Historical analogues of the 2008 extreme snow event over Central and Southern China

We used weather records contained in Chinese historical documents from the past 500 yr to search for extreme snow events (ESEs) that were comparable in severity to an event in early 2008, when Central and Southern China experienced persistent heavy snowfall with unusually low temperatures. ESEs can be divided into 3 groups according to the geographical coverage of snowfall, using the following criteria to define an ESE: >15 snowfall days, 20 snow-cover/icing days, and 30 cm total cumulated snow depth for an individual winter. The first group covers the whole of Eastern China (East of 105 degrees E), and ESEs occurred in 1654, 1660, 1665, 1670, 1676, 1683, 1689, 1690, 1700, 1714, 1719, 1830-32, 1840, 1877 and 1892; the second group is located mainly in the area south of Huaihe River (similar to 33 degrees N), and ESEs occured in 1694, 1887, 1929, and 1930; and the third group is confined within the central region between Yellow River and Nanling Mountain (roughly 26 degrees to 35 degrees N), and ESEs occurred in 1578, 1620, 1796, and 1841. We also examined the relationship between ESE occurrence and the temperature regimes within the 500 yr period. From the 20th century reanalysis data set of global atmospheric circulation available since 1871, we found a close association between the ESEs and the anomalous 500 hPa geopotential heights. This study presents cases of extreme winter snowfall occurring because of natural variability in global atmospheric circulation that can be used for paleo-climatology simulations and provide clues to understanding future extremes over China.