Moisture budget of the Arctic atmosphere from TOVS satellite data

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Abstract
The Arctic atmospheric moisture budget is an important component of the Arctic climate system, and moisture transport is a major mechanism by which both local and hemispheric atmospheric processes affect the Arctic Ocean. The lack of humidity data over the Arctic Ocean severely hampers present understanding of climatological and time‐varying features of the Arctic moisture budget. We combine daily satellite precipitable water retrievals from the NASA/NOAA TIROS Operational Vertical Sounder (TOVS) Polar Pathfinder data set with wind fields from the NCEP‐NCAR Reanalysis to create a new high‐resolution data set of the Arctic atmospheric moisture budget from October 1979 to December 1998. Products are at a horizontal resolution of (100 km)2 and include daily fields of precipitable water and precipitable water flux profiles at 16 vertical levels and net precipitation (i.e., precipitation minus evaporation, P‐E). We show that these retrievals compare well with rawinsonde‐derived moisture transport and reanalysis products, yet capture spatial and temporal variability that other data sets cannot owing to the sparse coverage of the conventional observation network in the Arctic Ocean. Our method yields an average annual net precipitation of 15.1 cm yr−1 over the polar cap (poleward of 70°N) and 12.9 cm yr−1 over the Arctic Basin. Poleward moisture transport into the Arctic is greatest from June to August and smallest in December. Over regions of known storm tracks, especially in the North Atlantic sector, we find that transient circulation features account for 32% of the net precipitation in the Greenland‐Iceland‐Norwegian Seas, 90% in the Nansen Basin, and 74% in the Arctic basin as a whole.