arabian Peninsula and increase dust emission from the Middle East.
  • The researchers also explain how the Indian Summer Monsoon has a reverse effect and can increase the winds in West Asia to produce yet more dust.

Transported aerosols

  • Deserts across the globe play important roles in monsoons.
  • The dust aerosols from deserts in West China such as the Taklamakan desert and the Gobi Desert can be transported eastward to eastern China and can influence the East Asia summer monsoon.
  • And in the southwest United States, we have some small deserts that influence the North African monsoon.

Anthropogenic contributions

  • Some studies have found that the anthropogenic aerosols emitted from the Indian subcontinent can decrease summer monsoon precipitation.
  • However, some others found that absorbing aerosols such as dust can strengthen the monsoon circulation.

Minor components

  • Earlier it was believed that dust from deserts across the globe will have the same components.
  • But it was found that different deserts have different chemical compositions and this can influence the dust’s properties.
  • For example, dust from the Middle East has the more absorbing ability of solar radiation than dust from North Africa and this difference in absorbing ability might influence monsoon systems.

By Root

Caretaker @civilsdaily

Monsoon Updates

Mawsynram: Wettest place on Earth sees a decreasing trend in rainfall

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Mawsynram

Mains level : Not Much

A recent study that looked at the rainfall pattern in the past 119 years found a decreasing trend at Cherrapunji and nearby areas.

Try this PYQ:

Q.“Climate is extreme, rainfall is scanty and the people used to be nomadic herders.” The above statement best describes which of the following regions?

(a) African Savannah

(b) Central Asian Steppe

(c) North American Prairie

(d) Siberian Tundra

Mawsynram

  • Mawsynram is a town in the East Khasi Hills district of Meghalaya state in northeastern India, 60.9 kilometres from Shillong.
  • Mawsynram receives the highest rainfall in India.
  • It is reportedly the wettest place on Earth, with an average annual rainfall of 11,872mm but that claim is disputed.
  • According to the Guinness Book of World Records, Mawsynram received 26,000 millimetres (1,000 in) of rainfall in 1985.

Why it rain highest in Mawsynram?

  • Because of the uneven relief of India due to the presence of a number of hill ranges, the monsoon is not able to shed its moisture evenly over India.
  • Windward sides receive more rainfall and leeward sides receive less rainfall.
  • Mawsynram lies in the funnel-shaped depression caused by the Khasi range in Meghalaya.
  • The Bay of Bengal branch of monsoons is trapped in it and causes heavy rainfall.

Decreasing rainfall trends

  • The research analysed daily rain gauge measurements during 1901–2019 and noted that the changes in the Indian Ocean temperature have a huge effect on the rainfall in the region.
  • There was a reduction in the vegetation area in northeast India in the past two decades, implying that human influence also plays an important role in the changing rainfall patterns.
  • The traditional way of cultivation known as Jhum cultivation or shifting cultivation is now decreased and being replaced by other methods.
  • Also, previous studies have noted there is sizable deforestation in the region.

By Root

Caretaker @civilsdaily

Monsoon Updates

[pib] National Monsoon Mission

Note4Students

From UPSC perspective, the following things are important :

Prelims level : National Monsoon Mission

Mains level : Determinants of Indian Monsoon

Under the National Monsoon Mission (NMM), Ministry of Earth Sciences has developed the state-of-the-art weather and climate prediction models, which are now in operational use.

Tap to read about the mechanism of Indian Monsoon System at:

The Southwest Monsoon Season (Jun – Sep) | Part 1

National Monsoon Mission (NMM)

  • Ministry of Earth Sciences (MoES) had launched NMM in 2012 with a vision to develop a state-of-the-art dynamical prediction system for monsoon rainfall on different time scales.
  • The responsibility of execution and coordination of this mission is vested to the Indian Institute of Tropical Meteorology (IITM), Pune.
  • Climate Forecast System (CFS) of USA has been identified as the basic modelling system for the above purpose, as it is one of the best among the currently available coupled models.

Targets of NMM

  • Development of a seamless prediction system using monsoon mission model, on different time scales, like Seasonal (for whole Monsoon season), extended-range (upto 4 weeks), short-range prediction (up-to 5days).
  • Initiate and coordinate the working partnership between Indian and foreign institutes to develop a system for prediction of extremes and climate applications
  • Develop and implement the system for climate applications having social impacts (such as agriculture, flood forecast, extreme events forecast, wind energy, etc.
  • Advanced data assimilation system for preparing high-quality data for model predictions.

Achievements of NMM during the last 3 years

  • Setting up of an advanced prediction system for Seasonal prediction; Extended range prediction and Very high-resolution Short-range prediction.
  • Commissioning of a Global Ensemble Forecast System (GEFS) for short and medium-range prediction at 12km.
  • The Cyclone track and intensity prediction has also shown a steady improvement over the last three years.
  • The operationalization of Monsoon Mission dynamical model (MMCFS) to prepare operational seasonal forecast of monsoon rainfall and temperatures during the hot and cold weather seasons over India.
  • Development of an algorithm to monitor and predict the Monsoon Intra-seasonal Oscillations (MISO) and Madden-Julian Oscillation (MJO) on the extended range.
  • Development of an index to predict the genesis and evolution of tropical cyclones and other cyclonic disturbances over the north Indian Ocean.

By Root

Caretaker @civilsdaily

Monsoon Updates

What are Rossby Waves?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Indian Monsoon, ENSO, Planetary Winds

Mains level : Determinants of Indian Monsoon

Droughts in India have historically been associated with El Nino, anomalous warming of the equatorial Pacific, but Indian scientists have found some relevance in Rossby Waves.

Q.The determinants of Indian Monsoon are no more limited to the Pacific and the Indian Ocean. Discuss.

El-Nino alone do not cause drought

  • The study says that nearly six out of 10 droughts, in non-El Nino years occurred during the Indian summer-monsoon season in the past century.
  • They may have been driven by atmospheric disturbances from the North Atlantic region.
  • In an El Niño year, abnormally warm equatorial Pacific waters pull moisture-laden clouds away from the subcontinent.
  • But the IISc Bangalore study shows that in non-El Nino years, these droughts are a consequence of a sudden and steep drop in rainfall in late August.

Then, how were droughts induced?

  • In an El Nino year, the rainfall deficit departure from a long-term average set in early around mid-June and progressively worsen.
  • Researchers tried to trace this drought back to a forcing agent or system that influences the behaviour over India.
  • They found, the winds that were prevalent in these non-El Niño drought years.

Another factor: The Rossby Waves

  • The researchers noted that winds in the upper atmosphere are interacting with a deep cyclonic circulation above the abnormally cold North Atlantic waters.
  • The resulting wave of air currents called a Rossby wave, curved down from the North Atlantic squeezed in by the Tibetan plateau and hits the subcontinent around mid-August.
  • This has a suppressing effect on rainfall and throws off the monsoon that was trying to recover from the June slump.

Now scratch your basics on Planetary Winds. “Go back to the NCERTs !”

What are Rossby Waves?

  • They are giant meanders in high-altitude winds that have a major influence on the weather.
  • They are influenced by the Coriolis force and pressure gradient.
  • The wave’s usual course is to go from west to east, but not towards the equator.

Points to be noted ……

  • The Indian Ocean and the Pacific Ocean seem to be at the forefront of all discussions surrounding Indian monsoon droughts.
  • Thus beyond looking at the Pacific Ocean it is important to consider other influences on the Indian monsoon from outside the tropics.
  • It is perhaps time to focus just as much on mid-latitude influences, which might aid in getting a better handle on enhanced predictability of monsoon variability.

By Root

Caretaker @civilsdaily

Monsoon Updates

Why has the Northeast Monsoon remained deficient this year?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Indian Monsson : Onset and Withdrawal

Mains level : El Nino and La Nina

Rainfall over the Southern peninsular region has been deficient so far due to prevailing La Nina conditions according to the India Meteorological Department (IMD).

Try this PYQ:

Q.La Nina is suspected to have caused recent floods in Australia. How is La Nina different from El Nino?

  1. La Nina is characterized by unusually cold ocean temperature in equatorial Indian Ocean whereas El Nino is characterized by unusually warm ocean temperature in the equatorial Pacific Ocean.
  2. El Nino has an adverse effect on south-west monsoon of India, but La Nina has no effect on monsoon climate.

Which of the statements given above is/are correct?

(a) Only 1

(b) Only 2

(c) Both 1 and 2

(d) Neither 1 nor 2

What is the Northeast monsoon?

  • India receives rainfall during two seasons.
  • About 75 per cent of the country’s annual rainfall is received from the Southwest monsoon between June and September.
  • The Northeast monsoon, on the other hand, occurs from October to December and is a comparatively small-scale monsoon, which is confined to the Southern peninsula.
  • After the complete withdrawal of the Southwest monsoon from the country takes place by mid-October, the wind pattern rapidly changes from the south-westerly to the north-easterly direction.
  • Also called the winter monsoon, the rainfall associated with the Northeast monsoon is important for almost entire South India.

Why it is important?

  • Tamil Nadu records about 48 per cent (447.4 mm) of its annual rainfall (943.7 mm) during these months, making it the key factor for undertaking agricultural activities and reservoir management in the state.
  • Some South Asian countries such as Maldives, Sri Lanka and Myanmar also record rainfall from October to December.

Why there are distortions?

  • The majority of districts in Tamil Nadu remain highly rain-deficient up this time.
  • The period after the Southwest monsoon season, from October to December, is the peak time for cyclonic activity in the North Indian Ocean region — covering the Arabian Sea and the Bay of Bengal.
  • The winds associated with the formation of low-pressure systems, depressions, or cyclones influence this monsoon, and therefore, the rainfall.
  • Officials at IMD have linked it to the prevailing La Niña conditions in the Pacific Ocean.

La Nina  link with the NE monsoon

  • While La Niña conditions enhance the rainfall associated with the Southwest monsoon, it has a negative impact on rainfall associated with the Northeast monsoon.
  • During La Niña years, the synoptic systems — low pressure or cyclones — formed in the Bay of Bengal remain significantly to the north of their normal position.
  • Besides, instead of moving westwards, these systems recurve. As they lie to the north of their normal position, not much rainfall occurs over southern regions like Tamil Nadu.

Back2Basics: El Nino and La Nina

  • While El Niño (Spanish for ‘little boy’), the more common expression, is the abnormal surface warming observed along the eastern and central regions of the Pacific Ocean (the region between Peru and Papua New Guinea).
  • The La Niña (Spanish for ‘little girl’) is an abnormal cooling of these surface waters.
  • Together, the El Niño and La Niña phenomena are termed as El Niño Southern Oscillation (ENSO).
  • These are large-scale ocean phenomena which influence the global weather — winds, temperature and rainfall. They have the ability to trigger extreme weather events like droughts, floods, hot and cold conditions, globally.
  • Each cycle can last anywhere between 9 to 12 months, at times extendable to 18 months — and re-occur after every three to five years.
  • Meteorologists record the sea surface temperatures for four different regions, known as Niño regions, along this equatorial belt.
  • Depending on the temperatures, they forecast either as an El Niño, an ENSO neutral phase, or a La Niña.

By Root

Caretaker @civilsdaily

Monsoon Updates

What is Global Warming Hiatus (GWH)?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Mascerene High, Global Warming Hiatus (GWH)

Mains level : Impact of global warming on Indian Monsoon

A new study on variability in the Mascarene High (MH) in the Southern Indian Ocean during global warming hiatus (GWH) has revealed that the region experienced significantly increased sea surface temperature (SST) during this period (1998-2016).

Try this PYQ:

Q.With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct? (CSP 2020)

  1. OMT is measured upto a depth of 26 degree Celsius isotherm which is 129 meters in the south-western Indian Ocean during January-March.
  2. OMT collected during January-March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.

Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

What is Global Warming Hiatus (GWH)?

  • A global warming hiatus is referred to a global warming pause, or a global warming slowdown, which is a period of relatively little change in globally averaged surface temperatures.
  • The hiatus, however, can result in an increase in the SST.

What is Mascarene High (MH)?

  • The Mascarene High (MH) is a semi-permanent subtropical high-pressure zone in the South Indian Ocean.
  • It is also called the Indian Ocean subtropical high, which is a high-pressure area located between 20° to 35° South latitude and 40° to 90° East longitude.
  • It is a region from where the cross-equatorial winds blow to India.
  • It has been named after the Mascarene Islands, in the Indian Ocean east of Madagascar consisting of the islands belonging to Mauritius as well as the French Réunion Islands.
  • Apart from its large influence on African and Australian weather patterns, it also helps in driving the inter-hemispheric circulation between the Indian Ocean in the south and subcontinental landmass in the north.

Role of MH

  • The warming in SST due to global warming has resulted in a decrease in the pressure gradient between the MH and the Indian landmass.
  • This in turn suppressed the intensity of low-level cross-equatorial winds over the western Indian Ocean affecting the onset of the monsoon over the Indian subcontinent and rainfall over East Asia.

By Root

Caretaker @civilsdaily

Monsoon Updates

Boreal Summer Intra-Seasonal Oscillation (BSISO)

Note4Students

From UPSC perspective, the following things are important :

Prelims level : BSISO

Mains level : Indian monsoon and its prediction

Researchers at the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad have reportedly found a way to better forecast the Boreal Summer Intra-Seasonal Oscillation (BSISO).

Try this PYQ:

Q.With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct? (CSP 2017)

  1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
  2. An IOD phenomenon can influence an El Nino’s impact on the monsoon.

Select the correct answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

What is BSISO?

  • The BSISO of the Asian summer monsoon (ASM) is one of the most prominent sources of short-term climate variability in the global monsoon system.
  • It is the movement of convection (heat) from the Indian Ocean to the western Pacific Ocean roughly every 10-50 days during the monsoon (June-September).
  • Compared with the related Madden-Julian Oscillation (MJO) it is more complex in nature, with prominent northward propagation and variability extending much further from the equator.
  • It represents the monsoon’s ‘active’ and ‘break’ periods, in which weeks of heavy rainfall give way to brilliant sunshine before starting all over again.
  • The active phase also enhances monsoon winds and hence the surface waves.

Why predict BSISO behaviour?

  • Some phases of boreal summer intraseasonal oscillation or BSISO induce high wave activity in the north Indian Ocean and the Arabian Sea, the researchers claimed.
  • Wave forecast advisories based on the BSISO would be more useful for efficient coastal and marine management.
  • This finding has a great significance in developing seasonal and climate forecast service for waves and coastal erosion for India.

By Root

Caretaker @civilsdaily

Monsoon Updates

Bay of Bengal Boundary Layer Experiment (BoBBLE)

Note4Students

From UPSC perspective, the following things are important :

Prelims level : BoBBLE

Mains level : Indian monsoon and its prediction

A team from IISc Bengaluru and UK based researchers has created a blueprint for accurate prediction of monsoon, tropical cyclones and another weather-related forecast under the BoBBLE Experiment.

Aspirants must note:

1) BoBBLE is headed by which organizations?

2) Its purpose and application

What is BoBBLE?

  • The Bay of Bengal Boundary Layer Experiment or BoBBLE in short is a project funded by Union Ministry of Earth Sciences and the Natural Environment Research Council of UK.
  • BoBBLE tries to determine, quantify and model ocean-atmosphere interactions that drive variability in the South Asian monsoon.
  • The experiment created a blueprint for future weather system observational experiments for accurately forecasting monsoon rainfall.

Why need BoBBLE?

  • The Bay of Bengal (BoB) plays a fundamental role in controlling the weather systems that make up the South Asian summer monsoon system.
  • In particular, the southern BoB has cooler sea surface temperatures (SST) that influence ocean-atmosphere interaction and impact the monsoon.
  • Compared to the southeastern BoB, the southwestern BoB is cooler, more saline receives much less rain, and is influenced by the summer monsoon current (SMC).
  • To examine the impact of these features on the monsoon, the BoB Boundary Layer Experiment (BoBBLE) was undertaken.

BONUS:

1) How technology development in monsoon forecasting can benefit realizing the dream of doubling farmers income by 2022?

2) Discuss the role of Bay of Bengal in monsoon dynamics. (Hint: the link between the two lies in Indian Ocean Dipole (IOD))

How is the experiment carried out?

  • BoBBLE will deploy two ships, six ocean gliders and eight floats to collect an unprecedented range of oceanic and air-sea flux observations.
  • These will occupy locations in the southwest and southeast Bay, as well as tracing east-west and north-south paths between those locations, measuring ocean temperature, salinity and currents.

With inputs from http://www.walker.ac.uk/research/projects/bay-of-bengal-boundary-layer-experiment-bobble/

By Root

Caretaker @civilsdaily

Monsoon Updates

Explained: What new monsoon dates mean

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Monsoon: Its onset and retreat

Mains level : Various factors causing uncertainty in monsoon predictions

 

The India Meteorological Department (IMD) had decided to revise the normal onset and withdrawal dates for the monsoon in some parts of the country from this year.

Onset of Monsoon

  • The four-month southwest monsoon season, which brings as much as 70 per cent of the country’s annual rainfall, officially begins on June 1, with the onset over Kerala, and ends on September 30.
  • It takes about a month and half after onset on the Kerala coast to cover the entire country; and about a month, beginning from the northwestern parts of the country on Sept. 1 to withdraw completely.
  • Although the June 1 date for the onset of the monsoon on the Kerala coast is unlikely to be changed, the dates for onset in many other parts of the country are expected to be revised.
  • Mumbai, for example, expects to start getting rain from June 10 the revision is likely to push this date back by a few days.
  • Effectively, the monsoon is now expected to have later arrival and withdrawal dates in most parts of the country.

Why was this revision needed?

  • The main reason for the revision in the normal dates is the changes in precipitation patterns that have been taking place over the last many years.
  • In the last 13 years, for example, only once has the onset over the Kerala coast happened on June 1.
  • While two or three days of earlier or later onset falls within the yearly variability in several years the onset happened five to seven days late.
  • Similarly, the commencement of withdrawal has happened in the first week of September only twice during this period, and last year, the withdrawal started as late as October 9 — and was completed in around just a week.

Recent peculiarity with the exam

  • One of the significant changes being noticed is that rainfall is getting increasingly concentrated within a narrow band of days within the monsoon season.
  • So, there are extremely wet days followed by prolonged periods of dry days.
  • IMD data show that over several previous years, nearly 95 per cent of monsoon precipitation in 22 major cities of the country had happened over a period of just three to 27 days.
  • Delhi, for example, had received almost 95 per cent of its monsoon rainfall over just 99 hours. And half of Mumbai’s monsoon rain had fallen over just 134 hours, or five and a half days, on average.

Regional variations

  • Patterns of regional variations in rainfall are also changing
  • Areas that have traditionally received plenty of rainfall are often remaining dry, while places that are not expected to get a lot of monsoon rain have sometimes been getting flooded.
  • Climate change could be one of the factors driving these changes, but there could be other reasons as well.

What will be the impact of IMD’s move?

For Farmers

  • The revisions are meant to reflect the changes in precipitation patterns in recent years.
  • New dates will likely nudge farmers in some parts of the country to make slight adjustments in the time of sowing their crops.
  • It would definitely have an impact on our agriculture practices — when to start sowing, when to harvest.
  • So, even if there is a delay in the arrival of monsoon by three to four days over a region, it would not matter much if there is a fairly good rainfall distribution thereafter.
  • The change in dates would affect water management practices as well.

For Industries

  • The planning that goes to beat the heat — several cities execute heat action plans — just ahead of the monsoon would have to factor in the need to be prepared for longer periods of heat.
  • Rajeevan said many other activities including industrial operations, the power sector, or those using cooling systems, would also need to change their behaviour.
  • The power grid can, for example, have more realistic planning for peak periods of electricity consumption in certain months.

Way Forward

  • The changed dates are expected to be announced in April, when the IMD makes its first forecast for the monsoon.
  • Agro-meteorologists, however, agree that more than the onset, it is the information about the spatio-temporal distribution of rainfall that will be more helpful for farmers.
  • Ultimately, the change in normal dates of the onset and withdrawal of the monsoon would help people understand when to expect rains, and to plan their activities accordingly.

By Root

Caretaker @civilsdaily

Monsoon Updates

Cloud Seeding Technology

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Cloud Seeding

Mains level : Artificial rainfall and its success


  • Haryana Dy. CM has written to PM Modi, requesting him to “undertake cloud seeding plan to combat the air pollution engulfing Delhi and NCR”.

What is Cloud Seeding?

  • Cloud seeding is a kind of weather modification technology to create artificial rainfall.
  • It works only when there are enough pre-existing clouds in the atmosphere.
  • Rain happens when moisture in the air reaches levels at which it can no longer be held, and cloud seeding aims to facilitate and accelerate that process by making available chemical ‘nuclei’ around which condensation can take place.
  • These ‘seeds’ of rain can be the iodides of silver or potassium, dry ice (solid carbon dioxide), or liquid propane. The seeds can be delivered by plane or simply by spraying from the ground.

Where all has it been tried earlier?

  • Cloud seeding is not new to India and it has earlier been attempted in Karnataka, Andhra Pradesh and Maharashtra to address drought.
  • Similar experiments of cloud seeding had earlier been tried in Australia, America, Spain and France.
  • In United Arab Emirates, the cloud seeding technique led to creation of 52 storms in Abu Dhabi.
  • Till last year, IMD had around 30 successful incidents of seeding.
  • Also, such seeding is routine in Russia and other cold countries where the technique is used to disperse fog at the airports.

What is the IIT Kanpur study?

  • The scientists at IIT Kanpur had prepared a project to induce artificial rain via cloud seeding to clear smog in Delhi.
  • Officials in the Environment Ministry had approved the project.
  • The project demanded an aircraft of National Remote Sensing Agency — an ISRO-affiliated body — to fly into the clouds.
  • It would inject silver iodide that would lead to the formation of ice crystals, making the clouds denser and causing them to condense into rain and settle atmospheric dust and clearing the sky.
  • It was in 2018 when IIT Kanpur had got all the clearances from DGCA and Defence and Home ministries for the project. But due to non-availability of the aircraft, the project could not take off.

Did state governments adopt this technology?

  • In May 2019, Karnataka Cabinet approved a budget of Rs 91 crore for cloud seeding for a period of two years. It involved two aircraft spraying chemicals on moisture-laden clouds to induce rainfall.
  • It was expected to begin by June end and continue for three months.
  • Hindustan Aeronautics Limited (HAL) had also partnered with IIT Kanpur and agreed to provide Dornier aircraft and their pilots to provide logistical support to the project.

How successful is the cloud seeding technology?

  • The Pune-based IIMT has been carrying out cloud seeding experiments for several years now.
  • These experiments have been done in areas around Nagpur, Solapur, Hyderabad, Ahmedabad, Jodhpur, and recently Varanasi.
  • The success rate of these experiments in inducing rains is about 60 to 70 per cent, depending on local atmospheric conditions, the amount of moisture in the air and cloud characteristics.
  • Apart from IITM, some private companies also offer cloud-seeding services.
  • It is these companies that have been engaged by Maharashtra and Karnataka in the last few years. These also received mixed success.

By Root

Caretaker @civilsdaily

Monsoon Updates

Indian Ocean Dipole (IOD)

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Indian Ocean Dipole (IOD)

Mains level : Role of IOD in Indian Monsoon


Record-breaking rainfall this year

  • The record-breaking rainfall this monsoon season, particularly during August and September, has left weather scientists confounded.
  • After a more than 30% shortfall in June, the season ended with 10% excess rainfall, the first time such a thing has happened since 1931.
  • The September rainfall (152% of long period average, or LPA) was the highest since 1917, the August rainfall was the highest since 1996, and the overall seasonal rainfall was the highest since 1994.

Indian Ocean Dipole (IOD)

  • With an influencer like El Niño Southern Oscillation (ENSO) in the Pacific remaining largely neutral this year, scientists are trying to pin down the exact reason for the unusual rainfall.
  • In the search for answers, one phenomenon attracting some attention is the Indian Ocean Dipole or IOD, an ocean-atmosphere interaction similar to El Niño, but in the Indian Ocean.
  • IOD is a measure of the difference in the sea-surface temperatures of the western Indian Ocean (Arabian Sea) and the eastern Indian Ocean, south of the Indonesian coast.
  • When the western waters are warmer than the eastern, IOD is said to be positive; in the opposite state, IOD is negative.
  • Like ENSO in the equatorial Pacific Ocean, IOD too influences weather and climate events, though its impact is weaker because the Indian Ocean is considerably smaller, and shallower, than the Pacific.
  • The IOD has an impact on the Indian monsoon: a positive IOD is understood to aid monsoon rainfall while negative IOD is known to suppress it.

Strongest ever IOD

  • This year’s IOD, which began developing around June and grew strong after August, has been one of the strongest on record.
  • IOD records are not very old. Accurate measurements are available only since 1960, according to the Australian Bureau of Meteorology (ACB).
  • The current positive Indian Ocean Dipole event has strengthened significantly over the past month.
  • This has led to scientists looking at IOD for possible clues to this year’s bumper rainfall, especially since such strong IOD events in previous years, too, were associated with high monsoon rainfall.

Earlier records

  • In previous years, we have had very strong IOD events in 1997 and 2006. In both those years, the southwest monsoon rainfall over India was around 100% of normal.
  • 1997 also happened to be a strong El Niño year (El Niño suppresses monsoon rainfall) but due to positive IOD the monsoon rainfall was normal that year.
  • This year the positive IOD started strengthening from July, and by September it evolved into the strongest positive IOD ever recorded in the history of Indian summer monsoon.

Tenuous link

  • Beyond the correlation, scientists are careful not to directly blame the IOD for this year’s rains.
  • That is because IOD’s link with the Indian summer monsoon is tenuous at best. It is only one of several factors that impact the monsoon, and not the most dominant.
  • In fact, the IOD’s influence on the monsoon is not fully understood. It is known to have a much weaker influence than ENSO, though.
  • IOD’s relationship with the Indian summer monsoon is also much less studied compared to that of ENSO.
  • Besides, it is not clear if the IOD influences the monsoon or if it is the other way round
  • The IOD generally takes shape towards the latter half of the summer monsoon, in August and September, and scientists do not rule out the possibility that the monsoon could play some role in its emergence.

By Root

Caretaker @civilsdaily

Monsoon Updates

Northeast Monsoon

Note4Students

From UPSC perspective, the following things are important :

Prelims level : NE Monsoon

Mains level : Factors affecting Monsoon


  • The southwest, or summer, monsoon, finally withdrew from the country, having overstayed and delayed its retreat by a record time.
  • The same day, the northeast, or winter, monsoon made its onset, on time.

Northeast Monsoon

  • The northeast monsoon does not have anything to do with the Northeast region of the country, though a part of the system does originate from the area above it.
  • The northeast monsoon derives its name from the direction in which it travels – from the northeast to the southwest.
  • On the other hand, the summer monsoon, at least the Arabian Sea branch of it, moves in exactly the opposite direction – from the southwest to the northeast.
  • That is why it is also called the southwest monsoon.

Role of ITCZ

  • The reversal of direction in the lower-atmosphere moisture-laden winds happens primarily due to the southward movement of Inter Tropical Convergence Zone (ITCZ) during the withdrawal phase.
  • The ITCZ is a dynamic region near the Equator where the trade winds of the northern and southern hemispheres come together.
  • The intense sun and warm waters of the ocean heat up the air in this region and increase its moisture content.
  • As the air rises, it cools, and releases the accumulated moisture, thus bringing rainfall.
  • During the monsoon season, this ITCZ is located over the Indian landmass.
  • By September, as the temperature in the northern hemisphere begins to go down, the ITCZ starts moving southwards, towards the Equator, and further into the southern hemisphere where the summer season begins to take shape.

Mechanism of NE Monsoon

  • The months of October, November and December are supposed to comprise the northeast monsoon season, though the normal date for the onset of this monsoon is only around October 20.
  • The southern peninsular region receives rains in the first half of October as well, but that is attributable to the retreating summer monsoon.
  • The summer monsoon season ends on September 30 but the withdrawal does not happen overnight.
  • From the beginning of the season, as it starts its northward journey over the Indian landmass, the monsoon takes a month and a half to cover the entire country.
  • The southward withdrawal takes place over a period of three to four weeks.
  • It usually starts around the second week of September and continues till about the second week of October, bringing rain as it retreats.

El Niño impact

  • Like the southwest monsoon, the northeast monsoon is also impacted by the warming and cooling of sea surface waters in the central Pacific Ocean. But the impact is the opposite.
  • The northeast monsoon is known to receive a boost from El Niño, when the sea surface temperatures in the equatorial Pacific Ocean, off the western coast of South America, are warmer than usual.
  • And, when the opposite phenomena La Niña happens, rainfall during the northeast monsoon is known to get depressed.
  • This year the El Niño Southern Oscillation, or ENSO, is in neutral state and is likely to remain like that for the rest of the year.

Another winter rains

  • Many other parts of the country, like the Gangetic plains and northern states, also receive some rain in November and December but this is not due to the northeast monsoon.
  • It is caused mainly by the Western Disturbances, an eastward-moving rain-bearing wind system that originates beyond Afghanistan and Iran, picking up moisture from as far as the Mediterranean Sea, even the Atlantic Ocean.

By Root

Caretaker @civilsdaily

Monsoon Updates

National Monsoon Mission

Note4Students

From UPSC perspective, the following things are important :

Prelims level : About the mission

Mains level : Various factors causing uncertainty in monsoon predictions


  • The new monsoon model, called the Coupled Forecast Model (CFS), deployed by the IMD under the National Monsoon Mission (NMM) has failed to forecast the excess rainfall received during Aug-Sept 2019.

National Monsoon Mission (NMM)

  • Ministry of Earth Sciences (MoES) had launched NMM in 2012 with a vision to develop a state-of-the-art dynamical prediction system for monsoon rainfall on different time scales.
  • The responsibility of execution and coordination of this mission is vested to the Indian Institute of Tropical Meteorology (IITM), Pune.
  • Climate Forecast System (CFS) of USA has been identified as the basic modelling system for the above purpose, as it is one of the best among the currently available coupled models.

Objective

To build an ocean atmospheric model for –

  • improved prediction of monsoon rainfall on extended range to seasonal time scale (16 days to one season) and
  • improved prediction of temperature, rainfall and extreme weather events on short to medium range time scale (up to 15 days).

About Coupled Forecast Model (CFS)

  • The American model called “Climate Forecast System” (CFS) is developed by National Centres for Environmental Prediction (NCEP), USA.
  • CFS is a coupled ocean-atmosphere modeling system that combines data from ocean, atmosphere and land for providing long range forecasting (seasonal prediction of Indian Monsoon).

By Root

Caretaker @civilsdaily

Monsoon Updates

[op-ed snap] If the rains fail

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Nothing Much

Mains level : Steps to handle impacts of a weak monsson

CONTEXT

Low retail food inflation, ample stocks of pulses and cereals give government leeway to plan for the exigencies of a poor monsoon.

Monsoon Data

  • The first half of this month has seen the country receive 43 per cent below-normal rainfall, on top of a 25 per cent deficiency in the pre-monsoon season (March-May).
  • Moreover, Gujarat, Maharashtra, northern Karnataka, coastal Andhra Pradesh and large areas in the Northeast have been experiencing an extended dry spell since the last post-monsoon period (October-December).
  • If current conditions persist — the US Climate Prediction Center has forecast an 81 per cent chance of El Nino, the abnormal warming of the equatorial eastern Pacific Ocean waters known to adversely impact rainfall in India, continuing till July and 66 per cent up to August — kharif crop production will take a hit.
  • The agriculture ministry’s data already shows a 9 per cent fall in plantings so far this kharif season compared with last year’s corresponding acreage, with even sharper declines for pulses (51 per cent) and coarse cereals (26 per cent).

Given the delayed onset of monsoon and likely rainfall deficit, farmers should be advised to sow short-duration pulses (moong and urad), soyabean, groundnut, sesame, guar and fodder crops, apart from maize and cotton that need less water than paddy or sugarcane.

More important, however, is to think beyond the immediate.

    • That would mean freeing up agricultural markets by totally abolishing stocking, Movement and export restrictions on produce;
    • Giving farmers the freedom to sell their crop to anybody and anywhere;
    • And replacing all input and output subsidies with per-acre direct benefit transfers.

Conclusion

The farm sector must no longer be viewed as a source of wage-goods for meeting industrialisation or inflation-targeting goals, but a potent instrument for raising rural incomes and reducing poverty.

By Root

Caretaker @civilsdaily

Monsoon Updates

[op-ed snap] Getting drought ready

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Nothing Much

Mains level : Reasons for water scarcity in India

CONTEXT

More than 40% of India faces drought this year—with half of this area set to experience severe to exceptional drought—as per a Business Standard analysis of the IIT Gandhinagar’s Drought Early Warning System.

Precarious Situation

  • The pre-monsoon rains have fallen short of usual by 23%—the worst deficit in six years. As of May 25, nearly 6% of India’s land area was in the exceptionally dry category, seven times the area that was classified as such the same time last year.
  • A little over 16% of the country’s area was in the extremely and exceptionally dry categories, nearly four times that last year. India’s future in the face of the unfolding climate crisis, as a 2013 World Bank study shows, is quite precarious.
  • Since the 1950s, there has been a decline in monsoon rainfall, while the frequency of heavy rainfall events has also increased.
  • Against such a backdrop, it is alarming that 60% of India’s districts are not drought-ready, as per a 2018 paper by researchers at two IITs, Indore and Gandhinagar—only 241 of India’s 634 districts are drought-resilient. Inter- and intra-state water disparity is a powder keg waiting to be lit as access to water dwindles in the coming years.

Factors affecting water security

  • The factors that affect India’s water-security are numerous, thus, there are multiple prescriptions for developing drought readiness.
  • To start with, the country needs to urgently add reservoir capacity—while it receives an annual precipitation of about 4,000 billion cubic metre (bcm), the country makes a heavy discount for evaporation, of 2,131 bcm. Of the remaining 1,869 bcm, the water eventually available for utilisation is 1,123 bcm—the government says “various constraints” don’t allow full usage.
  • Some of the constraints might be topographical or otherwise insurmountable, but surely India could do a lot better here.
  • Just 34% of India’s cultivated area has access to irrigation; this means the rain-fed majority is highly dependent on groundwater.
  • But, there too, vulnerability is increasing because of the rapid depletion of groundwater—even without climate change, 15% of India’s groundwater resources are over-exploited.
  • Part of the problem is the large subsidies given by states to the farm sector for power—which enables indiscriminate groundwater pumping—and fertiliser, the excessive application of which changes the soil’s water requirement.
  • Thankfully, states like Punjab are beginning to wean farmers away from this.
  • But, at the crux of this is farmers sowing crops ill-suited to a region’s soil type and water availability—a water-deficient Maharashtra dedicating two-thirds of its irrigation water to sugarcane, grown on just 4% of the state’s cultivated area, or a Punjab growing most of India’s rice for exports when West Bengal has an economic water productivity for the crop that is 2.5 times higher.

Conclusion

India’s water-stressed future looks much worse if it does nothing resolve these issues.

By Root

Caretaker @civilsdaily

Monsoon Updates

[op-ed snap] Eye on the monsoon

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Monsson

Mains level : Preparedness for monsoon is not upto the mark which will harm india's Interest.

CONTEXT

As India awaits the arrival of the annual summer monsoon, hopes are particularly high for normal rainfall that is so vital for agriculture, the health of forests, rivers and wetlands. The India Meteorological Department has forecast normal rainfall of 96% of the long period average of 89 cm rain, with an onset date in the first week of June in Kerala. It has also signalled a significant possibility of a deficit.

Monsoon’s Importance

The monsoon bounty is crucial for the 60% of gross cropped area in farming that is rain-fed, and represents, in the assessment of the National Commission on Farmers, 45% of agricultural output.

Given the erratic patterns of rainfall witnessed over the past few decades and their possible connection to atmospheric changes caused by a variety of pollutants, the distribution of monsoon 2019 will add to the insights.

The southwest monsoon is a determinant of India’s overall prosperity, and sustained efforts to make the best use of rainfall are absolutely important for farms, cities and industry.

Areas of Concern

Decline in groundwater

Considering that there has been a 52% decline in groundwater levels based on tests conducted last year over the previous decadal average, State governments should have pursued the setting up of new recharging wells and made improvements to existing ones on a war footing.

Delay in building infrastructure

They also have lagged in building structures to harvest surface water and helping farmers raise the efficiency of irrigation.

Ineffective Support

The approach to the farming sector, however, has been influenced more by the imperatives of an election year, and the Centre’s biggest intervention was to announce a cash handout to specified categories of small farmers.

Effects of Industrial Pollution

  • A normal summer monsoon over the subcontinent brings widespread prosperity, but does not guarantee a uniform spread.
  • This, as scientists point out, may be due to the effect of particulates released through various industrial and agricultural processes.
  • Some of these aerosols suppress the rainfall and disperse it across the land, causing long breaks in precipitation, while others absorb heat and lead to a convection phenomenon that increases rainfall in some places.

Work on Industrial Pollution

Such evidence points to the need for India to clean up its act on rising industrial emissions, and burning of fossil fuels and biomass in order to improve the stability of the monsoon.

Freshwater availability

An equally key area of concern is freshwater availability for households, which, NITI Aayog says, account for 4% of available supplies, besides 12% used by industry.

Conclusion

Urbanization trends and the severe water stress that residents experience underscore the need for mandatory rainwater harvesting policies and augmented efforts by States to preserve surface water by building new reservoirs. Yet, governments are adopting a commodity approach to the vital resource, displaying deplorable indifference to the pollution and loss of rivers, wetlands and lakes that hold precious waters. This is no way to treat a life-giving resource.

By Root

Caretaker @civilsdaily

Monsoon Updates

Pacific Decadal Oscillation (PDO)

Note4Students

From UPSC perspective, the following things are important :

Prelims level : PDO

Mains level : Factors affecting Monsoon

Low monsoon rainfall in NE

  • Northeast India, one of the wettest places on the Earth has been experiencing rapid drying, especially in the last 30 years.
  • Some places which used to get as high as 3,000 mm of rain during the monsoon season have seen a drop of about 25-30%.
  • This decreasing monsoon rainfall is associated with natural changes in the subtropical Pacific Ocean.
  • The team used observed rainfall and sea surface temperature data for the period 1901-2014 for the study.
  • The results show out that the reduction in rainfall during a major part of the last 114 years may be associated with global man-made factors, while the trend during the last 36 years is associated with natural phenomena.
  • Only about 7% of the rainfall in this region is associated with local moisture recycling, which means that anthropogenic activities can affect only this small percentage.
  • So the rapid drying is a part of inter-decadal variability of monsoonal rainfall which is strongly associated with the PDO.

Pacific decadal oscillation (PDO)

  • PDO is a long-lived El Niño-like pattern of Pacific climate variability.
  • Both PDO and ENSO have similar spatial climate fingerprints yet the major difference is that PDO persists for 20-30 years while the typical ENSO persists for 6 to 18 months.
  • The PDO, like ENSO, consists of a warm and cool phase which alters upper level atmospheric winds.
  • During a “warm”, or “positive”, phase, the west Pacific becomes cooler and part of the eastern ocean warms; during a “cool” or “negative” phase, the opposite pattern occurs.
  • Shifts in the PDO phase can intensify or diminish the impacts of ENSO according to its phase.
  • If both ENSO and the PDO are in the same phase, it is believed that El Niño/La Nina impacts may be magnified.
  • This in turn affects the northeast Indian summer monsoon during its negative phase.
  • Conversely, if ENSO and the PDO are out of phase, it has been proposed that they may offset one another, preventing “true” ENSO impacts from occurring.

By Root

Caretaker @civilsdaily

Monsoon Updates

Long Period Average: The IMD yardstick for determining rainfall

  • While releasing its monsoon forecast, the IMD expressed the projected rainfall in terms of Long Period Average (LPA), saying that it was expected to be 96% of LPA.

What is LPA of Monsoon

  • The LPA for the season is calculated on the basis of the mean rainfall during the four-month monsoon season over the 50-year period from 1951-2010.
  • It works out to an average of 89 cm for the country as a whole.
  • This is the average rainfall recorded during the months from June to September, calculated during the 50-year period.
  • It is kept as a benchmark while forecasting the quantitative rainfall for the monsoon season every year.
  • When IMD forecasts the category of rainfall, be it for country, region or month, the forecast is based on these standardised figures calculated for a period of 50 years.
  • As per the outputs obtained from the weather models, the rainfall is categorised as normal, below normal, or above normal.

Five Rainfall Distribution categories

  1. Normal or Near Normal: When per cent departure of actual rainfall is +/-10% of LPA, that is, between 96-104% of LPA
  2. Below normal: When departure of actual rainfall is less than 10% of LPA, that is 90-96% of LPA
  3. Above normal: When actual rainfall is 104-110% of LPA
  4. Deficient: When departure of actual rainfall is less than 90% of LPA
  5. Excess: When departure of actual rainfall is more than 110% of LPA

Region-wise LPA

  • 83 cm for East and Northeast India,
  • 55 cm for Central India,
  • 61 cm for South Peninsular India, and
  • 50 for Northwest India, which put together, bring the all-India figure to 88.75 cm.

By Root

Caretaker @civilsdaily

Monsoon Updates

[op-ed snap]The heat is on

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Nothing Much

Mains level : Preparations to deal with a weak Monsoon

CONTEXT

A forecast of a below average monsoon in 2019, after last year’s erratic rainfall that flooded Kerala and crippled agriculture in eastern and western States, is a cause for worry.

Forecast and predictions regarding Monsoon

  • If the assessment from one agency, Skymet, is any indication, there is a prospect of an El Niño, often associated with drought conditions, taking hold.
  • If the assessment from one agency, Skymet, is any indication, there is a prospect of an El Niño, often associated with drought conditions, taking hold.
  • Should the monsoon, which normally sets in between June 1 and July 15 across the country, turn out to be deficient, it will add to the pressures on rural employment and the economy as a whole.
  • Things may become clearer when the India Meteorological Department also issues its forecast, although error margins and the erratic nature of rainfall in different regions render the exercise fraught with uncertainty.
  • Last year, for instance, the realisation of rainfall was 91% of the long-term average, while the prediction was for 97%.

Preparations to handle an extreme situation

  • It is the responsibility of State administrations to prepare for the likelihood of a heat spike, particularly during April and May, to prevent loss of life and extreme distress to communities.
  • Official agencies and NGOs should start adopting the drill on this, using the template drawn up by the National Disaster Management Authority.

Steps to be taken

  • Small Precautions-The key elements of protection in a heat wave are avoiding exposure during the hottest part of the day around noon, especially in the case of senior citizens, staying adequately hydrated, wearing suitable clothing including headgear, and creating shade in public places.
  • Information technology-These messages and weather alerts can be disseminated through television, mobile phone messaging and social media platforms.
  • Local Bodies-Urban local bodies in particular have a responsibility to care for the large number of vulnerable city dwellers.

Challenges

  • During the current year, there is apprehension that the focus of administrators will mainly be on the conduct of the elections, relegating the public health risk of heat waves to the backburner.
  • With the availability of advance weather alerts, there is no reason why local bodies cannot institute remedial measures.
  • Mitigating the effect of heat waves is vital to ensuring a high turnout in the elections by making it safe for voters.

Conclusion

  • India is looking at another uncertain monsoon, bringing into sharp relief the neglected potential of decentralised water-harvesting.
  • It is more than a decade since the National Commission on Farmers suggested the wider adoption of both rainwater harvesting and aquifer recharge, in order to provide irrigation for small farmers.
  • It is time to take measures that will help communities achieve resilience.

By Root

Caretaker @civilsdaily

Monsoon Updates

Explained: How rocks in Meghalaya cave connect Northeast monsoon to El Niño

Note4students

Mains Paper 1: Geography | Salient features of World’s Physical Geography

From UPSC perspective, the following things are important:

Prelims level: El Nino, Karst Topography

Mains level: Impact of El-Nino


News

A new study led by researchers from a US university, on the rock formations in a cave near Cherrapunji in Meghalaya, has found new evidence to suggest that India’s winter rainfall are influenced by the state of the ocean waters in the faraway Pacific.

El Niño & monsoons

  • India’s summer monsoon which brings in about 70% of annual rainfall in the country, is already known to be heavily influenced by the variability in sea-surface temperatures of Pacific Ocean.
  • This is a condition referred to as El Niño Southern Oscillation (ENSO).
  • A warmer than usual Pacific Ocean, off the coast of South America, is known to suppress the monsoon rainfall in India.

Connection with retreating Monsoon

  • This relationship is not so strongly established with the winter monsoon, also called as the northeastern monsoon, which occurs during the months of October, November and December.
  • It is vital for several regions in the Northeast and India’s eastern coast.
  • More than 50% of the annual rains in coastal Andhra Pradesh, Rayalaseema, Tamil Nadu, south interior Karnataka, and Kerala comes during these winter months.
  • ENSO is known to have an impact on the winter monsoon as well but is weaker and opposite.
  • The warming of sea-surface waters, for example, is seen to help winter rainfall rather than suppressing it.
  • The impact varies in time and space. The influence is weaker in October and stronger in November and December.

Deducing monsoon variations from stalagmites

  • The latest study claims to have found new evidence to suggest that the state of Pacific Ocean do indeed impact the winter rains.
  • Their findings are based on more than three years of research on stalagmites (mineral deposits, mainly limestone, in caves) of the Mawmluh Cave, near Cherrapunji, in the East Khasi Hills district.
  • These solid stalagmite structures, or mineral deposits, are the result of slow but steady water dripping in the caves, and contain several thin layers of different kinds of minerals that get picked up while the water is flowing.
  • From a careful study of the composition of these stalagmites, scientists can deduce the amount of rainfall that could have happened over the caves in the past, or even whether the water was a result of local rainfall, or had flown in from a different place.
  • Using such techniques, the researchers in this case were able to estimate local variations in rainfall in the past, and then correlate it with old ocean records of the Pacific Ocean.

Stalagmites revives drought history

  • The stalagmites indicate the recurrence of intense, multi-year droughts in India over the last several thousand years.
  • Stalagmite records from monsoon regions, including India, are vital to understanding past variability in the global climate system and the underlying reasons for this variability.

Back2Basics

Karst Topography

  • Karst is a landscape which is underlain by limestone which has been eroded by dissolution, producing towers, fissures, sinkholes, etc.
  • Karst topography is a landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum.
  • It is characterized by underground drainage systems with sinkholes, caves etc.

Stalactite and Stalagmite

  • The water containing limestone in solution, seeps through the roof in the form of a continuous chain of drops.
  • A portion of the roof hangs on the roof and on evaporation of water, a small deposit of limestone is left behind contributing to the formation of a stalactite, growing downwards from the roof.
  • The remaining portion of the drop falls to the floor. This also evaporates, leaving behind a small deposit of limestone aiding the formation of a stalagmite, thicker and flatter, rising upwards from the floor.
  • Sometimes, stalactite and stalagmite join together to form a complete pillar known as the column.

By Root

Caretaker @civilsdaily

How does El Nino affect Indian Monsoon? A Comprehensive Explainer

As many reports speculated that El Nino is the main cause of the worsening Indian Monsoon and has played badly with Indian agriculture, we thought that we should take a big picture of El Nino and it’s scope in India.


 

  • The Monsoon is basically a result of the flow of moisture laden winds because of the variation of temperature across the Indian Ocean.
  • There are a number of climatic phenomena which affect it namely the El nino, La nina etc.
  • We will look at their origin, impact and way forward.

Now, let’s take a overview and develop our understanding. 

What happens in a Normal Year?

  • Peru Current = Humboldt Current = Cold Current.
  • During normal year 2 things are very strong – Cold Peru Current and Trade Winds.
  • As a result, cold water is dragged from Peru towards Australia.

What would be the result of this exchange?

  • Warm water region around Australia is called Western Pacific Pool (WPP).
  • WPP = low pressure = warm air ascends = cloud formation = rain over North Australia
  • This air also joins walker cell and begins descending near Peru.
  • Descending air = anti-cyclonic condition = high pressure = stability = no cloud/rain = Drought in Atacama Desert.

(Simply, Walker cell is the result of a difference in surface pressure and temperature over the western and eastern tropical Pacific Ocean)

What happens below the water from Peru to Australia ?

At Peru coast, cold water upwelling brings nutrient to surface + more lunch for Plankton + more fishes = Peru fishermen gets happy.

What happens above the water from Australia towards Peru?

Warm water + low atmospheric pressure = good rainfall over Australia & Indonesia.

What happens in La Nina Year?

Same things as in a “normal” year, but 2 things become even “stronger” –

  • Cold Peru Current
  • Trade Winds

What’s the Result?

  • Too many fishes at Peru coast = oversupply of fishes = prices become dirt cheap.
  • Too much rain / flood over Australia and Indonesia.

This is what happens in normal and La Nino year, Let’s back to El Nino!


 


 

What happens in an El Nino year?

Two things become weak.

  • Cold Peru Current
  • Trade Winds
  • As result, cold water is not dragged from Peru to Australia.
  • But reverse happens, warm water is dragged from Australia towards Peru.
  • Consequently, warm water + low pressure condition develops in the Eastern Pacific (Peru) and Cold condition + high pressure in Western Pacific (Australia).

What will happen if pressure is inversely related with amount of rainfall ?

  • Rain & Floods at Peru, Atacama and even Southern USA
  • Drought at Northern Australia, Indonesia- even bushfires.
  • Storms and Hurricanes in East Pacific.
  • Coral bleaching (high temperature coral dies)

But, what is the El Nino?

  • El Nino is an Oceanic and Atmospheric phenomenon that leads to unusual warming of water in the Peru coast, occurs every 3-5 years.
  • Consequently, warm water + low pressure condition develops in the Eastern Pacific (Peru) and Cold condition + high pressure in Western Pacific (Australia).
  • Since Pressure is inversely related with amount of rainfall, El Nino causes drought situation in Australia and South East Asia.
  • It weakens the trade winds and changes in Southern Oscillation, thereby affects the rainfall pattern across the world.

el-nino-phenomenon


What is Southern Oscillation?

  • Alternating of (tropical) sea level pressure between the eastern and western hemispheres.
  • We can measure Southern Oscillation by observing the pressure difference between Tahiti (French Polynesia) and Darwin (Australia).

How does El Nino affect Indian Monsoon?

  • El Nino-Southern Oscillation (ENSO) water circulation happens between Australia and Peru.
  • But, the wind movement is part of larger atmospheric circulation hence affects the rainfall over India. But, how?
  • We have learned that During normal year, the warm water moves towards Australia, this pool of warm water is called Western Pacific Pool (WPP).

So, from WPP air rises above and moves towards two walker cells –

  • Towards Peru coast = this affects rainfall in South America.
  • Towards Mascarene High Pressure zone near East Africa. So, this affect Indian monsoon.

Why should India worry about?

  • Drought condition decreases the agriculture output, leads to food inflation.
  • Declined supply of cotton, oilseeds and sugarcane negatively affects the textile, edible oil and food processing industries respectively.

What is the way forward?

Let’s discuss first Near-term Solutions?

  • Government must expand farm insurance cover and advice financial institutions to settle crop insurance claims in the drought-hit areas without delay. Otherwise, it results in farmer suicides (e.g. Maharashtra farmers’ suicide ).
  • High quality seeds of alternative crops must be distributed among farmers in drought-affected areas.
  • Need of realistic assessment of ground level situation in order to estimate the shortfall of oilseeds and pulses and help traders with market intelligence.
  • Scrapping the APMC Act and allowing free flow of agricultural goods among the states.
  • This would help bridge the mismatch of demand and supply of goods, which is the underlying factor contributing inflation.

What should be the Long-term Solutions?

  • Developing drought free crop varieties and distributing its subsidized seeds to the farmers. It is a part of National Action plan on climate change in Agriculture.
  • Using low water use technologies like drip and sprinkler irrigation.
  • The MSP regime in India has to provide more remuneration for less water consuming crops.
  • Strengthening community watershed management and development by protecting and conserving local water sources like ponds, lakes etc.
  • Developing early warning systems and alerting the farmers much in advance like recently launched Kisan SMS scheme.

Do you find more solutions or any way out? then, Let us know!


 

Published with inputs from Arun

By Root

Caretaker @civilsdaily

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