基于ERA-Interim资料分析青藏高原“湿池”变化特征

The Characteristics of the Moist Pool over the Tibet Plateau Based on ERA-Interim Data

论文利用ERA-Interim(0.5°×0.5°,简称ERA)、NCEP/NCAR2(2.5°×2.5°,简称NCEP2)两种不同分辨率的再分析资料和探空观测资料,首先分析了夏季(7月)和冬季(1月)青藏高原(以下简称高原)上大气水汽含量大值区(简称"湿池")的区域分布特征,然后基于ERA资料分析了1979—2012年间高原"湿池"的一些变化特征,发现了一些新的事实。主要结果包括:在对流层中上层,高原上无论夏、冬季都有大气水汽含量的高值中心——高原"湿池"存在。夏季7月高原"湿池"强度最强,ERA资料除了在高原南部有自西到东的连续高湿中心带外,在高原西北部还有一个高湿中心;NCEP2资料仅在高原东南部和西南部有两个高湿中心。冬季1月,两种资料均只在高原东南部有高湿中心。总体上,ERA资料与探空观测资料的高湿中心区更为接近。7月,高原南部高湿中心在1990年代中期(1994—1996年)之后持续偏强,西北部中心强度有弱—强—弱—强交替变化特征;1月,高湿中心在1980年代末期开始持续偏强。高原南部高湿中心带在7月几乎是一个连续的区域,1996年以后这一特征更为明显,在1月则是分为东西两段的高湿中心带。

The regional distribution characteristics of high precipitable water vapor centers(the Moist Pool) over the Tibet Plateau are analyzed with two reanalysis datasets of ERA- Interim(0.5° × 0.5°) and NCEP/NCAR2(2.5° × 2.5°) and sonde observation data. Then the variation characteristics of the Moist Pool are analyzed by using ERA data, and some new facts are found. The high water vapor centers, which are the Moist Pools, exist both in summer(July)and winter(January) in the middle-upper layer of troposphere. The Moist Pool has the strongest intensity in July. In addition to the existence of continuous wet centers of precipitable water vapor over the southern highlands of the Plateau, there is a wet center over the northwestern part of the Plateau as shown by ERA data. But NCEP2 data show that wet centers only exist over the southeastern and southwestern areas of the Plateau by. In January, both data show there are wet centers only over the southeast of the Plateau. In general, the wet centers shown by the ERA data is more close to those detected by sonde observation. The intensity of the centers over the southern highlands has kept been strong since the mid- 1990s(1994- 1996),while the northwest center has alternately been weak- strong- weak- strong. In January, the centers have continuously been strong since the late1980 s. The high water vapor centers over the southern region of the Plateau are almost a continuous area in July, and this feature is more obvious since 1996, but there are two wet zones in January.