On the Improvement of the DSAEF＿LTP Model to Heavy Precipitation Simulation of Landfalling Tropical Cyclones over China in 2018     

陈禹旭  贾莉  贾作  丁晨晨  任福民  李国平 《热带气象学报(英文版)》2021,27(3):232-245

In this study, the Dynamical-Statistical-Analog Ensemble Forecast model (DSAEF_LTP model) for landfalling tropical cyclone (LTC) precipitation was employed to simulate the precipitation of 10 LTCs that occurred Pover China in 2018. With adding parameter‘similarity region scheme’(SRS) values and introducing TC intensity into the generalized initial value (GIV), four groups of precipitation simulation experiments were designed to verify the forecasting ability of the improved model for more TC samples. Results show that the simulation ability of the DSAEF_LTP model can be optimized regardless of whether adding SRS values only, or introducing TC intensity into GIV, while the experiment with both the two improvements shows a more prominent advantage in simulating the heavier precipitation of LTCs. Compared with four NWP models (i.e., ECMWF, GFS, GRAPES and SMS-WARMS), the overall forecasting performance of the DSAEF_LTP model achieves a better result in simulating precipitation at the thresholds over 250 mm and performs slightly better than NWP models at the thresholds over 100 mm.  相似文献   

Impacts of Horizontal and Vertical Resolutions on the Microphysical Structure and Boundary Layer Fluxes of Typhoon Hato     

赵杨洁  李江南  李芳洲  阮子夕 《热带气象学报(英文版)》2021,27(1):10-23

We set four sets of simulation experiments to explore the impacts of horizontal resolution (HR) and vertical resolution (VR) on the microphysical structure and boundary layer fluxes of tropical cyclone (TC) Hato (2017). The study shows that higher HR tends to strengthen TC. Increasing VR in the upper layers tends to weaken TC, while increasing VR in the lower layers tends to strengthen TC. Simulated amounts of all hydrometeors were larger with higher HR. Increasing VR at the upper level enhanced the mixing ratios of cloud ice and cloud snow, while increasing VR at the lower level elevated the mixing ratios of graupel and rainwater. HR has greater impact on the distributions of hydrometeors. Higher HR has a more complete ring structure of the eyewall and more concentrated hydrometeors along the cloud wall. Increasing VR at the lower level has little impact on the distribution of TC hydrometeors, while increasing VR at the upper level enhances the cloud thickness of the eyewall area. Surface latent heat flux (SLHF) is influenced greatly by resolution. Higher HR leads to larger water vapor fluxes and larger latent heat, which would result in a stronger TC. A large amount of false latent heat was generated when HR was too high, leading to an extremely strong TC, VR has a smaller impact on SLHF than HR. But increasing VR at the upper-level reduces the SLHF and weakens TC, and elevating VR at the lower-level increases the SLHF and strengthens TC. The changes in surface water vapor flux and SLHF were practically identical and the simulation results were improved when HR and VR were more coordinated. The friction velocity was greater with higher VR. Enhancing VR at the lower level increased the friction velocity, while increasing VR at the upper level reduced it.  相似文献   

Re-examining Tropical Cyclone Fullness Using Aircraft Reconnaissance Data     

Zhehan CHEN  Qingqing LI 《大气科学进展》2021,38(9):1596-1607

We use FLIGHT+ aircraft reconnaissance data for tropical cyclones (TCs) in the North Atlantic and Eastern Pacific from 1997 to 2015 to re-examine TC fullness (TCF) characteristics at the flight level. The results show a strong positive correlation between the flight-level TCF and the intensity of TCs, with the flight-level TCF increasing much more rapidly than the near-surface TCF with increasing intensity of the TCs. The tangential wind in small-TCF hurricanes is statistically significantly stronger near the eye center than that in large-TCF hurricanes. Large-TCF hurricanes have a ring-like vorticity structure. No significant correlation is observed between the flight-level TCF and the comparative extent of the vorticity-skirt region occupied in the outer core skirt. The proportion of the rapid filamentation zone in the outer core skirt increases with increasing flight-level TCF. The differences in entropy between the radius of the maximum wind and the outer boundary of the outer core skirt also increase with increasing flight-level TCF.  相似文献   

与海南岛秋季暴雨有关的一类热带中尺度涡旋的动力学分析     

吴俞  李国平  冯文 《热带气象学报》2022,38(2):227-238

对惯性重力内波方程组分别通过线性和非线性求解探讨造成2010年10月海南岛一次特大暴雨中一类热带中尺度涡旋生成发展的动力、热力机制,研究发现:（1）在副热带高压和大陆冷高压南侧反气旋性纬向水平风切变大值区、静力不稳定大气层结、积云对流潜热释放、低空急流、适当强度的冷空气有利于热带中尺度涡旋的形成和发展;（2）非线性惯性重力内波的孤立波解与这类热带中尺度涡旋有很好的联系,在静力不稳定的大气层结下,热带中尺度涡旋的形态主要由对流凝结潜热加热所决定,即潜热加热下的孤立波解要求热带中尺度涡旋在垂直方向是一个浅薄的涡旋系统;另外强盛的对流凝结潜热对热带中尺度涡旋垂直运动振幅的增强起主要作用,更有利于涡旋的发展和维持。基于天气事实分析的理论研究为深化影响海南的热带中尺度涡旋乃至南海中尺度对流系统的机理认识进行了探索。   相似文献   

基于卫星遥感的热带气旋定强技术综述     

胡天慧  余晖  鲁小琴 《热带气象学报》2022,38(2):311-320

热带气旋大部分时间活动在常规观测缺乏的海洋上,卫星遥感作为大范围对地观测的主要技术,为热带气旋强度估算(定强)提供了重要支撑。近年来,热带气旋定强技术的资料应用逐渐从单通道数据拓展到红外、水汽、微波等多通道数据,建模方法也从人为特征提取的线性模型发展到自动特征工程的非线性深度学习模型。在未来,多通道和多卫星资料的融合应用依旧是重点,将人为定义的特征因子与深度学习方法相结合、在静止卫星上搭载微波探测仪器等预计会带来定强精度的新突破。   相似文献   

热带气旋对1975-2018年暖季中国极端降水气候态、变化趋势及其与温度关系的影响研究     

杨宝琛  罗亚丽  姜晓玲 《热带气象学报》2022,38(3):397-409

全球变暖背景下我国极端小时降水和极端日降水(EXHP、EXDP)气候态及变化趋势的区域差异明显, 其中热带气旋(TC)的影响尚不明确。利用1975-2018年暖季台站小时降水(P)和热带气旋最佳路径等资料, 采用百分位法定义极端小时降水与极端日降水, 并将总降水(All)客观分为热带气旋降水与非热带气旋(nonTC)降水, 分析热带气旋对中国东部All-P、All-EXHP、All-EXDP的气候态和变化趋势以及极端小时降水随温度变化的影响。主要结论如下: (1) TC-P、TC-EXDP、TC-EXHP占其对应总降水之比均从东南和华南沿海向西北内陆递减, 区域平均而言, TC-P占All-P之比与TC-EXHP占All-EXHP之比均约为11%, 而TC-EXDP占AllEXDP之比为15.8%;(2) 热带气旋和非热带气旋降水变化趋势的空间分布差别较大, 热带气旋对长江流域东部总降水增多的贡献高达49%, 并一定程度上改变了降水趋势的空间分布; (3) TC-EXHP强度与温度的关系在约21℃发生改变, 且截然不同于nonTC-EXHP, 华南、东南沿海TC-EXHP强度随温度的变化率明显低于nonTCEXHP, 造成nonTC-EXHP和All-EXHP随温度变化率不同, 且在东南沿海差异显著。   相似文献   

Growing Threat of Rapidly-Intensifying Tropical Cyclones in East Asia     

Kin Sik LIU  Johnny C.L.CHAN 《大气科学进展》2022,39(2):222-234

This study examines the long-term change in the threat of landfalling tropical cyclones(TCs) in East Asia over the period 1975–2020 with a focus on rapidly intensifying(RI) TCs. The increase in the annual number of RI-TCs over the western North Pacific and the northwestward shift of their genesis location lead to an increasing trend in the annual number of landfalling RI-TCs along the coast of East Asia. The annual power dissipation index(PDI), a measure of the destructive potential of RI-TCs at landfall, also shows a significant increasing trend due to increases in the annual frequency and mean landfall intensity of landfalling RI-TCs. The increase in mean landfall intensity is related to a higher lifetime maximum intensity(LMI) and the LMI location of the landfalling RI-TCs being closer to the coast. The increase in the annual PDI of East Asia is mainly associated with landfalling TCs in the southern(the Philippines, South China, and Vietnam) and northern parts(Japan and the Korean Peninsula) of East Asia due to long-term changes in vertical wind shear and TC heat potential. The former leads to a northwestward shift of favorable environments for TC genesis and intensification, resulting in the northwestward shift in the genesis, RI, and LMI locations of RI-TCs. The latter provides more heat energy from the ocean for TC intensification, increasing its chances to undergo RI.  相似文献   

Projection of the Future Changes in Tropical Cyclone Activity Affecting East Asia over the Western North Pacific Based on Multi-RegCM4 Simulations   总被引：1，自引：0，他引：1  

Jie WU  Xuejie GAO  Yingmo ZHU  Ying SHI  Filippo GIORGI 《大气科学进展》2022,39(2):284-303

Future changes in tropical cyclone(TC)activity over the western North Pacific(WNP)under the representative concentration pathway RCP4.5 are investigated based on a set of 21 st century climate change simulations over East Asia with the regional climate model RegCM4 driven by five global models.The RegCM4 reproduces the major features of the observed TC activity over the region in the present-day period of 1986-2005,although with the underestimation of the number of TC genesis and intensity.A low number of TCs making landfall over China is also simulated.By the end of the 21st century(2079-98),the annual mean frequency of TC genesis and occurrence is projected to increase over the WNP by16%and 10%,respectively.The increase in frequency of TC occurrence is in good agreement among the simulations,with the largest increase over the ocean surrounding Taiwan Island and to the south of Japan.The TCs tend to be stronger in the future compared to the present-day period of 1986-2005,with a large increase in the frequency of strong TCs.In addition,more TCs landings are projected over most of the China coast,with an increase of~18%over the whole Chinese territory.  相似文献   

A Climatological Perspective on Extratropical Synoptic-Scale Transient Eddy Activity Response to Western Pacific Tropical Cyclones     

Yao HA  Zhong ZHONG  Haikun ZHAO  Yimin ZHU  Yao YAO  Yijia HU 《大气科学进展》2022,39(2):333-343

An observational study focusing on the contribution of tropical cyclones(TCs)that form over the western North Pacific(WNP)to the synoptic-scale transient eddy activity(STEA)over the North Pacific during the boreal autumn and early winter in the period 1979–2019 is presented in this paper.Statistical results show that WNP TCs entering the midlatitudinal North Pacific provide significant positive effects on the pentad mean strength of STEA,which is primarily concentrated over the Kuroshio/Oyashio Extensions(KOE)and regions from east of Japan to 160°W in the lower and midto-upper troposphere,respectively.TC intensity is highly indicative of the subsequent STEA with a correlation coefficient of 0.37/0.33/0.45 at 300 hPa/500 hPa/850 hPa exceeding the 99%confidence level for the period 1979–2019.The strength of STEA in the upper troposphere associated with TCs presents a more significant linear growth with TC intensity than that at the mid-to-lower levels after the cyclones enter the KOE region,suggesting that the impact of TCs on STEA gradually increases with height.Further analyses reveal that the contribution of TCs accounts for 4%–6%of the total STEA change over the KOE region during the late autumn and early winter.In addition,the influence of TCs on STEA experienced an interdecadal decrease from the early 2000 s through the early 2010 s.  相似文献   

A Logistic-growth-equation-based Intensity Prediction Scheme for Western North Pacific Tropical Cyclones※     

Yanchen ZHOU  Jiuwei ZHAO  Ruifen ZHAN  Peiyan CHEN  Zhiwei WU  Lan WANG 《大气科学进展》2021,38(10):1750-1762

Accurate prediction of tropical cyclone (TC) intensity remains a challenge due to the complex physical processes involved in TC intensity changes. A seven-day TC intensity prediction scheme based on the logistic growth equation (LGE) for the western North Pacific (WNP) has been developed using the observed and reanalysis data. In the LGE, TC intensity change is determined by a growth term and a decay term. These two terms are comprised of four free parameters which include a time-dependent growth rate, a maximum potential intensity (MPI), and two constants. Using 33 years of training samples, optimal predictors are selected first, and then the two constants are determined based on the least square method, forcing the regressed growth rate from the optimal predictors to be as close to the observed as possible. The estimation of the growth rate is further refined based on a step-wise regression (SWR) method and a machine learning (ML) method for the period 1982?2014. Using the LGE-based scheme, a total of 80 TCs during 2015?17 are used to make independent forecasts. Results show that the root mean square errors of the LGE-based scheme are much smaller than those of the official intensity forecasts from the China Meteorological Administration (CMA), especially for TCs in the coastal regions of East Asia. Moreover, the scheme based on ML demonstrates better forecast skill than that based on SWR. The new prediction scheme offers strong potential for both improving the forecasts for rapid intensification and weakening of TCs as well as for extending the 5-day forecasts currently issued by the CMA to 7-day forecasts.  相似文献