Abstract:Combined with forecasting experiences in Shanghai Meteorological Bureau (SMB), the latest operational progress and future trend of Highresolution Numerical Model (HNM) are summarized. A real time severe storm is analyzed by applying products from SMB’s HNM. Two majors strengths of HNM are pointed out: to promote the predicting ability of forecasters on severe weather and to extened more refined warnings. Some limits of HNM in operational applications are also discussed and, finally, suggestions for accelerating operational application of HNM in China Meteorological Adiministration are proposed, which include setting up Hazardous Weather Testbed (HWT), attaching importance to model postprocessing and enhancing forecaster’s training on numerical weather prediction.

Abstract:Following the “frequency matching” concept, two approaches have been tested to improve ensemblebased precipitation forecasts for the case of Beijing “7.21” (21 July 2012) severe rainstorm and the period of rainy season from 1 May to 31 July 2010 in China. One approach is “probabilitymatched ensemble mean (PM)”, which uses ensemble memberbased precipitation frequency to calibrate the frequency of simple ensemble mean to correct smoothing effect caused by ensemble averaging; another is “bias correction”, which uses observed precipitation frequency to calibrate the precipitation frequency of each ensemble member to remove systematic forecast bias caused by model deficiency. The results show that (1) PM can effectively correct the problem of “toowidespread light precipitation and toomuchreduced heavy precipitation” in a simple ensemble mean, especially so for extremely heavy rains. The larger ensemble spread is, the more improvement will be achieved. However, PM can barely improve total precipitation amount forecasts and has no ability to correct the systematic bias of the model. (2) Although bias correction is not effective in correcting precipitation position errors, it can effectively remove systematic bias in precipitation amount forecasts and, consequently, improve ensemble spread and probabilistic forecasts significantly. Bias correction of ensemble mean forecast needs to be done independently rather than through biascorrected ensemble members via simple averaging. (3) PM approach also works well even after each ensemble member’s bias has been removed in advance. Therefore, both PM and bias correction need to be done jointly to maximize benefit through model forecast postprocessing in an operational environment.

Abstract:The daily precipitation of 652 rain gauges over the Huaihe River Basin and the daily precipitation forecasting products of ensemble system of China Meteorological Administration from TIGGE (THORPEX Interactive Grand Global Ensemble) archive are employed to construct new observation data processing methods. The methods are based on taking observation uncertainties into consideration when processing observational data to assess ensemble precipitation forecasts. The observation probability (OP) method and observation percentile (OPC) method are presented in the paper, which are compared with traditional method of dealing with observation when accessing ensemble precipitation prediction skill, reliability and resolution for different precipitation thresholds. The Brier Score and Brier Skill Score of three methods are calculated. The results show that the Brier Scores are degraded and this degradation means the Ensemble Prediction System (EPS) is better to use OP method and OPC method for all of the thresholds, especially for middle and lower precipitation thresholds. The results of Brier Skill Score indicate that, the prediction has forecast skill for 0.1, 5, 10, 15 and 25 mm·(24 h)-1 thresholds, respectively. New observation processing methods generally improve the resolution component of the Brier Skill Score, but a little bit degrade the reliability component of the Brier Skill Score.

Abstract:To investigate the application and impact of Lband high vertical resolution minutelevel sounding data which include balloons accurate drifting information at each level on data assimilation and numerical prediction, basic features of these data were preliminarily analyzed in this paper. On this basis, experiment of single station, precipitation case study and batch assimilation tests of the whole simulated domain were conducted using minutelevel sounding data via the two assimilating methods of profile and pointbypoint, then compared with the assimilation test using conventional sounding data. It was concluded that: (1) the vertical resolution of Lband minutely sounding data can better match the vertical layers in the model. It can provide additional vertical observation information and precise location data that the conventional sounding data cannot achieve. (2) Onestation assimilation test indicates that assimilating minutely sounding data can efficiently increase the weight of observations in the analysis, thus leading to the analysis field more similar to the observations, and differences of analysis field calculated by pointbypoint assimilation method and profile way mainly remain in the upper troposphere. (3) The case study and batch tests assimilating the minutely sounding data in the whole forecast region can affect the final analysis and forecast accuracy, and the difference of wind assimilation caused by the balloon’s advection drift mainly exists in the positions at 200 hPa, and the upperlevel jet stream over northern China. (4) The initial field in the model is overall improved by assimilating Lband minutly sounding data, which mainly positively affect the forecast of winds in the upper troposphere and intense precipitation in larger scales.

Abstract:The twotime level semiLagrangian advection scheme is designed to study the process of global advection based on the the spherical overset YinYang grid. A kind of new horizontal staggered grid named LE grid is adopted for the scheme in the spherical coordinate, and different interpolation methods have been employed to the overlapped area of the YinYang grid. Besides, some idealized numerical tests are carried out. Numerical tests show that the scheme is reasonable for simulating the global advection, the advection of the overset area is obviously sensitive to the boundary interpolation schemes; the semiLagrangian scheme can depict the structure, position and the evolution process of solid body and deformational vortex accurately, and can get good stability and high accuracy.

Abstract:The 8times daily 3 h forecast of the 2 m temperature forecast of GRAPES_RAFS (Global and Regional Assimilation and Prediction System_Rapid Analysis and Forecast System) during the period from 20 June to 20 July in 2013 is analyzed in this paper. It is found that the forecast can show the diurnal variation of the 2 m temperature fairly well, but, some deviations exist between the forecast and the observation. For instance, the forecasted values are 3℃ lower on average than the observation in Western Sichuan Plateau in eastern Tibetan, Yungui Plateau and Wuyi Mountains, but 3℃ higher than the observations in North China. In order to diminish the influence from those deviations, bias correction is conducted by mean method, biweight method, moving mean method and movingbiweight method respectively. The values before and after the bias correction are analyzed and compared. The results show that the average error is reduced to (-1-1℃) in most regions while the RMSE (root mean square error) is less than 2.5℃. The bias correction is more effective in areas with larger deviations like Western Sichuan Plateau in eastern Tibetan where the absolute of the average error is reduced from above 3℃ to within 1℃ and the RMSE is reduced from above 4℃ to within 3℃. Comparing the four methods of bias correction, we see that the biweight method is generally as effective as the mean method, but it works better than the mean method at some particular sites. The moving methods are more effective than the nonmoving methods. The movingbiweight method is the most effective method, which can reduce the average error down to be within (-0.5-0.5℃) in most area of China and no larger than (-1-1℃).

Abstract:By using nonhydrostatic WRF model, we did highresolution numerical simulation on the landfall process of Typhoon Morakot in this paper. The simulation, is triplenested with the highest resolution of 2 km, integrated 72 h (3 d). We also carried out careful comparison between the simulation result and the observation data. The result shows that WRF model successfully simulates the development and landing process of Typhoon Morakot, and the simulated path is quite consistent with the observation. At the same time, the model also successfully shows the evolving process and the feature of main radar echoes in the whole simulating period. Furthermore, with the highresolution simulation data we carried out diagnostic analysis on the landing process of Typhoon Morakot with the generalized waveactivity density M. The result shows that the abnormal values of wave action density M always cover the observed precipitation regions horizontal distribution and temporal evolution are quite similar.

Abstract:Based on the automatic identification mesoscale convective systems (MCSs), tracking radar echoes by crosscorrelation (TREC) and area overlap method (AOM) were used to complete the new tracking and nowcasting algorithm. TREC was used in the new algorithm to get motion vector, then this vector was used to extrapolate radar echoes of corresponding MCSs. According to extrapolation echoes and realtime radar echoes, AOM was used to make tracking, and simultaneously the MCSs nowcasting was completed. The performance of the algorithm was evaluated by applying four different types of severe convection cases. The results demonstrate that the algorithm can make tracking and nowcasting effectively. The speed of MCSs extracted by new algorithm is more stable, and does not fluctuate rapidly due to splitting, merging, developping and decaying. Forecast errors are reduced effectively and 6-60 min nowcasting errors are cut more than 20% by using the new algorithm instead of the old one. However, the new algorithm can extract stable moving speed of system, but it can not get propagating speed. The old algorithm can extract the integration of moving speed and propagating speed, but the extracted speed is unstable being easily affected by centroid variation and creating bigger nowcasting errors. The speed extracted by new algorithm is unstable during the dying period, causing the failure of tracking. When using the old algorithm, such failure may happen in the case of splitting or merging.

Abstract:Based on conventional observation data and ECMWF numerical forecast products, dynamic diagnostic analysis was carried out to find out the causes for the formation and weakening of sandstorms that happened in the Hexi Corridor of Gansu Province on 23 April 2014. The results showed that unstable trough develops strongly in front of the ridge of Mountain Ural at 500 hPa, steering strong cold air from the North Pole to move southward quickly, which is the largescale system leading to the sandstorm. And strong storms accompanying the surface cold front is the main cause for the outbreak of the severe sandstorm. The reason why the strong sandstorm gets enhanced in the Midwest of the Hexi Corridor is that nearly neutral temperature stratification in 700-850 hPa coupled with strong cold temperature advection and lowlevel jet of Hexi Corridor is conducive to the frontogenesis and downstream of momentum. The strong pressure gradient, temperature gradient and daily variation before and after the cold front causes explosive development of sandstorm in the eastern part of Hexi Corridor. In addition, the strong upward motion of low altitude near the Midwest of Hexi Corridor is in favor of increasing dust concentration. Strong differential temperature advection and vertical wind shear enhance thermal and dynamic instability. The reason why strong sandstorm weakens in eastern part of the Hexi Corridor is that the main weather system resulting in the strong sandstorm weakens and moves northerly, and the narrow tube effect disappears in the eastern part of Hexi Corridor. Besides, the diurnal change of temperature and pressure gradients at midnight lead to frontolysis. Even the rainy weather continues in the early stage so that the exposed surface soil becomes loose and deserts form a compacted layer to increase the difficulty of raising sand.

Abstract:According to the mechanism of rainstorm flood, we propose a dynamic critical rainfall index associated with the former water levels. The method for calculating critical rainfall of flood hazard is established by using HBV model in the upper Huaihe River Basin. First of all, the optimized model parameters is determined through the model calibration and validation. The stagedischarge relationship is then established for the rising levels of flood. Finally, the critical rainfall is determined according to the hazard water level by repeated model simulation. The case study in the upper Huaihe River Basin indicated that HBV model can well simulate the process of flood response to rainfall after model calibration by using daily meteorological and hydrological data for the period of 2002-2009. The model combined with the stagedischarge relationship is then used to calculate the dynamic critical rainfall over the Wangjiaba subregion. The critical rainfall decreases with the increase in former water level. The variation of critical rainfall with different former water level shows significantly nonlinear response characteristics.

Abstract:The influence mechanism of heat wave on coronary heart disease is preliminarily discussed through simulation experiment of heat wave impact on coronary heart disease rats in this paper. The heat wave process was simulated in an environmental test chamber (TEM1880). Eighteen coronary heart disease rats were randomly divided into control group, heat wave group and heat wave BH4 group with 6 rats in each group. The rats in heat wave group and BH4 group were placed into the simulation chamber. After the process of simulated heat wave, their blood was drawn by decollation and the mice hearts were extracted to measure the content of ET1, NO, HSP60, SOD, TNF, sICAM1 and HIF1α of rats in each group. The results showed that heat wave can lead to significant decrease of myocardial tissue’s SOD activity in coronary heart disease rats and increase of NO, HSP60, SOD, TNF, sICAM1 and HIF1α content. However, it has few effect on ET1 level. Through the analysis of biochemical index, heat waves can induce prominent increase of myocardial tissue’s HSP60 level in coronary heart disease rats. Superabundant HSP60 can activate immune cells, induce endothelial cells and macrophages to secrete a large number of inflammatory cytokines (such as ICAM1 and TNFα), and then activate inflammation system in the body, damage coronary vascular endothelial cells structure, increase vascular endothelial permeability and decrease heart tissue SOD activity, increase the lipoprotein of oxidation blood, generate a large amount of cholesterol, speed up the deposit of cholesterol on the lining of blood vessels through the lining, result in atherosclerosis and aggravation of coronary heart disease, then induce increase of vascular active matter such as ICAM1 and thromboxane, increase blood viscosity which is conducive to the formation of blood clots, restrain lipoprotein lipase activity, induce lipid infiltration of vascular intima which is conductive to arteriosclerosis plaque; and control the cholesterol metabolism of macrophage at the same time, which is conducive to the deposition of lipid material in vascular wall and thus increase risk of coronary artery disease. This is the preliminary mechanism of how high temperature and heat wave lead to exacerbation of coronary heart disease and even death, and can lay a foundamental theoretical basis for warning high temperature and heat wave in public service.

Abstract:The appearance of warm ridge in low attitude implies that an unstable weather factor is forming.Therefore, recognizing the warm ridge correctly based on temperature field data is important for weather forecasting. In view of the exposed problems when extracting the warm ridge lines using the ridge line algorithm, this paper proposes a section extreme value correction (SEVC) algorithm, by which candidate warm ridge feature points are extracted, and establishes rules based on weather characteristics to exclude non warm ridge feature points. According to the idea of least squares method used in fitting curve, this paper puts forward a kind of smooth medial axis fitting (SMAF) algorithm to get higher quality of warm ridge lines, which coincide with that weather forecasters manually draw. A large number of experiments show that the recognition rate is as high as 97% and mistaken recognition rate is zero.

Abstract:The test and comparison of sustainability and suitability of agricultural meteorological index is very meaningful for improving agricultural meteorological operations. This paper counts the accuracy of defining rice cold damage with meteorological indicators in different ages by using the daily air temperature data in 1960-2010 and rice yield data from representative stations in the north of China. The application effect of rice cold damage indicators for elayed growthtype and steriletype is tested, and their differences are compared. The results show that the accuracy of May to September temperature indexes for defining the delay growthtype cold damage is around 78%, and the index is stable, showing good sustainability, and the accumulated temperature difference index is stable too, able to continue to apply. However, the accuracy of accumulated temperature anomaly index of elayedtype cold damage significantly is lower, not suitable to continue to use in most regions. For most of the representative counties, the indicators of daily average temperature, daily lowest temperature and its duration when defining the steriletype cold damage are applicable at the present stage, but the accuracy is low in a few counties and they should susped using, but the accuracy of lowest temperature indicator is slightly higher than the daily average temperature indicator. The elements and mechanism of these indicators have not changed, but their stability and sustainability have differences in regions and ages, so the indicators should be used selectively and revised timely to adapt to climate change and rice cultivation.

Abstract:The following are the main characteristics of the general circulation of atmosphere in March 2015. There are two polar vortex centers in the Northern Hemisphere located more southward than normal years. The circulation presents latitudinal patterns in middlehigh latitudes. The average south branch trough is located near 70°E. Besides, the subtropical high is much more stronger than normal years, and located more westward than normal years. The monthly mean precipitation is 21.8 mm, which is 26.1% less than normal (29.5mm). The monthly mean temperature is 5.8℃, which is 1.7℃ higher than normal (4.1℃). There are five cold air processes and five rainfall processes in the month. Meanwhile, fog and haze weather appears in the central and eastern part of China. Moreover, five sanddust processes occur in northern part of China.