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利用由美国NOAA系列卫星观测的OLR资料研究了影响华东地区热带气旋年频数(记为ATC)与热带对流场的关系,结果表明两者存在密切的联系:(1)当华东地区热带气旋年频数ATC为异常偏多(少)时,ITCZ位置累积距平为正(负)值,即ITCZ位置异常偏北(南);(2)利用OLR设计了Walker综合指数WI,该指数的强弱可以反映ATC的异常情况,即当ATC为异常偏多(少)时,walker环流圈异常强(弱);(3)OLR距平累积量场能较好的表征ATC异常年份所对应的低纬度及中高纬地区大气环流的配置,其可以作为预测影响华东地区热带气旋年频数的强信号。 相似文献
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热带气旋路径集合预报方法研究Ⅰ——正压模式结果的初步分析 总被引:2,自引:4,他引:2
选择1979~1993年间的热带气旋为试验个例,通过扰动热带气旋初始位置和初始结构,构造集合成员, 用正压原始方程模式,进行路径集合预报试验, 并初步探讨预报成员的集合方法。试验结果表明:热带气旋定位误差影响路径预报,但扰动初始位置的集合平均预报与控制试验的预报水平相接近。扰动热带气旋初始结构的集合预报试验表明,约有60 %~70 %个例的集合路径预报得到改进。此外,试验结果还表明,当环境引导气流较弱时,进行扰动热带气旋初始结构的集合预报,预报结果的改善较明显。 相似文献
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THE ENSEMBLE FORECASTING OF TROPICAL CYCLONE MOTION I:USING A PRIMITIVE EQUATION BAROTROPIC MODEL 总被引:2,自引:1,他引:2
1INTRODUCTIONErrorsofnumericalforecastingcomprisethoseintheinitialvalue,modelandcomputationandthefirstkindoferrorbecomesmoreandmoreoutstandingwiththeon-goingdevelopmentofcomputersandnumericalmodels.Subjecttoavailableobservationmeans,therealatmosphereisanythingbutapproximatelymeasured.Meanwhile,oneshouldpayattentiontothepossibility,assuggestedbyLorenz[1],thatanyslightdifferencesduringtheinitialstatemayleadtoresultsthatturnouttobetotallydissimilarfromwhatwouldbeexpectedotherwise,asfarasdefi… 相似文献
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利用NOAA提供的逐月欧亚大陆雪盖面积指数资料,分析了欧亚大陆雪盖月际动态演变特征,结果表明其月际动态演变特征非常复杂,且具有明显的年代际和年际变化,此外,还初步探讨了其与后期区域气候的关系。 相似文献
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The purpose of this study is to investigate the effectiveness of two different ensemble forecasting (EF) techniques–the lagged-averaged forecast (LAF) and the breeding of growing modes (BGM). In the BGM experiments, the vortex and the environment are perturbed separately (named BGMV and BGME). Tropical cyclone (TC) motions in two difficult situations are studied: a large vortex interacting with its environment, and an apparent binary interaction. The former is Typhoon Yancy and the latter involves Typhoon Ed and super Typhoon Flo, all occurring during the Tropical Cyclone Motion Experiment TCM- 90. The model used is the baroclinic model of the University of New South Wales. The lateral boundary tendencies are computed from atmospheric analysis data. Only the relative skill of the ensemble forecast mean over the control run is used to evaluate the effectiveness of the EF methods, although the EF technique is also used to quantify forecast uncertainty in some studies. In the case of Yancy, the ensemble mean forecasts of each of the three methodologies are better than that of the control, with LAF being the best. The mean track of the LAF is close to the best track, and it predicts landfall over Taiwan. The improvements in LAF and the full BGM where both the environment and vortex are perturbed suggest the importance of combining the perturbation of the vortex and environment when the interaction between the two is appreciable. In the binary interaction case of Ed and Flo, the forecasts of Ed appear to be insensitive to perturbations of the environment and/or the vortex, which apparently results from erroneous forecasts by the model of the interaction between the subtropical ridge and Ed, as well as from the interaction between the two typhoons, thus reducing the effectiveness of the EF technique. This conclusion is reached through sensitivity experiments on the domain of the model and by adding or eliminating certain features in the model atmosphere. Nevertheless, the forecast tracks in some of the cases are improved over that of the control. On the other hand, the EF technique has little impact on the forecasts of Flo because the control forecast is already very close to the best track. The study provides a basis for the future development of the EF technique. The limitations of this study are also addressed. For example, the above results are based on a small sample, and the study is actually a simulation, which is different than operational forecasting. Further tests of these EF techniques are proposed. 相似文献
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非对称的非绝热加热对热带气旋移动影响的数值研究 总被引:18,自引:3,他引:15
采用中尺度数值模式(MM4),以9414号台风为个例,应用卫星资料,引入非对称的非绝热加热,讨论其对9414号台风移动的影响。计算结果表明,引入与实况吻合的非对称非绝热加热分布后,该台风的路径预报和降水预报有明显改进,若同时考虑台风范围初始水汽场的非对称分布,这种改进作用尤为明显。从业务应用考虑,还构造了几种典型的螺旋状结构的非绝热加热计算方案引入模式的热力过程中,结果表明:不同螺旋状结构的加热分布对台风的移动有不同的影响,当选择与实况云系分布相近的螺旋状结构时,也可提高台风路径预报正确率,可应用于业务模式。 相似文献
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