Reconstruction of Northern Hemisphere 500?hPa geopotential heights back to the late 19th century |
| |
Authors: | D-Y Gong H Drange Y-Q Gao |
| |
Institution: | (1) Key Laboratory of Environmental Change and Natural Disaster, College of Resources Science and Technology, Beijing Normal University, Beijing, China;(2) Bjerknes Center for Climate Research/Nansen Environmental and Remote Sensing Center, University of Bergen, Norway;(3) Nansen-Zhu International Research Center, IAP, Beijing, China |
| |
Abstract: | Summary In this study the authors have developed a statistical method and have reconstructed Northern Hemisphere 500 hPa heights back
to the late 19th century using one temperature and three sea level pressure (SLP) data sets. First, the relationship between
ERA40 500 hPa heights and surface temperature and SLP was screened using stepwise multiple regression based on the calibration
period of 1958–2002 (1998/2000 according to the availability of SLP data). All selected predictors (temperature and SLP) were
significant and their variance contribution was greater than 1%. On average, there were 8.1 variables retained in the final
regression equations. Second, the regression equations were applied to compute the 500 hPa height through to the late 19th
century for the whole Northern Hemisphere. As the SLP and temperature coverage improved over time, the number of predictors
decreased by about 1 in the most recent periods, and the root mean squared error decreased by about 0.8 m. A leave-one-out
cross-validation method was used to test the skill and stability of the regression models. The reduction of error during the
cross-validation period of 1958–1997 varied from 0.33 to 0.56, depending on the SLP data. Reconstructions were also checked
using NCEP/NCAR 500 hPa heights from January 1949 to December 1957, and compared with the historical reconstruction over Europe.
Reconstructions show high consistency with these independent data sets. Generally, the reconstruction provides a valuable
opportunity to analyze, as well as to validate climate simulations of the variability in free atmosphere circulations over
the past one hundred years. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|