(Current Affairs) Science & Technology, Defence, Environment | November : 2017

::Science & Technology, Defense, Environment::

Tracking urban heat island effect

  • Between February and May, most of the 89 Indian cities that are to be developed as Smart Cities have been found to be 1-5 degrees C cooler during the day relative to the surrounding non-urban areas. More than 60% of the total 89 urban areas are 1-5 degrees C cooler during April (it’s 70% in May).
  • This observation is in variance with the globally witnessed phenomenon of urban areas getting significantly warmer during the day compared with the surrounding areas as a result of urban heat island effect.
  • In contrast, during the post-monsoon period (October to January), about 80% of the urban areas show typical urban heat island effect and are 1-6 degrees C warmer than the surrounding non-urban areas.
  • During the night, all the cities studied are warmer (1-5 degrees C) than the surrounding non-urban areas due to urban heat island effect regardless of the season and location.
  • Compared with other cities, urban areas in semi-arid and arid regions of western India show higher warming in the night.
  • The night time warming is driven mainly by heat stored in buildings and impervious concrete areas.
  • These cities (Kurnool, Vijayawada, Badami, Bijapur, Aurangabad and cities in Gujarat and Rajasthan) are typically located in western and central parts of India.
  • However, cities (Varanasi, Lucknow, Allahabad, Kanpur, and Patna) in the Gangetic Plain, north-western India (Punjab and Haryana) and southern tip of the west coast show typical urban heat island effect during the day; these cities are 3-5 degrees C warmer than the surrounding non-urban areas during the pre-monsoon (February-May) and post-monsoon (October-January) periods.
  • The non-urban areas in these areas have vegetation in the form of trees or agriculture and have moisture due to irrigation.
  • There are two reasons why urban areas in western and central parts of India become cooler than non-urban areas during summer. The non-urban areas have no crop and moisture, the soil is dry and day-time air temperature is above 40 degrees C.
  • On the other hand, the urban areas have vegetation cover and water bodies. This is why cities are cooler than the surrounding non-urban areas during the day.
  • More than 70 of the 89 cities studied are surrounded by non-urban areas which have more than 50% of total land cover under agriculture between November and March.
  • This results in non-urban areas being cooler than the cities during the post-monsoon season. The results were published in the journal Scientific Reports .
  • Aerosols too have an effect in reducing the temperature but their role in cooling during day time is less compared with vegetation and irrigation.
  • During heat-waves, the prominent night urban heat island effect which is prevalent across cities could worsen the levels of discomfort.
  • The researchers used satellite data (2000-2014) and community land model to identify the impact of irrigation and show the cooling seen in cities is due to lack of vegetation and moisture in non-urban areas relative to cities.

6000 year old skull likely to the world’s oldest known tsunami victim

  • A 6,000-year-old skull found in Papua New Guinea is likely the world’s oldest-known tsunami victim, experts said after a new analysis of the area it was found in.
  • The partially preserved Aitape Skull was discovered in 1929 by Australian geologist Paul Hossfeld, 12 km inland from the northern coast of the Pacific nation.
  • It was long thought to belong to Homo erectus (upright man), an extinct species thought to be an ancestor of the modern human that died out some 1,40,000 years ago.
  • But more recent radiocarbon dating estimated it was closer to 6,000 years old, making it a member of our own species — Homo sapiens . At that time, sea levels were higher and the area would have been near the coast.
  • An international team led by the University of New South Wales returned to the site to collect the same geological deposits observed by Hossfeld.
    Back in the lab, they studied details of the sediment including its grain size and geochemical composition, which can help identify a tsunami inundation.
  • They also identified a range of microscopic organisms from the ocean in the sediment, similar to those found in soil after a devastating tsunami hit the region in 1998.
  • The conclusions, aided by researchers from the United States, France, New Zealand and Papua New Guinea, are published in the journal PLOS ONE .
  • Mr. Goff, a world authority on tsunamis, said while the bones of the skull had been well-studied previously, little attention had been paid to the sediments where they were unearthed.
  • “The geological similarities between these sediments and the sediments laid down during the 1998 tsunami made us realise that human populations in this area have been affected by these massive inundations for thousands of years,” he said.
  • “After considering a range of possible scenarios, we believe that, on the balance of the evidence, the individual was either killed directly in the tsunami, or was buried just before it hit and the remains were redeposited.”
  • Following the 1998 tsunami, which penetrated up to five kilometres inland, attempts to retrieve victims were called off after a week because crocodiles were feeding on the corpses, leading to their dismemberment.
  • This may also explain why the skull of the person who died 6,000 years ago was found on its own, without any other bones, the researchers said.

From 2019, the kilogram will become more accurate

  • For 125 years, a salt-shaker-sized cylinder housed at the Bureau International des Poids et Mesures (BIPM), Paris and weighing exactly a kilogram served as the definition of the measure.
  • India’s National Physical Laboratory (NPL) too has a replica of this, since 1957, and it has served as the reference for a variety of industries to keep their weights accurate
  • However, an international conference of heads of metrology institutes decided,inSevres, France, that the kilogram will no longer be pegged to this cylinder made of 90% platinum and 10% iridium.
  • In the last 60 years, several standard units — the second, metre, ampere, Kelvin, mole, candela and, the kilogram — have all ceased to be defined by physical objects.
  • One metre, for instance, was a platinum-iridium bar of that measure. In 1960, the metre was defined as the distance travelled by light in vacuum in 1/299,792,458 seconds.
  • In essence, the units were freed from being defined on the basis of artefacts, as these being objects, were subject to wear and tear and sources of eventual error. The new artefacts, according to the International Committee for Weights and Measures, ought to derive from the constants of nature that are all interdependent.
  • These include constants such as the Planck constant — the ratio of the electromagnetic radiation from a photon to its frequency — and the charge of an electron.
  • The kilogram was the only one among the units still pegged to a real object and now — after a formal vote in 2018 — the world is set to redefine the kilogram in terms of the Planck constant, the second and the metre.
  • The undoing of the cylinder has been the Kibble balance. It is a set of scales, which uses the force produced by a current-carrying wire in a magnetic field to balance the weight of a mass.
  • Through this, accurate measures of the Planck constant — the fulcrum of several of the standard units — can be made.

Monsoon prediction to become more accurate

  • Scientists have developed a new tool for objectively defining the onset and demise of the summer monsoon — a colossal weather system that affects millions of people annually.
  • The researchers from Florida State University in the U.S. developed a method that uses rainfall rates to mark the span of the Indian Summer Monsoon (ISM) at any given location throughout the affected region.
  • For generations, scientists have struggled to produce a model for reliably defining the duration of the monsoon. No existing system has allowed researchers to reliably define the parameters of the season at this fine a scale, researchers said.
  • The lack of a clear, granular and objective benchmark for ISM onset and demise for all areas of the country has been a long-time source of consternation for people, researchers said. In some parts of the country, the torrents of rain that characterise monsoon season account for more than 90% of the total annual precipitation, they said.
  • Researchers said many rhythms of Indian political and agricultural life can be destabilised by dubious or false claims of monsoon onset.
  • That leads to tremendous amounts of frustration and confusion for the general public and for the people who are trying to monitor the monsoon because nobody has really gotten down to do it at a granular scale.
  • The new system, which ties the onset of the monsoon to location-specific rainfall thresholds, can work to allay that frustration.
  • Up until now, regional meteorological departments have relied on their own ad hoccriteria for determining ISM onset, which can often lead to contradicting claims.

RCom to close down its 2G business

  • Debt-laden Reliance Communications (RCom) has decided to close down its 2G wireless business due to mounting losses.
  • RCom has 81 million subscribers of which about 40 million use its 2G network.
  • “The company’s 4G-led strategy will be executed as at present on the back of capital-light access to India’s most extensive 4G mobile network through already operational spectrum-sharing and ICR arrangements with Reliance Jio,” the spokesperson added, without elaborating.
  • Its 2G subscribers give RCom an average revenue per user of less than Rs. 80 a month. Migrating to 4G would cost them at least Rs. 150 a month.
  • The operator’s headcount has fallen to about 2,500 from 5,000 a year earlier. With the closure of the 2G business, an additional 1,000-1,200 employees may lose their jobs, said a source privy to the development. In June, RCom chairman Anil Ambani had said the ongoing stress in the sector would lead to a loss of 30,000-40,000 jobs this year.
  • With a debt of Rs. 46,000 crore, RCom had a moratorium on servicing loans till December 2017 to repay Rs. 25,000 crore, failing which lenders may convert a part of the debt into equity.
  • “RCom will look to merge its ILD voice, consumer voice and postpaid 4G dongle operations into its enterprise unit, provided it is profitable to do so,” a source in RCom said.
  • It plans to close down all other parts of its business, with the exception of its towers unit, which has deals in place with other operators, such as Reliance Jio. RCom’s DTH television licence expires on Nov. 21. It does not plan to renew it.

Recapitalization bonds will be liquidity-neutral’

  • The Centre’s move to infuse Rs. 2.11 lakh crore capital into public sector banks through recapitalisation bonds and budgetary support is a welcome step, according to Urjit Patel, Governor, Reserve Bank of India.
  • He added the recapitalisation bonds will be liquidity-neutral for the government except for interest payment.
  • The banks will be recapitalised over a period of two years through recapitalisation bonds and budgetary provision.
  • Dr. Patel said a well-capitalised banking system was a pre-requisite for stable economic growth and this package to restore the health of the banking system was a monumental step forward in safeguarding the country’s economic future.
  • The move will involve participation of private shareholders of public sector banks by requiring that parts of the capital needs be met by market funding, he said. The Governor said healthier banks with could get the capital first which will prompt others to also address the balance sheet issues.
  • Last, but not the least, it will allow for a calibrated approach whereby banks that have better addressed their balance sheet issues and are in a position to use fresh capital injection for immediate credit creation can be given priority while others shape up to be in a similar position.
  • The central bank Governor said for the first time in the last decade, there was a real chance that all the policy pieces of the jigsaw puzzle will be in place for a comprehensive and coherent, rather than piece-meal, strategy to address the banking sector challenges.
  • Commenting that financial sector policies should support growth while maintaining financial stability, Dr. Patel said RBI is looking forward to working with the government in ensuring these plans reached their natural completion for the benefit of the broader Indian economy.

Railways floating a global tender

  • In a first, the Ministry of Railways has floated a global tender to procure seven lakh tonne of rail, worth about Rs. 3,500 crore, instead of purchasing from the Steel Authority of India Limited (SAIL), in a bid to clear pending track renewal work.
  • At present, the Railways procures rail solely from public sector SAIL which is the largest steel producer in the country. The move comes five months after the Union Cabinet approved a policy to provide preference to domestically manufactured iron and steel products in government procurement.
  • The Ministry had decided that the rails earmarked for constructing new lines would be diverted for renewing tracks in accident-prone areas in the wake of rising derailment cases.
  • SAIL had committed to supply 11.45 lakh tonne rail to the Railways in 2017-18, leaving a deficit of 3.14 lakh tonnes. A NITI Aayog report earlier this year raised concerns over delay in overdue track replacement that could likely lead to train accidents. In 2016-17, the Railways renewed 2,487 km tracks compared with 2,794 km in 2015-16 and 2,424 km in 2014-15.
  • According to a ‘White Paper on Indian Railways’ published in February 2015, the Railways has a total track length of 1,14,907 km and on average, 4,500 km should be ideally renewed every year.

LIGO

  • With the 2017 Nobel Prize for physics going to the LIGO-VIRGO collaboration for having directly observed gravitational waves for the first time, black hole mergers have become a byword. The instrumentation to differentiate and detect this faint signal from the noise was a crucial contributions made by Nobel Laureate Rainer Weiss.
  • The first gravitational waves that were detected were small fluctuations of spacetime caused by a violent merging of two black holes about 1.3 billion light years away. We know that light bends due to a change in refractive index of the air near hot objects like a heated asphalt road.
  • Light also bends when spacetime curves due to the presence of massive gravitational fields. When a gravitational wave is incident on the detector, the laser beam behaves in a similar manner.
  • One main difference is the magnitude. The difference between bending of light in cool air and hot air is about 1%, whereas the bending caused by a gravitational wave is about one billion times smaller than the thickness of a human hair.
  • The photodetectors are sensitive to the brightness of the incoming signal. When there is no signal, the two arms of the LIGO detector are arranged so that there is cancellation of contribution of light. There is still some small amount of light coming through. When there is a signal, this light shows a variation.
  • The electronics converts photons into electrons. Like in the human ear, there is an electrical signal which has to be turned into sound. The detection is in the range of frequencies from about 20 Hz to 10 kHz.
  • LIGO’s interferometers are a ten orders of magnitude improved as compared to the first interferometer made by Albert Michaelson in 1881, which was able to measure a displacement in nanometres.
  • Under the high degree of vacuum needed, stainless steel has the problem that the hydrogen separates out. So a special stainless steel called low-hydrogen stainless steel was needed. The steel tubes are also used to house the lasers and have to be very clean. These are being made at Institute for Plasma Research in Ahmedabad.
  • In all, the tubes measure 8 km in length and have a diameter of 1.2 m. “So it’s quite a large empty space, and it’s all one piece. No one had made such a large vacuum chamber earlier, so this is the largest empty space in the world,” Prof. Adhikari smiles.

Supermassive black holes discovered

  • Scientists, including one of Indian origin, have identified five pairs of supermassive black holes, each millions of times the mass of the Sun, that could help better understand the phenomenon of gravitational waves.
  • These black hole couples formed, when two galaxies collided and merged with each other, forcing their supermassive black holes close together.
  • The black hole pairs were uncovered by combining data from a suite of different observatories, including NASA’s Chandra Xray Observatory, the WideField Infrared Sky Explorer Survey (WISE), and the groundbased Large Binocular Telescope in Arizona, researchers said.
  • Researchers used optical data from the Sloan Digital Sky Survey, to identify galaxies where it appeared that a merger between two smaller galaxies was underway.
  • Seven merging systems, containing at least one supermassive black hole were found with this technique.
  • Closelyseparated pairs of Xray sources were found in five systems, providing compelling evidence that they contain two growing (or feeding) supermassive black holes.
  • The research has implications for the burgeoning field of gravitational wave astrophysics. However, the merging black holes discovered have been of the smaller variety.
  • The merging black holes in the centres of galaxies are much larger. When these supermassive black holes draw closer, they should start producing gravitational waves.

Human brains may drain out waste

  • By scanning the brains of healthy volunteers, researchers have found longsought evidence that our brains may drain out some waste through lymphatic vessels, the body’s sewer system.
  • Now, a research team has discovered lymphatic vessels in the dura, the leathery outer coating of the brain. The results, published online in the journal eLife , further suggest that the vessels could act as a pipeline between the brain and the immune system.
  • Lymphatic vessels are part of the body’s circulatory system. In most of the body they run alongside blood vessels. They transport lymph, a colourless fluid containing immune cells and waste, to the lymph nodes.
  • Blood vessels deliver white blood cells to an organ and the lymphatic system removes the cells and recirculates them through the body. The process helps the immune system detect whether an organ is under attack from bacteria or viruses or has been injured.
  • Brain scans and autopsy studies of brains from nonhuman primates confirmed the results seen in humans, suggesting the lymphatic system is a common feature of mammalian brains. “These results could change the way we think about how the brain and immune system interrelate,” said Walter Koroshetz, Director, NINDS.
  • Researchers are planning to investigate whether the lymphatic system works differently in patients who have multiple sclerosis or other neuroinflammatory disorders.

Six decades since Sputnik

  • Six decades after Sputnik, a refined version of the rocket that put the first artificial satellite in orbit remains the mainstay of Russia’s space programme as a stunning tribute to the country’s technological prowess, but also a sign that it has failed to build upon its achievements.
  • And unlike the Cold War era when space was a key area of the rivalry between the United States and the Soviet Union, space research now appears to rank low on the Kremlin’s priorities.
  • The Soyuz booster, currently the only vehicle that launches crews to the International Space Station, is a modification of the R7 rocket that put Sputnik in orbit on Oct. 4 1957. Another Sovietdesigned workhorse, the heavylift Proton rocket that has been used to launch commercial satellites to high orbits, was developed in the 1960s.
  • Glitches found in Proton and Soyuz in 2016 were traced to manufacturing flaws at the plant in Voronezh that builds engines for both rockets.
  • Work on a new spacecraft intended to replace the Soyuz capsule designed 50 years ago has crawled slowly.
  • Attempts to send unmanned probes to Mars in 1996 and one of the Martian moons, Phobos, in 2011 failed due to equipment problems. It has struggled for years to build its own scientific module for the International Space Station.
  • Amid funding shortages, Roscosmos has also decided to cut the size of its ISS crews.

Second Submarine- Khanderi begins sea trials

  • Slowly but steadily, the Scorpene submarine programme is making progress. While the first submarine awaits commissioning, the second one has just begun sea trials, and Mazagon Docks Ltd. (MDL) is gearing up to launch the third vessel.
  • After the monsoon, the second Scorpene Khanderi began sea trials last week. As per schedule, it is expected to be commissioned within this year.
  • The third submarine, Karanj, is on track to be launched by the year-end.
  • Khanderi, named after an island fort of Maratha ruler Chhatrapati Shivaji, was launched in January and had undergone some testing. Trials were held up by the rough sea.

Noble prize in physics awarded for discovery of gravitational waves

  • U.S. astrophysicists Rainer Weiss, Barry Barish and Kip Thorne and were awarded the Nobel Physics Prize for the discovery of gravitational waves — a phenomenon that opens a door on the extreme Universe.
  • Predicted by Albert Einstein a century ago as part of his theory of general relativity, but only detected in 2015, gravitational waves are “ripples” in space-time, as the theoretical fabric of the cosmos is called.
  • They are caused by ultra-violent processes, such as colliding black holes or the collapse of stellar cores.
  • “Their discovery shook the world,” said Goran K. Hansson, the head of the Swedish Royal Academy of Sciences, which selects the Nobel recipients.
  • They made their discovery in September 2015 and announced it in February 2016, a historic achievement that culminated from decades of scientific research. And since then, they have clinched all the major astrophysics prizes to be had.
  • Mr. Thorne and Mr. Weiss co-created the Laser Interferometer Gravitational-wave Observatory (LIGO) at the prestigious California Institute of Technology, which has taken home 18 Nobels since the prizes were first awarded in 1901. Mr. Barish then brought the project to completion.
  • The first-ever direct observation of gravitational waves was the result of an event some 1.3 billion light years away. “Although the signal was weak when it reached Earth, it is already promising a revolution in astrophysics. Gravitational waves are an entirely new way of following the most violent events in space and testing the limits of our knowledge,” the Academy said.
  • Since 2015, the enigmatic ripples have been detected three more times: twice more by LIGO and once by the Virgo detector located at the European Gravitational Observatory in Cascina, Italy.

3-fold rise in extreme rainfall events in Central India

  • There has been an average 10% decline in summer monsoon (June to September) rainfall over central India between 1950 and 2015 as a result of weakening of the summer monsoon winds.
  • However, the frequency and intensity of extreme rainfall (more than 150 mm per day for two-three days covering an area of 250 by 250 km) events during the same period over central India (from Gujarat in the west to Odisha and Assam in the east) has been on the rise.
  • There has been a three-fold increase in widespread extreme events over central India during 1950-2015. In the 1950s, there were two extreme rainfall events per year, while in recent years the number of events has increased to six per year.
  • Models suggest further increase in extreme events over most parts of the Indian subcontinent by the end of the century.
  • The weakening of the monsoon winds has resulted in less supply of moisture to the Indian subcontinent. The warm ocean temperatures in the northern Arabian Sea result in large fluctuations in the monsoon winds leading to occasional surges of increased moisture transport.
  • These sudden surges of the monsoon winds bring in plenty of moisture and that is what is causing extreme rainfall events across the central Indian belt.
  • While the central Indian Ocean has warmed up, the Indian peninsular region has not warmed up compared to other regions in the tropics leading to reduced land-sea temperature difference.
  • Probably the cooling caused by aerosol and the reduced land-sea temperature difference in recent years is what is causing the weakening of the monsoon winds and decline in monsoon rainfall.
  • At the same time, the northern Arabian Sea is becoming increasingly warm leading to more moist air over the Arabian Sea. In addition, the northern Arabian Sea gets warmer (1-2 degrees C) 2-3 weeks prior to extreme events.
  • As a result, there is 20-40% more evaporation and increased moisture levels over the Arabian Sea before an extreme event. This gets transported over central India resulting in extreme rainfall events. The results were published in the journalNature Communications .
  • The Arabian Sea supplies more moisture to the extreme rainfall events than the Bay of Bengal and the central Indian Ocean combined.
  • The study found that the Arabian Sea contributes 36% of the total moisture to central India, while the Bay of Bengal’s is 26% and the Indian Ocean’s is 9%.
  • Interestingly, land evo-transpiration contributes 29% moisture, which is much more than even the Bay of Bengal. Moisture from land evotranspiration is often neglected in monsoon studies.

Solar storm hits Mars

  • An unexpectedly strong solar storm hit Mars, sparking a global aurora and doubling radiation levels on the red planet, NASA scientists say.
  • The solar event on September 11 sparked an aurora more than 25 times brighter than any previously seen by the MAVEN orbiter, which has been studying the Martian atmosphere’s interaction with the solar wind since 2014.
  • It produced radiation levels on the surface more than double any previously measured by the Curiosity rover’s Radiation Assessment Detector (RAD) since that mission’s landing in 2012. The high readings lasted more than two days.
  • NASA’s distributed set of science missions is in the right place to detect activity on the Sun and examine the effects of such solar events at Mars as never possible before.
  • It occurred in conjunction with solar activities during what is usually a quiet period in the Sun’s 11-year sunspot and storm-activity cycle.
  • This event was big enough to be detected at Earth too, even though Earth was on the opposite side of the Sun from Mars.
  • RAD monitored radiation levels inside the encapsulated spacecraft that carried Curiosity from Earth to Mars in 2011 and 2012 and has been steadily monitoring the radiation environment at Mars’ surface for more than five years.
  • RAD findings strengthen understanding of radiation’s impact on Mars habitability, a key objective of the Curiosity mission.

A plant based ink likely to kill cancer cells

  • A plant-based ink, that has been used by Chinese calligraphers for hundreds of years, could non-invasively kill cancer cells, scientists claim.
  • As cancer cells leave a tumour, they frequently make their way to lymph nodes, which are part of the immune system.
  • In this case, the main treatment option is surgery, but this can result in complications.
  • Photothermal therapy (PTT) is an emerging non-invasive treatment option in which nanomaterials are injected and accumulate in cancer cells. A laser heats up the nanomaterials, and this heat kills the cells.
  • Many of these nanomaterials are expensive, difficult-to-make and toxic.
  • However, a traditional Chinese ink called Hu-Kaiwen (Hu-ink) has similar properties to the nanomaterials used in PTT.
  • For example, they are the same colour, and are both carbon-based and stable in water.
  • The researchers also noted that Hu-ink could act as a probe to locate tumours and metastases because it absorbs near-infrared light, which goes through skin.

Forest trees are good, not just for the environment but for your coffee too

  • Forest trees are good, not just for the environment but for your coffee too: having more forest trees in coffee plantations maintains tree diversity and also increases coffee production and quality, shows a study.
  • This could be vital information as native trees are being replaced with exotics in coffee-growing landscapes to increase coffee production.
  • India, the world's sixth largest coffee-producer, grows 'shade' coffee, under the canopies of naturally occurring native trees such as jackfruit, Black dammar (dhup) and Magnolia (champa) which are legally-protected.
  • However, some planters now replace dead native trees with exotics like Silver oaks which are not protected and can be felled for timber. Silver oaks also serve well as pepper stands, and cultivating pepper on them supplements planters’ incomes.
  • This 'intensification' – reducing and replacing native shade tree cover – contributes to forest loss in the tropics, where coffee is cultivated.
  • Scientists at ETH Zurich (Switzerland) and the College of Forestry (Kodagu) examined whether this intensi-fication affects native tree biodiversity and coffee productivity in Karnataka's Kodagu district, which produces more than one-third of India's coffee.
  • They studied tree species diversity in 25 coffee plantations varying in native shade tree cover, with some having only non-native Silver oaks as canopies.
  • Their results, published in the journal Agriculture, Ecosystems and Environment , show that 95 native tree species offer shade for coffee in Kodagu; and intensification decreases this tree diversity.
  • Some plantations, which still retained native trees, even had red-listed tree species (designated as threatened by the IUCN), and some of them in high numbers.
  • The team found that such plantations produced more coffee, which was also of better quality . Silver oak-dominated plantations showed more single-seeded fruits and attacks by the Coffee berry borer, a major pest.

Convergence and divergence of water vapour govern Indian monsoon rainfall

  • In2014, India recorded a 12% seasonal rain deficit with a record drought in the month of June.
  • Scientists from the Department of Meteorology and Oceanography atAndhra University studied the climate data and found that divergence of water vapour was one of the main reasons for the drought.
  • The analysis of the moisture transport patterns revealed that convergence and divergence of water vapour are important factors governing the Indian summer monsoon rainfall. The results were recently published in Climate Dynamics .
  • Data from June 1 to September 30 for the period 2000-2014 were collected from the Climate Forecasting System model at the Pune’s IITM and National Centre for Environmental Prediction (NCEP) final analysis from the U.S.
  • The data showed that all parts of the country had received scanty monthly rainfall at least once during the four months in 2014. The overall seasonal rainfall over India was 775.5 mm which is a 12% less than the normal.
  • The researchers examined the water vapour transport as earlier studies by others had shown it could affect rainfall.
  • The divergence of moisture flux could have caused the low rainfall in June which was only 57.5 % of the average. In August 2014, there was a break in monsoon with rainfall only over northeastern and central parts of India.
  • The regions with rainfall showed convergence of moisture and in the areas with no rainfall there was divergence. In September, the rainfall over many parts of India showed significant increase and also excess in some parts.
  • The overall rainfall was 108.1% of the average. These values support the contention that over the land, moisture flux has a major influence on rainfall.
  • The other physical processes that cause drought were analysed. The El Nino effect on 2014 monsoon rainfall was very small as the air-sea coupling weakened the effect, resulting in ENSO neutral conditions.
  • Thus the results of this study suggest that the process of water vapour transport is an important physical process influencing the monsoons. The magnitude of convergence agreed with the rainfall in quantity and divergence caused drought.
  • The study emphasises that moisture flux should be taken into consideration for accurate prediction of future climate.

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