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多种再分析资料中热带气旋潜在生成指数分析 总被引：3，自引：3，他引：0
根据7套再分析资料计算的热带气旋潜在生成指数(GPI),分析了GPI对西北太平洋区域台风盛季(7—9月)热带气旋生成的表征能力。结果表明,虽然这些再分析资料计算得到的GPI的空间分布与观测的热带气旋生成特征都比较一致。但是,在时间变化上7套再分析资料计算的GPI对观测热带气旋生成的表征能力差异较大,其中ERA-40(欧州中期天气预报中心再分析资料)和MERRA(美国国家航空和航天局研究和应用再分析资料)的GPI与观测的相关系数较高。进一步分析表明,各套资料GPI之间时间变化的差异主要来自相对湿度,而ERA-40和MERRA的GPI与观测值有较高的相关系数,也与相对湿度有密切关系。 相似文献
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应用ATOVS资料和非对称Bogus资料对登陆台风韦帕的4DVAR数值模拟分析 总被引：3，自引：1，他引：2
前人研究中BDA方法采用的轴对称Bogus台风不能反映个别台风具体特征并弃掉了背景场的合理成分,也没有考虑大环境场的影响及湿热要素的同化。因此,提出一种充分融合分析场信息和实际观测信息并考虑副高影响的精细非对称台风Bogus方法,并在MM5的伴随同化系统中引入快速辐射传输模式RTTOV8,通过四维变分同化(4DVAR)技术,加入海面风场和气压场Bogus资料及多颗卫星多条轨道上的ATOVS红外和微波卫星辐射亮温资料并考虑Noah陆面过程方案来对登陆台风韦帕进行数值模拟,结果表明,单独同化海面Bogus资料的BDA方案可间接产生初始场非对称三维环流结构和暖心结构,但对湿度场及台风周围大环境场的调整不足,台风登陆后的路径预报改善也不明显;引入陆面过程方案弥补了Bogus资料对台风登陆后路径预报的不足;加入ATOVS资料能对湿度场及台风周围环境场做出调整,重构了大量中尺度结构信息,取得更为精细的初始台风环流和温压湿场结构,保持BDA方案路径及强度预报的优势的同时,使预报的降水强度增加,降水落区发生改变。 相似文献
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热带气旋影响陵水县降水的不同强度特征 总被引：1，自引：1，他引：0
利用1988～2008年《台风年鉴》和《热带气旋年鉴》资料,统计分析近20年来进入陵水县预报警戒区的编号热带气旋,并对比每日4次的2 5.×2 5°NCEP全球再分析资料,对热带气旋影响过程的物理量特征进行诊断分析,找出在热带气旋影响下,陵水产生强降水的一般特征及预报思路.分析结果显示,陵水县降水强弱与热带气旋生成源地... 相似文献
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西北太平洋热带气旋变性过程结构演变及其环境分析 总被引：1，自引：0，他引：1
用气旋相空间方法（Cyclone Phase Space,简称CPS）对58个经历变性过程的西北太平洋热带气旋的2 021个样本（时次间隔为6 h）资料进行分析,得到该区域热带气旋在变性阶段的气旋结构及其环境特征。聚类分析结果显示,强的热带气旋更易发生变性,变性开始于气旋非对称性增加,随之伴有高层冷心出现和加强,最后完成于低层出现冷心,变性维持平均时间约28 h。利用美国国家环境预报中心（NCEP）再分析资料对各聚类环境场的动态合成分析表明,发生变性的热带气旋在北移过程中逐渐嵌入西风带,在中高纬斜压系统影响下变性为温带气旋。对于发生并完成变性的热带气旋,其西北侧始终有明显的位涡梯度存在,而且在环境中有明显的水汽输送通道。 相似文献
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西北太平洋热带气旋频数的年际、年代际变化及预测 总被引：4，自引：0，他引：4
利用1950-2009年60 a的热带气旋资料、NOAA海温、NCEP再分析资料及74项环流指数等资料,研究了西北太平洋热带气旋频数的年际、年代际变化特征,结果表明,西北太平洋热带气旋生成频数既有显著的年际变化,同时也存在明显的年代际变化。自1950年以来,西北太平洋热带气旋频数经历了一个先增加再减少的过程,其中转折点在20世纪70年代中后期,与之相对应,热带气旋路径频数也呈现明显年代际变化。在此基础上,通过分析前期春季海温场、大气环流异常及环流指数与夏季(6-10月)热带气旋生成频数的相关关系,选取了影响夏季西北太平洋热带气旋活动频数的预测因子,建立了一个夏季西北太平洋热带气旋生成频数的多元回归预测模型。检验结果表明,该模型能较好地拟合1951-2003年夏季西北太平洋热带气旋生成频数的年际变化,拟合率为0.6。对2004-2009年夏季热带气旋生成频数的独立样本预测试验表明,该模型对夏季西北太平洋热带气旋活动频数具有较好的预测能力,可以为热带气旋业务预报提供一定参考。 相似文献
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主分量分析在热带气旋强度客观预报中的试用 总被引：3，自引：0，他引：3
为了解主分量因子分析在热带气旋强度客观预报中的应用效能,在NCEP再分析资料、T106L19模式产品和热带气旋历史观测资料基础上,采用主分量因子分析技术,结合多元线性回归和BP型人工神经网络,开展了西北太平洋热带气旋的强度客观预报技术研究试验。试验包含完全预报法原理下的预报因子有无主分量分析、线性与非线性预报方法建模等方面的比较。结果表明,预报因子的主分量分析通过降低线性回归和BP人工神经网络模型的维数,提高因子间独立性,可减小模型强度预报平均绝对误差,提高模型实际预报能力。 相似文献
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1引言纵观近十多年来影响我国的热带气旋所造成的损失，分析各种客观预报模式中出现的大误差样本，主要是由一些为数不多，难度较大的热带气旋所引起的。在这方面，国内外曾做过不少研究，虽然在热带气旋路径的分析与预报方面取得了一定的进展[1-3]，但对路径异常，移速突变的热带气旋效果是不够理想的。众所周知，热带气旋的气候特征是热带气旋分析预报必不可少的参考依据，它本身可作为预报的第一近似值。在资料不足的低纬热带洋面和长期预报中，气候规律尤其重要。在预报热带气旋移动路径时，对当时的环境流场背景和各种影响因素的具体分… 相似文献
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利用雷达回波特征和地面资料确定热带气旋强度 总被引：2，自引：0，他引：2
1引言在热带气旋监测预报中，有经验的预报员，一般都能根据不同热带气旋的回波结构，定性地判断热带气旋强度，但怎样认定性地判断提高到定量地确定热带气旋强度，这个问题，关键在于怎样选择与热带气旋强度有密切关系的回波特征要素和地面资料要素。本文以1983～1993年对影响珠江三角洲附近地区11个热带气旋的雷达回波资料和地面资料，用相关法筛选出6个能描述热带气旋强度的因子，尝试制作一种可用人机结合定量确定热带气旋强度的方法。2选择与热带气旋强度有密切关系的因子根据历年热带气旋各时次强度所对应的雷达回波要素和地面资料要… 相似文献
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该文提出一个热带气旋定量降水预报(QPF) 的动力相似方案。方案应用热带气旋初始参数、历史过程的天气形势场和物理量场及数值预报产品, 构造预报区域内当前时刻至未来时刻环境要素场的多元客观相似判据。通过定义非线性的相似指数综合评估历史热带气旋样本与预报热带气旋在多元判据下的连续动态相似程度, 以此找到相似样本。应用相似样本的历史降水量记录进行相似指数的权重综合, 得到热带气旋未来6~48 h降水量的定点、定量预报值。预报试验表明该方案具有一定的预报技巧。 相似文献
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西北太平洋热带气旋强度变化的若干特征 总被引：2，自引：0，他引：2
使用NOAA海表温度资料、ECMWF再分析资料和JTWC台风最佳路径数据,对1984—2013年30年西北太平洋热带区域（100 °E~180 °,0~60 °N）内热带气旋（TC）的强度变化特征及其与环境风垂直切变（VWS）、海表温度（SST）、最大风速半径（RMW）的关系作了统计分析,尤其关注TC强度突变。结果表明:（1）在研究区域内,TC样本中35.2%强度稳定,52.8%强度变化缓慢,仅12.0%强度突变,约92.7%的迅速加强TC样本发生在其台风及以上强度等级;（2）2000年以来,TC强度稳定样本减少,强度迅速变化样本增多。5月和9—10月是TC强度突变的高频期;（3）超过12 m/s的环境VWS下TC迅速加强较少,且只有台风及以上强度TC才能在大于12 m/s的VWS下迅速加强;（4）TC加强和迅速加强主要在28.5~30.0 ℃的SST洋面上发生,在较低SST下仍迅速加强的TC强度等级较高;（5）TC样本的RMW多小于100 km,其中强度突变TC RMW峰值区在20~40 km;（6）加强TC的RMW的24 h变化一般减小,减弱TC的RMW则增大;其中强度突变TC尤其明显,超强台风发生迅速加强时,RMW减小的比率达84.6%,但仍有15.4%比率的RMW增大。 相似文献
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Using tropical cyclone （TC） observations over a 58-yr period （1949-2006） from the China Meteorological Administration, the 40-year ECMWF Reanalysis （ERA-40）, NCEP-NCAR reanalysis, and the Hadley Centre sea ice and sea surface temperature （HadISST） datasets, the authors have examined the behaviors of tropical cyclones （TCs） in the western north Pacific （WNP） in boreal winter （November-December-January-February）. The results demonstrate that the occurrences of wintertime TCs, including super typhoons, have decreased over the 58 years. More TCs are found to move westward than northeastward, and the annual total number of parabolic-track-type TCs is found to be decreasing. It is shown that negative sea surface temperature anomalies （SSTAs） related to La Nifia events in the equatorial central Pacific facilitate more TC genesis in the WNP region. Large-scale anomalous cyclonic circulations in the tropical WNP in the lower troposphere are observed to be favorable for cyclogenesis in this area. On the contrary, the positive SSTAs and anomalous anticyclonic circulations that related to E1 Nifio events responsible for fewer TC genesis. Under the background of global warming, the western Pacific subtropical high tends to intensify and to expand more westward in the WNP, and the SSTAs display an increasing trend in the equatorial eastern-central Pacific. These climate trends of both atmospheric circulation and SSTAs affect wintertime TCs, inducing fewer TC occurrences and causing more TCs to move westward. 相似文献
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Summary A pilot tropical cyclone reanalysis project was conducted to construct a reliable, high temporal and spatial resolution tropical
cyclone dataset for selected western Pacific typhoons in summer 2004, with the application of the latest satellite observations
and a 4-dimensional variational data assimilation method. Primary data used for the reanalysis include SSM/I rain rate, GOES-retrieved
upper-level wind, QuikSCAT surface wind, Aqua AIRS/AMSU retrieved temperature and moisture profiles, and JTWC best track data.
A regular reanalysis procedure was established and up to 12 western Pacific typhoons have been reanalyzed. The reanalysis
period covers the entire life cycle of a tropical cyclone, from a few days prior to its genesis to its final decay stage.
A preliminary analysis shows that the reanalysis product significantly improves typhoon intensity, structure, and track, compared
to the NCEP operational final analysis. The validation of the TC structure against independent observations shows that the
reanalysis reproduces well the asymmetric characteristics of TC rain bands and cloud bands. A further modeling experiment
with an initial condition from the reanalysis product reveals a significant improvement in typhoon intensity forecast compared
to a parallel experiment with an initial condition from the NCEP final analysis, which provides a further indication of quality
of the tropical cyclone reanalysis. The reanalysis product and the raw observational data will soon be posted on the data
server of the IPRC Asia-Pacific Data-Research Center () for public use. 相似文献
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A statistical analysis of the initial vortexes leading to tropical cyclone(TC) formation in the western North Pacific(WNP) is conducted with the ECMWF ERA5 reanalysis data from 1999 to 2018. It is found that TCs in the WNP basically originate from three kinds of vortexes, i.e., a mid-level vortex(MV), a low-level vortex(LV), and a relatively deep vortex with notable vorticity in both the lower and middle troposphere(DV). Among them, LV and DV account for 47.9% and24.2% of tropical cyclogenesis e... 相似文献
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The extratropical transitions(ETs)of tropical cyclones(TCs)over China and the ocean east to 150°E are investigated by the use of best-track data and JRA-25 reanalysis spanning 1979-2008.The ET events occurring north of 25°N and in the warm season(from May to October)are extracted from the reanalysis to emphasize the interaction between TC and midlatitude circulation.Statistical analysis shows that 18.5%of the warm-season TCs go through land ETs north of 25°N in the western North Pacific.And 20.5%of the ET events occur over the ocean east of 150°E.Most(62.2%)ET TCs over China gradually die out after ET,but more(70.7%)ocean ET cases have post-ET reintensification.The evolutions in cyclone phase space and the composite fields for land and ocean ETs,as well as the ET cases with and without post-ET reintensification,are further analyzed.It is found that most TCs with ET over China and those without post-ET reintensification evolve along the typical ET phase path as follows:emergence of thermal asymmetry→losing upper-level warm core→losing lower-level cold core→evolving as extratropical cyclone.The TCs undergoing ETs over ocean and those with post-ET reintensification form a high-level cold core before the ET onset.The TCs with land ET have long distance between the landing TC and a high-level trough.That makes the TC maintain more tropical features and isolates the TC flow from the upstream and downstream jets of the midlatitude trough.The structure of circulation leads to weak development of baroclinicity in land ET.On the contrary,shorter distance between ocean TC and high-level trough makes the high-level trough absorb the TC absolutely.Under that baroclinicity-favorable environment,strong cold advection makes the TC lose its high-level warm core before ET onset.The composite fields confirm that the TC with ocean ET has stronger baroclinic features.Generally,the TC at land ET onset is located to the south of the ridge of the subtropical high,which tends to prevent the TCs from interacting with midlatitude circulation.But for the ocean ET,the situation is just the opposite.Similar analyses are also carried out for the TCs with and without post-ET reintensification over both land and ocean east of 150°E.The results further prove that the TC with stronger baroclinic characteristics,especially in the circumstance favorable to its interaction with high-level midlatitude systems,has more opportunity to reintensify as an extratropical cyclone after ET. 相似文献
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In this study,tropical cyclone data from China Meteorological Administration(CMA) and the ECMWF reanalysis data for the period 1958-2001 was used to propose a possible mechanism for the impacts of air-sea interaction on the activity of tropical cyclones(TCs) affecting China.The frequency of TCs affecting China over past 40 years has trended downward,while during the same period,the air-sea interaction in the two key areas of the Pacific region has significantly weakened.Our diagnoses and simulations suggest that air-sea interactions in the central North Pacific tropics and subtropics(Area 1) have an important role in adjusting typhoon activities in the Northwest Pacific in general,and especially in TC activity affecting China.On the contrary,impacts of the air-sea interaction in the eastern part of the South Pacific tropics(Area 2) were found to be rather limited.As both observational analysis and modeling studies show that,in the past four decades and beyond,the weakening trend of the latent heat released from Area 1 matched well with the decreasing Northwest Pacific TC frequency derived from CMA datasets.Results also showed that the weakening trend of latent heat flux in the area was most likely due to the decreasing TC frequency over the Northwest Pacific,including those affecting China.Although our preliminary analysis revealed a possible mechanism through which the air-sea interaction may adjust the genesis conditions for TCs,which eventually affect China,other relevant questions,such as how TC tracks and impacts are affected by these trends,remain unanswered.Further in-depth investigations are required. 相似文献
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This paper investigates the possible sources of errors associated with tropical cyclone (TC) tracks forecasted using the Global/Regional Assimilation and Prediction System (GRAPES). The GRAPES forecasts were made for 16 landfalling TCs in the western North Pacific basin during the 2008 and 2009 seasons, with a forecast length of 72 hours, and using the default initial conditions (“initials”, hereafter), which are from the NCEP-FNL dataset, as well as ECMWF initials. The forecasts are compared with ECMWF forecasts. The results show that in most TCs, the GRAPES forecasts are improved when using the ECMWF initials compared with the default initials. Compared with the ECMWF initials, the default initials produce lower intensity TCs and a lower intensity subtropical high, but a higher intensity South Asia high and monsoon trough, as well as a higher temperature but lower specific humidity at the TC center. Replacement of the geopotential height and wind fields with the ECMWF initials in and around the TC center at the initial time was found to be the most efficient way to improve the forecasts. In addition, TCs that showed the greatest improvement in forecast accuracy usually had the largest initial uncertainties in TC intensity and were usually in the intensifying phase. The results demonstrate the importance of the initial intensity for TC track forecasts made using GRAPES, and indicate the model is better in describing the intensifying phase than the decaying phase of TCs. Finally, the limit of the improvement indicates that the model error associated with GRAPES forecasts may be the main cause of poor forecasts of landfalling TCs. Thus, further examinations of the model errors are required. 相似文献
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《大气科学进展》2016,(7)
This paper investigates the possible sources of errors associated with tropical cyclone(TC) tracks forecasted using the Global/Regional Assimilation and Prediction System(GRAPES). The GRAPES forecasts were made for 16 landfalling TCs in the western North Pacific basin during the 2008 and 2009 seasons, with a forecast length of 72 hours, and using the default initial conditions("initials", hereafter), which are from the NCEP-FNL dataset, as well as ECMWF initials. The forecasts are compared with ECMWF forecasts. The results show that in most TCs, the GRAPES forecasts are improved when using the ECMWF initials compared with the default initials. Compared with the ECMWF initials, the default initials produce lower intensity TCs and a lower intensity subtropical high, but a higher intensity South Asia high and monsoon trough, as well as a higher temperature but lower specific humidity at the TC center. Replacement of the geopotential height and wind fields with the ECMWF initials in and around the TC center at the initial time was found to be the most efficient way to improve the forecasts. In addition, TCs that showed the greatest improvement in forecast accuracy usually had the largest initial uncertainties in TC intensity and were usually in the intensifying phase. The results demonstrate the importance of the initial intensity for TC track forecasts made using GRAPES, and indicate the model is better in describing the intensifying phase than the decaying phase of TCs. Finally, the limit of the improvement indicates that the model error associated with GRAPES forecasts may be the main cause of poor forecasts of landfalling TCs. Thus, further examinations of the model errors are required. 相似文献
20.
湿地边界层通量影响热带气旋登陆维持和降水的数值试验 总被引：11，自引：3，他引：8
用MM5v3模式及其TC Bogus方案对台风Nina(7503)在中国大陆上的维持加强过程进行模拟,并通过各种敏感性试验,研究了饱和湿地对热带气旋在大陆上维持和降水的影响。结果表明:湿地边界层内各通量对登陆热带气旋的强度、结构及其降水具有明显影响。潜热通量和感热通量均有利于热带气旋的维持和加强,其中潜热输送的作用显著,感热输送的作用较小。潜热和感热通量有利于热带气旋雨带螺旋结构的维持,对台风降水分布有明显影响,动量通量对热带气旋风场有显著的削弱作用,是其能量耗散、低压填塞的主要原因,但对台风降水具有局地增幅作用。 相似文献