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Anomalies of Precipitation over China on Days with Tropical Cyclone Activity over the Bay of Bengal: Role of Moisture Transport

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Journal of Meteorological Research 2024年第2期38卷 368-382页

作者： Na WEI Ying LI Xiaoting FAN Nanjing Joint institute for atmospheric sciences Nanjing 210041 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 department of atmospheric and oceanic sciences and institute of atmospheric sciences Fudan UniversityShanghai 200433

Tropical cyclones over the Bay of Bengal(BoBTC)affect the precipitation over China,with distinct seasonal and daily variabilities.This study quantitatively examines the daily standardized precipitation anomalies(SPAs)over China on the days with BoBTC activities(storm-days)and related circulations,based on rainfall measurements at surface meteorological stations and ECMWF reanalysis data on a 0.25°×0.25°resolution during 1979-2019.Significant positive SPA is found over the stations in the two adjacent regions around BoB(Southwest China in May/November and southern Tibetan Plateau in October)and three distant regions(Southeast China and the northeastern boundary of the Qinghai-Tibet Plateau in May,and central North China in October).The SPA distributions are remarkably consistent with the integrated water vapor transport(IVT)anomalies.Enhanced IVT is found associated with the interaction between southwesterly(southerly)of the BoBTC circulation and low-level monsoonal flow in May(midlevel westerly in winter months).The probabilities of extreme precipitation(EP)occurrences over the above regions all increase on storm-days.For adjacent regions,EP is significantly correlated with the northward IVT anomalies to the east of BoBTC circulation,which strengthen the water vapor input through the southern border.Such IVT anomalies are stronger in May,benefited by the deep monsoonal southwesterlies than those in November.For distant regions,EP is more closely related to the IVT anomaly extending back from BoB.Enhanced moisture from BoB concentrates along a local low-level convergence line over Southeast China,being further facilitated by coexistence of the BoBTC depression and midlevel westerly trough in midlatitudes.Our results highlight the interactions between BoBTCs and local weather systems that influence the general precipitation anomalies and occurrence of EP over China,especially over distant regions.

关键词： tropical cyclone Bay of Bengal precipitation anomaly moisture transport

Synergistic Effects of Bay of Bengal Tropical Cyclones and Tibetan Plateau Vortices on Water Vapor Transport over the Tibetan Plateau in Early Summer

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Journal of Meteorological Research 2024年第2期38卷 383-398页

作者： Jialu LIN Ying LI Beiyao LIU Pengchao AN State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 University of Chinese Academy of sciences Beijing 100049 department of atmospheric and oceanic sciences and institute of atmospheric sciences Fudan UniversityShanghai 200433

The Bay of Bengal(BoB)tropical cyclones(TCs)and the Tibetan Plateau vortices(TPVs)are two crucial weather systems influencing the Tibetan Plateau(TP).Their synergistic effects can lead to widespread heavy precipitation events on the TP.In this study,we employ the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model to track the trajectory of water vapor transport during three large-scale precipitation events on the TP under the combined influence of BoB TCs and TPVs.The results indicate that low-level water vapor from the BoB under the influence of BoB TCs was cyclonically entangled into the cyclonic circulation,lifted and transported northward by southwesterly flow to the southeastern part of the TP,which contributes to the moistening of the entire troposphere there.Additionally,convergence of the cyclonic circulation of the TPVs on the northern TP further transports water vapor collected in the southeastern TP northward,conducive to the maintenance and development of precipitation systems,thus inducing widespread heavy precipitation events over the TP.

关键词： Bay of Bengal(BoB) tropical cyclones(TCs) Tibetan Plateau vortices(TPVs) trajectory tracing water vapor transport

Cloud Microphysical Characteristics of Typhoon Meranti(2016) during Its Rapid Intensification: Model Validation and SST Sensitivity Experiments

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Journal of Meteorological Research 2024年第3期38卷 542-557页

作者： Rui WANG Yihong DUAN Jianing FENG department of atmospheric and oceanic sciences & institute of atmospheric sciences Fudan University State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological Administration

Cloud microphysics plays an important role in determining the intensity and precipitation of tropical cyclones(TCs). In this study, a high-resolution numerical simulation by WRF(version 4.2) of Typhoon Meranti(2016) during its rapid intensification(RI) period was conducted and validated by multi-source observations including CloudSat and Global Precipitation Mission satellite data. The snow and ice particles content were found to increase most rapidly compared with other hydrometeors during the RI process. Not all hydrometeors continued to increase. The graupel content only increased in the initial RI stage, and then decreased afterwards due to precipitation during the RI process. In addition, sea surface temperature(SST) sensitivity experiments showed that, although the intensity of the TC increased with a higher SST, not all hydrometeors increased. The graupel content continued to increase with the increase in SST, mainly due to the accumulation of more lower-temperature supercooled water vapor at the corresponding height. The content of snow decreased with the increase in SST because stronger vertical motion at the corresponding height affected the aggregation of ice crystals.

关键词： tropical cyclone rapid intensification cloud microphysical characteristics sea surface temperature (SST)

Roles of Upper-Level Descending Inflow in Moat Development in Simulated Tropical Cyclones with Secondary Eyewall Formation

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Advances in atmospheric sciences 2024年第6期41卷 1100-1114页

作者： Nannan QIN Liguang WU Nanjing Joint institute for atmospheric sciences Nanjing 210041China Shanghai Typhoon institute China Meteorological AdministrationShanghai 200030China department of atmospheric and oceanic sciences and institute of atmospheric sciences Fudan UniversityShanghai 200438China Innovation Center of Ocean and Atmosphere System Zhuhai Fudan Innovation Research InstituteZhuhai 518057China

This study investigated the effects of upper-level descending inflow(ULDI)associated with inner-eyewall convection on the formation of the moat in tropical cyclones(TCs)with secondary eyewall formation(SEF).In our numerical experiments,a clear moat with SEF occurred in TCs with a significant ULDI,while no SEF occurred in TCs without a significant ULDI.The eyewall convection developed more vigorously in the control run.A ULDI occurred outside the inner-eyewall convection,where it was symmetrically unstable.The ULDI was initially triggered by the diabatic warming released by the inner eyewall and later enhanced by the cooling below the anvil cloud.The ULDI penetrated the outer edge of the inner eyewall with relatively dry air and prevented excessive solid-phase hydrometeors from being advected further outward.It produced extensive sublimation cooling of falling hydrometeors between the eyewall and the outer convection.The sublimation cooling resulted in negative buoyancy and further induced strong subsidence between the eyewall and the outer convection.As a result,a clear moat was generated.Development of the moat in the ongoing SEF prevented the outer rainband from moving farther inward,helping the outer rainband to symmetrize into an outer eyewall.In the sensitivity experiment,no significant ULDI formed since the eyewall convection was weaker,and the eyewall anvil developed relatively lower,meaning the formation of a moat and thus an outer eyewall was less likely.This study suggests that a better-represented simulation of inner-eyewall convective structures and distribution of the solid-phase hydrometeors is important to the prediction of SEF.

关键词： tropical cyclone secondary eyewall formation upper-level descending inflow eyewall convection

The source of Double ITCZ induced by the SST bias over the tropical western Pacific as reflected in CAS-ESM2 Model

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Science China Earth sciences 2024年第5期67卷 1604-1615页

作者： Jinning TONG Fei ZHENG Jiangbo JIN Ruowen YANG Jiang ZHU Qingcun ZENG department of atmospheric sciences Yunnan UniversityKunming 650091China International Center for Climate and Environment Science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

“Double ITCZ”is a common precipitation bias over the tropical Pacific in current climate models and Earth system models,but the reasons for its formation are still worth exploring and discussing.In this study,we adopted the second version of Chinese Academy of sciences Earth System Model(CAS-ESM2),by comparing a set of sea surface temperature(SST)bias correction experiments over the tropical Pacific,to explore the possible mechanism of SST bias on inducing the“Double ITCZ”from the perspective of the climatic annual mean bias in the coupled model.We revealed that the simulated climatic annual mean SST bias over the tropical Pacific can affect the bias of latent heat flux through the saturation specific humidity,and the bias of latent heat flux can further affect that of vertical velocity of humid air by the condensation release mechanism,and finally modulate the simulated bias in precipitation.Furthermore,through the inter-comparison between different experiments,it is found that the source of Double ITCZ might mainly come from the annual mean SST bias over the tropical western Pacific through the proposed air-sea coupled process of“SST-saturated specific humidity-latent heat flux-vertical velocity-precipitation”,indicating a possible way on reducing the couple biases in models over the tropical Pacific to improve the accuracy of CAS-ESM2 for climate simulation.

关键词： SST bias Double ITCZ Nudging SST CAS-ESM2

Spatial continuous modeling of early Cenozoic carbon cycle and climate

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National Science Review 2024年第4期11卷 30-32页

作者： Yonggang Liu Jian Zhang Haoyue Zuo Zhilin He Jiaqi Guo Qifan Lin Haonan Yu Jiawenjing Lan Jing Han Zhihong Song Zihan Yin Liang Zhao Yongyun Hu Zhengtang Guo Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

The partial pressure of atmospheric CO2（pCO2） is determined by the carbon cycle that involves climate, biogeochemistry, and plate tectonics. In this cycle,atmospheric CO2is converted into organic carbon and carbonates by biological activities and silicate weathering, and buried as sediments. The sediments on the ocean floor are subducted into the Earth’s interior, and subsequently converted back into CO2and outgassed into the atmosphere.

关键词： atmospheric CO2

A Physics-informed Deep-learning Intensity Prediction Scheme for Tropical Cyclones over the Western North Pacific

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Advances in atmospheric sciences 2024年第7期41卷 1391-1402页

作者： Yitian ZHOU Ruifen ZHAN Yuqing WANG Peiyan CHEN Zhemin TAN Zhipeng XIE Xiuwen NIE department of atmospheric and oceanic sciences&institute of atmospheric sciences Fudan UniversityShanghai 200438China Shanghai Typhoon institute of China Meteorological Administration Shanghai 200030China department of atmospheric sciences and International Pacific Research Center University of Hawaii at ManoaHonolulu 96822USA Key Laboratory of Mesoscale Severe Weather/MOE and School of the Atmospheric SciencesNanjing UniversityNanjing 210023China School of Computer Science Fudan UniversityShanghai 200438China

Accurate prediction of tropical cyclone(TC)intensity is challenging due to the complex physical processes involved.Here,we introduce a new TC intensity prediction scheme for the western North Pacific(WNP)based on a time-dependent theory of TC intensification,termed the energetically based dynamical system(EBDS)model,together with the use of a long short-term memory(LSTM)neural network.In time-dependent theory,TC intensity change is controlled by both the internal dynamics of the TC system and various environmental factors,expressed as environmental dynamical efficiency.The LSTM neural network is used to predict the environmental dynamical efficiency in the EBDS model trained using besttrack TC data and global reanalysis data during 1982–2017.The transfer learning and ensemble methods are used to retrain the scheme using the environmental factors predicted by the Global Forecast System(GFS)of the National Centers for Environmental Prediction during 2017–21.The predicted environmental dynamical efficiency is finally iterated into the EBDS equations to predict TC intensity.The new scheme is evaluated for TC intensity prediction using both reanalysis data and the GFS prediction data.The intensity prediction by the new scheme shows better skill than the official prediction from the China Meteorological Administration(CMA)and those by other state-of-art statistical and dynamical forecast systems,except for the 72-h forecast.Particularly at the longer lead times of 96 h and 120 h,the new scheme has smaller forecast errors,with a more than 30%improvement over the official forecasts.

关键词： tropical cyclones western North Pacific intensity prediction EBDS LSTM

Quantitative estimation of global mean precipitation throughout the Phanerozoic era

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Science China Earth sciences 2024年第5期67卷 1616-1624页

作者： Xiujuan BAO Yongyun HU Laboratory for Climate and Ocean-atmospheric Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China

Quantitatively estimating the global mean precipitation(GMP)throughout Earth's history is crucial for enhancing our understanding of long-term climate evolution and the hydrological cycle.However,currently there is no established methodology for estimating global mean paleoprecipitation.Here,we present the first study that estimates GMP in the Phanerozoic era.The relationship between GMP and global mean surface temperature(GMST)is investigated by analyzing data from 23 models in the Coupled Model Intercomparison Project phase 6(CMIP6).The result reveals consistent and significant impact of temperature on precipitation,with a sensitivity range of 2–3%K^(-1).Additionally,we propose a method for accessing latitudinal variations in precipitation caused by land area distributions and paleo-Koppen climatic belts.These climatic belts are determined based on geological indicators such as coals,evaporites,and glacial deposits.The GMP is thus quantitatively estimated by combining variations in GMST,land area distributions,and paleo-koppen climatic belts,spanning from 540 Ma to the present day.The quantitative GMP curve demonstrates fluctuations in GMP about 500 mm yr^(-1),with values ranging from 948 to1442 mm yr-1over the Phanerozoic era.This curve aligns closely with findings derived from numerical simulations.The presented paleoprecipitation variations facilitate a more comprehensive understanding of the interconnected geological and paleoclimatic developments.

关键词： Paleoprecipitation Paleoclimate K?ppen climatic belts Global mean precipitation Hydrological cycle

New findings on the influence of El Nino events on tropical cyclone formation

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Science China Earth sciences 2024年第3期67卷 892-893页

作者： Liguang WU department of atmospheric and oceanic sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China

Tropical cyclones typically form over warm tropical and subtropical ocean surfaces, as their formation and intensification rely primarily on the energy provided by the ocean. Pioneering research by Gray (1968) revealed that the formation of tropical cyclones requires the sea surface temperature (SST) to be no less than 26.5℃. Consequently, SST is commonly recognized as a crucial parameter among the environmental factors influencing tropical cyclone formation(Gray, 1979;Emanuel and Nolan, 2004).

关键词： tropical cyclone ocean