A new set of Infrared Atmospheric Sounding Interferometer （IASI） channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvem...A new set of Infrared Atmospheric Sounding Interferometer （IASI） channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvement in the analysis outputs from a one-dimensional variational analysis （1D-Var） for the Unified Model （UM） data assimilation system at the Met Office, using the channel score index （CSI） as a figure of merit. Then, 200 channels were selected in order by counting each individual channel＇s CSI contribution. Compared with the operationally used 183 channels for the UM at the Met Office, the new set shares 149 channels, while the other 51 channels are new. Also examined is the selection from the entropy reduction method with the same 1D-Var approach, Results suggest that channel selection can be made in a more objective fashion using the proposed CSI method. This is because the most important channels can be selected across the whole IASI observation spectrum. In the experimental trial runs using the UM global assimilation system, the new channels had an overall neutral impact in terms of improvement in forecasts, as compared with results from the operational channels. However, upper-tropospheric moist biases shown in the control run with operational channels were significantly reduced in the experimental trial with the newly selected channels. The reduction of moist biases was mainly due to the additional water vapor channels, which are sensitive to the upper-tropospheric water vapor.展开更多
This paper evaluates the microwave instruments onboard the latest Chinese polar-orbiting satellite, Fengyun 3D (FY- 3D). Comparing three months of observations from the Microwave Temperature Sounder 2 (MWTS-2), the Mi...This paper evaluates the microwave instruments onboard the latest Chinese polar-orbiting satellite, Fengyun 3D (FY- 3D). Comparing three months of observations from the Microwave Temperature Sounder 2 (MWTS-2), the Microwave Humidity Sounder 2 (MWHS-2), and the Microwave Radiation Imager (MWRI) to Met Office short-range forecasts, we characterize the instrumental biases, show how those biases have changed with respect to their predecessors onboard FY- 3C, and how they compare to the Advanced Technology Microwave Sounder (ATMS) onboard NOAA-20 and the Global Precipitation Measurement Microwave Imager (GMI). The MWTS-2 global bias is much reduced with respect to its predecessor and compares well to ATMS at equivalent channel frequencies, differing only by 0.36 ± 0.28 K (1σ) on average. A suboptimal averaging of raw digital counts is found to cause an increase in striping noise and an ascending- descending bias. MWHS-2 benefits from a new calibration method improving the 183-GHz humidity channels with respect to its predecessor and biases for these channels are within ± 1.9 K to ATMS. MWRI presents the largest improvements, with reduced global bias and standard deviation with respect to FY-3C;although, spurious, seemingly transient, brightness temperatures have been detected in the observations at 36.5 GHz (vertical polarization). The strong solar-dependent bias that affects the instrument on FY-3C has been reduced to less than 0.2 K on average for FY-3D MWRI. Experiments where radiances from these instruments were assimilated on top of a full global system demonstrated a neutral to positive impact on the forecasts, as well as on the fit to the background of independent instruments.展开更多
Microwave radiances from passive polar-orbiting radiometers have been,until recently,assimilated in the Met Office global numerical weather prediction system after the scenes significantly affected by atmospheric scat...Microwave radiances from passive polar-orbiting radiometers have been,until recently,assimilated in the Met Office global numerical weather prediction system after the scenes significantly affected by atmospheric scattering are discarded.Recent system upgrades have seen the introduction of a scattering-permitting observation operator and the development of a variable observation error using both liquid and ice water paths as proxies of scattering-induced bias.Applied to the Fengyun 3 Microwave Temperature Sounder 2(MWTS-2)and the Microwave Humidity Sounder 2(MWHS-2),this methodology increases the data usage by up to 8%at 183 GHz.It also allows for the investigation into the assimilation of MWHS-2118 GHz channels,sensitive to temperature and lower tropospheric humidity,but whose large sensitivity to ice cloud have prevented their use thus far.While the impact on the forecast is mostly neutral with small but significant short-range improvements,0.3%in terms of root mean square error,for southern winds and low-level temperature,balanced by 0.2%degradations of short-range northern and tropical low-level temperature,benefits are observed in the background fit of independent instruments used in the system.The lower tropospheric temperature sounding Infrared Atmospheric Sounding Interferometer(IASI)channels see a reduction of the standard deviation in the background departure of up to 1.2%.The Advanced Microwave Sounding Unit A(AMSU-A)stratospheric sounding channels improve by up to 0.5%and the Microwave Humidity Sounder(MHS)humidity sounding channels improve by up to 0.4%.展开更多
China＇s FengYnn 3 （FY-3） polar orbiting satellites axe set to become an important sonrce of observational data for nu- merical weather prediction （NWP）, atmospheric reanalyses, and climate monitoring studies over...China＇s FengYnn 3 （FY-3） polar orbiting satellites axe set to become an important sonrce of observational data for nu- merical weather prediction （NWP）, atmospheric reanalyses, and climate monitoring studies over the next two decades. As part of the Climate Science for Service Partnership China （CSSP China） prograln, FY-3B Microwave Humidity Sounder 1 （MWHS-1） and FY-3C MWHS-2 observations have been thoroughly assessed and prepared for operational assimilation. This represents the first time observations from China＇s polar orbiting satellites have been used in the UK＇s global NWP model. Since 2016, continuous data quality monitoring has shown occasional bias changes found to be correlated to changes in the energy supply scheme regulating the platform heating system and other transient anomalies. Nonetheless, MWHS-1 and MWHS-2 significantly contribute to the 24-h forecast error reduction by 0.3% and 0.6%, respectively, and the combination of both instruments is shown to improve the fit to the model background of independent sounders by up to 1%. The observations from the Microwave Radiation Imager （MWRI） also are a potentially significant source of benefits for NWP models, but a solar-dependent bias observed in the instrument half-orbits has prevented their assimilation. This paper presents the bases of a correction scheme developed at the Met Office for the purpose of a future assimilation of MWRI data.展开更多
Tea is an important global commodity,with important tea-growing regions spanning across South America,Africa,and Asia,and burgeoning smaller-scale and artisanal tea production in the UK and Europe.In each of these reg...Tea is an important global commodity,with important tea-growing regions spanning across South America,Africa,and Asia,and burgeoning smaller-scale and artisanal tea production in the UK and Europe.In each of these regions,the quality and quantity of tea production,with their economic and social consequences,are highly sensitive to variations in the climate on both short-term weather,seasonal and climate change timescales.The provision of tailored climate information in a timely and accessible manner through the development,delivery and use of climate services can help tea-farmers and other relevant stakeholders better understand the impacts of climate variability and climate change on decision-making and a range of adaptive actions.This paper presents an overview of the Tea-CUP project(Co-developing Useful Predictions),a joint initiative between UK and Chinese partners,which aims to develop and implement solutions for improving robust decision-making.Co-production principles are core,ensuring that the resultant climate services are usable and useful;users'needs are met through close engagement and joint research and decision-making.The paper also reports on the exchange of knowledge and experiences,such as between tea growers in China and the UK,which has resulted from this collaborative work,fostering global knowledge sharing,enriching understanding,and driving innovation by integrating diverse perspectives and expertise from different countries.This is an unintended but valuable side-effect of the collaborative approach taken and highlights the benefits of a highly relational and multidisciplinary approach to climate services development that will inform future work in the field.展开更多
We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the ...We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the rainfall in this region during June is contributed by the mei-yu rain band.We find that similar skill exists for predicting the East Asian summer monsoon index(EASMI)on monthly time scales,and that the latter could be used as a proxy to predict the regional rainfall.However,there appears to be little to be gained from using the predicted EASMI as a proxy for regional rainfall on monthly time scales compared with predicting the rainfall directly.Although interannual variability of the June mean rainfall is affected by synoptic and intraseasonal variations,which may be inherently unpredictable on the seasonal forecasting time scale,the major influence of equatorial Pacific sea surface temperatures from the preceding winter on the June mean rainfall is captured by the model through their influence on the western North Pacific subtropical high.The ability to predict the June mean rainfall in the middle and lower Yangtze River basin at a lead time of up to 4 months suggests the potential for providing early information to contingency planners on the availability of water during the summer season.展开更多
The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean te...The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean temperature.This event exerted serious impacts in the region on agriculture,plant phenology,electricity transmission systems,and human health.In this paper,the contributions of human-induced climate change and anomalous anticyclonic circulation to this event are investigated using the newly homogenized observations and updated Met Office Hadley Centre system for attribution of extreme events,as well as CanESM2(Second Generation Canadian Earth System Model)simulations.Results indicate that both anthropogenic influences and anomalous anticyclonic circulation played significant roles in increasing the probability of the 2018 hottest spring.Quantitative estimates of the probability ratio show that anthropogenic forcing may have increased the chance of this event by ten-fold,while the anomalous circulation increased it by approximately two-fold.The persistent anomalous anticyclonic circulation located on the north side of China blocked the air with lower temperature from high latitudes into eastern China.Without anthropogenic forcing or without the anomalous circulation in northern China,the occurrence probability of the extreme warm spring is significantly reduced.展开更多
Nested simulations of a downslope windstorm over Cangshan mountain,Yunnan,China,have been used to demonstrate a method of topographic smoothing that preserves a relatively large amount of terrain detail compared to ty...Nested simulations of a downslope windstorm over Cangshan mountain,Yunnan,China,have been used to demonstrate a method of topographic smoothing that preserves a relatively large amount of terrain detail compared to typical smoothing procedures required for models with terrain-following grids to run stably.The simulations were carried out using the Met Office Unified Model(MetUM)to investigate downslope winds.The smoothing method seamlessly blends two terrain datasets to which uniform smoothing has been applied—one with a minimum of smoothing,the other smoothed more heavily to remove gradients that would cause model instabilities.The latter dataset dominates the blend where the steepest slopes exist,but this is localised and recedes outside these areas.As a result,increased detail is starkly apparent in depictions of flow simulated using the blend,compared to one using the default approach.This includes qualitative flow details that were absent in the latter,such as narrow shooting flows emerging from roughly 1-2 km wide leeside channels.Flow separation is more common due to steeper lee slopes.The use of targeted smoothing also results in increased lee side temporal variability at a given point during the windstorm,including over flat areas.Low-/high-pass filtering of the wind perturbation field reveals that relative spatial variability above 30 km in scale(reflecting the background flow)is similar whether or not targeting is used.Beneath this scale,when smoothing is targeted,relative flow variability decreases at the larger scales,and increases at lower scales.This seems linked to fast smaller scale flows disturbing more coherent flows(notably an along-valley current over Erhai Lake).Spatial variability of winds in the model is unsurprisingly weaker at key times than is observed across a local network sampling mesoscale variation,but results are compromised due to relatively few observation locations sampling the windstorm.Only when targeted smoothing is applied does the model capture the downslope windstorm's extension over the city of Dali at the mountain's foot,and the peak mean absolute wind.展开更多
The article[Predicting June Mean Rainfall in the Middle/Lower Yangtze River Basin],written by[Gill M.MARTIN,Nick J.DUNSTONE,Adam A.SCAIFE,and Philip E.BETT],was originally published electronically on the publisher’s ...The article[Predicting June Mean Rainfall in the Middle/Lower Yangtze River Basin],written by[Gill M.MARTIN,Nick J.DUNSTONE,Adam A.SCAIFE,and Philip E.BETT],was originally published electronically on the publisher’s internet portal on[10 December 2019]without open access.展开更多
The simulation and prediction of the climatology and interannual variability of the East Asia winter monsoon(EAWM),as well as the associated atmospheric circulation,was investigated using the hindcast data from Global...The simulation and prediction of the climatology and interannual variability of the East Asia winter monsoon(EAWM),as well as the associated atmospheric circulation,was investigated using the hindcast data from Global Seasonal Forecast System version 5(GloSea5),with a focus on the evolution of model bias among different forecast lead times.While GloSea5 reproduces the climatological means of large-scale circulation systems related to the EAWM well,systematic biases exist,including a cold bias for most of China’s mainland,especially for North and Northeast China.GloSea5 shows robust skill in predicting the EAWM intensity index two months ahead,which can be attributed to the performance in representing the leading modes of surface air temperature and associated background circulation.GloSea5 realistically reproduces the synergistic effect of El Niño–Southern Oscillation(ENSO)and the Arctic Oscillation(AO)on the EAWM,especially for the western North Pacific anticyclone(WNPAC).Compared with the North Pacific and North America,the representation of circulation anomalies over Eurasia is poor,especially for sea level pressure(SLP),which limits the prediction skill for surface air temperature over East Asia.The representation of SLP anomalies might be associated with the model performance in simulating the interaction between atmospheric circulations and underlying surface conditions.展开更多
This paper presents an efficient algorithm for generating a spherical multiple-cell(SMC)grid.The algorithm adopts a recursive loop structure and provides two refinement methods:(1)an arbitrary area refinement method a...This paper presents an efficient algorithm for generating a spherical multiple-cell(SMC)grid.The algorithm adopts a recursive loop structure and provides two refinement methods:(1)an arbitrary area refinement method and(2)a nearshore refinement method.Numerical experiments are carried out,and the results show that compared with the existing grid generation algorithm,this algorithm is more flexible and operable.展开更多
Dear Editor,Surface solar radiation(SSR)refers to the solar shortwave radiation(SWR)that reaches the Earth’s surface,serving as the primary energy source for life on our planet and the major force in land surfacemode...Dear Editor,Surface solar radiation(SSR)refers to the solar shortwave radiation(SWR)that reaches the Earth’s surface,serving as the primary energy source for life on our planet and the major force in land surfacemodels.1,2 Variations in SSR can affect climate change,plant photosynthesis,and solar energy utilization.3 Satellite remote sensing,characterized by its robust data continuity and extensive coverage,stands out as one of themost effective means for monitoring changes in SSR.4 However,even the current state-of-the-art satellite SSR products,such as Clouds and the Earth’s Radiant Energy System(CERES)and the International Satellite Cloud Climatology Project,have spatial resolutions that are limited to only a few hundred kilometers,which significantly hinders the refined observation and application of SSR.展开更多
In order to understand the current and potential use of ensemble forecasts in operational tropical cyclone(TC)forecasting,a questionnaire on the use of dynamic ensembles was conducted at operational TC forecast center...In order to understand the current and potential use of ensemble forecasts in operational tropical cyclone(TC)forecasting,a questionnaire on the use of dynamic ensembles was conducted at operational TC forecast centers across the world,in association with the World Meteorological Organisation(WMO)High-Impact Weather Project(HIWeather).The results of the survey are presented,and show that ensemble forecasts are used by nearly all respondents,particularly in TC track and genesis forecasting,with several examples of where ensemble forecasts have been pulled through successfully into the operational TC forecasting process.There is still however,a notable difference between the high proportion of operational TC forecasters who use and value ensemble forecast information,and the slower pull-through into operational forecast warnings and products of the probabilistic guidance and uncertainty information that ensembles can provide.Those areas of research and development that would help TC forecasters to make increased use of ensemble forecast information in the future include improved access to ensemble forecast data,verification and visualizations,the development of hazard and impact-based products,an improvement in the skill of the ensembles(particularly for intensity and structure),and improved guidance on how to use ensembles and optimally combine forecasts from all available models.A change in operational working practices towards using probabilistic information,and providing and communicating dynamic uncertainty information in operational forecasts and warnings,is also recommended.展开更多
Changes in climate pose major challenges to society, and so decision-makers need actionable climate information to inform their planning and policies to make society more resilient to climatic changes. Climate service...Changes in climate pose major challenges to society, and so decision-makers need actionable climate information to inform their planning and policies to make society more resilient to climatic changes. Climate services are being developed to provide such actionable climate information. The successful development and use of climate services benefits greatly from close engagement between developers, providers, and users of the services. The Climate Science for Service Partnership China(CSSP China) is a China–UK collaboration fostering closer engagement between climate scientists, providers of climate services, and users of climate services. We describe the process within CSSP China of co-developing climate services through trials with users to revise and improve a prototype. Examples are provided covering various scientific capabilities, user needs, and parts of China. The development process is yielding many benefits, such as increasing the engagement between providers and users, making users more aware of how climate information can be of use in their decision-making, giving the climate service providers a better understanding of the users’ requirements for climate information, and shaping future scientific research and development. In addition to the benefits, we also document some challenges that have emerged, along with ways of alleviating them. We have two key recommendations from our experiences: make the time and space for effective engagement between the users and developers of any climate service;bring the needs of the users in to the design and delivery of the climate service as early as possible and throughout the development cycle.展开更多
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 h...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.展开更多
Despite advances in forecasting and emergency preparedness, weather related disasters continue to cost many lives, to displace populations and to cause wide-spread damage. Therefore, High Impact Weather Project (HIWea...Despite advances in forecasting and emergency preparedness, weather related disasters continue to cost many lives, to displace populations and to cause wide-spread damage. Therefore, High Impact Weather Project (HIWeather), a 10-year research project (https://public.wmo.int/en/resources/buHetin/hiweather-10-yearresearch- project), was established in 2016 by WM0 (World Meteorology Organization) WWRP (World Weather Research Program: https://www.wmo.int/pages/prog/arep/wwrp/new/wwrp_new_en. html). HIWeather aimed at achieving dramatic improvements in the effectiveness of weather-related hazard warnings, following recent advancement in numerical weather prediction at km-scale and in disaster risk reduction. The implementation plan was developed under the concept of warning chain, which comprises all components and the connections between to a successful weather-hazards warning: observations, weather forecast, hazard forecast, impact forecast, the generation of warnings and decision making (Fig. 1). A successful warning relies on information produced by the meteorological and related physical sciences, thus its effectiveness of delivery depends on applications of social, behavioral and economic sciences. The workshop of WM0 High Impact Weather Project was held in Beijing during 20-22 November of 2018, attracted a diverse and interdisciplinary group of over 70 scientists from 25 countries in the broad field of physical and social science, during which all elements of the warning chain were discussed critically.展开更多
This paper summarizes the forecast methods,outputs and skill offered by twelve agencies for seasonal tropical cyclone(TC)activity around the world.These agencies use a variety of techniques ranging from statistical mo...This paper summarizes the forecast methods,outputs and skill offered by twelve agencies for seasonal tropical cyclone(TC)activity around the world.These agencies use a variety of techniques ranging from statistical models to dynamical models to predict basinwide activity and regional activity.In addition,several dynamical and hybrid statistical/dynamical models now predict TC track density as well as landfall likelihood.Realtime Atlantic seasonal hurricane forecasts have shown low skill in April modest skill in June and good skill in August at predicting basinwide TC activity when evaluated over 2003-2018.Real-time western North Pacific seasonal TC forecasts have shown good skill by July for basinwide intense typhoon numbers and the ACE index when evaluated for 2003-2018.Both hindcasts and real-time forecasts have shown skill for other TC basins.A summary of recent research into forecasting TC activity beyond seasonal(e.g.,multi-year)timescales is included.Recommendations for future areas of research are also discussed.展开更多
Uncertainty is an inherent characteristic of climate forecasts and projections. While there is an expanding body of international research on identifying what climate information users need to know about uncertainty, ...Uncertainty is an inherent characteristic of climate forecasts and projections. While there is an expanding body of international research on identifying what climate information users need to know about uncertainty, and how this should be communicated, very little of this has been conducted in a Chinese cultural context. In this paper, we report on the findings of interviews with climate experts(n = 28) and(potential) users of climate information in China(n =18) at seasonal and multidecadal timescales, with the objective of addressing the following research questions:(1)What information about uncertainty in climate forecasts and projections is currently provided to users in China?(2)What do climate experts believe that users need to know about uncertainty?(3) What information about uncertainty would(potential) users like to receive?(4) What challenges do providers and users perceive with respect to the communication of uncertainty? We find that while seasonal forecasts are predominantly presented deterministically, current and potential users are aware that there is uncertainty associated with them. Climate experts highlight the probabilistic nature of forecasts and the conditional nature of forecast quality, as areas for communication development. Interviews with(potential) users indicate that(1) preferences for deterministic information are not unanimous;(2) probabilities associated with conditions being above/below normal may only be considered useful for decision-making if they are > 60%;and(3) forecasts that provide tailored statements on probability of user-relevant thresholds are preferred. At multidecadal timescales, we observe lower engagement with projections, and less evidence of interaction between providers and recipients, suggesting that development of climate services at multidecadal timescales will need to first highlight the added value of these. We present key recommendations for communicating uncertainty in seasonal forecasts and explore the potential value of multidecadal projections.展开更多
Here we discuss recent progress in understanding tropical cyclone(TC)subseasonal variability and its prediction.There has been a concerted effort to understand the sources of predictability at subseasonal time-scales,...Here we discuss recent progress in understanding tropical cyclone(TC)subseasonal variability and its prediction.There has been a concerted effort to understand the sources of predictability at subseasonal time-scales,and this effort has continued to make progress in recent years.Besides the Madden-Julian Oscillation(MJO),other modes of variability affect TCs at these time-scales,in particular various equatorial waves.Additionally,TC activity is also modulated by extratropical processes via Rossby wave breaking.There has also been progress in the ability of models to simulate the MJO and its modulation of TC activity.Community efforts have created multi-model ensemble datasets,which have made it possible to evaluate the forecast skill of the MJO and TCs on subseasonal time-scales in multiple forecasting systems.While there is positive skill in some cases,there is strong dependence on the ensemble system considered,the basin examined,and whether the storms have extratropical influences or not.Furthermore,the definition of skill differs among studies.Forecasting centers are currently issuing subseasonal TC forecasts using various techniques(statistical,statistical-dynamical and dynamical).There is also a strong interest in the private sector for forecasts with 3-4 weeks lead time.展开更多
基金supported by the KMA Research and Development Program under Grant No.KMIPA 20151060supported by the BK21 Plus Project of the Korean government
文摘A new set of Infrared Atmospheric Sounding Interferometer （IASI） channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvement in the analysis outputs from a one-dimensional variational analysis （1D-Var） for the Unified Model （UM） data assimilation system at the Met Office, using the channel score index （CSI） as a figure of merit. Then, 200 channels were selected in order by counting each individual channel＇s CSI contribution. Compared with the operationally used 183 channels for the UM at the Met Office, the new set shares 149 channels, while the other 51 channels are new. Also examined is the selection from the entropy reduction method with the same 1D-Var approach, Results suggest that channel selection can be made in a more objective fashion using the proposed CSI method. This is because the most important channels can be selected across the whole IASI observation spectrum. In the experimental trial runs using the UM global assimilation system, the new channels had an overall neutral impact in terms of improvement in forecasts, as compared with results from the operational channels. However, upper-tropospheric moist biases shown in the control run with operational channels were significantly reduced in the experimental trial with the newly selected channels. The reduction of moist biases was mainly due to the additional water vapor channels, which are sensitive to the upper-tropospheric water vapor.
基金This work was supported by the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund.
文摘This paper evaluates the microwave instruments onboard the latest Chinese polar-orbiting satellite, Fengyun 3D (FY- 3D). Comparing three months of observations from the Microwave Temperature Sounder 2 (MWTS-2), the Microwave Humidity Sounder 2 (MWHS-2), and the Microwave Radiation Imager (MWRI) to Met Office short-range forecasts, we characterize the instrumental biases, show how those biases have changed with respect to their predecessors onboard FY- 3C, and how they compare to the Advanced Technology Microwave Sounder (ATMS) onboard NOAA-20 and the Global Precipitation Measurement Microwave Imager (GMI). The MWTS-2 global bias is much reduced with respect to its predecessor and compares well to ATMS at equivalent channel frequencies, differing only by 0.36 ± 0.28 K (1σ) on average. A suboptimal averaging of raw digital counts is found to cause an increase in striping noise and an ascending- descending bias. MWHS-2 benefits from a new calibration method improving the 183-GHz humidity channels with respect to its predecessor and biases for these channels are within ± 1.9 K to ATMS. MWRI presents the largest improvements, with reduced global bias and standard deviation with respect to FY-3C;although, spurious, seemingly transient, brightness temperatures have been detected in the observations at 36.5 GHz (vertical polarization). The strong solar-dependent bias that affects the instrument on FY-3C has been reduced to less than 0.2 K on average for FY-3D MWRI. Experiments where radiances from these instruments were assimilated on top of a full global system demonstrated a neutral to positive impact on the forecasts, as well as on the fit to the background of independent instruments.
基金This work was supported by the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund.
文摘Microwave radiances from passive polar-orbiting radiometers have been,until recently,assimilated in the Met Office global numerical weather prediction system after the scenes significantly affected by atmospheric scattering are discarded.Recent system upgrades have seen the introduction of a scattering-permitting observation operator and the development of a variable observation error using both liquid and ice water paths as proxies of scattering-induced bias.Applied to the Fengyun 3 Microwave Temperature Sounder 2(MWTS-2)and the Microwave Humidity Sounder 2(MWHS-2),this methodology increases the data usage by up to 8%at 183 GHz.It also allows for the investigation into the assimilation of MWHS-2118 GHz channels,sensitive to temperature and lower tropospheric humidity,but whose large sensitivity to ice cloud have prevented their use thus far.While the impact on the forecast is mostly neutral with small but significant short-range improvements,0.3%in terms of root mean square error,for southern winds and low-level temperature,balanced by 0.2%degradations of short-range northern and tropical low-level temperature,benefits are observed in the background fit of independent instruments used in the system.The lower tropospheric temperature sounding Infrared Atmospheric Sounding Interferometer(IASI)channels see a reduction of the standard deviation in the background departure of up to 1.2%.The Advanced Microwave Sounding Unit A(AMSU-A)stratospheric sounding channels improve by up to 0.5%and the Microwave Humidity Sounder(MHS)humidity sounding channels improve by up to 0.4%.
基金supported by the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund
文摘China＇s FengYnn 3 （FY-3） polar orbiting satellites axe set to become an important sonrce of observational data for nu- merical weather prediction （NWP）, atmospheric reanalyses, and climate monitoring studies over the next two decades. As part of the Climate Science for Service Partnership China （CSSP China） prograln, FY-3B Microwave Humidity Sounder 1 （MWHS-1） and FY-3C MWHS-2 observations have been thoroughly assessed and prepared for operational assimilation. This represents the first time observations from China＇s polar orbiting satellites have been used in the UK＇s global NWP model. Since 2016, continuous data quality monitoring has shown occasional bias changes found to be correlated to changes in the energy supply scheme regulating the platform heating system and other transient anomalies. Nonetheless, MWHS-1 and MWHS-2 significantly contribute to the 24-h forecast error reduction by 0.3% and 0.6%, respectively, and the combination of both instruments is shown to improve the fit to the model background of independent sounders by up to 1%. The observations from the Microwave Radiation Imager （MWRI） also are a potentially significant source of benefits for NWP models, but a solar-dependent bias observed in the instrument half-orbits has prevented their assimilation. This paper presents the bases of a correction scheme developed at the Met Office for the purpose of a future assimilation of MWRI data.
基金funded by the Met Office Climate Science for Service Partnership(CSSP)China project under the International Science Partnerships Fund(ISPF)supported by funds from the National Natural Science Foundation of China(Grant No.42475022).
文摘Tea is an important global commodity,with important tea-growing regions spanning across South America,Africa,and Asia,and burgeoning smaller-scale and artisanal tea production in the UK and Europe.In each of these regions,the quality and quantity of tea production,with their economic and social consequences,are highly sensitive to variations in the climate on both short-term weather,seasonal and climate change timescales.The provision of tailored climate information in a timely and accessible manner through the development,delivery and use of climate services can help tea-farmers and other relevant stakeholders better understand the impacts of climate variability and climate change on decision-making and a range of adaptive actions.This paper presents an overview of the Tea-CUP project(Co-developing Useful Predictions),a joint initiative between UK and Chinese partners,which aims to develop and implement solutions for improving robust decision-making.Co-production principles are core,ensuring that the resultant climate services are usable and useful;users'needs are met through close engagement and joint research and decision-making.The paper also reports on the exchange of knowledge and experiences,such as between tea growers in China and the UK,which has resulted from this collaborative work,fostering global knowledge sharing,enriching understanding,and driving innovation by integrating diverse perspectives and expertise from different countries.This is an unintended but valuable side-effect of the collaborative approach taken and highlights the benefits of a highly relational and multidisciplinary approach to climate services development that will inform future work in the field.
基金supported by the UK–China ResearchInnovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund
文摘We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the rainfall in this region during June is contributed by the mei-yu rain band.We find that similar skill exists for predicting the East Asian summer monsoon index(EASMI)on monthly time scales,and that the latter could be used as a proxy to predict the regional rainfall.However,there appears to be little to be gained from using the predicted EASMI as a proxy for regional rainfall on monthly time scales compared with predicting the rainfall directly.Although interannual variability of the June mean rainfall is affected by synoptic and intraseasonal variations,which may be inherently unpredictable on the seasonal forecasting time scale,the major influence of equatorial Pacific sea surface temperatures from the preceding winter on the June mean rainfall is captured by the model through their influence on the western North Pacific subtropical high.The ability to predict the June mean rainfall in the middle and lower Yangtze River basin at a lead time of up to 4 months suggests the potential for providing early information to contingency planners on the availability of water during the summer season.
基金the National Key Research and Development Program of China(Grant No.2018YFC1507702)the National Natural Science Foundation of China(Grant No.41775082)+3 种基金Y.SUN was supported by the National Key Research and Development Program of China(Grant No.2016YFA0600701)the National Natural Science Foundation of China(Grant No.41790471)N.CHRISTIDIS and P.A.STOTT were supported by the Met Office Hadley Centre Climate Programme funded by BEIS,Defrathe UK−China Research and Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund,China.
文摘The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean temperature.This event exerted serious impacts in the region on agriculture,plant phenology,electricity transmission systems,and human health.In this paper,the contributions of human-induced climate change and anomalous anticyclonic circulation to this event are investigated using the newly homogenized observations and updated Met Office Hadley Centre system for attribution of extreme events,as well as CanESM2(Second Generation Canadian Earth System Model)simulations.Results indicate that both anthropogenic influences and anomalous anticyclonic circulation played significant roles in increasing the probability of the 2018 hottest spring.Quantitative estimates of the probability ratio show that anthropogenic forcing may have increased the chance of this event by ten-fold,while the anomalous circulation increased it by approximately two-fold.The persistent anomalous anticyclonic circulation located on the north side of China blocked the air with lower temperature from high latitudes into eastern China.Without anthropogenic forcing or without the anomalous circulation in northern China,the occurrence probability of the extreme warm spring is significantly reduced.
基金supported by the UK–China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund
文摘Nested simulations of a downslope windstorm over Cangshan mountain,Yunnan,China,have been used to demonstrate a method of topographic smoothing that preserves a relatively large amount of terrain detail compared to typical smoothing procedures required for models with terrain-following grids to run stably.The simulations were carried out using the Met Office Unified Model(MetUM)to investigate downslope winds.The smoothing method seamlessly blends two terrain datasets to which uniform smoothing has been applied—one with a minimum of smoothing,the other smoothed more heavily to remove gradients that would cause model instabilities.The latter dataset dominates the blend where the steepest slopes exist,but this is localised and recedes outside these areas.As a result,increased detail is starkly apparent in depictions of flow simulated using the blend,compared to one using the default approach.This includes qualitative flow details that were absent in the latter,such as narrow shooting flows emerging from roughly 1-2 km wide leeside channels.Flow separation is more common due to steeper lee slopes.The use of targeted smoothing also results in increased lee side temporal variability at a given point during the windstorm,including over flat areas.Low-/high-pass filtering of the wind perturbation field reveals that relative spatial variability above 30 km in scale(reflecting the background flow)is similar whether or not targeting is used.Beneath this scale,when smoothing is targeted,relative flow variability decreases at the larger scales,and increases at lower scales.This seems linked to fast smaller scale flows disturbing more coherent flows(notably an along-valley current over Erhai Lake).Spatial variability of winds in the model is unsurprisingly weaker at key times than is observed across a local network sampling mesoscale variation,but results are compromised due to relatively few observation locations sampling the windstorm.Only when targeted smoothing is applied does the model capture the downslope windstorm's extension over the city of Dali at the mountain's foot,and the peak mean absolute wind.
文摘The article[Predicting June Mean Rainfall in the Middle/Lower Yangtze River Basin],written by[Gill M.MARTIN,Nick J.DUNSTONE,Adam A.SCAIFE,and Philip E.BETT],was originally published electronically on the publisher’s internet portal on[10 December 2019]without open access.
基金supported by the State Key Program of the National Natural Science of China(Grant No.41730964)the National Key Research and Development Program on Monitoring,Early Warning and Prevention of Major Natural Disaster(2018YFC1506000)+2 种基金the National Natural Science Foundation of China(Grant Nos.41975091 and 42175047)National Basic Research Program of China(2015CB453203)UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund.
文摘The simulation and prediction of the climatology and interannual variability of the East Asia winter monsoon(EAWM),as well as the associated atmospheric circulation,was investigated using the hindcast data from Global Seasonal Forecast System version 5(GloSea5),with a focus on the evolution of model bias among different forecast lead times.While GloSea5 reproduces the climatological means of large-scale circulation systems related to the EAWM well,systematic biases exist,including a cold bias for most of China’s mainland,especially for North and Northeast China.GloSea5 shows robust skill in predicting the EAWM intensity index two months ahead,which can be attributed to the performance in representing the leading modes of surface air temperature and associated background circulation.GloSea5 realistically reproduces the synergistic effect of El Niño–Southern Oscillation(ENSO)and the Arctic Oscillation(AO)on the EAWM,especially for the western North Pacific anticyclone(WNPAC).Compared with the North Pacific and North America,the representation of circulation anomalies over Eurasia is poor,especially for sea level pressure(SLP),which limits the prediction skill for surface air temperature over East Asia.The representation of SLP anomalies might be associated with the model performance in simulating the interaction between atmospheric circulations and underlying surface conditions.
基金The National Key Research and Development Program of China under contract No.2018YFC1407000.
文摘This paper presents an efficient algorithm for generating a spherical multiple-cell(SMC)grid.The algorithm adopts a recursive loop structure and provides two refinement methods:(1)an arbitrary area refinement method and(2)a nearshore refinement method.Numerical experiments are carried out,and the results show that compared with the existing grid generation algorithm,this algorithm is more flexible and operable.
基金supported by the National Natural Science Foundation of China,China(42025504)supported by the National Satellite Meteorological Center,Chinese Meteorological Administration,China+1 种基金the Center for Environmental Remote Sensing,Chiba University,Japanand the ICARE Data and Services Center,University of Lille,France.The SSRC data derived from the GSNO system will be accessible through the CARE homepage(www.slrss.cn/care/sp/pc/)upon publication of the corresponding paper.
文摘Dear Editor,Surface solar radiation(SSR)refers to the solar shortwave radiation(SWR)that reaches the Earth’s surface,serving as the primary energy source for life on our planet and the major force in land surfacemodels.1,2 Variations in SSR can affect climate change,plant photosynthesis,and solar energy utilization.3 Satellite remote sensing,characterized by its robust data continuity and extensive coverage,stands out as one of themost effective means for monitoring changes in SSR.4 However,even the current state-of-the-art satellite SSR products,such as Clouds and the Earth’s Radiant Energy System(CERES)and the International Satellite Cloud Climatology Project,have spatial resolutions that are limited to only a few hundred kilometers,which significantly hinders the refined observation and application of SSR.
文摘In order to understand the current and potential use of ensemble forecasts in operational tropical cyclone(TC)forecasting,a questionnaire on the use of dynamic ensembles was conducted at operational TC forecast centers across the world,in association with the World Meteorological Organisation(WMO)High-Impact Weather Project(HIWeather).The results of the survey are presented,and show that ensemble forecasts are used by nearly all respondents,particularly in TC track and genesis forecasting,with several examples of where ensemble forecasts have been pulled through successfully into the operational TC forecasting process.There is still however,a notable difference between the high proportion of operational TC forecasters who use and value ensemble forecast information,and the slower pull-through into operational forecast warnings and products of the probabilistic guidance and uncertainty information that ensembles can provide.Those areas of research and development that would help TC forecasters to make increased use of ensemble forecast information in the future include improved access to ensemble forecast data,verification and visualizations,the development of hazard and impact-based products,an improvement in the skill of the ensembles(particularly for intensity and structure),and improved guidance on how to use ensembles and optimally combine forecasts from all available models.A change in operational working practices towards using probabilistic information,and providing and communicating dynamic uncertainty information in operational forecasts and warnings,is also recommended.
基金Supported by the UK–China Research and Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund。
文摘Changes in climate pose major challenges to society, and so decision-makers need actionable climate information to inform their planning and policies to make society more resilient to climatic changes. Climate services are being developed to provide such actionable climate information. The successful development and use of climate services benefits greatly from close engagement between developers, providers, and users of the services. The Climate Science for Service Partnership China(CSSP China) is a China–UK collaboration fostering closer engagement between climate scientists, providers of climate services, and users of climate services. We describe the process within CSSP China of co-developing climate services through trials with users to revise and improve a prototype. Examples are provided covering various scientific capabilities, user needs, and parts of China. The development process is yielding many benefits, such as increasing the engagement between providers and users, making users more aware of how climate information can be of use in their decision-making, giving the climate service providers a better understanding of the users’ requirements for climate information, and shaping future scientific research and development. In addition to the benefits, we also document some challenges that have emerged, along with ways of alleviating them. We have two key recommendations from our experiences: make the time and space for effective engagement between the users and developers of any climate service;bring the needs of the users in to the design and delivery of the climate service as early as possible and throughout the development cycle.
基金supported by the National Key Basic Research and Development Program of China(2018YFC1507400)the National Natural Science Foundation of China(41775050)+1 种基金the Basic Research&Operation Funding of Chinese Academy of Meteorological Sciences(2017Z006)supported by the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund
文摘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.
基金supported by 2018 Open Research Program of the Chinese State Key Laboratory of Severe Weatherthe National Natural Science Foundation of China(41330421,41875052)
文摘Despite advances in forecasting and emergency preparedness, weather related disasters continue to cost many lives, to displace populations and to cause wide-spread damage. Therefore, High Impact Weather Project (HIWeather), a 10-year research project (https://public.wmo.int/en/resources/buHetin/hiweather-10-yearresearch- project), was established in 2016 by WM0 (World Meteorology Organization) WWRP (World Weather Research Program: https://www.wmo.int/pages/prog/arep/wwrp/new/wwrp_new_en. html). HIWeather aimed at achieving dramatic improvements in the effectiveness of weather-related hazard warnings, following recent advancement in numerical weather prediction at km-scale and in disaster risk reduction. The implementation plan was developed under the concept of warning chain, which comprises all components and the connections between to a successful weather-hazards warning: observations, weather forecast, hazard forecast, impact forecast, the generation of warnings and decision making (Fig. 1). A successful warning relies on information produced by the meteorological and related physical sciences, thus its effectiveness of delivery depends on applications of social, behavioral and economic sciences. The workshop of WM0 High Impact Weather Project was held in Beijing during 20-22 November of 2018, attracted a diverse and interdisciplinary group of over 70 scientists from 25 countries in the broad field of physical and social science, during which all elements of the warning chain were discussed critically.
基金supported by the G.Unger Vetlesen Foundationfinancial support from the European Union’s Horizon 2020 Research and Innovation programme(EUCP+5 种基金grant agreement no.776613)from the Ministerio de Economia y Competitividad(MINECO)as part of the CLINSA(CGL2017-85791-R)and HIATUS(CGL2015-70353-R)projectssupport of JSPS KAKENHI Grant Numbers JP17K14395 and JP17K01223financial support from the National Typhoon Center at the Korea Meteorological Administration("Research and Development for Numerical Weather Prediction and Earthquake Services"project)support from the UK Public Weather Service research programmesupported by the Research Grants Council of the Hong Kong Special Administrative Region of China Grant E-CityU101/16.
文摘This paper summarizes the forecast methods,outputs and skill offered by twelve agencies for seasonal tropical cyclone(TC)activity around the world.These agencies use a variety of techniques ranging from statistical models to dynamical models to predict basinwide activity and regional activity.In addition,several dynamical and hybrid statistical/dynamical models now predict TC track density as well as landfall likelihood.Realtime Atlantic seasonal hurricane forecasts have shown low skill in April modest skill in June and good skill in August at predicting basinwide TC activity when evaluated over 2003-2018.Real-time western North Pacific seasonal TC forecasts have shown good skill by July for basinwide intense typhoon numbers and the ACE index when evaluated for 2003-2018.Both hindcasts and real-time forecasts have shown skill for other TC basins.A summary of recent research into forecasting TC activity beyond seasonal(e.g.,multi-year)timescales is included.Recommendations for future areas of research are also discussed.
基金Supported by the UK–China Research and Innovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund (112459)。
文摘Uncertainty is an inherent characteristic of climate forecasts and projections. While there is an expanding body of international research on identifying what climate information users need to know about uncertainty, and how this should be communicated, very little of this has been conducted in a Chinese cultural context. In this paper, we report on the findings of interviews with climate experts(n = 28) and(potential) users of climate information in China(n =18) at seasonal and multidecadal timescales, with the objective of addressing the following research questions:(1)What information about uncertainty in climate forecasts and projections is currently provided to users in China?(2)What do climate experts believe that users need to know about uncertainty?(3) What information about uncertainty would(potential) users like to receive?(4) What challenges do providers and users perceive with respect to the communication of uncertainty? We find that while seasonal forecasts are predominantly presented deterministically, current and potential users are aware that there is uncertainty associated with them. Climate experts highlight the probabilistic nature of forecasts and the conditional nature of forecast quality, as areas for communication development. Interviews with(potential) users indicate that(1) preferences for deterministic information are not unanimous;(2) probabilities associated with conditions being above/below normal may only be considered useful for decision-making if they are > 60%;and(3) forecasts that provide tailored statements on probability of user-relevant thresholds are preferred. At multidecadal timescales, we observe lower engagement with projections, and less evidence of interaction between providers and recipients, suggesting that development of climate services at multidecadal timescales will need to first highlight the added value of these. We present key recommendations for communicating uncertainty in seasonal forecasts and explore the potential value of multidecadal projections.
文摘Here we discuss recent progress in understanding tropical cyclone(TC)subseasonal variability and its prediction.There has been a concerted effort to understand the sources of predictability at subseasonal time-scales,and this effort has continued to make progress in recent years.Besides the Madden-Julian Oscillation(MJO),other modes of variability affect TCs at these time-scales,in particular various equatorial waves.Additionally,TC activity is also modulated by extratropical processes via Rossby wave breaking.There has also been progress in the ability of models to simulate the MJO and its modulation of TC activity.Community efforts have created multi-model ensemble datasets,which have made it possible to evaluate the forecast skill of the MJO and TCs on subseasonal time-scales in multiple forecasting systems.While there is positive skill in some cases,there is strong dependence on the ensemble system considered,the basin examined,and whether the storms have extratropical influences or not.Furthermore,the definition of skill differs among studies.Forecasting centers are currently issuing subseasonal TC forecasts using various techniques(statistical,statistical-dynamical and dynamical).There is also a strong interest in the private sector for forecasts with 3-4 weeks lead time.
