An Appraisal of Spatio-Temporal Characteristics of Temperature and Precipitation Using Gridded Datasets over NW- Himalaya

Abstract

Recent reports by IPCC have surfaced the warming trends prevalent over various parts of the globe and more impact was found on high altitude areas like Himalaya. High concentration of glacial masses in the region (Himalaya) underscores the need for climate change studies but such studies are constrained by paucity of observations especially from High Mountains. Gridded datasets offer better spatial and temporal coverage, but they demand rigorous validation prior to their use especially over Himalayan region. Thus our study is a maiden attempt to validate the performance of 08 gridded datasets, i.e. APHRODITE, ERA-I, CRU-TS, TRMM, GPCC, GPCP, NCEP-NCAR and UDEL over North-West Himalaya (NWH) in Indian sub-region and then study of spatio-temporal variability of climate through selected datasets. The salient findings of this study are:

• ERA-I and CRU-TS overpowered other datasets in precisely capturing temperature and precipitation amount and trends over different zones of NWH. ERA-I based values showed lesser bias than CRU-TS which makes ERA-I more reliable than CRU-TS. The spatial distribution of temperature and precipitation was also well captured by both datasets. However, the bias in dataset based values underpins the need for bias correction of these datasets.

• During 30 years (1985–2015), all zones of NWH experienced warming at varying rates which was also captured by both datasets. ERA-I showed higher rate of warming over Lower Himalaya (LH) followed by Great Himalaya (GH) and Karakoram Himalaya (KH) which resonates well with increased urbanization and consequently population rise in LH lately. Increased population and tourist influx could have added to more greenhouse gas (GHG) emissions and consequently more rate of warming. Despite having coarser spatial resolution than ERA-I, long term (1901-present) data availability by CRU-TS highlights its utility. CRU-TS based temperature trends during 1901–1970s were found in agreement to those reported by Bhutiyani et al. (2007) for NWH.

• Temperature and precipitation trends pre and post 2000 revealed comparative slowdown in warming/rate of precipitation decline after year 2000 which was linked with reported findings about increased snow-cover area (SCA) and comparatively less negative glacier mass budget in westerly dominated areas like NWH.