About the observed and future changes in temperature extremes over India |
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Authors: | J V Revadekar D R Kothawale S K Patwardhan G B Pant K Rupa Kumar |
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Institution: | (1) Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India;(2) World Meteorological Organization, Geneva, Switzerland |
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Abstract: | An attempt is made in the present study to analyse observed and model simulated temperature extremes over Indian region. Daily
maximum and minimum temperature data at 121 well-distributed stations for the period 1970–2003 have been used to study the
observed changes in objectively defined values of temperature extremes. In addition, an assessment of future scenarios of
temperature extremes associated with increase in the concentration of atmospheric greenhouse gases is done using simulations
of a state-of-the-art regional climate modelling system known as PRECIS (Providing Regional Climate for Impact Studies) performed
to generate the climate for the present (1961–1990) and future projections for the period 2071–2100. Observational analysis
done with 121 stations suggests the widespread warming through increase in intensity and frequency of hot events and also
with decrease in frequency of cold events. More than 75% stations show decreasing trend in number of cold events and about
70% stations show increasing trend in hot events. Percentage of stations towards the warming through intensity indices of
highest maximum temperature, lowest minimum temperature is 78 and 71% stations, respectively. Remaining stations show opposite
trends, however, most of them are statistically insignificant. Observational analysis for India as a whole also shows similar
results. Composite anomalies for monthly temperature extremes over two equal parts of the data period show increase (decrease)
in the frequency of hot (cold) events for all months. In general, PRECIS simulations under both A2 and B2 scenarios indicate
increase (decrease) in hot (cold) extremes towards the end of twenty-first century. Both show similar patterns, but the B2
scenario shows slightly lower magnitudes of the projected changes. Temperatures are likely to increase in entire calendar
year, but the changes in winter season are expected to be prominent. Diurnal temperature range is expected to decrease in
winter (JF) and pre-monsoon (MAM) months. |
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