Abstract:El Ni〖AKn~D〗oSouth Oscillation (ENSO), as a dominant mode on the interannual variability, has a big implication in shortterm climate prediction in China. In the past three decades, significant changes occurred in ENSO phenomenon such as its own properties, types and climate impacts, which have brought a big challenge for climate prediction and disaster prevention and reduction in China. Since 2012, Beijing Climate Center in China Meteorological Administration (BCC/CMA) has pushed forward the research and development for the new generation of ENSO monitoring, analysis and prediction system (SEMAP2.0) in order to markedly improve the operational capability of ENSO monitoring and prediction in BCC/CMA. The SEMAP2.0 integrates several latest results in international ENSO studies and develops many new techniques for ENSO monitoring and prediction further. This new system is made up of five subsystems including the realtime monitoring, dynamical diagnosis and attribution analysis, physicsbased statistical prediction for the two type s of ENSO, interpretation and application of ensemble forecasts in climate model, and analoguedynamical correction prediction. The 20yr independent validation shows a relatively highlevel prediction skill that the temporal anomaly correlation score reaches 0.8 in terms of ensemblemean Ni〖AKn~D〗o3.4 sea surface temperature anomaly index with 6 months lead. The SEMAP2.0 started running as an operational system in BCC/CMA at the end of 2015 and has issued a bunch of operational products on the website. During its development, this system has been applied to realtime operational applications. It has given a basically reasonable indication for the El Ni〖AKn~D〗o fluctuation occurring in the 2014 summerautumn seasons, accurately predicting the weak centralPacific El Ni〖AKn~D〗o type in the 2014/2015 winter and its continual growth after the 2015 spring as well as the type transferring to the strong easternPacific El Ni〖AKn~D〗o type during the 2015 summer. Also, this system has exactly caught the peak intensity and time of the super El Ni〖AKn~D〗o event as initiating in September 2015, one season lead, and further predicted that this super event will terminate at the late spring in 2016.

Abstract:A super El Ni〖AKn~D〗o event occurred over the equatorial centraleastern Pacific during 2014-2016. It peaked in November 2015 with its strength larger than two other super El Ni〖AKn~D〗o events (1982/1983 and 1997/1998 events), ranking as the strongest El Ni〖AKn~D〗o event since 1951. By April 2016, it has lasted for 20 months, thus becoming the longest El Ni〖AKn~D〗o event since 1951. During the developing process of this El Ni〖AKn~D〗o, the atmospheric circulation from the tropical Pacific to East Asia has shown significant responses. The convection over the equatorial centraleastern Pacific was more active than normal, and anomalously ascending motion. However, over the equatorial western Pacific, the convection was inhibited and anomalous subsidence prevailed. The anomalous lowlevel Philippine Sea anticyclone persistently controlled northwestern Pacific and became gradually stronger with the development of El Ni〖AKn~D〗o. As a result, the western Pacific subtropical high (WPSH) has become stronger than normal, and its west boundary extended more westward. The WPSH in winter 2015 has been the strongest since 1980. Meanwhile, precipitation was above normal in the southern part of 〖JP2〗the Yangtze River Valley in China during autumn and winter of 2015, with the mean precipitation over South China (Guangdong, Guangxi and Hainan) in winter 2015 ranking as the first since 1951. Recently, this super El Ni〖AKn~D〗o event has been decaying. However, its further influences on the climate anomaly in China may still persist during the following spring and summer of 2016.

Abstract:Based on the current standard of National Climate Centre, China Meteorological Administration, the recent status and evolution of the 2015/2016 El Ni〖AKn~D〗o event are introduced and compared to the 1982/1983 and 1997/1998 El Ni〖AKn~D〗o events. Monitoring results show that the 2015/2016 El Ni〖AKn~D〗o event is the third super El Ni〖AKn~D〗o event since 1951 after the 1982/1983 and 1997/1998 events, and it exceeded the former two super events based on the index of duration, peak intensity, accumulated SSTA and the months in which SSTA consecutively exceeds 2.0℃. The several westerly bursts over the equatorial centralwestern Pacific drove the eastward propagation of the anomalous warm subSST, resulting in the development of the El Ni〖AKn~D〗o event. The intensity of the warm SSTA center in the peak period of 2015/2016 event is weaker, and the range is smaller than the former two super El Ni〖AKn~D〗o events, so is the intensity of the anomalous westerly in the westerly bursts.

Abstract:The possible impacts of the tropical western Pacific SSTA on China’s precipitation during the El Ni〖AKn~D〗o developing phases are emphasized in this paper. Analyses of all the 17 summers during the El Ni〖AKn~D〗o developing phases show that precipitation in these summers varies from year to year and does not exhibit a significant relationship with the El Ni〖AKn~D〗o indices (Ni〖AKn~D〗o3 and Ni〖AKn~D〗o3.4 index). However, further analyses reveal that the precipitation is closely related to the tropical western Pacific SSTA during these summers. When the tropical western Pacific is warmer, it is wetter in the south of the Yangtze River and drier in the north, and vice versa. The possible mechanism is also proposed. The different conditions of the western Pacific SST anomalies indicate different distribution features of the SSTA in the tropic Oceans. The different tropical SST patterns can induce different responses to the tropical and the subtropical atmospheric circulation near East Asia. Therefore, the precipitation in the east of China is affected. Besides, the anomalous warm SST in the western Pacific may contribute to the precipitation anomaly in the summer of 2014. The tropical western Pacific in the summer of 2014 is warmer than all the previous 17 summers during the El Ni〖AKn~D〗o developing phases. Such a condition of the tropical western Pacific favors more precipitation in the south of the Yangtze River and less in the north. And the observation of precipitation is also characterized by such a feature. Thus, the tropical western Pacific SSTA may exert an impact on the summer precipitation in 2014.

Abstract:Fiftyone physical parameters are calculated by using upper sounding data from the Xuzhou, Sheyang and Nanjing Stations from June to August in 2004-2013. Based on the significance test of the correlation coefficient between physical parameters and flashheavyrain events (flash heavy rain that occurred after 0-6 h of the observation time) and the analysis of numerical distribution of physical parameters in the flashheavyrain samples and the nonflashheavyrain samples, 16 physical parameters of prediction are selected finally. Through analyzing the indication to the flashheavyrain events of different types of physical parameters, and according to the different threshold of physical parameters in each month, different criteria for the flashheavyrain events are determined respectively. 〖JP2〗Thus, the flashheavyrain〖JP〗 forecast model for summer shorttime heavy rains in Jiangsu is established by the membership function conversion method. The fitting test and forecasting test of the forecast model are verified, and the results are good.

Abstract:A severe hail event occurred along Yangtze River in Jiangsu on 28 April 2015. Based on the data of AWS observation, geostationary satellite, Doppler weather radar and wind profiler radar, this paper analyzes the characteristics of the synoptic weather pattern, thermodynamic conditions, changes of ambient wind field before hailstorm, and structure of the supercell storms. The results show that first, with Northeast vortex and the dry and cold airflow at the back of vortex trough, unstable stratification is formed by the dry and cold airflow in the midhigh level and the warm and humid airflow in the low level, the configuration of the high and low level jet and the surface convergence system provide a favorable thermal condition. The high CAPE values, inversion layer, favorable water vapor in the low layer and the strong deep vertical wind shear are conducive to the occurrence of severe hail weather. Second, the vertical distribution of physical quantity fields, such as average divergence, the mean vertical velocity, relative storm helicity, vertical wind shear, retrieved by the Doppler weather radar and the wind profiler radar data can reflect the rapid change of the ambient field, which is gradually adjusted into the pattern of lowlevel convergence and upperlevel divergence, and the values of the helicity and vertical wind shear are gradually increased before the convective system moves into the area of the radar station. Such situation indicates that the ambient field is suitable for the maintenance and development of the severe convective system. Third, besides the TBSS phenomena and the front inflow notch found in the radar echo of the severe hail supercell, the prominent bounded weak echo area and suspended high strong echo area are made by the persistent deep mesocyclone. The inner loop structure of the supercell is revealed by the application of the dualDoppler radar wind field retrieval technique. The ambient field is cyclonic rotation in the low level while rotation in the middle level is strengthened and the wind field in the high level is diverged. The emergence and maintenance of the vortex in the supercell contribute to the growth of large hail in the air.

Abstract:The severe rainstorm process which occurred in the central part of Hebei on 1 July 2013 was analyzed by using the conventional sounding data, NCEP reanalysis data, automatic stations data, FY2E satellite data and radar data. The results show that: (1) The rainstorm can be divided into warm sector rainstorm and cold shear rainstorm. During the process of warm sector rainstorm, lowlevel moisture flux convergence was dramatically enhanced. (2) Strong ageostrophicwet〖WTHX〗Q〖WTBZ〗 vector convergence took place before the warm sector rainstorm, and it has good performance in forecasting the warm sector rainstorm. Large value area of ·〖WTHX〗Q〖WTBZ〗* only with convective condensation heating in warm sector can be used to indicate the heavy rainfall area. Furthermore, condensation heating plays an important role in ageostrophicwet〖WTHX〗Q〖WTBZ〗 vector convergence. (3) Warm sector rainstorm occurred in the developing stage of warm mesoβ scale convective clouds, influenced by the surface mesoscale vortex. Then, cold shear convective clouds incorporated with warm sector convective clouds formed PECS, which worked in with the surface convergence line causing rainstorm again. (4) The radar echoes show that mesoγ scale convergence lines in the mesoβ scale cyclone flow field creates a favorable dynamic condition for banded strong rainfall echo in Sizhilan Area.

Abstract:From 14 to 25 December 2013, a heavy haze pollution process occurred in the central and southern part of Hebei. By analyzing the meteorological conditions, flow field and characteristics of pollutants, the causes of this process are discussed. This pollution process which was closely related to haze presented such features as long duration, wide range and great intensity. With largescale stagnant meteorological condition and nearsurface atmospheric stratification, pollutants accumulated rapidly in the convergence zone of surface wind, leading to the formation of this heavy pollution process. There were two weak cold air activities during this period, but they were too weak to change the stagnant atmospheric stratification. Thus, the heavy pollution process, this time lasted a long time.

Abstract:Based on a homogenized daily air temperature dataset from 1971 to 2010 and quantity controlled hourly air temperature data of BeijingTianjinHebei Region in 2011, the multiscale temporal characteristics of urban heat island effect for Beijing, Tianjin and Shijiazhuang are analyzed in this paper. The results show that the urban heat island effect on the mean, maximum, minimum air temperature is asymmetrical. The heat island effect on the minimum temperature is the strongest, followed by the effect on the mean temperature and the effect on the maximum temperature is the weakest. The mean temperature in Beijing is affected by urban heat island effect most significantly, followed by Tianjin’s. Shijiazhuang’s heat island effect is relatively weak, but showing the trend of significantly increasing during the late 40 years, up to 0.13℃ every 10 years. For the maximum temperature, urban heat island effect in Shijiazhuang is the strongest, followed by Beijing’s. Tianjin’s heat island effect is relatively weak. Beijing’s heat island effect on maximum temperature increases slowly during the 40 years, being 0.06℃ every decade. No significant change in Tianjin. Shijiazhuang’s heat island effect shows a weak downward trend. For the minimum temperature, Beijing’s heat island effect is the strongest, then is Tianjin’s. Shijiazhuang’s heat island effect is the weakest. Tianjin’s heat island effect on lowest temperature increases in the 40 years, 0.18℃ every decade. Tianjin has no significant change, followed by the Shijiazhuang’s. Beijing’s heat island effect shows a slight downward trend. Generally, the three cities heat island effect intensities for mean and maximum air temperature are characterized by weak in summer and strongest in winter, for maximum temperature, they are different with change of seasons. The seasonal heat island effect from automatic weather station is similar to the heat island effect calculated from the data in 1971-2010. The heatisland effect in a day is characterized by low during the daytime and high during the nighttime.

Abstract:Based on the observation data of daily precipitation and air temperature of 20 weather stations in Beijing Area from 1978 to 2012, the empirical relationship between precipitation and air temperature and the differences between urban and suburban areas in summer (June to August) were analyzed. The results showed that: (1) Daily precipitation presented a first increasing then decreasing trend with air temperature rising. For moderate and heavy rainfalls, precipitation kept stable and varied weakly with air temperature increasing after air temperature reached a threshold. While the air temperature rose further to a certain threshold value, precipitation decreased rapidly with air temperature rising. Before it reached the maximum value, the heavier the precipitation was, the closer the precipitation increase rate was to ClausiusClapeyron (CC) variability. (2) The critical values of precipitation frequency and intensity varying separately with air temperature variation were not the same. When air temperature was higher than the threshold, precipitation frequency and intensity also began to weak. The different magnitudes of precipitation varying with the air temperature had similar trends between the urban and suburban areas. However, precipitation increase rate before precipitation reached the maximum value was bigger in urban area than in the suburb, which indicated that precipitation in urban areas was more sensitive to temperature than that in suburbs.

Abstract:Based on the daily meteorological data of 50 weather stations and daily runoff data from the Cuntan Gauging Station, HBV and SWAT hydrological models were calibrated and validated by using DEM, land use data and soil texture information. Possible impact of future climate change on river runoff was analyzed through forcing HBV and SWAT models by CCLM dynamic downscaled climatic data. The results show that both of HBV and SWAT models are suitable for simulating monthly river runoff in the Cuntan catchment, with NashSutcliffe efficiency coefficient of about 0.90 in the calibration and validation period. But it is also clear that the SWAT is good at simulating floodpeak value while HBV has good performance on baseflow value. Compared with baseline period (1986-2005), mean temperature, maximum temperature and minimum temperature in the Cuntan catchment will increase obviously with persistent rising trend by CCLM in 2011-2040 under RCP4.5 scenario. Annual precipitation is also expected to rise a bit in 2011-2040, but will decrease slightly since 2030. From the ensemble mean of the two hydrological modeling results and changes in runoff quantile, we can see that the annual runoff will increase 14.2% with probability of higher flood volumes in 2011-2040 than 1986-2005.

Abstract:Using the wind observation data of automatic weather stations (AWSs) in Zhejiang Province during December and February from 2010 to 2014 and the retrieved ASCAT winds, and by means of the Fuzzy Cluster Mean (FCM), an offshore wind speed calculation formula is established and the error analysis for ASCAT products during cold air events in the Zhejiang coast is carried out. The results show that the most AWSs in northern Zhejiang coast have a southerly vector difference compared with the winds at Zhoushan Buoy, the AWSs in the southern coast have a southeasterly vector difference compared with the Wenzhou Buoy, and the AWSs wind speeds generally are smaller than wind speeds from the buoys. The analysis also indicates that altitudes impact little the wind speed differences (δ) between the AWSs and buoys, and the distance of the stations from the coastline is the main factor that impacts the δ value. When cold air strikes the Zhejiang offshore, the distribution of the correlation coefficients between the ASCAT and observations has the characteristics of paralleling to the coastline and increasing from the west to the east. Generally, the distance from the stations to the coastline is usually more than 30 km when coefficients are more than 0.5. The observed winds from Zhoushan and Wenzhou Buoys have a good correlation with the retrieved ASCAT winds. But there is a large special difference in the ASCAT winds error in Zhejiang offshore. The distribution of the corrected ASCAT wind speed also has a characteristic of paralleling to the coastline and increasing from the west to the east, and its absolute error is less than 2 m·s-1 compared with the observed speed.

Abstract:Based on field experiments, statistical analysis and modelling were carried out to investigate the changes of climatic resources utilization, risk of heat and chilling stress as well as suitable varieties and sowing date for single season rice to switch from indica to japonica type in Hubei Province. The results showed that changing rice from indica to japonica type can improve resource efficiency of climate, and reduce the risk of chilling injury during heading period, but increase heat stress. Among five tested cultivars, Yongyou1540 (indicajaponica hybrid) shows the best suitability across all ecological regions, while the performance of Rejingyou35 and Zhongdao1 is less satisfactory or with less suitability than Yongyou varieties. It is concluded that rice of japonica type should be sowed in the last tenday period of April in the northern part of Hubei, and in the early and middle May in the southern part. Sowing in this window, 80% of the years could avoid heat stress during heading period.

Abstract:The mediumrange forecasting performances of T639, ECMWF and Japan models from December 2015 to February 2016 are verified and compared. The results show that all of the three models can predict the variation and adjustment of the atmospheric circulation over Asian middle and high latitudes well, of which the performance of ECMWF model is the best. For temperature at 850 hPa, Japan model's mean forecast error is smaller than the errors of other two models. ECMWF model forecasts higher temperature for both the northern and southern parts of China, while T639 model produces a lower temperature forecast for northern part of China. For the surface high forecasting during the nationwide cold wave process in January 2016, T639 model performs much better in forecasting the intensity of cold high than ECMWF and Japan models, which underestimate the intensity in most time.

Abstract:The main characteristics of the general atmospheric circulation in February 2016 are as follows: There are two polar vortex centers in the Northern Hemisphere. The circulation presents meridional patterns in middlehigh latitudes. The south branch trough behaves actively， and the mean position is located at 90°E nearby. The subtropical high is a little weaker than normal years, and the average south branch trough is also weaker than normal years. The monthly mean precipitation is 12.3 mm, and 29.4% less than normal （17.4 mm）. The monthly mean temperature is -1.6℃, and 0.1℃ higher than normal （-1.7℃）. There is one cold wave process nationwide. Meanwhile, sanddust weather first appeared in Northwest China this year.