Multidecadal variability of dust activity in Gobi desert and its connection with the pacific decadal oscillation

Abstract

The multidecadal changes of dust column mass density (DCMD) in Gobi desert (GD) in spring are investigated based on the Modern-Era Retrospective analysis for Research and Applications version 2 dataset. In addition, the possible effects of the atmospheric circulation and sea surface temperature (SST) forcing on the multidecadal changes are analyzed. Results show that the dust aerosol over GD experienced a decadal change in 1999 with about 30% higher dust loading during 2000–2013 in comparison to that during 1987–1999. Further analysis indicates that the decadal change of dust aerosol over GD is attributed to the more strengthened northwesterly wind anomaly extending from lower to middle troposphere and the anticyclonic anomaly in middle troposphere over GD during the latter epoch, which is favorable to the increase of local dust activities. Furthermore, the decadal change of DCMD in GD is associated with the switch of Pacific Decadal Oscillation (PDO) phase. From 2000 to 2013, the PDO was in the negative phase, which induced to a positive potential height anomaly and northwesterly wind anomalies in the middle troposphere over GD. The dry and cold air brought by the anomalous northwesterly wind associated with the negative PDO phase reduces the relative humidity in the lower troposphere further amplify the effect of strengthened wind speed, being favorable for the increase of local dust loading and the resultant increase of DCMD there.