Heavy snowfall over Himalayas makes drought over India more likely
Scientists from the Walker Institute at the University of Reading have helped to explain why heavy snowfall over the Himalayas in winter and spring can lead to drought over India, especially in the early part of the summer monsoon. This work forms part of the Climate Programme of the National Centre for Atmospheric Science (NCAS).
(Media-Newswire.com) - Scientists from the Walker Institute at the University of Reading have helped to explain why heavy snowfall over the Himalayas in winter and spring can lead to drought over India, especially in the early part of the summer monsoon. This work forms part of the Climate Programme of the National Centre for Atmospheric Science ( NCAS ).
As far back as the 1880s scientists have known that increased snow over the Himalayas can be linked with weaker summer monsoon rains over India. However, the mechanisms explaining this link have never been properly understood.
The new research, published this week in Climate Dynamics, studies the mechanisms using the Met Office/Hadley Centre climate model. It shows that greater snowfall reflects more sunlight and produces a cooling over the Himalayas. This in turn means a weakening of the monsoon winds that bring rain to India. The relationship is strongest in the absence of warm ( El Nino ) or cold ( La Nina ) conditions in the tropical Pacific, because these are normally the dominant control over Indian rains.
Dr Andy Turner, lead author of the research, says "Our work shows how, in the absence of a strong influence from the tropical Pacific, snow conditions over the Himalayas and Tibetan Plateau could be used to help forecast seasonal monsoon rainfall for India, particularly over northern India during the onset month of June. The onset timing of the monsoon is very important for agriculture; a lack of rainfall early in the growing season can have a devastating impact on crops."
Previous studies have also found links between snowfall over a much larger area of northern Eurasia, but this study suggests that the Himalayan region has a stronger influence on Indian rainfall.
The monsoon rains over India and the rest of South and East Asia are relied on by more than a third of the world's population.
This research is based on a large number of experiments with the Met Office/Hadley Centre climate model which have been used to show robust relationships between the monsoon and winter/spring snow. This study shows in detail the mechanisms linking heavy snowfall over the Himalayas and Tibet in winter and spring with summer monsoon drought, particularly in the early part of the season ( June ).
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Notes to editors:
1. Reference: Using idealized snow forcing to test teleconnections with the Indian summer monsoon in the Hadley Centre GCM. Andrew Turner and Julia Slingo, Climate Dynamics ( 2010 ) published online, http://dx.doi.org/doi:10.1007/s00382-010-0805-3
2. The University of Reading's Walker Institute for Climate System Research aims to improve understanding of future climate and its impacts. See www.walker-institute.ac.uk
3. The NERC National Centre for Atmospheric Science ( NCAS ) is a world leader in atmospheric science, with research programmes on: the science of climate change, including modelling and prediction; atmospheric composition, including air quality; weather, including hazardous weather and technologies for observing and modelling the atmosphere.
University of Reading is rated as one of the top 200 universities in the world ( THE-QS World Rankings 2009 ).
The University of Reading is one of the UK's top research-intensive universities. The University is ranked in the top 20 UK higher education institutions in securing research council grants worth nearly £10 million from EPSRC, ESRC, MRC, NERC, AHRC and BBSRC. In the RAE 2008, over 87% of the university's research was deemed to be of international standing. Areas of particular research strength recognised include meteorology and climate change, typography and graphic design, archaeology, philosophy, food biosciences, construction management, real estate and planning, as well as law. Standards of teaching are excellent - the University scored highly in the National Student Survey 2009. 87% of Reading students responding to the survey stated they were satisfied with the quality of their course. The University is estimated to contribute £600 million to the local economy annually. University of Reading is a member of the 1994 Group of 19 leading research-intensive universities. The Group was established in 1994 to promote excellence in university research and teaching. Each member undertakes diverse and high-quality research, while ensuring excellent levels of teaching and student experience. www.1994group.ac.uk
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