Biography
Biography: Weihong Qian
Abstract
The study of general circulation has a long history since Halley (1686) and Hadley (1735) to Maury (1855) and Ferrel (1856), from the single-cell model, the two-cell model, and to the three-cell model. In 1921, V. Bjerknes proposed the four-cell model based on his theoretical speculation. Using four sets of reanalysis products and a climate model simulation, the four-cell model has been confirmed through zonally averaged calculation from basic atmospheric variables. The fourth cell located over the two polar areas is respectively named as the Arctic cell in the Northern Hemisphere (NH) and the Antarctic cell in the Southern Hemisphere (SH). The Hadley, Ferrel, Polar, and Arctic/Antarctic cells exist in each hemisphere but their intensities vary from day to day and from month to month.
In the NH, the strengthening and broadening trends of the Hadley cell have been revealed, while the existence of the Arctic cell has also been confirmed in previous studies (Qian et al., 2015a,b; 2016a,b). Qian et al. (2016b) and Qian (2017) extended previous strengthening trend analysis of the Hadley cell to the Polar and Arctic cells in the NH and explored their climate influences. The results showed that the Polar cell experienced an abrupt change from a slow to a rapid strengthening trend in 1989, while the Arctic cell showed an insignificant strengthening trend and a significant weakening trend successively. The strengthening subsidence associated with the Polar and Arctic cells can partly explain the warming surface air temperature (SAT) and declining sea ice concentration (SIC) in the NH, through the increasing tropospheric height and temperature trends.