Temperature over the Himalayan foothill state of Uttarakhand: Present and future

Abstract

Uttarakhand, a hill state of India, covers an area of 51,125 km ². The geographic position is highly crucial with in the Central Himalayas (CH), for agro-climate, water resource management, food-processing, tourism, etc., having enriched bio-diversity and forest. Present study investigates the spatio-temporal characteristics and distribution of temperature of Uttarakhand state. Observation and model (under different Representative Concentration Pathways (RCPs) at radiative forcing 2.6, 4.5 and 8.5 W/m ²) temperature fields are studied to assess the present and future trends. Standard temperature fields from AphroTemp, Climate Research Unit (CRU) and ECMWF Reanalysis-Interim (ERA-Interim) are used. Attempt is to find orographic responses on the surface temperature at seasonal scale. Elevation dependent warming (EDW) is higher at higher elevations as compared to lower elevations. In particular, it reaches to maximum during Indian summer monsoon months (JJAS) as estimated from AphroTemp during 1970–2007. Munsiyari region experiences highest warming rate by 0.038°C/decade. Elevational temperature trends show higher increase with statistical significance at 99% confidence level from <500 to 3000 m elevation belt during JJAS. For elevation >3000 m, highest warming trend is observed during MAM. Further, temperature trends analysed using one of the regional climate models REMO of the CORDEX-SA suite, depict an increase by 0.019°C/yr. Future temperature trends under RCP2.6, RCP4.5 and RCP8.5 show warming trends by 0.008°, 0.022°, and 0.064°C/yr, respectively.