卫星高光谱红外大气探测的正演模拟研究

利用精确的红外大气辐射传输计算模型KCARTA,模拟计算了光谱分辨率、通道光谱响应函数、光谱定标精度、大气倾斜路径和表面发射率对高光谱观测亮温的影响.正演计算的结果表明:1)提高光谱分辨率明显增加了可探测的大气亮温;2)各种内、外部因素的变化对高光谱仪器将产生远较低光谱仪器更大的观测亮温差.本研究可为我国高光谱大气探测仪器的设计以及高光谱大气探测反演算法研究的开展提供科学的参考依据.

Forecasting tropical cyclone rainfall and flooding hazards and impacts

This review summarizes the rapporteur report on advances in monitoring and forecasting of rainfall associated with tropical cyclones(TCs)and its impact during 2014–18,as presented to the 10th International Workshop on TCs(IWTC-10)held in Bali,Indonesia during 5th–9th December 2022.Major physical processes that can modulate TC rainfall distribution,including topography,storm motion,vertical wind shear,and intensity,along with the fundamental physics of rain bands and clouds as simulated by numerical models,diurnal variation of rainfall,and various synoptic and mesoscale features controlling the rainfall distribution are briefly discussed.Improvements to the dynamic core and physical processes in global models are providing useable forecasts nearly up to 7 days.This report also summarizes,some tools that have been developed to predict TC rainfall.Lately there is a tendency for operational forecasting centers to utilize multi-model ensemble systems for rainfall forecasting that demonstrate superior performance than individual models,ensemble members,or even single model ensembles.Major impacts include pluvial and fluvial floods,and landslides.The techniques developed by various forecasting centers to assist in predicting and communicating the impacts associated with these events are also presented in this report.

Objective satellite methods including AI algorithms reviewed for the tenth International workshop on tropical cyclones(IWTC-10)

Here we explore the latest four years(2019–2022)of using satellite data to objectively analyze tropical cyclones(TC)and issue recommendations for improved analysis.We first discuss new methods of direct retrieval from SAR and geostationary imagers.Next,we survey some of the most prominent new techniques in AI and discuss their major capabilities(especially accuracy in nonlinear TC behavior,characterization of model uncertainty and creation of synthetic satellite imagery)and limitations(especially lack of transparency and limited amount of training data).We also identify concerns with biases and unlabeled uncertainties in the Best Track records as being a first-order limitation for further progress in objective methods.The article concludes with recommendations to improve future objective methods,especially in the area of more accurate and reliable training data sets.

Recent advances in seasonal and multi-annual tropical cyclone forecasting

Seasonal tropical cyclone(TC)forecasting has evolved substantially since its commencement in the early 1980s.However,present operational seasonal TC forecasting services still do not meet the requirements of society and stakeholders:current operational products are mainly basin-scale information,while more detailed sub-basin scale information such as potential risks of TC landfall is anticipated for decision making.To fill this gap and make the TC science and services move forward,this paper reviews recent research and development in seasonal tropical cyclone(TC)forecasting.In particular,this paper features new research topics on seasonal TC predictability in neutral conditions of El Ni˜no–Southern Oscillation(ENSO),emerging forecasting techniques of seasonal TC activity including Machine Learning/Artificial Intelligence,and multi-annual TC predictions.We also review the skill of forecast systems at predicting landfalling statistics for certain regions of the North Atlantic,Western North Pacific and South Indian oceans and discuss the gap that remains between current products and potential user's expectations.New knowledge and advanced forecasting techniques are expected to further enhance the capability of seasonal TC forecasting and lead to more actionable and fit-for-purpose products.

RECENT PROGRESS IN STORM SURGE FORECASTING

This report briefly summarizes recent progress in storm surge forecasts, one of topics discussed during the fourth International Workshop on Tropical Cyclone Landfall Process(IWTCLP 4) held during 5-8 December, 2017. In the workshop, improvement of storm surge forecasting system was mainly discussed with relevance to the problem of estimating the impacts of tropical cyclone landfall.To deal with storm surges, accurate TC condition(predictions and forecasts) as input, reasonable storm surge predictions(with forecasting systems), and effective advisories/warnings(i.e. useful information products) are necessary. Therefore, we need to improve storm surge related matters systematically: input, prediction system, and ef fective information.This report tries to highlight recent progress in the field of storm surges in relation to three key points: improvement in storm surge forecasting models/system, TC conditions as input for storm surge predictions, and informative products for end users.

RETRIEVING ATMOSPHERIC TEMPERATURE FROM NOAA-15 ATOVS MEASUREMENTS

This paper describes briefly the sounding capabilities of TOVS/ATOVS onboard the NOAA polar-orbiting meteorological satellites,followed by a more detailed review of the retrieval schemes.The ICI physical retrieval scheme with some adaptations is implemented in our experiment.The analyses of the Chinese regional NWP model are utilized to create a rolling library of initial guess field.Retrieval results validated against both NWP analyses and radiosondes indicate good agreement between ICI retrievals and conventional observations.Preliminary result from the PC-ATOVS Windows display system of NSMC will also be shown.

Science and prediction of monsoon heavy rainfall

With the increasing incidence of heavy rainfall events,particularly over the monsoon regions,the highly dense populations are more vulnerable[1].Research initiatives on observation,modeling,and prediction of monsoon heavy rainfall have been promoted actively by World Weather Research Programme's(WWRP)Working Group on Tropical Meteorology Research(WGTMR)of the World Meteorological Organization(WMO)since 2010.Series of monsoon-heavy-rainfall workshops were held in Beijing(2011),Petaling Jaya(2012),and New Delhi(2015)to benefit scientists worldwide and forecasters from the National Meteorological and Hydrological Services.An international Research and Development Project,namely,the Southern China Monsoon Rainfall Experiment(SCMREX)[2]was established in 2013 to coordinate field campaign experiments and to conduct scientific research on presummer(April-June)heavy rainfall processes in southern China.

OPERATIONAL PERSPECTIVES ON TROPICAL CYCLONE INTENSITY CHANGE PART 2:FORECASTS BY OPERATIONAL AGENCIES

This review summarizes experiences at operational centers to forecast tropical cyclone(TC) intensity change as presented to the International Workshop on Tropical Cyclones(IWTC-9) in Hawaii in 2018. Some operational forecast centers have been able to leverage advances in intensity guidance to increase forecast skill, albeit incrementally, while others have struggled to make any significant improvements. Rapid intensity changes continue to present major challenges to operational centers and individual difficult cases illustrate the forecasting challenges.It is noteworthy that the realization of a recommendation from IWTC-8 in 2014, to adapt guidance initially developed for the North Atlantic and North-East Pacific to other basins, has led to improved forecast skill of some agencies. Recent worldwide difficult cases are presented so that the research community can further investigate, potentially leading to improved intensity forecasts when similar cases are observed in the future.

Mineralogical characteristics of soil dust from source regions in northern China

Mineral compositions of aerosol particles were investigated at four sites （Aksu, Dunhuang, Zhenbeitai, and Tongliao） in desert regions of northern China from March to May in 2001 and 2002 during the intensive field campaign period of ACE-Asia （Aerosol Characterization Experiments-Asia）. The X-ray diffraction （XRD） results show the main minerals for Asian dust are illite, chlorite, kaolinite, quartz, feldspar, calcite, and dolomite. Gypsum, hornblende, and halite are also detected in several samples. Semi-quantitative mineralogical data of aerosol samples show that carbonate content decreases from western to eastern source areas; that is, soil dust collected at western source area sites of Dunhuang and Aksu are enriched with carbonate, while northeastern source area site of Tongliao is associated with low carbonate content. But the spatial distribution of feldspar exhibits a different pattern as compared to carbonate, increasing from the western to the eastern sources. The total clay content is significantly higher （73% in average） at the deposition site of Changwu than those at source areas. Air-mass back trajectory studies for the three dust storm events observed at Changwu, showed that soil dust transport pathways were as expected from carbonate content for the source identification, further demonstrating that carbonate was a useful tracer for eolian dust on regional scale in northern China.

THE WORLD METEOROLOGICAL ORGANIZATION FOURTH INTERNATIONAL WORKSHOP ON TROPICAL CYCLONE LANDFALL PROCESSES(IWTCLP-IV): A SUMMARY

The Fourth International Workshop on Tropical Cyclone Landfall Processes(IWTCLP-4) was held in Macao, China from 5-7 December 2017. The workshop was organized by the World Meteorological Organization(WMO) Expert Team on Tropical Cyclone Landfall Processes in partnership with the WMO Tropical Cyclone Program. The workshop provided a forum for discussion between researchers and forecasters on the current status of tropical cyclone landfall processes and on priorities and opportunities for research. More than 60 leading research scientists and warning specialists working on topics related to tropical cyclone landfall examined current knowledge, forecasting and research trends from an integrated global perspective. The workshop offered a number of recommendations for future forecasting studies and research with special regard to the varying needs of different tropical cyclone af fected regions. The recommendations emanating from the workshop will be presented at the upcoming Ninth International Workshop on Tropical Cyclones(IWTC-9)(Hawaii, USA, 3-7 December 2018).

OPERATIONAL PERSPECTIVES ON TROPICAL CYCLONE INTENSITY CHANGE PART 1:RECENT ADVANCES IN INTENSITY GUIDANCE

This review summarizes techniques used by operational centers to forecast tropical cyclone intensity change as presented to the International Workshop on Tropical Cyclones(IWTC-9)in Hawaii in 2018.Recent advances and major changes over the past four years are presented,with a special focus on forecasting rapid intensity changes.Although intensity change remains one of the most difficult aspects of tropical cyclone forecasting,objective guidance has shown some improvement.The greatest improvements are realized when consensus methods are utilized,especially those that blend statistical-dynamical based guidance with dynamical ocean-coupled regional models.These models become even more skillful when initialized with inner core observational data.Continued improvement and availability of intensity guidance along with associated forecaster training are expected to deliver forecasting improvements in the future.