Indian Institute of Tropical Meteorology

www.tropmet.res.in
Pune, India

The Indian Institute of Tropical Meteorology or IITM is a scientific institution based in India for expanding research in meteorology of the tropics in general with special reference to monsoon meteorology of India. The current in charge director of IITM is Dr. R. Krishnan Wikipedia.

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News Article | May 10, 2017
Site: www.bbc.co.uk

The historic site of Buddha's birthplace in Nepal faces a serious threat from air pollution, scientists and officials have warned. Recent data collected from air quality monitoring stations in five places across the country show Lumbini is highly polluted. The warnings have come amid expanding industrialisation near the sacred site. It is already located in a pollution hotspot on the Gangetic plains. For the month of January, fine particulate matter (PM2.5) in Lumbini, in southwest Nepal, was measured at 173.035 micrograms per cubic metre. The reading for the neighbouring town of Chitwan was 113.32 and the capital, Kathmandu, which is known for its high pollution levels, was at 109.82. The World Health Organization (WHO) safe limit for the pollutant is 25 micrograms per cubic metre and the Nepal government has set the national standard at 40. Scientific studies have also highlighted the increasing levels of pollution in and around the historic site. "The combined effect of trans-boundary transport from the pollution rich Indo-Gangetic Plain region and trapped local industrial pollution due to temperature inversion is responsible for severe winter pollution," says a study done by the Indian Institute of Tropical Meteorology in collaboration with the WHO. "For other seasons, local emissions are largely responsible for bad air quality." It found that levels of PM 2.5 fine particles, which can enter human blood vessels, were more than 10 times above the WHO safe limit. Another study conducted by the IUCN and Unesco found that the pollution had begun to threaten the Lumbini World Heritage site. "The expansion of the carbon emission industries within the Lumbini Protected Zone has caused several problems such as threats to biodiversity, health hazards to local residents, archaeological properties, social and cultural values." An IUCN study on three monuments of the historic site concluded that the sacred garden - the core place - was polluted by air dispersed gaseous and solid compounds. "On the samples of the Ashoka pillar (that was established in 249 BC by Emperor Ashoka to mark the birthplace of Buddha) gypsum, calcite, dolomite and magnesite are present in the form of fine powder that deposits on the surface," says the report authored by Italian archaeologist Constantino Meucci of the University of Rome. "All compounds are part of the cement production cycle." A government body had designated 15km aerial distance from the north east and west boundary of the historic site as the Lumbini Protected Zone. Adjoining the LPZ is an expanding industrial corridor that has cement, steel, paper and noodle factories and brick kilns. Several of these factories are well within the LPZ and environmentalists say that is in clear violation of the government regulation. Tourists and monks visiting the site have told the BBC they felt uneasy while breathing in the air. "At times I have difficulty in breathing properly and I have to cough," said Monk Vivekananda who runs an international meditation centre in Lumbini. He and a few others were meditating with their face masks on near the Mayadevi temple that marks the exact spot where Gautam Buddha was born more than 2,600 years ago. "We had at our meditation centre certain [people] who have had asthma conditions and during their stay here in Lumbini, it has badly affected them," he told the BBC. "In at least three cases, [they] had to cut their retreat short and go back because they could not tolerate the conditions here any more." Health workers in the area said the conditions were getting worse. "When the wind brings more pollution, we see many monks meditating here with their masks on," said Shankar Gautam, who has just retired after working as a health official for 30 years. "Studies have shown that in the past 10 years the number of people with lung related diseases has gone up. "The dust coming in here has also led to a huge increase in skin-related diseases." A major pilgrimage for Buddhists, Lumbini is also a major tourist destination. Last year it saw one million visitors and the government plans to develop it as a global tourism destination. "My feeling at this time is that it is more polluted than seven or eight years ago," said Nguyen Duy Nhan, a Vietnamese tourist. "I can see a lot of dust on the leaves and trees on the way we were coming in here." His friend Victor Vlodovych nodded in agreement and said: "Maybe if I stay longer it will affect [me] a lot, I can feel that there is a lot of construction and manufacturing around [this place]." Factory operators say they are reasonably far away from the sacred site. "Yes certainly this is very near to the birthplace of Lord Gautam Buddha," admitted Ajay Ajad, a manager with the biggest cement factory in the area. "Obviously cement factories emit some dust but we are at a reasonably safe distance and therefore the deposition of our dust particles on the sacred site is minimised. He says dust is not a problem confined to Lumbini: "It is all over Nepal and even at places where there are no cement factories." Government officials are aware of the problem. "Based on recent data, we know that Lumbini is more polluted than Kathmandu," said Shankar Prasad Poudel, chief of the air pollution measurement section at the environment department. "We plan to detect the sources of the pollution using a drone in the near future and hopefully this will help minimise the problem."


Yadav R.K.,Indian Institute of Tropical Meteorology
Quarterly Journal of the Royal Meteorological Society | Year: 2017

The dominant mode of July–August seasonal variability of Indian summer monsoon rainfall obtained by performing an empirical orthogonal function analysis over India, excluding northeast India, for the period 1979–2014 is highly correlated to the quasi-stationary midlatitude Eurasian Rossby wave train, known as the ‘Silk Road’ pattern. A new hypothesis has been proposed and tested using observed Indian rainfall and the ERA-Interim dataset, by which the positive feedback between the midlatitude Rossby wave and the Indian summer monsoon circulation has been established. A Rossby wave train features successive upper-tropospheric negative and positive geopotential height anomalies over the northeast of the Mediterranean and northwest of India, respectively. The negative height anomaly decreases the sum of the vertical integral of potential and internal energy, while this increases in the region of positive geopotential height anomalies. This is associated with middle to lower tropospheric midlatitude descent and ascent anomalies at 40°E and 50°E, which cause negative surface temperature anomalies over Syria, Iraq, Jordan and Saudi Arabia, and a positive surface temperature anomaly over Iran, respectively. The negative and positive surface temperature anomalies are associated with positive and negative surface pressure anomalies over Saudi Arabia and Iran, respectively, which generate anomalous northwesterly winds over eastern Saudi Arabia and the Persian Gulf. Further downstream this anomalous northwesterly wind combines with the climatological background cross-equatorial southwesterly flow in the Arabian Sea. The flow further converges towards central and northwest India. The flow also acts as a source of moisture supply from the warm Arabian Sea and Persian Gulf for the deep convection over the Western Ghats, northwest and central India and hence reinforces active Indian summer monsoon conditions. © 2017 Royal Meteorological Society


Beig G.,Indian Institute of Tropical Meteorology
Journal of Geophysical Research: Space Physics | Year: 2011

A detailed overview of long-term secular trends in temperature of the mesosphere and lower thermosphere considered to be induced by increase in greenhouse gases has been provided by Beig et al. (2003). Since then, quite a few new results have been emerged as some of the data series have become sufficiently large enough to provide results with improved confidence. Our understanding on the nature of temperature trends in the mesosphere/lower thermosphere (MLT) region is relatively better now. In the mesosphere, some of the results confirmed the earlier findings, and some new results obtained by satellite and lidar data over the tropical region have indicated a relatively weaker cooling trend as compared to the past but nevertheless strengthened the conclusion about the cooling trends. However, in the mesopause region, some of the new results now indicate a break in trend and tendency of negative signal where earlier no trend feature was noticed. This slice of no trend feature in between two cooling regimes was puzzling the modeling community, who were in search of a convincing explanation. This paper briefly outlines the progress made over the recent past in the field of MLT region secular temperature trends attributed mainly to growth of greenhouse gases near the Earth's surface. Copyright 2011 by the American Geophysical Union.


Beig G.,Indian Institute of Tropical Meteorology
Journal of Geophysical Research: Space Physics | Year: 2011

Understanding trends in any atmospheric quantity typically requires the ability to distinguish between naturally occurring processes that result in trends, such as the 11 year solar cycle, and potential anthropogenic secular trends that occur simultaneously. After the review of mesospheric and lower thermospheric temperature response to solar activity by Beig et al. (2008), a few new results along with some modified results by revisiting the older data sets have been reported recently. Main improvement is due to the length of data series and amount of data which have been accounted in recent years. This article summarizes the progress made in the field of temperature variability due to changing solar activity as reported recently. Recent investigations revealed that the solar signal becomes stronger with increasing latitude in the mesosphere. Temperature response to solar activity at the lower part of mesopause region is around a few degrees per 100 solar flux units (sfu), which becomes stronger (4-5 K/100 sfu) in the upper part of this region in both hemispheres. The overall global picture indicates that the solar signal in the mesopause region temperature in the Northern Hemisphere is relatively stronger in recent time in a majority of locations compared to results reported in earlier reviews. Copyright 2011 by the American Geophysical Union.


Yadav R.K.,Indian Institute of Tropical Meteorology
Climate Dynamics | Year: 2013

This study examines the emerging role of Indian Ocean sea surface temperature (SST) on the inter-annual variability (IAV) of Indian north-east monsoon rainfall (NEMR). The IAV of NEMR is associated with the warm SST anomaly over east Bay-of-Bengal (BoB) (88.5oE-98.5oE; 8.5oN-15.5oN) and cool SST anomaly over east equatorial Indian Ocean (80.5oE-103.5oE; 6.5oS-3.5oN). The gradient of SST between these boxes (i.e. northern box minus southern box) shows strong and robust association with the Indian NEMR variability in the recent decades. For establishing the teleconnections, SST, mean sea level pressure, North Indian Ocean tropical storm track, and circulation data have been used. The study reveals that during the positive SST gradient years, the inter-tropical convergence zone (ITCZ) shifts northwards over the East Indian Ocean. The tropical depressions, storms and cyclones formed in the North Indian Ocean moves more zonally and strike the southern peninsular India and hence excess NEMR. While, during the negative SST gradient years, the ITCZ shifts southwards over the Indian Ocean. The tropical depressions, storms and cyclones formed in the North Indian Ocean moves more northwestward direction and after crossing 15oN latitude re-curve to north-east direction towards head BoB and misses southern peninsular India and hence, deficient NEMR. © 2012 Springer-Verlag Berlin Heidelberg.


Yadav R.K.,Indian Institute of Tropical Meteorology
International Journal of Climatology | Year: 2012

This study examines decadal changes of the El Niño/Southern Oscillation (ENSO) influence on the interannual variability (IAV) of Indian northeast monsoon rainfall (NEMR). In recent decades, the ENSO influence has strengthened over the NEMR variability. During El Niño years, the subsidence anomaly over the warm-pool region of Indonesia was much stronger in the recent decades as compared to the earlier decades. The zonally elongated warm sea surface temperatures (SSTs) of the warm-pool region along the tropical Indo-Pacific Ocean were much warmer than the earlier decades, which had intensified the deep convections over the Indian Ocean. The northwestward propagating trailing Rossby-gyres, formed in the western portion of the equatorial deep convection and stratiform heating, intensified as tropical storms and cyclones over north Indian Ocean. These storms and cyclones strike southern peninsular India and hence flood northeast monsoon (NEM) years. During the recent decades in the La Niña years, the contracted warm SSTs over the warm-pool region were much warmer than the earlier decades which intensified the deep convection and stratiform heating over there. The tropical storms and cyclones that formed due to Rossby-gyre dynamics had to travel a long distance towards the northwestward direction over the Bay of Bengal and misses southern peninsular India, and hence, the drought NEM years. © 2011 Royal Meteorological Society.


Tree growth-climate relationship analysis revealed the important role of soil moisture availability in development of annual growth rings. Winter season (October-March) Palmer Drought Severity Index (PDSI) is an important factor in developing annual tree-rings during subsequent growing seasons. The chronology was strongly correlated with winter PDSI in recent few decades, more so than in the earlier period, indicating that tree growth is more dependent on climate. Many low growth years detected during El Nino events are probably related to moisture deficiency. The result indicates that the tree growth is mostly affected by the soil moisture availability during the recent warm periods over the region. © 2011 Elsevier Ltd and INQUA.


Tree-ring chronologies of fir (Abies pindrow) and spruce (Picea smithiana) show highly significant positive correlation with Palmer Drought Severity Index (PDSI) as compared to rainfall over the region. This study indicates that soil moisture availability during summer season (April-September) plays a vital role in developing the annual ring-width pattern. Higher mean, maximum, and minimum temperatures during the summer season are not found to be conducive for the growth of the trees. The summer seasons' PDSI of the region has been reconstructed from AD 1820-1981. © 2011 Elsevier Ltd and INQUA.


Debaje S.B.,Indian Institute of Tropical Meteorology
Environmental Science and Pollution Research | Year: 2014

In this study, we estimate yield losses and economic damage of two major crops (winter wheat and rabi rice) due to surface ozone (O3) exposure using hourly O3 concentrations for the period 2002-2007 in India. This study estimates crop yield losses according to two indices of O3 exposure: 7-h seasonal daytime (0900-1600 hours) mean measured O3 concentration (M7) and AOT40 (accumulation exposure of O3 concentration over a threshold of 40 parts per billion by volume during daylight hours (0700-1800 hours), established by field studies. Our results indicate that relative yield loss from 5 to 11 % (6-30 %) for winter wheat and 3-6 % (9-16 %) for rabi rice using M7 (AOT40) index of the mean total winter wheat 81 million metric tons (Mt) and rabi rice 12 Mt production per year for the period 2002-2007. The estimated mean crop production loss (CPL) for winter wheat are from 9 to 29 Mt, account for economic cost loss was from 1,222 to 4,091 million US$ annually. Similarly, the mean CPL for rabi rice are from 0.64 to 2.1 Mt, worth 86-276 million US$. Our calculated winter wheat and rabi rice losses agree well with previous results, providing the further evidence that large crop yield losses occurring in India due to current O3 concentration and further elevated O3 concentration in future may pose threat to food security. © 2014 The Author(s).


Roxy M.,Indian Institute of Tropical Meteorology
Climate Dynamics | Year: 2014

Over the tropical oceans, higher sea surface temperatures (SST, above 26 °C) in summer are generally accompanied by increased precipitation. However, it has been argued for the last three decades that, any monotonic increase in precipitation with respect to SST is limited to an upper threshold of 28-29.5 °C, and beyond this, the relationship fails. Based on this assessment it has often been presumed that, since the mean SSTs over the Asian monsoon basins (Indian Ocean and north-west Pacific) are mostly above the threshold, SST does not play an active role on the summer monsoon variability. It also implies that increasing SSTs due to a changing climate need not result in increasing monsoon precipitation. The current study shows that the response of precipitation to SST has a time lag, that too with a spatial variability over the monsoon basins. Taking this lag into account, the results here show that enhanced convection occurs even up to the SST maxima of 31 °C averaged over these basins, challenging any claim of an upper threshold for the SST-convection variability. The study provides us with a novel method to quantify the SST-precipitation relationship. The rate of increase is similar across the basins, with precipitation increasing at ~2 mm day-1 for an increase of 1 °C in SST. This means that even the high SSTs over the monsoon basins do play an active role on the monsoon variability, challenging previous assumptions. Since the response of precipitation to SST variability is visible in a few days, it would also imply that including realistic ocean-atmosphere coupling is crucial even for short term monsoon weather forecasts. Though recent studies suggest a weakening of the monsoon circulation over the last few decades, results here suggest an increased precipitation over the tropical monsoon regions, in a global warming environment with increased SSTs. Thus the signature of SST is found to be significant for the Asian summer monsoon, in a quantifiable manner, seamlessly through all the timescales-from short-term intraseasonal to long-term climate scales. © 2013 Springer-Verlag Berlin Heidelberg.

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