Work package 2 – Comparison with available gridded/re-analysed precipitation products such as remote sensing products for precipitation magnitude or snow cover (Resp: D. Aryal, D. Shrestha)
The available reanalysis precipitation products such as ERA-interim, ERA-5, MERRA, APHRODITE, NCEP, HAR, CRU etc. are derived from low altitude meteorological stations at resolutions generally coarser than tens of kilometres (depending on the products). Satellite data are also used to produce gridded datasets for precipitation (Tropical Rainfall Measuring Mission TRMM, 25km resolution; GSMaP, 0.1° resolution, IMERG, 0.1° resolution; CMORPH, 0.08° resolution), and for snow cover extent, generally available at higher resolution ( 1km or less, e.g MODIS, Sentinel, resolution depending on the product). These re-analysed or satellite-based datasets over high altitude Himalayan basins require field-based validation which has been seldom done5, . These available datasets are not able to capture the spatial and temporal variability of precipitation at high elevation13, . The WATER-HIMAL precipitation network at high elevation will allow the validation or calibration of available precipitation gridded datasets and will be of prime importance in developing the hydrological models for runoff estimates at higher confidence level.
Khadka et al.9 already compared in-situ meteorological variables collected by stations with reanalysis data such as ERA-5 data and HAR data18. More specifically in WATER-HIMAL, any precipitation products will be analysed and compared to field measurements. D. Shrestha has a recognized expertise in precipitation satellite products like TRMM precipitation in the Himalayas. For instance, the study of Shrestha et al. will be extended over a period of more than 20 years compared to 11 years in the initial study, with an extensive comparison with in-situ data, and any other relevant precipitation products. In addition, training on processing of MODIS, Sentinel images for the assessment of snow cover extent, and evaluation of available satellite, and re-analysis precipitation products will be carried out.

Updated on 8 April 2022