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871.
Abdullah M. S. Al-Amri 《Geophysical Journal International》1999,136(2):421-430
872.
台风移动规律的研究 Ⅰ.非绝热加热与水平温度分布的影响 总被引:1,自引:1,他引:0
根据大气运动原始方程组导出一个支配台风中心移动的基本方程。方程中包括了非绝热加热、温度场分布、地形与摩擦等各种可能影响台风移动的强迫因子。对非绝热加热与水平温度分布的作用所作分析表明,非轴对称的非绝热引导作用可使台风加速、减速或转向运动;温度场上的冷区对台风有吸引作用。 相似文献
873.
The midwinter suppression(MWS) of the North Pacific storm track(NPST) has been an active research topic for decades. Based on the daily-mean NCEP/NCAR reanalysis from 1948 to 2018, this study investigates the MWS-related atmospheric circulation characteristics in the Northern Hemisphere by regression analysis with respect to a new MWS index, which may shed more light on this difficult issue. The occurrence frequency of the MWS of the upper-tropospheric NPST is more than 0.8 after the mid-1980 s. The MWS is accompanied by significantly positive sea-level pressure anomalies in Eurasia and negative anomalies over the North Pacific, which correspond to a strengthened East Asian winter monsoon. The intensified East Asian trough and atmospheric blocking in the North Pacific as well as the significantly negative low-level air temperature anomalies, lying upstream of the MNPST, are expected to be distinctly associated with the MWS. However, the relationship between the MWS and low-level atmospheric baroclinicity is somewhat puzzling.From the diagnostics of the eddy energy budget, it is identified that the inefficiency of the barotropic energy conversion related to the barotropic governor mechanism does not favor the occurrence of the MWS. In contrast, weakened baroclinic energy conversion, buoyancy conversion, and generation of eddy available potential energy by diabatic heating are conducive to the occurrence of the MWS. In addition, Ural blocking in the upstream region of the MNPST may be another candidate mechanism associated with the MWS. 相似文献
874.
875.
北半球中纬度地区上层臭氧变化的合成分析研究 总被引:1,自引:1,他引:0
应用逆转方法(C),对北半球中纬度地区8个观测质量较好的O3地面站的近30年地面遥感逆转资料进行标准处理。采用合成分析方法,对中纬度带上层O3进行了分析研究,发现上层O3总的长期演变趋势较为平坦,仅80年代初及90年代初在36km以上层O3含量有突降现象。这可能与EL Chichon大火山焊发和Pinatubo大火山爆发有较大关系。此外。在上层O3含量的长期演变过程中,还可看到准11年周期,并证实28~36km层及36km以上层O3含量季节变化位相相反。本研究结果可能对南极O3洞的形成机制及近年来O3层变浅薄的机制的认识提供依据并产生影响。
相似文献
876.
877.
Vertical and cross-wind profiles of mean currents were measured systematically in vertical cross-sections of two wind-wave
tanks with aspect ratios of order one to study the secondary flow in the tanks. A pair of Langmuir cells turned out to be
driven by a close combination of the pressure gradient along the tank and the side-wall effects. That is, part of the adverse
pressure gradient produced a parabolic cross-wind profile with the smallest downwind current at the centerline and the largest
current along the two sidewalls. As a result, upwelling occurred in the center zone where the return flow was strongest, probably
because of the entrainment action of the wind-driven current. In order to compensate for this upwelling, downwelling occurred
along the two side-walls from the flow continuity. The resulting vertical circulation formed a pair of Langmuir circulations
across the span and served to maintain the parabolic profile formed by the pressure gradient. A positive feedback mechanism
is thus found between the primary and secondary circulations through upwelling of the return flow in the center zone. Vertical
shears of the span-averaged downwind current measured in two tanks were found to be systematically different from each other.
This difference seems to depend on the magnitude of the advective Reynolds stresses in the two tanks. 相似文献
878.
利用CMIP5的15个全球气候系统模式对东亚及周边地区(70~150°E,0°~60°N)地面气温的回报结果进行超级集合(简称SUP)试验,以欧洲中期天气预报中心ERA逐月气温资料作为观测值,并采用均方根误差(RMSE)、距平相关系数(ACC)、绝对误差(MAE)对多模式集合平均(EMN)以及超级集合(SUP)的回报结果进行检验和评估。结果表明,超级集合回报结果一定程度上取决于训练期的长度。随训练期长度的增加,距平相关系数呈增大的趋势,均方根误差呈减小的趋势,但训练期达到一定长度后,误差不再有明显的减小,甚至出现误差增长。15个全球气候系统模式对东亚及周边地区的地面气温具有一定的回报能力,可以较好地回报出地面气温的年际变化和空间分布,海洋上回报的均方根误差小于陆地。但不同模式回报的结果不尽相同,在单模式中CCSM4对地面气温的回报效果最好。多模式集成的回报效果优于单模式的回报效果,SUP的回报效果优于EMN,其区域平均的均方根误差比多模式集合平均小0.43℃,超级集合极大地改善了地面气温的回报效果。 相似文献
879.
Based on the analysis of NCEP height, wind and OLR data, the influence of spring equatorial
eastern Pacific SSTA on the seasonal change from spring to summer of eastern Asian circulation has been
investigated. Results show that related to the warm (cold) spring SSTA in the equatorial eastern Pacific, the
anomalous anticyclone (cyclone) circulation emerges around the South China Sea and the Philippines, the strong
(weak) west Pacific subtropical high locates to the west (east) of its normal position, which induces to the late
(early) onset of the South China Sea monsoon. The numerical simulations have also shown that the remarkable
influence of spring SSTA in the equatorial eastern Pacific on the spring seasonal change of eastern Asian
circulation will last till summer. 相似文献
880.