Relationship between large scale atmospheric circulation, temperature and precipitation in the Extensive Hexi region, China, 1960–2011

This study investigates the relationship between large scale atmospheric circulation and changes in temperature and precipitation within the Extensive Hexi region during the period 1960–2011. This was accomplished by statistically analyzing data from 26 meteorological stations along with monthly mean geopotential height, wind fields at 500 hPa, SLP data and the NCEP/NCAR reanalysis data set. The variation of large scale atmospheric circulation has contributed greatly to regional warming, especially via the increasing geopotential height. Regional warming is further caused by increased anticyclonic circulation in the summer and increased anomalous cyclonic circulation and westerly currents in winter. The strong convergence of water vapor in part explained the precipitation increase. Additionally, warm and wet flow moving to the north and west brought more precipitation under the strong western pacific subtropical high. Moreover, precipitation and precipitation extremes showed positive anomaly in the La Nina I and El Nino I years, whereas they displayed negative anomalies in the La Nina II and El Nino II years.