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GS Paper: GS1-15.Geographical features and their location- Changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.

  • Super Cyclone Amphan and its threats

    The storm system in the Bay of Bengal, Amphan, developed into a super cyclone and is expected to make landfall along the West Bengal-Bangladesh coast very soon.

    Realted PYQ:

    Q. In the South Atlantic and South Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason? (CSP 2015)

    (a) Sea Surface temperature are low
    (b) Inter Tropical Convergence Zone seldom occurs
    (c) Coriolis force is too weak
    (d) Absence of land in those regions

    Super Cyclone Amphan

    • Cyclone Amphan is a tropical cyclone formed over the Bay of Bengal that has intensified and likely to turn into a “super cyclonic storm (maximum wind speed is 224 kmph)”.
    • It has been named by Thailand.
    • Amphan is the equivalent of a Category 5 hurricane on the Saffir-Simpson Hurricane Wind Scale.
    • By the time it makes landfall in West Bengal, Amphan is expected to tone down into a category 4 Extremely Severe Cyclonic (ESC) storm with a wind speed of 165-175 kmph and gusting to 195 kmph.

    What makes it a nightmare?

    • This is the first super cyclone to form in the Bay of Bengal after the 1999 super cyclone that hit Odisha and claimed more than 10,000 lives.
    • It is the third super cyclone to occur in the North Indian Ocean region after 1999 which comprises of the Bay of Bengal, the Arabian Sea and the northern part of the Indian Ocean.
    • The other two super cyclones were Cyclone Kyarr in 2019 and Cyclone Gonu in 2007.

    Recent cyclones in the region

    • From 1965 to 2017, the Bay of Bengal and the Arabian Sea collectively registered 46 ‘severe cyclonic storms’.
    • More than half of them occurred between October and December.
    • Seven of them occurred in May and only two (in 1966 and 1976) were recorded in April, according to data from the IMDs cyclone statistics unit.
    • Cyclone Phailin in 2013 and the super cyclone of 1999 — both of which hit coastal Odisha — have been the most powerful cyclones in the Bay of Bengal in the past two decades in terms of wind speed.
    • Last year, Fani, which was an ESC made landfall in Odisha and ravaged the State, claiming at least 40 lives.

    Back2Basics: Tropical Cyclones

    • Cyclones are formed over slightly warm ocean waters.
    • The temperature of the top layer of the sea, up to a depth of about 60 metres, need to be at least 28°C to support the formation of a cyclone.
    • This explains why the April-May and October-December periods are conducive for cyclones.
    • Then, the low level of air above the waters needs to have an ‘anticlockwise’ rotation (in the northern hemisphere; clockwise in the southern hemisphere).
    • During these periods, there is an ITCZ in the Bay of Bengal whose southern boundary experiences winds from west to east, while the northern boundary has winds flowing east to west.
    • This induces the anticlockwise rotation of the air.
    • Once formed, cyclones in this area usually move northwest. As it travels over the sea, the cyclone gathers more moist air from the warm sea and adds to its heft.

    What strengthens them?

    • A thumb rule for cyclones is that the more time they spend over the seas, the stronger they become.
    • Hurricanes around the US, which originate in the vast open Pacific Ocean, are usually much stronger than the tropical cyclones in the Bay of Bengal, a relatively narrow and enclosed region.
    • The cyclones originating here, after hitting the landmass, decay rapidly due to friction and absence of moisture.

    Grading of Cyclones

    • Tropical cyclones in the Bay of Bengal are graded according to maximum wind speeds at their centre.
    • At the lower end are depressions that generate wind speeds of 30 to 60 km per hour, followed by:
    1. cyclonic storms (61 to 88 kmph)
    2. severe cyclonic storms (89 to 117 kmph)
    3. very severe cyclonic storms (118 to 166 kmph)
    4. extremely severe cyclonic storms (167 to 221 kmph) and
    5. super cyclones (222 kmph or higher)

  • Bay of Bengal Boundary Layer Experiment (BoBBLE)

    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/

  • [pib] River erosion in Ladakh Himalayas

    Indian researchers have studied rivers in Ladakh Himalaya, bringing out 35 thousand-year histories of river erosion and identified hotspots of erosion and wide valleys that act buffer zones.

    Click here to read more about the Himalayan river systems and its orogeny

    Erosion hotspot: Ladakh region

    • The Ladakh Himalaya forms a high altitude desert between Greater Himalayan ranges and Karakoram Ranges.
    • The Indus and its tributaries are major rivers flowing through the terrain.
    • The Zanskar River is one of the largest tributaries of the upper Indus catchment, draining orthogonally through highly deformed Zanskar ranges.

    Zanskar: A major river in Ladakh

    • Two prominent tributaries of Zanskar River are the Doda and Tsrap Lingti Chu, which confluence at Padam village in the upper valley to form the Zanskar River.
    • Zanskar catchment was explored to understand the landform evolution in the transitional climatic zone, using morpho-stratigraphy and study of landforms like valley fill terraces, alluvial fans (triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt).

    Zanskar Padam

    • Zanskar river makes a deep gorge in its lower reaches with the headwaters in upper Zanskar makes wide basin called as Padam.
    • The basin stores large amount of sediments in form of fans and river terrace deposits
    • The research suggested that the wide valley of Padam, with an area of 48 square km, in the upper Zanskar, has stored a vast amount of sediments in these landforms.
    • Thus Padam valley is a hotspot of sediment buffering in the Zanskar.

    Sediment study reveals the erosion

    • The study suggested that most sediments were derived from Higher Himalayan crystalline that lies in the headwater region of Zanskar.
    • It was found out that dominant factors responsible for sediment erosion were deglaciation and Indian Summer Monsoon derived precipitation in the headwaters despite the presence of a geomorphic barrier (the deep, narrow gorge).

    Significance of the study

    • The scientists have traced where the rivers draining Himalaya and its foreland erode the most and identify the zones that receive these eroded sediments and fill up.
    • The study will help understand river-borne erosion and sedimentation, which are the main drivers that make large riverine plains, terraces, and deltas that eventually become the cradle to evolving civilizations.
    • It will also help study the dynamics of devastating floods created by these Himalayan rivers in recent times.
    • Thus, the understanding of water and sediment routing becomes crucial while developing infrastructure and for other development works in the river catchment area.

  • New list of names of tropical cyclones over north Indian Ocean

    The India Meteorological Department (IMD) has released a new list containing 169 names of future tropical cyclones that would emerge in the Bay of Bengal and the Arabian Sea.

    When is the name of a Tropical Cyclone declared?

    • Names are declared when TCs are diagnosed with maximum sustained surface wind-speed of 34 knots (62 kmph) or more as per Global Data Processing and Forecasting System (GDPFS) Manual of WMO.
    • Panel Members’ names will be listed alphabetically country-wise.

    We can expect a statement based prelim question like – Which of the following criterion are followed while naming a tropical cyclone?

    Who is involved in the naming of Tropic Cyclone?

    • Worldwide there are six regional specialised meteorological centres (RSMCs) and five regional Tropical Cyclone Warning Centres (TCWCs) mandated for issuing advisories and naming of tropical cyclones.
    • IMD is one of the six RSMCs to provide tropical cyclone and storm surge advisories to 13 member countries under WMO/ESCAP Panel.
    • The panel countries include Bangladesh, India, Iran, Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, United Arab Emirates and Yemen.
    • RSMC, New Delhi is also mandated to name the Tropical Cyclones developing over the North Indian Ocean (NIO) including the Bay of Bengal and the Arabian Sea.

    Since when did naming begin?

    • The WMO/ESCAP Panel on Tropical Cyclones (PTC) at its twenty-seventh Session held in 2000 in Muscat, agreed in principle to assign names to the tropical cyclones in the Bay of Bengal and the Arabian Sea.
    • After long deliberations among the member countries, the naming of the tropical cyclones over the north Indian Ocean commenced from September 2004.
    • This list contained names proposed by the eight member countries of WMO/ESCAP PTC, viz., Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand.

    Why name Cyclones?

    The naming of Tropical Cyclones (TC) helps the scientific community, disaster managers, media and general masses to-

    • identify each individual cyclone.
    • create awareness of its development.
    • remove confusion in case of simultaneous occurrence of TCs over a region
    • remember a TC easily
    • rapidly and effectively disseminate warnings to a much wider audience

    Major criteria adopted for naming

    • The proposed name should be neutral to (a) politics and political figures (b) religious believes, (c) cultures and (d) gender
    • The name should be chosen in such a way that it does not hurt the sentiments of any group of the population over the globe
    • It should not be very rude and cruel in nature
    • The maximum length of the name will be eight letters
    • The Panel reserves the right to reject any name if any of the criteria above are not satisfied
    • The names of tropical cyclones over the north Indian Ocean will not be repeated. Once used, it will cease to be used again.

    Back2Basics

    https://www.civilsdaily.com/news/explained-naming-of-cyclones/

  • Daporijo Bridge and its significance

    A key bridge over the Subansiri River in Arunachal Pradesh close to the Line of Actual Control (LAC) was constructed by the Border Roads Organisation (BRO) in record 27 days.

    North-East has seen the construction of a series of bridges by BRO in recent times post-Doklam standoff. Make a note of all such bridges and the corresponding rivers over which they are built.

     Daporijo Bridge

    • This Bridge is one of the two over River Subansiri which connect Daporji in North Subansiri dist. with rest of state.
    • This and the other bridge at Tamin sustaining more than 600 villages and troops strength of around 3000 personnel manning the LAC which includes disputed Areas of Asaphila and Maza.
    • All supplies, rations, constructional material and medicines pass over this bridge.
    • The new bridge now can withstand 40 tonnes of weight allowing a safe passage for heavier vehicles catering for the requirements of the Indian Army as well as future infrastructure development requirements.

    Significance

    • India has speeded up the construction of critical infrastructure in its northeast in the past half a dozen years including airports, railways and roads with an eye on China that has motorable roads right up to the border.
    • Arunachal Pradesh was the scene of the 1962 India-China border conflict that ended badly for India. China on its parts claims all of the state as “Southern Tibet.”
    • Of the 3488 km long Line of Actual Control with China 1126 lies with Arunachal Pradesh alone.
    • The two countries are yet to demarcate their border with the two sides patrolling the LAC but reporting incursions by the other side since the frontier is not clearly marked.

  • Matterhorn Mountain of the Swiss Alps

    Switzerland has expressed solidarity with India in its fight against the coronavirus pandemic by projecting the tricolour on the famous Matterhorn Mountain in the Swiss Alps.

    It has been long time since a question on global mountains/mountain ranges has not been asked in the prelims. Gear up for the uncertainty. Make a special sheet of geographical locations in news.

    Mt. Matterhorn

    • The Matterhorn is a mountain of the Alps, separating the main watershed and border between Switzerland and Italy.
    • It is a large, near-symmetric pyramidal peak in the extended Monte Rosa area of the Pennine Alps, whose summit is 4,478 metres.
    • It is one of the highest summits in the Alps and Europe (Mont Blanc being highest).
    • The four steep faces, rising above the surrounding glaciers, face the four compass points and are split by the Hörnli, Furggen, Leone/Lion, and Zmutt ridges.

    Its formation

    • The Matterhorn is mainly composed of gneisses originally fragments of the African Plate before the Alpine orogeny.
    • The mountain’s current shape is the result of cirque erosion due to multiple glaciers diverging from the peak, such as the Matterhorn Glacier at the base of the north face.

    Back2Basics: Alps mountain range

    • The Alps are the highest and most extensive mountain range system that lies entirely in Europe.
    • It stretches approximately 1,200 kilometres across eight Alpine countries (from west to east): France, Switzerland, Monaco, Italy, Liechtenstein, Austria, Germany, and Slovenia.
    • The mountains were formed over tens of millions of years as the African and Eurasian tectonic plates collided.
    • Extreme shortening caused by the event resulted in marine sedimentary rocks rising by thrusting and folding into high mountain peaks such as Mont Blanc and the Matterhorn.
    • Mont Blanc spans the French–Italian border, and at 4,809 m (15,778 ft) is the highest mountain in the Alps.

  • Earth’s seismic noise levels

    Scientists at the British Geological Survey (BGS) reported a change in the Earth’s seismic noise and vibrations amid the coronavirus lockdown. This change has been monitored through a space-based seismograph.

    Ever heard of space-based monitoring of seismic activities?  This topic creates a scope for potential prelims question…

    What is seismic noise?

    • In geology, seismic noise refers to the relatively persistent vibration of the ground due to a multitude of causes.
    • It is the unwanted component of signals recorded by a seismometer– the scientific instrument that records ground motions, such as those caused by earthquakes, volcanic eruptions, and explosions.
    • This noise includes vibrations caused due to human activity, such as transport and manufacturing, and makes it difficult for scientists to study seismic data that is more valuable.
    • Apart from geology, seismic noise is also studied in other fields such as oil exploration, hydrology, and earthquake engineering.

    How are vibrations generated?

    • We measure ground vibrations from earthquakes using seismometers.
    • These are incredibly sensitive so they also pick up other sources of vibration too, including human activity, such as road traffic, machinery and even people walking past.
    • All these things generate vibrations that propagate as seismic waves through the Earth.

    Reasons for the decline

    • Due to the enforcement of lockdown measures around the world to tackle the novel coronavirus pandemic, the Earth’s crust has shown reduced levels of vibration.

    How do the reduced noise levels help scientists?

    • The seismic noise vibrations caused by human activity are of high frequency (between 1-100 Hz), and travel through the Earth’s surface layers.
    • Usually, to measure seismic activity accurately and reduce the effect of seismic noise, geologists place their detectors 100 metres below the Earth’s surface.
    • However, since the lockdown, researchers were able to study natural vibrations even from surface readings, owing to lesser seismic noise.
    • Due to lower noise levels, scientists are now hoping that they would be able to detect smaller earthquakes and tremors that had slipped past their instruments so far.

     

  • [pib] Ionospheric based monitoring of large earthquakes

    Scientists of Indian Institute of Geomagnetism (IIG) an autonomous institution of the DST have extensively studied the signatures of recent large earthquakes into the ionosphere with an ambitious aim to derive the seismic source characteristics from the ionosphere.

    CLAIMS

    • The research is a part of the interdisciplinary program ‘Coupled Lithosphere-Atmosphere- Ionosphere-Magnetosphere System (CLAIMS)’ of IIG.
    • CLAIMS focuses on energy transfer to the atmosphere during solid Earth processes such as earthquakes as well as tsunamis.

    Key terms: Co-seismic Ionospheric Perturbations (CIP)

    • In general, the Earth crust uplift during an earthquake produces compressional (i.e. pressure) waves in the overlying atmosphere.
    • These waves propagate upward in the region of exponentially decreasing atmospheric neutral density, and thus, wave amplitude increase with atmospheric heights.
    • On arrival at ionospheric heights, the waves redistribute ionospheric electron density and produce electron density perturbations (disruption) known as CIP.

    Objective of CLAIMS

    • The spatial distribution of near field co-seismic Ionospheric perturbations (CIP) associated with this event could reflect well the ground deformation pattern evolved around the epicentre.
    • These CIPs were derived using the Global Positioning System (GPS) measured Total Electron Content (TEC).
    • The CIP distribution was estimated at Ionospheric piercing point (IPP) altitude.

    Other factors affecting CIP

    The major effective non-tectonic forcing mechanisms at ionospheric altitudes are the-

    1. orientation between the ambient geomagnetic field and seismic induced neutral wave perturbations.
    2. orientation between the moving satellite line of sights and the wave perturbations.
    3. ambient ionospheric electron density gradient.

    Back2Basics

    Ionosphere

    • The ionosphere is the ionized part of Earth’s upper atmosphere, from about 60 km to 1,000 km altitude.
    • It is a region that includes the thermosphere and parts of the mesosphere and exosphere.
    • It is ionized by solar radiation.

  • Pink Supermoon/ Paschal Moon

    A supermoon is all scheduled to show up in the sky on April 7. It would be the biggest and brightest full moon of 2020.

    Pink Supermoon

    • According to NASA, a supermoon takes place when a full moon is at its closest to the Earth.
    • When the full moon appears at perigee (closest point from the earth) it is slightly brighter and larger than a regular full moon — and that is what we call a “supermoon.”
    • They are called Supermoons because they are 7 per cent bigger and 15 per cent brighter, compared to an average full Moon.
    • The moon will not be originally pink in colour. It got its name from the pink wildflowers – Wild Ground Phlox – that bloom in the spring and are native to North America.
    • It is also called Paschal moon because, in the Christian calendar, this is used to calculate the date for Easter – the first Sunday after the Paschal Moon is Easter Sunday.

  • Earth’s spin has slowed over time

     

    Earth spun 372 times a year 70 million years ago, compared to the current 365. This means the day was 23½ hours long, compared to 24 today.

    Faster Earth in the olden days

    • It has long been known that Earth’s spin has slowed over time.
    • Previous climate reconstructions, however, have described long-term changes over tens of thousands of years.
    • The new study looked at daily and annual variations in the mollusc shell.

    About the Mollusc

    • A mollusc is an invertebrate of a large phylum which includes snails, slugs, mussels, and octopuses. They have a soft unsegmented body and live in aquatic or damp habitats, and most kinds have an external calcareous shell.
    • The ancient mollusc, Torreites Sanchez, belonged to an extinct group called rudist clams.
    • At 70 million years ago, it belonged to the Late Cretaceous — it was around the time this epoch ended, some 65 million years ago, that dinosaurs went extinct.

    How did researchers conclude this variation?

    • Torreites sanchezi grew very fast, laying down daily growth rings.
    • Using lasers on a single individual, scientists sampled tiny slices and counted the growth rings accurately.
    • This allowed them to determine the number of days in a year 70 million years ago, and more accurately calculate the length of a day.

    Significance of the research

    • It is important to note that the period of Earth’s orbit has remained the same. In other words, one year 70 million years ago was as long as one year today.
    • However, if there were a calendar then, the year would have been 372 “days” long, with each “day” half-an-hour shorter than one day today.
    • Today, Earth’s orbit is not exactly 365 days, but 365 days and a fraction, which is why our calendars have leap years, as a correction.

    The Moon’s retreat

    • Friction from ocean tides, caused by the Moon’s gravity, slows Earth’s rotation and leads to longer days.
    • And as Earth’s spin slows the Moon moves farther away at 3.82 cm per year.
    • If this rate is projected back in time, however, the Moon would be inside the Earth only 1.4 billion years ago.
    • This new measurement, in turn, informs models of how the Moon formed and how closes it has been to Earth over their 4.5-billion-year gravitational relationship.