The Possible Influence of Arctic Sea Ice on the Precipitation Distribution Pattern of July in East of Northwest China

Abstract

Using the observed precipitation data of 154 meteorological stations in East of Northwest China， NCEP/NCAR atmosphere reanalysis and Arctic sea ice data from 1961 to 2020， the possible impacts and mechanisms of the key area Arctic sea ice on the main distribution mode of precipitation in July during the main flood season in East of Northwest China was analyzed using SVD and other climatic statistic methods.The results show that there are two mainly sea ice modes influencing the distribution pattern of precipitation anomaly in July in East of Northwest China.One is that when the sea ice density in the Barents Sea and the Kuril Islands is relatively small （large）， and that in Davis Strait is relatively large （small）， wave trains propagating southeastward from the Davis Strait and southwestward from the Sea of Okhotsk are stimulated， resulting in the anomaly field of "high in the west and low in the east" （"low in the west and high in the east"） at the 500 hPa geopotential height anomaly field over the East of Northwest China， which leads to the regional precipitation anomaly exhibiting a "consistent less （more）" pattern.The other is that when the sea ice density in the eastern part of the Beaufort Sea is relatively small， the wave train from the Caspian Sea to the Okhotsk Sea is stimulated and matched with the positive geopotential height anomaly over South China， making the cold air path eastward and southward， as well as the subtropical high stronger， which together lead to the precipation characterized by "less in the north and more in the south"， on the contrary， the pattern of precipitation anomaly is reversed.The prediction model， which is established with sea ice in key areas as the prediction factors derived by “SVD projection method”， has certain prediction ability for grasping the precipitation anomaly trend and the spatial distribution pattern of the main flood season in July in East of Northwest China， especially for the "regional consistent less type" and "north more and south less type".

Keywords

• east of northwest china
• precipitation in flood season
• arctic sea ice
• prediction model