摘要
利用青藏高原东北侧区域平均降水量资料（１９５８～１９９７年）和同期ＮＣＥＰ／ＮＣＡＲ再分析５００ ｈＰａ网格资料（２．５°ｘ ２．５°），分析发现：（１）高原东北侧汛期降水份额最大的７、８、９月３个月近４０年降水明显减少，过去明显存在的准３年周期振荡８０年代以来处于低潮；（２）日本—北太平洋附近位势高度降低，鄂霍茨克海阻高加强是高原东北侧７、８、９月干旱最典型的标志；（３）就干旱流型而言，７月干旱环流与江淮梅雨环流特征十分相似，表现在江淮多梅雨年，一般是高原东北侧重旱年；（４）高原东北侧７～９月的典型旱年流型，实际就是 ＥＩ Ｎｉｎｏ流型；（５） ＥＩ Ｎｉｎｏ事件对高原东北侧降水有明显影响，表现在该区域典型少雨年，一般发生于 ＥＩ Ｎｉｎｏ事件当年。从阶段看，以 ７～９月降水总量与 ＥＩ Ｎｉｎｏ事件相关最为显著，从月际看，尤以 ９月关系最好。
The NCEP / NCAR reanalysis monthly 500 hPa grid data (2.5°x 2.5°Lat / Lon) and the monthly precipitation of the Tibetan Plateau Northeastern side from 1958 to 1997 are used and analyzed. The results show that: (l) The precipitation for the recent fourly years is obviously decreased in July, August and September when the precipitation is most concentrated. And the quasi-three year period oscillation, which distinctly existed in the past years, has been in low phase since the 1980s in the Tibetan Plateau Northeastern side. (2) It is the most typical drought indicator in July, August and Sep- tember of the Tibetan Plateau Northeastern side that the reduction of geopotential height near Japan to the northern Pacific and the intensification of Okhotsk blocking high. (3) For the drought flow patterns, the circulation of the drought years is very similar to that of the Changjiang-Huaihe Meiyu in July. In general, the heavy drought years occur in the Tibetan Plateau northeastern side when the rainy years occur in the Changjiang-Huaihe river basin. (4) The typical flow patterns during July to September for drought years in the Tibetan Plateau northeastern side are actually the EI Nino patterns. (5) The EI Nin o events have evident influence on the precipitation in the Tibetan Plateau northeastern side, i.e., the typical drought years usually appear in the EI Nino events years. In view of the time stage, the total precipitation during July to September is most closely correlated to the EI Nino events, and the relationship is most notable in September.
出处
《大气科学》
CSCD
北大核心
2000年第6期775-784,共10页
Chinese Journal of Atmospheric Sciences
基金
国家"九五"重中之重项目! 96-908-05-03
甘肃省气象局科研项目! 98-04
关键词
青藏高原
降水
流型
厄尔尼诺
Tibetan Plateau
precipitation
flow pattern, EI Nino
