The influence of the Arctic Oscillation on the atmospheric moisture budget

We exploit the underutilized daily precipitable water retrievals from TOVS along with NCEP-NCAR reanalysis wind fields to create a high resolution Arctic atmospheric moisture budget data set. The products include daily fields of precipitable water, precipitable water flux, and net precipitation from October 1979 to December 1998. Using the Arctic Oscillation (AO) as a proxy for daily and interannual wind variability, we find significant wind-driven variability in both precipitable water fluxes and net precipitation.

In winter, high AO periods accentuate the poleward precipitable water transport and Arctic convergence pattern seen in the seasonal mean. We compute statistically significant positive net precipitation differences between high and low AO days over most of the Arctic. Over the Arctic basin as a whole, net precipitation is 29% greater on high AO days and 20% lesser on low AO days. In summer, during high phase AO periods, the cyclonic circulation present in the seasonal and monthly mean is strengthened. Increased PW transport into and throughout the Arctic accompanies this strengthened circulation. Correspondingly, net precipitation increases rather uniformly throughout the Arctic on high AO days (12% greater than the 18-year mean). Year-to-year variations of the frequencies of high and low AO days explain significant interannual variability of the moisture budget during both the winter and summer seasons.