In this study,the nonlinear local Lyapunov exponent(NLLE)approach was used to quantitatively determine the predictability limit of tropical cyclone(TC)tracks based on observed TC track data obtained from the Joint Typ...
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In this study,the nonlinear local Lyapunov exponent(NLLE)approach was used to quantitatively determine the predictability limit of tropical cyclone(TC)tracks based on observed TC track data obtained from the Joint Typhoon Warning *** results show that the predictability limit of all TC tracks over the whole western North Pacific(WNP)basin is about 102 h,and the average lifetime of all TC tracks is about 174 *** predictability limits of the TC tracks for short-,medium-,and long-lived TCs are approximately 72 h,120 h,and 132 h,*** predictability limit of the TC tracks depends on the TC genesis location,lifetime,and intensity,and further analysis indicated that these three metrics are closely *** more intense and longer-lived TCs tend to be generated on the eastern side of the WNP(EWNP),whereas the weaker and shorter-lived TCs tend to form in the west of the WNP(WWNP)and the South China Sea(SCS).The relatively stronger and longer-lived TCs,which are generated mainly in the EWNP,have a longer travel time before they curve northeastwards and hence tend to be more predictable than the relatively weaker and shorter-lived TCs that form in the WWNP region and ***,the results show that the predictability limit of the TC tracks obtained from the best-track data may be underestimated due to the relatively short observational records currently *** work is needed,employing a numerical model to assess the predictability of TC tracks.
Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere,despite the transition from an El Ni?o to neutral conditions. In 2024, both global sea surface temper...
Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere,despite the transition from an El Ni?o to neutral conditions. In 2024, both global sea surface temperature(SST) and upper2000 m ocean heat content(OHC) reached unprecedented highs in the historical record. The 0–2000 m OHC in 2024exceeded that of 2023 by 16 ± 8 ZJ(1 Zetta Joules = 1021 Joules, with a 95% confidence interval)(IAP/CAS data), which is confirmed by two other data products: 18 ± 7 ZJ(CIGAR-RT reanalysis data) and 40 ± 31 ZJ(Copernicus Marine data,updated to November 2024). The Indian Ocean, tropical Atlantic, Mediterranean Sea, North Atlantic, North Pacific, and Southern Ocean also experienced record-high OHC values in 2024. The global SST continued its record-high values from2023 into the first half of 2024, and declined slightly in the second half of 2024, resulting in an annual mean of 0.61°C ±0.02°C(IAP/CAS data) above the 1981–2010 baseline, slightly higher than the 2023 annual-mean value(by 0.07°C ±0.02°C for IAP/CAS, 0.05°C ± 0.02°C for NOAA/NCEI, and 0.06°C ± 0.11°C for Copernicus Marine). The record-high values of 2024 SST and OHC continue to indicate unabated trends of global heating.
The rapid decrease in Arctic sea ice cover and thickness not only has a linkage with extreme weather in the midlatitudes but also brings more opportunities for Arctic shipping routes and polar resource exploration,bot...
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The rapid decrease in Arctic sea ice cover and thickness not only has a linkage with extreme weather in the midlatitudes but also brings more opportunities for Arctic shipping routes and polar resource exploration,both of which motivate us to further understand causes of sea-ice variations and to obtain more accurate estimates of seaice cover in the ***,a novel data-driven method,the causal effect networks algorithm,is applied to identify the direct precursors of September sea-ice extent covering the Northern Sea Route and Transpolar Sea Route at different lead times so that statistical models can be constructed for sea-ice *** whole study area was also divided into two parts:the northern region covered by multiyear ice and the southern region covered by seasonal *** forecast models of September sea-ice extent in the whole study area(TSIE)and southern region(SSIE)at lead times of 1–4 months can explain over 65%and 79%of the variances,respectively,but the forecast skill of sea-ice extent in the northern region(NSIE)is limited at a lead time of 1 *** lead times of 1–4 months,local sea-ice concentration and sea-ice thickness have a larger influence on September TSIE and SSIE than other teleconnection *** the lead time is more than 4 months,the surface meridional wind anomaly from northern Europe in the preceding autumn or early winter is dominant for September TSIE variations but is comparable to thermodynamic factors for NSIE and *** suggest that this study provides a complementary approach for predicting regional sea ice and is helpful in evaluating and improving climate models.
There is increasing evidence of the possible role of extratropical forcing in the evolution of ENSO. The Southern Hemi- sphere Annular Mode (SAM) is the dominant mode of atmospheric circulation in the Southern Hemis...
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There is increasing evidence of the possible role of extratropical forcing in the evolution of ENSO. The Southern Hemi- sphere Annular Mode (SAM) is the dominant mode of atmospheric circulation in the Southern Hemisphere extratropics. This study shows that the austral summer (December-January-February; DJF) SAM may also influence the amplitude of ENSO decay during austral autumn (March-April-May; MAM). The mechanisms associated with this SAM-ENSO relationship can be briefly summarized as follows: The SAM is positively (negatively) correlated with SST in the Southern Hemisphere middle (high) latitudes. This dipole-like SST anomaly pattern is referred to as the Southern Ocean Dipole (SOD). The DJF SOD, caused by the DJF SAM, could persist until MAM and then influence atmospheric circulation, including trade winds, over the Nifio3.4 area. Anomalous trade winds and SST anomalies over the Nifio3.4 area related to the DJF SAM are further developed through the Bjerkness feedback, which eventually results in a cooling (warming) over the Nifio3.4 area followed by the positive (negative) DJF SAM.
The Cloud Feedback Model Intercomparisons Project (CFMIP) Observation Simulator Package (COSP) is adopted in the Grid-point Atmospheric Model of IAP LASG (GAMIL2) during CFMIP at Phase II to evaluate the model cloud f...
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The Cloud Feedback Model Intercomparisons Project (CFMIP) Observation Simulator Package (COSP) is adopted in the Grid-point Atmospheric Model of IAP LASG (GAMIL2) during CFMIP at Phase II to evaluate the model cloud fractions in a consistent way with satellite observations. The cloud simulation results embedded in the Atmospheric Model Intercomparison Project (AMIP) control experiment are presented using three satellite simulators: International Satellite Cloud Climatology Project (ISCCP), Moderate Resolution Imaging Spectroradiometer (MODIS), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar onboard the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Overall, GAMIL2 can produce horizontal distributions of the low cloud fraction that are similar to the satellite observations, and its similarities to the observations on different levels are shown in Taylor diagrams. The discrepancies among satellite observations are also shown, which should be considered during evaluation.
Raman spectroscopy has shown considerable potential in the study of organic macerals in source rocks due to its significant benefits of accuracy, efficiency, and in situ nondestructive detection. This technology succe...
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Raman spectroscopy has shown considerable potential in the study of organic macerals in source rocks due to its significant benefits of accuracy, efficiency, and in situ nondestructive detection. This technology successfully applies to the reconstruction of paleotemperature and pressure environments, the quantitative evaluation of organic matter maturity, and the construction of a carbon Raman spectroscopy geothermometer model. The present study systematically examines the intrinsic relationship and the application between Raman parameters and material composition and molecular structure, as well as the application, challenges, and future directions of Raman spectroscopy in the current research field of source rock evaluation.
Forecasting tropical cyclone track and intensity is a great challenge for the meteorological community,and safeguarding the life and property of people living near the coast is an important *** major reason for challe...
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Forecasting tropical cyclone track and intensity is a great challenge for the meteorological community,and safeguarding the life and property of people living near the coast is an important *** major reason for challenging forecasts is the lack of observations over the vast *** tropical cyclone Mulan between 8 and 10 August 2022 over the northern part of the South China Sea,the meteorological authority and research institutes of Chinese mainland collaborated with the meteorological service in Hong Kong on conducting the first-ever ground–space–sky observing system experiment on tropical cyclone *** enhanced targeted observations collected during the experiment include Geostationary Interferometric Infrared Sounder,round-trip radiosondes,and aircraft-launched *** paper describes the campaign,technical details of the meteorological models used,and impact of the additional targeted observation data on the tropical cyclone ***,similar enhanced observation campaigns could be conducted in the future,not only in the northern part of the South China Sea,but also in other ocean basins.
The authors examine the effects of external forcing agents such as greenhouse gases (GHGs) and aerosols, as well as solar variability and ozone, on global land monsoon precipitation by using a coupled climate model ...
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The authors examine the effects of external forcing agents such as greenhouse gases (GHGs) and aerosols, as well as solar variability and ozone, on global land monsoon precipitation by using a coupled climate model HadGEM1, which was developed by the Met Office Hadley Centre for Climate Research. The results indicate that HadGEM1 performs well in simulating the observed decreasing trend of global land monsoon precipitation over the past 50 years. This trend mainly occurred in the Northern Hemisphere and is significantly different from the trend of natural variability due to ocean-atmosphere-land interactions. The coherence between the simulation and the observations indicates that the specified external forcing agents, including GHGs and aerosols as well as solar variability and ozone, are important factors that have affected the decreasing trend of global land monsoon precipitation in the past 50 years.
The propagation and underlying mechanisms of the boreal summer quasi-biweekly oscillation(QBWO)over the entire Asian monsoon region are investigated,based on ECMWF Interim reanalysis(ERA-Interim)data,GPCP precipit...
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The propagation and underlying mechanisms of the boreal summer quasi-biweekly oscillation(QBWO)over the entire Asian monsoon region are investigated,based on ECMWF Interim reanalysis(ERA-Interim)data,GPCP precipitation data,and an atmospheric general circulation model(AGCM).Statistical analyses indicate that the QBWO over the Asian monsoon region derives its main origin from the equatorial western Pacific and moves northwestward to the Bay of Bengal and northern India,and then northward to the Tibetan Plateau(TP)area,with a baroclinic vertical *** propagation of the QBWO is promoted by three main mechanisms:barotropic vorticity,boundary moisture advection,and surface sensible heating(SSH).It is dominated by the barotropic vorticity effect when the QBWO signals are situated to the south of 20°*** the propagation taking place farther north toward the TP,the boundary moisture advection and SSH are the leading *** use an AGCM to verify the importance of SSH on the northward propagation of the *** simulations confirm the diagnostic conclusion that the equatorial western Pacific is the source of the ***,the model can accurately simulate the propagation pathway of the QBWO signals over the Asian monsoon ***,sensitivity experiments demonstrate that the SSH over northern India and the southern slope of the TP greatly contributes to the northward propagation of the QBWO as far as the TP area.
Against the backdrop of global warming, China has been facing increasingly frequent and severe extreme weather and climate events, with a prominent risk of compound extreme events induced by interactions among multipl...
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Against the backdrop of global warming, China has been facing increasingly frequent and severe extreme weather and climate events, with a prominent risk of compound extreme events induced by interactions among multiple climate drivers and/or hazards. The present study first reviews the definition and classification of compound extreme events in China. Then, it summarizes research progress on the evolutionary characteristics, formation mechanisms, and future projections of different types of compound extreme events. The potential risks and possible impact pathways of three specific event types—namely, continuous day–night hot extremes, temperature–humidity compound events, and high-temperature–ozone compound events—on the health of the Chinese population are then explored. Finally, a framework for assessing the hazard risk of compound extreme events is constructed, accompanied by response strategies based on carbon neutrality targets. Building on existing research achievements, five future research directions are proposed: (1) identifying the risk chains of compound events; (2) addressing the constraints of observational records and coupled model performances; (3) attributing and understanding the drivers of compound extreme events; (4) finding optimal pathways for carbon reduction and air quality improvement; and (5) promoting inter-disciplinary, multi-regional, and cross-sectoral collaboration. Strengthening research in these directions will deepen our understanding of compound extreme events and provide technological support for climate change adaptation and health risk responses in China. 在全球变暖的背景下, 中国面临着日益频繁和严峻的极端天气气候事件, 其中以多种气候驱动因子和/或灾害相互作用而形成的复合型极端事件风险尤为突出.本文首先回顾了中国区域复合型极端事件的定义与分型;然后综述了不同类型复合型极端事件的演变特征,形成机制以及未来预估等方面的研究进展;随后, 探讨了日夜持续型极端高温事件,温湿复合事件以及高温–臭氧复合事件等三类事件对我国人群健康的潜在风险及可能的影响途径;最后, 阐述了复合型极端事件灾害风险评估框架, 并在此基础上提出了基于碳中和目标的应对策略.在总结既有研究成果的基础上, 提出了五个未来亟需关注的研究方向:(1)复合事件灾害风险链的识别问题;(2)观测资料和耦合模式性能的制约问题;(3)复合型极端事件的归因与成因问题;(4)碳减排与空气质量改善的最优路径问题;(5)多学科,多区域,多部门的合作问题.加强上述方
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