On the Variability and Increasing Trends of Heat Waves over India

P Rohini,M Rajeevan,A K Srivastava

doi:10.1038/srep26153

P Rohini, M Rajeevan + Show 1 more

Open Access

https://doi.org/10.1038/srep26153

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Abstract

Over India, heat waves occur during the summer months of April to June. A gridded daily temperature data set for the period, 1961–2013 has been analyzed to examine the variability and trends in heat waves over India. For identifying heat waves, the Excess Heat Factor (EHF) and 90th percentile of maximum temperatures were used. Over central and northwestern parts of the country, frequency, total duration and maximum duration of heat waves are increasing. Anomalous persistent high with anti-cyclonic flow, supplemented with clear skies and depleted soil moisture are primarily responsible for the occurrence of heat waves over India. Variability of heat waves over India is influenced by both the tropical Indian Ocean and central Pacific SST anomalies. The warming of the tropical Indian Ocean and more frequent El Nino events in future may further lead to more frequent and longer lasting heat waves over India.

Highlights

Climatological normal of maximum and minimum temperatures for the period 1971–2000 was calculated for each station
Since there were no appreciable differences in the results, we have considered the results based on the HADISST and NCEP-NCAR reanalysis data sets for discussions
The Daily Mean Temperature (DMT) averaged over a three-day period is compared against a climate reference value to characterize this index

Summary

Introduction

This data set was developed using daily minimum (nighttime) and maximum (daytime) temperature data from 395 synoptic stations spread uniformly over the country. Climatological normal of maximum and minimum temperatures for the period 1971–2000 was calculated for each station. For analyzing the physical relationships of heat waves with atmospheric and ocean parameters, we have used different climate data sets. Since there were no appreciable differences in the results, we have considered the results based on the HADISST and NCEP-NCAR reanalysis data sets for discussions.

Results

Conclusion