A possible recovery of the near-surface wind speed in Eastern China during winter after 2000 and the potential causes

A lasting decrease in the near-surface wind speed (SWS) in China has been revealed, but a following short-term strengthening in the SWS was rarely noted. In this paper, the daily mean SWS observed datasets from 328 measurement stations in Eastern China during the period 1981-2011 were used to investigate the facts and causes of the observed short-term strengthening in winter SWS in recent decades. The major results are summarized as follows: the SWS showed a significant decrease in the last 30years, but a short-term strengthening in SWS was observed during the winter since 2000 in Eastern China. The SWS in Eastern China showed a significant decrease of -0.11ms(-1)decade(-1) from 1981 to 1999, followed by a weak increase of 0.0008ms(-1)decade(-1) from 2000 to 2011. The short-term strengthening in the SWS since 2000 was mainly induced by the changes of the pressure-gradient force (PGF), which could be attributed to the changes of the sea-level pressure (SLP) in the region (51 degrees-69.75 degrees N, 51.75 degrees-111.75 degrees E). Furthermore, the changes of the PGF during the two periods of 1981-1999 and 2000-2011 were consistent with those of the SLP in the region (51 degrees-69.75 degrees N, 51.75 degrees-111.75 degrees E). The correlation coefficient between PGF and SLP was 0.32 and 0.66 during the period 1981-1999 and 2000-2011, respectively. Therefore, the effects of the changes in SLP over the region (51 degrees-69.75 degrees N, 51.75 degrees-111.75 degrees E) on changes of SWS in the Eastern China should be significant.