A Proposal for WWRP/WMO Research and Development Project (RDP)

Transcription

1 CAS/WWRP/JSC5/Doc. 4.4 : p. 1 WORLD METEOROLOGICAL ORGANIZATION COMMISSION FOR ATMOSPHERIC SCIENCES (CAS) 5 th Joint Science Committee of the World Weather Research Programme WMO Geneva, Switzerland (11-13 April 2012) CAS/WWRP/JSC5/DOC4.4 (9 March 2012) Item: 4.4 A Proposal for WWRP/WMO Research and Development Project (RDP) Southern China Monsoon Rainfall Experiment (SCMREX) Proposed by State Key Laboratory of Severe Weather (LaSW), Chinese Academe of Meteorological Sciences (CAMS) China Meteorological Administration P. R. China January

2 CAS/WWRP/JSC5/Doc. 4.4 : p. 2 Table of Contents Summary 1. Background 1.1 Introduction 1.2 Motivation 1.3 Current observation network 2. Goals and Objectives 2.1 Goals 2.2 Objectives 3. Field Campaigns 3.1 Experiment time 3.2 Experiment areas 3.3 Experiment measurements 3.4 Data processing and database 3.5 NWP experiments 4. Strategy and Management 4.1 Principles 4.2 Organization 4.3 Data management 4.4 Funding 4.5 International participation and collaboration Acknowledgements References Annex Annex I: Professor Renhe Zhang s Resume Annex II: Professor Donghai Wang s Resume Annex III: Professor Yali Luo s Resume Annex IV: Comments of Monsoon Panel Expert Team 2

3 CAS/WWRP/JSC5/Doc. 4.4 : p. 3 Summary From the onset of the South China Sea monsoon in middle or late May to the northward shift of the monsoon rain belt to the Yangtz-Huai River Valleys in middle or late June, the first rainy season in southern China reaches its peak in terms of occurrence frequency and intensity of heavy rainfall, which usually leads to flash floods and waterlogging disasters, causing tremendous losses to lives and properties and can bring huge damages to the economy of the society. In order to better understand the heavy rainfall during the first rainy season in southern China and to improve the capability of numerical weather prediction (NWP) for heavy rainfalls, the Southern China Monsoon Rainfall Experiment (SCMREX) is planned. The aim is to study precipitation processes by means of a synergy of a new generation of in-situ and remote sensing observational systems operated on ground, aircraft, and satellites. These new systems will depict the details of the internal structure of convective clouds and their environment over southern China during the onset of the South China Sea monsoon therefore allowing us to elucidate the physical mechanisms of the convection and heavy rainfall of the southern China monsoon in late spring and early summer. The data sets collected will also be used to evaluate NWP forecasts and to study ways to improve the physical schemes in NWP models. The field campaign phase of the project will be performed during the period of 1 st May to 15 th June It will be conducted in the observation region at three levels of scale, i.e., the meso-α, meso-β, and meso-γ scales, covering the southern China provinces of Guangdong, Guangxi and Hainan, and Hong Kong and the adjacent oceanic areas. The field experiments will be built upon the operational observation network that consists of automatic weather stations, GPS water vapor stations, upper air radiosound stations, weather radars, and satellites. In addition, the field campaign will conduct intensive observations of clouds and precipitation, meso-scale wind fields, land-sea boundary layer, thunder and lightning activities, as well as radiosound observations at enhanced time-and-space resolutions. A number of NWP models will be running during the experimental period and efforts will be made to evaluate their performance and improve their accuracy in real time heavy rainfall forecasts. 3

4 CAS/WWRP/JSC5/Doc. 4.4 : p Background 1.1 Introduction The first rainy season (also called pre-summer rainy period) in southern China usually begins in April and ends in middle or late June when the rain belt moves northward to the Yangtze-Huai River Valleys (Ding, 1994). Heavy rainfall over southern China occurs more frequently and at larger rates after the outbreak of the South China Sea monsoon in middle or late May (Fig. 1), which indicates the onset of the East Asian summer monsoon. Therefore, the first rainy season in southern China reaches its peak in terms of occurrence frequency and intensity of heavy rainfall during the period from middle or late May to middle or late June (Zhou et al., 2003). This period is referred to hereafter as the monsoon rainy period of southern China. It is the time with frequent occurrences of torrential rains in southern China that usually lead to serious flooding and waterlogging disasters, endangering the safety of lives and properties and can bring huge damages to the economy of the society. Fig. 1 (a) Occurrence frequencies of heavy rainfall (>50 mm day -1 ) averaged over southern China during the pre-monsoon, monsoon-active, monsoon-break, and entire monsoon rainy periods. (b) Histograms of the heavy rainfall over southern China during the pre-monsoon and entire monsoon periods. Precipitation over southern China during the monsoon rainy period is characterized by heavy and convective rainfall. Occurrences of torrential rainfall with 4

5 CAS/WWRP/JSC5/Doc. 4.4 : p. 5 a rate of more than 100 mm hr -1 are not uncommon. Heavy rainfall (i.e., more than 50 mm day -1 ) contributes more than 50% to the maxima of the climatologically accumulated rainfall amount during the monsoon rainy period of southern China, which are distributed over the coastal areas of the Guangdong and Guangxi provinces, the northern Guangxi, as well as the western and northern Fujian (Fig. 2). Due to the intermittence of the Asia summer monsoon, the monsoon rainy period of southern China consists of monsoon active and break periods. Nearly 95% of the rainfall amount in the monsoon rainy season falls in the active periods. The duration of the monsoon rainy period varies year by year. During the most recent 13 years ( ), the shortest is 13 days and longest is 41 days. On average, about 65% of the days are the monsoon active periods when extensive rain bands frequently cover southern China. These rain bands have an average life period of 5 days, indicating the persistent nature of the precipitation events. During the monsoon break period, precipitation is mostly caused by local convection which tends to be of smaller temporal and spatial scales. About 95% of the total precipitation amount is produced by rainy systems that exhibit convective activities, based on analyses of the Tropical Rainfall Measuring Mission (TRMM) observations. Therefore, convective clouds and mesoscale convective systems (MCSs) are indeed the dominant producer of heavy rainfall during the monsoon rainy period of southern China. Fig. 2 (a) Total precipitation during the monsoon rainy period over southern China in ; 5

6 CAS/WWRP/JSC5/Doc. 4.4 : p. 6 (b) Contribution of heavy rainfall (>50 mm day -1 ) to total precipitation; (c) Occurrence frequency of heavy rainfall in the first rainy season in southern China during (%); (d) Distribution of terrain and coastal lines in southern China and the adjacent areas. Previous studies (e.g., Xue, 1999; Sun and Zhao, 2000; Zhou et al., 2003; Xia et al., 2006) suggest that occurrence of the heavy rainfall result from interactions of weather systems at scales ranging from the cloud-scale to the synoptic scale. The most important weather systems are probably the front at the surface and the moist low-level southwesterly flow. Although the heavy rainfall occurs mostly to the south of the surface front, i.e., within the warm-air area, it is closely related to activity of cold air from the north. The southwesterly low-level jet (LLJ) at synoptic or sub-synoptic scales, being embedded in the monsoon flow, also plays a critical role through transporting moisture and energy to southern China. The synoptic-scale shear line at the low-level, sometimes along with mesoscale vortices on it, is also a favoring factor for the initiation and enhancement of convection. These larger-scale weather systems provide environmental conditions that favor formation of deep convective clouds, i.e., large convective available potential energy (CAPE), abundant moisture, and large-scale upward motion. The theoretical and modeling studies (e.g., Shen et al., 2005) and diagnostic studies (e.g., Mu at al., 2008) have provided evidence that not only the large-scale environment conditions but also the internal circulations of convective clouds and MCSs can play important roles in the convection initiation, upscale growth of convective clouds and their organization to form MCSs. Meanwhile, recent studies have focused on the cloud microphysical processes associated with the development of heavy rainfall during the monsoon rainy period of southern China. The impacts of ice clouds on the development of convective systems have been intensively studied using cloud-resolving model simulations (e.g., Yoshizaki, 1986; Nicholls, 1987; Fovell and Ogura, 1988; Tao and Simpson, 1989; McCumber et al., 1991; Tao et al., 1991; Liu et al., 1997; Grabowski et al., 1999; Wu et al., 1999; Li et al., 1999; Grabowski and Moncrieff, 2001; Wu, 2002; Grabowski, 2003). Gao et al. (2006) and Ping et al. (2007) conducted two-dimensional (2D) cloud-resolving model simulations with imposed large scale vertical velocity derived 6

7 CAS/WWRP/JSC5/Doc. 4.4 : p. 7 from Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE) data and with zero imposed large-scale vertical velocity, respectively, to study the effects of ice microphysics on tropical thermodynamic states. Both studies showed that the total exclusion of ice microphysics (the exclusion of both ice microphysical and radiative effects) leads to a cold temperature bias and the enhancement of cloud water. The total exclusion of ice microphysics generated a dry bias in the simulation imposed with zero largescale vertical velocity whereas it produced a moist bias in the simulation imposed with TOGA COARE-derived large-scale vertical velocity. For the monsoon heavy rainfall over southern China, the torrential rainfall case has been well simulated using a two-dimensional (2D) cloud-resolving model experiment that is validated against available observational data (Wang et al. 2009a, 2010a), and associated sensitivity experiments have been conducted and analyzed to study effects of vertical wind shear, radiation, and ice clouds on torrential rainfall (Wang et al. 2009b, 2010b, 2010c, Shen et al. 2011). Studies showed that ice clouds play an important role in the development of heavy rainfall, and the dominant contributions of vapor condensation to the growth of water hydrometeors and the increase in atmospheric temperature and found that rainfall starts with warm rain processes and is followed by cold rain processes where ice hydrometeors melt into rain. The dynamic effects reveal a transport of hydrometeor concentration from convective regions to raining stratiform regions, which is a major source for stratiform rainfall in many precipitation systems. The net condensation rate is significantly larger over convective regions than over raining stratiform regions. The first field experiment aiming at better understanding of the heavy rainfall during the first rainy season of southern China was conducted in (Huang et al., 1986). It was found that the heavy rainfall in the first rainy season is mainly the warm-area heavy rains and is very closely related to the LLJ. The second heavy rainfall experiment in southern China took place in 1998 (Zhou et al., 2003), which led to the revealing of some structural features of the meso-β-scale weather systems as well as their development mechanisms. It also suggested that, with the use of the 7

8 CAS/WWRP/JSC5/Doc. 4.4 : p. 8 meteorological observation data at scales of ~10 times of the rainstorm scale, meso-scale models can simulate the meso-β-scale structure and processes of the torrential rains with some success. During May-July of 2008 and 2009, the South China Heavy Rainfall Experiment (SCHeREX; Zhang et al. 2011) was staged by the State Key Laboratory of Severe Weather (LaSW), Chinese Academy of Meteorological Sciences (CAMS). The SCHeREX led to establishment of 4 mesoscale observing networks over southern China, the middle reaches of Yangtze River, the Yangtze-Huai River Valleys, and the lower reaches of Yangtze River, respectively. Capability of these mesoscale observing networks was enhanced by utilization of advanced equipment such as millimeter-wave radar, dual-polarization Doppler weather radar, wind profiler, and drop sounding aircraft. Abundant observational datasets at the meso-β scale were collected and applied not only in fine resolution analysis and retrieval of three dimensional (3D) wind fields, but also in short-term forecasts with timely data updates which enabled interactions between the field experiment and operational forecast and thus improved the heavy rainfall forecast. 1.2 Motivation The previous experiments and studies have confirmed that the heavy rainfall in southern China is closely related to meso-scale convective complex after the onset of the South China Sea monsoon. However, there is still a lack of in-depth studies on the detailed processes covering a range of scales, i.e., from convective cloud cells to convective cloud clusters to mesoscale convective weather systems and finally to regional rainstorms. The prediction skills remain on the stage of foreseeing heavy rain event, unable to accurately forecast where and when the heavy rains will be occurring. The skill of weather forecasts for the heavy rainfalls in southern China in May and June is quite low and is worse than the forecast for heavy rainfall in other regions of the mainland China such as the Yangtze-Huai River Valleys (Fig. 3). The skill of meoscale models is also not better in comparison with global models using conventional verification parameters. Rainfall verification is also a challenge. 8

9 CAS/WWRP/JSC5/Doc. 4.4 : p. 9 Fig. 3 TS scores of accumulative rainfall forecast of southern China (Guangdong, Guangxi and Hainan) in (a) May and (b) June of Colors represent forecaster, global models (T639, Japan and Germany), mesoscale models (MM5 and GRAPES), respectively. (Data source: Numerical Prediction Center, China Meteorological Administration) To improve the forecast skill of the heavy rains, it is desirable to explore the reasons for convection initiation and formation of convective clouds, as well as the processes and conditions for the development, intensification and upscale organization of the convective clouds. The relevant scientific questions are broadly as follows: (1) In terms of convection initiation, what determines its timing and location? What are the roles of the LLJ, low-level shear line, and vortices? What role does the cold air play? What are the roles of the underlying surface (i.e., mountains, coasts)? What is the role played by the convection initiation in forming clouds and 9

10 CAS/WWRP/JSC5/Doc. 4.4 : p. 10 precipitation? (2) In the respect of upscale growth and organization of convective clouds, why can the convective clouds grow? How are they organized to form MCSs, and through what dynamical and physical processes? What are the roles of the internal circulations of the convective clouds and the environmental factors, respectively? What roles do the warm rain and ice-phase cloud microphysical processes play? How does their relative importance vary with the clouds evolution? (3) Regarding the internal structure of convective clouds and their relations to surface rainfall, what are the horizontal and vertical distributions of microphysical properties (hydrometeor phase, type, and size distribution) within the interior of the convective clouds and MCSs? How do these properties evolve during the life cycles of the clouds/mcss? How are the microphysical properties of the clouds related to the thermodynamic fields and dynamical circulations of the clouds themselves and of their environmental atmosphere? How are the properties of the clouds and atmosphere aloft related to rainfall at the surface? There have been innumerable studies aiming at better understanding of convection in different locations around the world. Although the basic physics of convective systems, such as those summarized by Emanuel (1993) and Houze (2004), are probably universally valid, convective systems at southern China are expected to possess some uniqueness and thus further study is needed for a few reasons. First, structure and mechanism of convective systems significantly depend upon environmental atmospheric conditions (CAPE, moisture, vertical shear of horizontal wind) and the strong East Asia summer monsoon does provide more abundant moisture at southern China than many other places where convective systems occur frequently, e.g., central United States where the Bow Echo and MCV Experiment (BAMEX) took place. At least one study, by analyzing mesoscale reanalysis data generated using the Local Analysis and Prediction System (LAPS; developed and operated by the United States Earth System Research Laboratory) with observations collected during SCHeREX (Xu et al. 2011), has shown obvious differences in structure and mechanisms between a mesoscale convective vortex in the environment 10

11 CAS/WWRP/JSC5/Doc. 4.4 : p. 11 of the East Asian summer monsoon and those observed during BAMEX (Davis and Trier, 2007). Second, the unique topography at southern China should play an important role in formation and evolution of convection, which can be inferred from the distributions of convective and non-convective precipitation features (PFs) viewed by TRMM (Fig. 4). Note that the locations of the maximal occurrences of the PFs (Fig. 4) correspond to those of maximal rainfall accumulation observed by the surface stations (Fig. 2a). The convective storms occurred the most frequently at the coastal area of Guangdong and the areas with trumpet-shaped topography in both Guangxi and Guangdong. In contrast, the non-convective precipitation systems were present the most frequently in the mountainous areas at northwestern Fujian. Although case studies have suggested topographic effects on rainfall location and intensity in the region (e.g., Zhao et al. 2008), there is still a lack of sufficient knowledge on how the surface features, e.g., the coast line, influence the atmospheric conditions of the planetary boundary layer (PBL) and thus formation and evolution of convective systems at southern China. Fig. 4 (a) Topographical map of southern China. (b-d) Distributions of occurrence frequency of three categories of precipitation feature (PF) observed by TRMM. A PF is defined as a contiguous area consisting of the TRMM 2A25 (Iguchi et al. 2000) near surface raining pixels. 11

12 CAS/WWRP/JSC5/Doc. 4.4 : p. 12 The PFs are categorized into MCS-, submcs- and Other-types, based on the PF area and existence of convective pixel in the PF. The criterion of a convective pixel is based on the TRMM 2A23 product (Awaka et al. 1998). If there is no convective pixel in a PF, the PF is categorized into the Other-type, which may be part of a decayed convective system or stratiform system; If a PF has at least one convective pixel and its area larger than 1000 km 2, it is considered as an MCS-type PF, otherwise it is a submcs-type PF. The low skill of weather forecasts for the heavy rainfall in the first rainy season in southern China is directly related to the low skill of the NWP models for short- and medium-range Quantitative Precipitation Forecast (QPF). It remains difficult for the state-of-the-art NWP models to accurately predict the occurrence, intensity and duration of the MCSs in a detailed, quantitative, and timely manner, although the models can produce the mesoscale dynamical and physical processes to a certain extent, given accurate large-scale information. This difficulty is mainly due to insufficient information of clouds and their environmental atmosphere at the fine-scales in the initial conditions and also contributed by uncertainties associated with the physical schemes in the models. Among the various physical schemes in the models, the schemes that represent the PBL and cloud microphysics deserve special attention for several reasons. First, the most important weather systems relevant to these heavy rainfalls occur within the PBL and, however, impacts of the unique topographical features at southern China on PBL atmosphere and thus convective systems at the region are not well known. Second, convection initiation is directly linked to the dynamic (such as convergence) and thermodynamic (such as moisture distribution) conditions of the PBL, while convection development is significantly impacted by the cloud microphysical processes. Third, more and more numerical simulations and predictions are made at the explicit deep convective-scale, i.e., the use of deep convection parameterizations is avoided, and hence parameterizations of cloud microphysics and PBL become more important. Fourth, very few studies have evaluated the 3D fine-scale structures of the PBL atmosphere and the convective clouds/cloud-systems from predictions and simulations, mainly due to a lack of suitable observations. Therefore, performance of the physical schemes, in terms of representation of the southern China heavy rainfall, is largely unknown. 12

13 CAS/WWRP/JSC5/Doc. 4.4 : p. 13 The difficulties in efficient monitoring by the meteorological operational observing network and in successful simulation of the convective clouds and MCSs have hindered rapid progress in the mechanism studies and NWP of the heavy rains, because of the direct influences on the formation and evolution of the heavy rains by the convective clouds and MCSs. Through the previous field experiments, the SCHeREX in particular, atmospheric scientists in China have accumulated valuable experience in collecting and processing various non-conventional observational datasets (Ni et al., 2011), and in applying these data to scientific research and operational forecasts (Zhang et al., 2011). However, in the previous field experiments observations of the intra-cloud and underlying surface processes during heavy rainfall events were not well conducted. The observations were not applied to the improvement of the physical schemes in NWP models. Compared to the time of previous experiments, we now have an increased number of advanced mobile observing instruments to better detect clouds and rainy systems. Moreover, progress has been made in development of retrieval algorithms, which can make use of measurements from the new remote sensors to quantify the microphysical, dynamic and thermodynamic properties of the clouds. Furthermore, marine meteorological observations are now available to observe features of the boundary layer atmosphere over both the land and offshore areas over southern China and South China Sea, and thus enable studies on local and regional scale air-land, air-sea, and land-sea interactions. Therefore, we propose to launch the Southern China Monsoon Rainfall Experiment (SCMREX), aiming at better observing precipitation processes by means of a synergy of a new generation of in-situ and remote sensing systems operated on ground, aircraft, and satellites in order to depict details of the internal structure of convective clouds and their environment. This will then allow us to invesigate the relevant physical mechanisms of the southern China heavy rainfall, and to improve the initial conditions for NWP models, and to evaluate and refine the physical schemes in the models. There have been several recent WWRP RDP/FDP projects focusing on weather in 13

14 CAS/WWRP/JSC5/Doc. 4.4 : p. 14 mountainous regions and flash flood events including the Mesoscale Alpine Experiment (MAP) and its successor, MAP D-Phase, both conducted in the Alps, as well as the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE) project conducted in the Cascades. The Sydney 2000 FDP focused on advancing and demonstrating summer convective nowcasting systems. The Beijing 2008 FDP was conducted with the goal to demonstrate nowcasting advances since 2000 and facilitate technology transfer into operations, while the Beijing 2008 RDP was carried out with a focus on mesoscale ensemble prediction. Both Beijing 2008 FDP and RDP focused on precipitation prediction, convective initiation and summer severe weather. Recently, SNOW V10 (Science of Nowcasting Olympic Weather for Vancouver 2010) rather uniquely focused on nowcasting winter weather in complex terrain. The presently proposed project is expected to both advance understanding of processes and improve models for better NWP of the high impact weather over southern China during the South China Sea monsoon onset. 1.3 Current observation network The meteorological operational observation network over the 3 provinces of Guangdong, Guangxi and Hainan in southern China are currently well equipped and can be used in mesoscale field experiments. Capability of this observation network will be further enhanced by a range of advanced remote sensing observations. To carry out the SCMREX, we have had the following observation bases: 1) Operational surface observation network: Automatic weather stations (AWSs) have been established densely over the southern China region. The AWSs are classified into national-level AWSs with observers on duty, national-level AWSs without observers on duty, and regional AWSs. The average distance between the AWSs is ~10 km which essentially meets the requirements of mesoscale detection. Moreover, real-time quality control of the AWS observations is now conducted at the operational meteorological centers of China. 14

15 CAS/WWRP/JSC5/Doc. 4.4 : p. 15 2) Operational upper-air observation network: China Meteorological Administration (CMA) has built 14 radiosounding stations in South China, with 5 in Guangdong, 6 in Guangxi, 2 in Hainan, and 1 in Xisha islands. 3) Ground-based GPS water vapor observation network: There are 21 ground-based GPS water vapor observation stations in the Guangdong province that can measure precipitable water in the atmospheric column. 4) Weather radar network: There are 9 weather radars in Guangdong, 7 in Guangxi, and 3 in Hainan. Moreover, the Guangdong Provincial Meteorological Bureau has installed 8 wind profilers in the province. 5) Mobile observation system: A range of advanced instruments will be utilized in the field campaign, including the C-band dual polarization radar, X-band dual polarization radar, 8-mm wavelength radar, wind profiler, lidar, microwave radiometer, etc. 6) Satellite observation system: The FY-series operational meteorological satellites of China (FY-2D, FY-2E, FY-3A and FY-3B) will all be part of the field experiments. 7) Marine meteorological observation system: There are two Atmospheric Boundary-layer Observation Towers along the coastal line of Guangdong and two Sea Atmospheric Boundary Observation Towers over the Beibu Gulf and over southern China and South China Sea. In addition, there are m anemometer towers along the coast and in the offshore. 2. Goals and Objectives 2.1 Goals The proposed project aims to (1) advance our understanding of processes that are most relevant to formation of heavy rains over southern China during the South China Sea monsoon onset, and (2) to improve model parameterizations for better NWP of the southern China heavy rains. More specifically, we are going to carry out comprehensive analyses and studies using the data to be obtained in the field 15

16 CAS/WWRP/JSC5/Doc. 4.4 : p. 16 campaign along with the historical data, (a) to reveal the thermodynamic and dynamic structures as well as microphysical features of the convective clouds and their evolutions, (b) to better understand the interactions between the convective clouds and the MCSs as well as their relation to surface rainfall, and (c) to better understand the mechanisms governing the interactions among the multi-scale weather systems and their effects on heavy rainfall over southern China during the South China Sea monsoon onset. Based on outputs from such studies, we will evaluate and improve current physical schemes and even develop new schemes, the cloud microphysical and PBL schemes in particular, that are more suitable for the cloud-resolving modeling of heavy rainfall in southern China. The refined physical schemes in models, in combination with development of advanced data assimilation technique, will help us toward the final goal of improving the skill of NWP for the heavy rainfall in southern China. 2.2 Objectives The specific objectives of this project are as follows: 1) Microscale features and processes of convective clouds By combining the to-be-collected observational datasets, mesoscale reanalysis, and high-resolution modeling: To investigate the microscale structures of the convective clouds at southern China, i.e., properties of hydrometeors and flows in the interior of the clouds, and how they evolve; To understand the processes that govern evolution of the microscale properties of the convective clouds, focusing on the roles of the mesoscale thermodynamic and dynamic conditions of their environmental atmosphere and the interactions between the ambient atmosphere and the clouds. 2) Properties and processes in the PBL By combining the to-be-collected observational datasets, mesoscale reanalysis, and high-resolution modeling: To analyze the 3D dynamic and thermodynamic structures of PBL; To reveal interactions between PBL and convection; To investigate topographical effects on PBL and thus convective systems. 16

17 CAS/WWRP/JSC5/Doc. 4.4 : p. 17 3) NWP Model physical schemes for cloud-resolving modeling of the southern China heavy rainfall To evaluate the state-of-the-art physical schemes in models, the cloud microphysical and PBL schemes in particular, through comparing between the observations and simulations; To refine the schemes and even develop new schemes for better modeling of heavy rainfall in southern China at the explicit-deep convection scale (i.e., cloud-resolving scale). 4) Data assimilation techniques for short-term forecast of the southern China heavy rainfall To improve the technology of error estimate and assimilation of various observational data; To identify the dominant observational elements for developing comprehensive analysis and quick integration systems; To develop 3D cloud analysis technology to integrate multiple types of observations from satellites, soundings, radars and other ground-based observations; To develop and improve the technique and methods for short-term forecast of heavy rainfall events in southern China. 5) NWP model evaluation for QPF in southern China A number of NWP models will be run in real time during the field campaign. The advanced data assimilation technique and real-time radar data assimilation will be performed for model comparisons and the regional ensemble NWP will also be conducted for the region during the campaign. Detailed in-depth evaluation will be performed during and after the field campaign using the to-be-obtained observational data sets. Based on the evaluation results, more studies will be conducted to improve at least parts of the models in terms of QPF in southern China. 3. Field Campaigns 3.1 Experiment time The field experiment is planned to take place in southern China from 1 st May to 15 th June 2013, which is the climatological heavy rainfall period in southern China 17

18 CAS/WWRP/JSC5/Doc. 4.4 : p. 18 during the East Asian summer monsoon. This is the southern China pre-meiyu period that starts from the South China Sea monsoon onset in middle or late May and ends in the northward shift of the rain belt to the Yangtze-Huai River Valleys in middle or late June, where the rainfall is defined traditionally by the term Meiyu. 3.2 Experiment areas The selected observation areas will be located at Guangdong, Guangxi, Hainan, Hong Kong and the adjacent oceanic areas. The observation regions of the field campaign are designed at three levels of scale, i.e., the meso-α, meso-β, and meso-γ scales (Fig. 5). 1) Meso-α-scale observing network This network builds upon the meteorological operational observation network at Guangdong, Guangxi, Hainan, and Hong Kong, that consists mainly of the radiosound sounding stations, weather radars, ground-based GPS water vapor stations, AWSs, and satellites. The temporal frequency of the radio sounding observations within this network will be increased during the field campaign. Moreover, the marine meteorological observing system will also be part of this observing network (Fig. 6). 18

19 CAS/WWRP/JSC5/Doc. 4.4 : p. 19 Fig. 5 Observing networks at three levels of scale, i.e., the meso-α, meso-β, and meso-γ scales. Fig.6 Coastal observation network 2) Meso-β-scale observing network This network covers the Guangdong province and the adjacent oceanic areas, as well as eastern Guangxi. A mobile dual polarization Dopplar radar will be placed at about km from the operational weather radars at Guangzhou (23.10 N, E) and Shenzhen (22.32 N, E) to form two pairs of radars, and a mobile Dopplar radar at about km from the operational weather radars at Yangjiang (21.50 N, E) to form another pair, so that 3D wind retrieval can be conducted with measurements from the three pairs of the Doppler radars as inputs (Doviak and Peter, 1976; Peter et al., 1980). The vapor observations by the GPS and microwave radiometers, the thunder and lightning observations, the land surface boundary layer observations, and the marine atmospheric boundary layer observations will also be part of this observing network. 3) Meso-γ-scale observing network In the coastal areas of Guangdong where torrential rains occur the most 19

20 CAS/WWRP/JSC5/Doc. 4.4 : p. 20 frequently (Fig. 2c) due to frequent occurrences of convective storms (Fig. 4), we will choose several observing sites to conduct intensive observations at the meso-γ-scale, including profiling observations of clouds and precipitation, focusing on properties of their microphysics (such as hydrometeor phases, droplet spectrums, water contents) and airflows. 3.3 Experiment measurements 1) Sounding observations (a) The radiosonde observation stations in Guangdong, Guangxi, Hainan, Hong Kong will increase their observation frequency from twice a day to 4 times a day at the area where exists the weather system, and for the sites Shenzhen and Yangjiang in the meso-γ-scale observation network to 8 times a day when weather system appears. (b) The mobile GPS sounding equipment will be used to enhance the upper-air observations in space, and the observations of the mobile GPS sounding will also be used to correct humidity errors in the radiosoundings. (c) Air-borne dropsonde observations will be done over southern China and South China Sea. The Vaisala dropsonde system has been installed in a Y-7 plane, which can fly up to ~8 km and continuously for a period of 8 hours. 2) Cloud and precipitation observation (a) Operational weather radars: The Doppler weather radars in Guangdong, Guangxi and Hainan and the Doppler radar at Hong Kong will scan in the 6-min volume mode, to detect the 3D distribution of precipitation echo and radial velocity, and to catch the convergence at the low levels and locations of new-born convective cells. (b) Mobile instrument: The vertically-pointing (Ka-band) millimeter wave radars, micro-precipitation radars, microwave radiometers, and rain-drop disdrometers will be used together to detect vertical distributions of the cloud-precipitation microphysical properties. The vertically-pointing 8-mm-wavelength radar can detect 20

21 CAS/WWRP/JSC5/Doc. 4.4 : p. 21 echo intensity, radial velocity, width of the velocity spectrum, and depolarization factor. This radar is capable of gathering I/Q signal and, in combination with microwave radiometers, can provide measurements to retrieve hydrometeor phases, drop spectra, water contents, locations of cloud top/cloud base, and vertical airflows. Adopting the 1.2-cm-wavelength CW (continuous wave) observing model, the micro-precipitation radars can get the precipitation parameters such as spectral size distribution of rain particles, water content, and rainfall amount. The multi-channel microwave radiometers can obtain profiles of air temperature, relative humidity, and liquid water continuously in time at heights up to 10 km. 3) Detection of mesoscale wind fields (a) The network of operational wind profiler and mobile wind profiler can detect the high-frequency variations of the wind fields surrounding the precipitating systems, and thus can catch signals of the low-level jet flow, low-level convergence, and shear line. (b) The mobile C-band and X-band dual linear polarization radars, Doppler radar, and operational weather radars can be combined to retrieve 3D wind fields of precipitation system. 4) Land-sea boundary layer observation The marine meteorological observing systems in Guangdong and Hainan provinces make possible observations of the vertical structure of atmospheric boundary layer, meteorological parameters at the surface, and marine environmental elements, while over the offshore areas both the atmospheric boundary layer and the marine boundary layer will be observed. The major equipment includes the 100-m boundary layer tower, wind profiler, wind-temperature-humidity gradients observing system, Doppler velocity profile observing instruments, ocean wave instruments, and buoys. 5) Thunder and lightning observation 21

22 CAS/WWRP/JSC5/Doc. 4.4 : p. 22 (a) The CMA lightning location operation system can monitor lightning events over a large area including the meso-α-scale observing network. (b) The local lightning monitoring network can detect in real time the polarity, types, and characteristics of lightning, and thus provide 3D information of lightning events in the meso-β-scale observing network. 6) Satellite measurements The geostationary satellites FY-2D and FY-2E will operate in the dual-satellite intensive observation mode, which means that FY-2D and FY-2E will each catch 20 more images in addition to the normal 28 images every day and that the target area will obtain geostationary satellite data every 15 minutes. The polar orbiting satellites FY-3A and FY-3B are going to work in the normal operational mode, i.e., they will get data over the target area twice a day, once in the morning and once in the afternoon. 3.4 Data processing and database 1) Data transmission and collection (a) The initial data observed by the meteorological operational network including the AWSs, radiosound stations, GPS water vapor stations, weather radars, and satellites will be conveyed to the National Meteorological Information Centre (NMIC) and CAMS in real time. (b) Other (non-operational) data will be collected and sorted out after the field experiment. The intensive observation data will be collected by the instrument people that participate in the field campaign. 2) Processing of the radar measurements (a) The radar measurements will be quality controlled to remove non-meteorological echo and to provide uncertainty estimate of the radar measurements. 22

23 CAS/WWRP/JSC5/Doc. 4.4 : p. 23 (b) 3D gridded radar reflectivity (at coordinates of longitude, latitude, and altitude) will be produced using the Radar Mosaic System developed by the State Key Laboratory of Severe Weather, CAMS. 3) Retrieval products from remote sensing measurements (a) Gridded rainfall estimate: A gridded rainfall data product will be generated by integrating measurements from the radars (including the operational weather radars, X-band radar, and dual linear polarization radar) and the records obtained at the surface rainfall stations. (b) Vertical profiles of cloud water and rain water contents, droplet spectra, and hydrometeor phases will be derived by combining the data from conventional observations and more advanced remote sensing instruments, such as the millimeter wave radar, wind profilers, and microwave radiometers. (c) 3D wind fields within the precipitation systems will be retrieved using the dual Doppler retrieval algorithm, while clear-sky wind fields can be obtained with the technique of wind profiler networking. (d) Precipitable water of the atmosphere will be determined in real time using the GAMIT software to process the GPS measurements of water vapor. 3.5 NWP experiments (a) Initial conditions of regional NWP models will be refined by application of the ensemble Kalman filter (EnKF) to assimilate observations at high temporal-and-spatial resolutions and their impacts on heavy rainfall forecast will be investigated. (b) Intercomparison among various NWP models and regional ensemble NWP will be conducted to examine their skill of real-time QPF for the southern China monsoon heavy rainfall. (c) Modeling results will be evaluated by comparing the simulated internal properties of convective clouds and PBL atmosphere with the observations, focusing 23

24 CAS/WWRP/JSC5/Doc. 4.4 : p. 24 on performance of the cloud microphysics and PBL schemes in terms of representation of the southern China monsoon heavy rainfall. 4.Strategy and Management 4.1 Principles To achieve the experiment goals and provide practically usable data for the relevant scientific studies, the following principles are followed: 1) Scientists from home and abroad with different research backgrounds (including instrument experts, retrieval algorithm developers, synoptic and mesoscale meteorologists, NWP experts, experts of physical schemes in models, etc.) and the associated operational centers will collaborate closely before, during, and after the field campaign. 2) Instruments calibration, data intercomparison, and validation of retrieval algorithms will be conducted and well documented in advance. 3) Types and contents of the data that will be obtained from each instrument will be clarified and well documented in advance. 4) Observing network and strategy will be designed and planned according to both the scientific objectives and the capability of each instrument, and will be clearly documented. 4.2 Organization 1) Steering Committee The CMA Administrator will act as the head of the Steering Committee including members from the Department of Science and Technology and Climate Change, Department of Forecasting and Information System, Department of Integrated Observations, Department of International Cooperation of CMA, Chinese Academy of Meteorological Sciences as well as the leaders of the meteorological bureaus of 24

25 CAS/WWRP/JSC5/Doc. 4.4 : p. 25 Guangdong, Guangxi, Hainan, and Hong Kong. The Steering Committee is responsible for leading the field experiment and organizing and coordinating the participating units. 2) Science Advisory Committee and Science Committee The Science Advisory Committee (SAC) consists of leading international experts, co-chief Scientists and working group leaders and other scientists as required. The purpose of the committee is to instruct and deliberate the design of this field experiment and other research-related work, and to oversee the operation of the field experiment. Professor Richard JOHNSON, Colorado State University, U.S.A. (co-chair) Dr Jiao Meiyan, China Meteorological Administration (co-chair) Professor Chih-Pei CHANG, Naval Postgraduate School, U.S.A. Professor Robert FOVELL, University of California at Los Angeles, U.S.A. Professor Dong-In LEE, Pukyong National University, SOUTH KOREA Professor Zhiyong MENG, Peking University, CHINA Dr Nathaniel SERVANDO, Administrator, Philippine Atmospheric, Geophysical and Astronomical Services Administration, PHILIPPINES Professor Hiroshi UYEDA, Nagoya University, JAPAN Dr. YAP Kok Seng, Director General, Malaysian Meteorological Department, MALAYSIA Prof Donghai Wang, CMA, CHINA (Co-Chief Scientist) prof Yali Luo, CMA, CHINA (co-chief Scientist) 3) Project Director/Principal Investigator (PD/PI) and Chief Scientist The Project Director/Principal Investigator (PD/PI) is the leader of the project and has overall responsibilities. The co-chief Scientists are responsible for the field experiments and scientific aspects of the project. Professor Renhe Zhang will act as the PD/PI, and professors Donghai Wang and Yali Luo as co-chief Scientists. In the Annex I III their resumes are given, respectively. 25

26 CAS/WWRP/JSC5/Doc. 4.4 : p. 26 4) Working Groups The project will establish 4 working groups, including Observation Working Group, Data Working Group, Modeling Working Group, and Forecast Working Group. Each working group will consist of some interested scientists/researchers with 1-2 leaders, who will be responsible for the research and various work related to the field campaign under the leadership of the Co-chief Scientists. 5) Leading and participating units and scientists This field experiment is leaded and organized by the State Key Laboratory of Severe Weather at CAMS, along with Guangzhou Institute of Tropical and Marine Meteorology and Wuhan Institute of Heavy Rains of CMA. The participating units in mainland China include the National Meteorological Centre, National Satellite Meteorological Centre, National Meteorological Information Centre, National Meteorological Observation Center, Guangdong Meteorological Bureau, Guangxi Meteorological Bureau, Hainan Meteorological Bureau, the Meteorological Department of Hong Kong Special Administrative Region, Institute of Atmospheric Physics of Chinese Academy of Sciences, Peking University, Nanjing University, Nanjing University of Information Science and Technology. The project will have heavy participation of international scientists, which is described in section Data management 1) Dataset After collection/organization/quality control of all the data collected during the field experiment, a data base will be set up at the National Meteorological Information Center/CMA to provide these data along with their uncertainty estimates. For users convenience, the data products will be stored in standard, internationally common, self explanatory formats. 26

27 CAS/WWRP/JSC5/Doc. 4.4 : p. 27 2) Data sharing The sharing of data products will be according to the WMO guidelines. 4.4 Funding The necessary basic funding for carrying out this project will be provided by the CMA. Additional funding will also be requested from the Chinese Ministry of Science and Technology (MOST) and the National Natural Science Foundation of China (NSFC). 4.5 International participation and collaboration We will collaborate very closely with the Mesoscale Working Group of WWRP on modeling and model verification and the Monsoon Panel of the WMO/CAS Working Group on Tropical Meteorology Research (WGTMR) on monsoon heavy rainfall study. Scientists from Japan, Korea, and U.S. have expressed strong interests in participating in the project. Both the Pukyong University in Korea and Nagoya University in Japan may join the project through coordination of the observation periods of their related projects in and around Korea, Japan and East China Sea with the proposed field experiment. The NRL-Marine Meteorology division in U.S. is interested in doing regional data assimilation and model forecast using the COAMPS model. Other scientists and associated universities and institutes overseas, especially those in southern and southeastern Asian countries, will be considered to be invited to participate in this project. Acknowledgements. This proposal is prepared by Professors Renhe Zhang, Liping Liu, Donghai Wang, Yonghui Lin, and Yali Luo at the State Key Laboratory of Severe Weather, CAMS. The proposal is formed mainly based on discussions in a meeting held on 23 May 2011 that was attended by more than 30 scientists in the related research fields in China, to whom we are very grateful for their contributions. The proposal was reported in The WMO/WWRP Monsoon Heavy Rainfall Workshop organized by the WGTMR Monsoon Panel held in Beijing on October In the workshop a session was specialized in discussion of the SCMREX. The WGTMR 27

28 CAS/WWRP/JSC5/Doc. 4.4 : p. 28 Monsoon Panel and Invited Experts also held a special meeting for reviewing the proposal, and a summary of suggestions was formed (see Annex IV). Constructive comments from the experts in the Workshop are greatly appreciated. References: Awaka, J., T. Iguchi, and K. Okamoto, 1998: Early results on rain type classification by the Tropical Rainfall Measuring Mission (TRMM) precipitation radar, Proc. 8th URSI Commision F Open Symp., Aveiro, Portugal, pp Ding, Y., 1994:Monsoons 0ver China.Dordrecht/Boston/London:Kluwer Academic Publishers, 419pp. Doviak, R. J., and S. R. Peter, 1976: Error estimation in wind fields derived from dual-doppler radar measurement. J. Applied. Meteor., 15, Davis, C.A., and S.B. Trier, 2007: Mesoscale convective vortices observed during BAMEX. Part I: Kinematic and thermodynamic structure. Mon. Wea. Rev., 135, Emanuel, K. A., 1994: Atmospheric Convection, Oxford University Press. ISBN , 580pp. Fovell, R.G., and Y. Ogura, 1988: Numerical simulation of a midlatitude squall line in two dimensions. J. Atmos. Sci., 45, Gao, S., L. Ran, and X. Li, 2006: Impacts of ice microphysics on rainfall and thermodynamic processes in the tropical deep convective regime: a 2D cloud-resolving modeling study. Mon. Wea. Rev., 134, Grabowski, W.W., X. Wu, and M. W. Moncrieff, 1999: Cloud-resolving model of tropical cloud systems during Phase III of GATE. Part III: effects of cloud microphysics. J. Atmos. Sci., 56, Grabowski, W. W., and M. W. Moncrieff, 2001: Large-scale organization of tropical 28

29 CAS/WWRP/JSC5/Doc. 4.4 : p. 29 convection in two-dimensional explicit numerical simulations. Q. J. R. Meteorol. Soc., 127, Grabowski, W. W., 2003: Impact of ice microphysics on multiscale organization of tropical convection in two-dimensional cloud-resolving simulations. Q. J. R. Meteorol. Soc., 129, Houze, R. A., Jr., 2004: Mesoscale convective systems, Rev. Geophys., 42, RG4003, doi: /2004rg Huang, S., Z. Li, C. Bao, and coauthors, 1986: Torrential Rains in the First Rainy Season of South China. Guangzhou: Guangdong Science and Technology Press, 230pp. (in Chinese) Iguchi, T., T. Kozu, R. Meneghin, J. Awaka, and K. Okamoto, 2000: Rain-profiling algorithm for the TRMM precipitaton radar. J. Appl. Meteor., 39, Li, X., C. -H. Sui, K. -M. Lau, and M. -D. Chou, 1999: Large-scale forcing and cloudradiation interaction in the tropical deep convective regime. J. Atmos. Sci., 56, Liu, C., M. W. Moncrieff, and E. J. Zipser, 1997: Dynamic influence of microphysics in tropical squall lines: a numerical study. Mon. Wea. Rev., 125, McCumber, M., W. -K. Tao, J. Simpson, R. Penc, and S. -T. Soong, 1991: Comparison of ice-phase microphysical parameterization schemes using numerical simulations of tropical convection. J. Appl. Meteorol., 30, Mu, J., J. Wang, and Z. Li, 2008: A study of environment and mesoscale convective systems of continuous heavy rainfall in the south of China in June Acta Meteor. Sinica, 66, (in Chinese) Ni, Y., C. Cui, H. Li, J. Peng, X. Qiu, Y. Zhang, X. Xu, M. Gao, L. Jie, and W. Zhang, 2011: High-resolution mesoscale analysis data from the South China heavy rainfall experiment (SCHeREX): Data generation and quality evaluation. Acta Meteor. Sinica, 25, Nicholls, M. E., 1987: A comparison of the results of a two-dimensional numerical 29