Author(s): Nehar Mandal; Kironmala Chanda
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Abstract: Arctic rivers contribute a large part of the global freshwater discharge into the Arctic Ocean although the later comprises of a very small fraction of the global ocean volume (Wang et al., 2025). The present study investigates the terrestrial water balance (WB) of two major Arctic river basins, the Ob and the Lena. The Ob river basin is one of the largest Arctic-draining basins, covering approximately 30,00,000 km², with headwaters in the Altai Mountains and drainage northward into the Kara Sea. The Lena river basin, drains an approximate area of 25,00,000 km² and flows into the Laptev Sea. In the current study, the monthly water balance components – precipitation (Pr), evapotranspiration (ET), change in storage (dS) and runoff (RO) – from multiple satellite, reanalysis and land-surface model products are utilized to examine the basin scale water balance of the aforementioned Arctic basins during the period 2003 to 2020. Gridded Pr data are obtained from Global Precipitation Climatology Centre (GPCC), Global Precipitation Climatology Project (GPCP), Integrated Multi-satellitE Retrievals for GPM (IMERG), Multi-Source Weighted Ensemble Precipitation (MSWEP), Multi-Source Weather (MSWX), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) and TerraClimate. Further, gridded ET data are obtained from fifth-generation ECMWF reanalysis (ERA5), the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System (FLDAS), the NASA Global Land Data Assimilation System (GLDAS), the Global Land Evaporation Amsterdam Model (GLEAM), Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA2) and TerraClimate. Four post processed versions of dS products from GRACE: CSR (Center for Space Research), GFZ (GeoforschungsZentrum Potsdam), JPL (Jet Propulsion Laboratory), and JPL-Mascons are used. Additionally, the recently reconstructed GRACE like dataset (BNML TWSA) developed by Mandal et al. (2025) has been used in this study as a fifth dS product and also for filling the data gaps in the GRACE based products. For the RO data, ERA5, FLDAS, MERRA2 and TerraClimate are used in this study. The multiple gridded data products used here are available at different spatial resolutions; the basin average of all the grids falling with the study basins are considered. Figure 1 shows the location of the study basins Lena and Ob along with the median monthly water balance residuals (from eq 1) calculated from the screened ensemble dataset.
Year: 2026