Verification of short- and medium-range precipitation forecasts from the ensemble modeling system of the hydrometcenter of Russia

Precipitation forecasts from short- and medium-range ensemble prediction system of the Hydrometeorological Research Center of the Russian Federation (Hydrometcenter of Russia) are verified. The verification system includes probabilistic and deterministic scores. The precipitation forecast quality is analyzed for different seasons and large-scale circulation types. Further development of ensemble modeling and verification at the Hydrometcenter of Russia is discussed.     

Forecasting the transport and transformation of atmospheric pollutants with the COSMO-ART model

The COSMO-ART model is used at the Hydrometcenter of Russia for the routine forecast of air pollutant concentrations. The COSMO-Ru7-ART system is able to simulate adequately the values of concentration of impurities in the atmosphere. The system includes the module for estimating the emission of pollutants to the atmosphere from forest fires that was successfully tested on the case of forest fires occurred in the summer of 2010 for the European part of Russia. The accurate forecast of pollutant concentration has also a positive effect on the air temperature forecast due to taking into account the aerosol feedback on radiation.     

Preliminary results of testing the snowstorm short-range forecast algorithm

In the significant part of the territory of Russia and other northern countries, the snowstorm is a frequently observed hazardous meteorological phenomenon. The significant duration of the cold period and the presence of vast snow areas as well as synoptic and orographic factors that cause the formation of strong winds, create the conditions for the snowstorm activity in the most part of Russia. In the present paper, an algorithm is proposed of the snowstorm forecast (separately for overall and ground snowstorms) for Murmansk region and Central Federal District based on the data of WRF-ARW modern hydrodynamic regional model used in the operational practice in the Hydrometcenter of Russia.     

Diagnosis and forecast of the Caspian Sea level with the operational hydrodynamic model

The observational data on sea level at Tyulenii Island station were compared with the results of the Caspian Sea level simulation with the three-dimensional hydrodynamic model with different spatial horizontal resolution (3 and 1 nautical miles). The sea motion is induced by the air pressure gradients and tangential wind stress that are obtained from the COSMO model forecast and specified on the surface. The results of diagnostic calculations of the sea level for June-October 2014 and 60 forecasts for September 2014 demonstrated that the model with the 1-mile resolution meets the simulation accuracy requirements of the Hydrometcenter of Russia and can be used for the short-range forecasting of the Caspain Sea level.     

Medium-range forecast of air temperature and of some dangerous phenomena using the technique of the hydrometcenter of Russia

The improved forecasting technique is presented of weather element computation developed at the Hydrometcenter of Russia for the medium-range forecasting on the basis of statistical interpretation of the results of integration of hydrodynamic atmospheric models. The methodology of numerical forecasting algorithms is described. The methods of forecasting the air temperature for ten-day periods and the extreme air temperature detailed for every day for the territory of Russia are realized on the basis of the weather element computation technique. According to the resolution of the Central Methodical Committee for Hydrometeorological and Heliogeophysical Forecasts, these methods are introduced into the operational practice as the basic ones. The examples of forecasts and the data on their accuracy are given. The approach is developed to the solution of the problem of the dangerous phenomena forecast (of anomalously cold and anomalously hot weather) with the earliness of 48–96 h within the frameworks of this technique.     

Practical predictability of the standardized precipitation index on monthly and seasonal timescales

The SL-AV global semi-Lagrangian model of Hydrometcenter of Russia is used for considering the issues of practical predictability of the Standardized Precipitation Index (SPI) recommended by WMO. The index values are computed using the actual data (observations and reanalysis) taken as a reference and the forecast (hindcast) data interpolated to the stations (236 stations on the CIS territory). The analysis of practical predictability is based on diagnostic verification as well as on the model verification measures recommended by WMO. The statistically significant useful signal was detected on monthly and seasonal integration intervals. No useful information is found for the second- and third-month forecasts. A case study for the Republic of Kazakhstan (July 1989) demonstrates the dependence of forecast skill on the atmospheric circulation patterns. It is revealed that in the case of meridional atmospheric circulation forms the model resolution increases and, in some cases, not only moderate but also severe drought can be predicted.     

Complex forecast of surface meteorological parameters

The statistical scheme using the results of the best foreign global schemes and the COSMO-RU7 regional scheme is proposed for forecasting surface temperature for five days and the amount of precipitation for three days. Presented are the estimates of prognostic values of the surface air temperature and amount of precipitation for the period of July 2010–June 2013. The joint statistical taking account of different types of systematic errors in the complex forecasting scheme enables excelling all initial schemes in quality. A scheme of the complex forecast is operationally used and its results are daily updated on the website of the Hydrometcenter of Russia at 09:15. The forecasts of extreme temperature, dew-point temperature, and wind speed near the surface are also presented on the website.     

Downscaling of the global seasonal forecasts of hydrometcenter of Russia for North Eurasia

Proposed is a method of downscaling of the global ensemble seasonal forecasts of air temperature computed using the SLAV model of the Hydrometcenter of Russia. The method is based on the regression and suggests a probabilistic interpretation of forecasts based on the assessment of uncertainty associated with the regression and model forecast ensemble spread. The verification of the method for 70 weather stations of North Eurasia using the rank probability skill score RPSS showed a significant advantage of downscaled forecasts over the forecasts interpolated from the model grid points. It is concluded that the use of the downscaling method is reasonable for the long-range forecasting of the station air temperature for North Eurasia.     

Simulation of the summer Indian monsoon beginning during the experiments with the atmosphere general circulation model of Hydrometcenter of Russia

The influence of the Earth’s gravitational field on the simulation of the time of the beginning of monsoon circulation in Asia by the model is analyzed. The results of numerical experiments carried out with the circulation model of the Hydrometcenter of Russia during ten years (1979–1988) following the AMIP protocol are considered. Two standards were used during the analysis of results. The data of NCEP/NCAR (the United States) reanalysis were used for the comparison of circulation characteristics and the data of GPCP (Global Precipitation Climatology Project), for the precipitation analysis. Four different criteria of the monsoon beginning are analyzed: the occurrence of the negative divergence in the area under study, the beginning of heavy precipitation fall, the marked kinetic energy increase in the lower troposphere, and the origination of anticyclonic vorticity. The comparison of the data obtained during the numerical experiments with the chosen standards demonstrated that, in all cases, taking account of gravitation field variations results in the improvement of the simulation of the time of monsoon circulation beginning by the model.     

区域空气质量数值预报模型

给出了区域尺度空气质量数值预报模型的基本物理构架, 重点介绍了欧拉型输送／沉降模式对各种物理 （沉降、输送）、化学 （气相化学与液相化学） 过程、初值与边界条件等问题的处理／简化; 利用本模型作了一周的预报实验, 实验结果与分析说明, 区域空气质量数值预报模型能够较好地反映全国重点城市的空气质量以及污染物随时间的演变态势; 最后, 指出了需要进一步完善的工作。     

A tide in the operational model for short-range forecast of current velocity and sea level in the Barents and White seas

The operational model for the short-range forecast of velocity of currents and the sea level of the Barents and White seas is introduced into the automatic system of operational data processing of Hydrometcenter of Russia and works in the operational mode. The tidal block of the model is verified using eight major harmonics of the tide in the Barents and White seas. It is revealed that the model simulates adequately the large-scale features of tidal circulation in the Barents Sea. The model verification is based on the comparison between the diagnostic computation of the total sea level and the observational data on the sea level from the automatic buoy station. Demonstrated is a good agreement between the total sea level computations and the observations in the area of Teriberka settlement. The model takes account of the ice presence and simulates the ice effects on the currents. It is established that the ice presence affects significantly the amplitude and phase of tidal waves, especially in coastal regions.     

Estimating the computation accuracy of mixed waves in the ocean on the basis of present-day numerical models

An estimate of the computation accuracy of wind waves is obtained on the basis of three mathematical models used for the diagnosis and forecast of wind waves at the Hydrometcenter of Russia, US National Weather Service, and European Centre for Medium-Range Weather Forecasts. The accuracy estimation was carried out for the whole year 2006 by means of the comparison of model computations based on different wind fields with hourly instrumental observations of waves at 16 buoys in the North Atlantic. The computation accuracy was estimated on the basis of six statistical characteristics. Besides, the estimates for various wave height ranges for months and seasons of the year are made for all buoys and grouped into three geographical areas: the coasts of the United States, Canada, and Great Britain. The essential differences are revealed in the accuracy of model-based computation of waves in the areas of the ocean with different wind wave regimes, in different seasons of the year, and within various wave height ranges. The obtained results indicate the necessity to improve the present-day methods of diagnosis and forecast of wind waves.     

GRAPES区域集合预报尺度混合初始扰动构造的新方案

集合预报初始扰动能否准确反映预报误差的结构特征是决定区域集合预报质量的关键因素之一。本文针对GRAPES区域数值预报模式,发展设计了一种基于资料同化思想的混合尺度初始扰动构造新方案。该方案以全球大尺度信息为背景场,区域模式预报作为观测资料,借助GRAPES三维变分同化系统,将高质量的全球大尺度信息与区域模式预报中质量较高的中小尺度信息有效融合,构造混合尺度区域集合预报初始扰动,并通过个例试验和批量试验,比较分析了新方案和原区域集合预报的性能。试验结果表明,基于资料同化构造的初始扰动能够有效融合全球大尺度信息和中小尺度天气系统的信息,其降水概率预报更具参考价值。总体上看,区域集合预报混合初始扰动新方案能够较好地改进区域集合预报质量,尤其是对高度场和温度场效果更为显著,但对风场的集合预报性能影响略小。     

区域初始分析误差对梅雨锋中尺度低压数值预报的影响

以梅雨锋中尺度低压个例为研究对象,根据目标观测的思想,采用NCEP和T106再分析资料分析了区域初始分析误差对梅雨锋中尺度低压数值预报误差的影响。结果表明:区域初始分析误差对数值预报误差有重要影响,改善某些特定区域初始场质量有可能改善随后数值预报的效果。但是,区域初始分析误差对数值预报误差的影响较为复杂,它与天气类型、不同个例和区域间误差相互作用等因素密切相关。对梅雨锋中尺度低压短期数值预报有较大影响的初始分析误差与梅雨锋锋区及其附近地区的要素场关系密切,相比较而言,风场似乎更加重要一些。如果对梅雨锋带中低层风切变区及相伴低空急流区有更好的描述,这将对梅雨锋中尺度低压系统数值预报效果的改善有着积极的作用。在此基础上,就相关的目标观测设计问题作了简要讨论。     

华南暖区暴雨预报的模式初始场质量敏感性分析

本文利用高分辨率中尺度数值预报模式WRF和两组再分析资料,在研究不同模式初值对华南暖区暴雨预报质量差异明显的基础上,利用合成初值方法进行了模式初值对暖区暴雨预报的敏感性数值试验研究,讨论了模式初始场关键物理量对暖区暴雨预报质量的影响,重点开展了模式初值湿度场质量对华南暖区暴雨降水预报的敏感性分析。结果表明：模式初始场质量的较小差异,可显著影响本次华南暖区暴雨预报的降水强度、降水落区以及降水发生时间等的质量。初始水汽场对暖区暴雨预报影响最大,也最为敏感,是准确预报对流单体的发生发展以及地面强降水的基础。风场和温度场对暖区暴雨预报的影响相对较小。对流层低层较强的风速辐合是本次暖区暴雨强对流单体触发、生成和加强发展以至产生暖区强降水的物理基础。     

GIS-Amur system of flood monitoring,forecasting, and early warning

GIS-Amur system offlood monitoring, forecasting, and early warning was developed at the Hydrometcenter of Russia and Planeta Research Center for Space Hydrometeorology for the effective surveill ance of hydrological conditions in the Amur River basin. The system is based on the use of hydrometeorological information, that is, observational data from weather and gaging stations, data from hydrological forecasts, and satellite data. The GIS- and web-based GIS-Amur system provides high reliability, safety, and operational speed. During the operational practice in the spring and summer 2015, the system demonstrated the forecast accuracy and reliability, the timely delivery of output products to end users, and the great variety of the output product types and formats. The system provides near-real time access to all available hydrometeorological data in the Amur River basin that favors correct and timely decision-making for flood risk reduction.     

数值预报中自由度的压缩及误差相似性规律

利用历史资料的有用信息提高数值模式预报水平是长期以来人们努力的目标。该文提出了一种在气候吸引子上缩小初始场自由度的相似选取方法,有效滤除了小尺度分量,避开了原有相似选取中自由度太大,相似选取困难的问题。分析表明:相似初值间的模式预报误差存在相似性,依此估计的预报误差与实际预报误差很接近。在空间分布特征上,相似初值间的模式预报误差也有很好的一致性。这为发展相似-动力方法,利用历史资料改进数值模式提供了支持。     

Identification of zones of atmospheric fronts as a problem of postprocessing the results of numerical prediction

Presented is a review of the results of the studies that have been carried out in recent 15 years at the Hydrometcenter of Russia and deal with the objective analysis of atmospheric fronts and with diagnostic computations on the base of the results obtained. A unique experiment on the quantitative estimation of the measure of subjectivity of the frontal analysis carried out by weather forecasters in operational mode was accomplished in the process of the method development. Differences turned out to be so significant that no concrete synoptic archive can be considered as a source of actual data on the position of fronts. At the same time, the degree of agreement between different forecasters concerning the position of primary cold and warm fronts remains practically significant. The statistical method of objective analysis of atmospheric frontal zones is worked out as a method of postprocessing the results of numerical forecast (objective analysis) of the fields of pressure (geopotential), temperature, and humidity. The proposed method was operationally tested and recommended for the operational use by the Roshydromet Central Methodological Committee for Hydrometeorological and Heliophysical Forecasts. The data on precipitation at the stations (a degree of precipitation intensity on the front characterizes its activity) are used as a predictant (criterion of the absence or presence of a front). The frontal parameter initially obtained as a probability of the fact that the forecaster draws the front through the given grid cell is (in its physical essence) a quantitative characteristic of baroclinity near the surface and in the layers of 850-500 and 925-700 hPa and of cyclonicity of the surface pressure field. This variable turned out to be an effective diagnostic characteristic of baroclinic forcing of vertical circulations and formation of clouds and precipitation in frontal zones. The spectra of the frequency of precipitation of various intensity for different seasons and regions of the European part of the former USSR are constructed using the long-term data on two main characteristics of precipitation forcing, namely, the frontal parameter and the height of the convection level. Given are other potential application areas of the frontal parameter including the verification of numerical models.