Helicity as a Method for Forecasting Severe Weather Events

This paper introduces a method for forecasting severe weather which is yieded by integrating helicity as a dynamical parameter with K and TOT indexes as thermal parameters.The results of operational tests for two years ure detailed.And the seasonal suitability of the method applications is discussed as well.     

Research on Technical Innovation of Numerical Weather Forecasting

The PRC Ministry of Science and Technology officially approved the implementation of the project as one of National Key Science and Technology Projects in November 2001 and entrusted the China Meteorological Administration (CMA) with the leadership. The news briefing of the project staring-up was held ceremoniously at CMA on 29 December 2001.Project Goal: under the conditions of high-performance supercomputers and high temporal and spatial resolution meteorological data, making good use of both international and domestic new scientific achievements, to develop our new generation numerical weather forecasting operation system independently so to meet the needs of the development of the country and its meteorological service.     

Sensitivity of Medium-Range Weather Forecasts to the Use of Reference Atmosphere

In this paper, the authors develop the earlier work of Chen Jiabin et al. (1986). In order to reduce spectral truncation errors, the reference atmosphere has been introduced in ECMWF model, and the spectrally-represented variables, temperature, geopotential height and orography, are replaced by their deviations from the reference atmosphere. Two modified semi- implicit schemes have been proposed to alleviate the computational instability due to the introduction of reference atmosphere. Concerning the deviation of surface geopotential height from reference atmosphere, an exact computational formulation has been used instead of the approximate one in the earlier work. To re duce aliasing errors in the computations of the deviation of the surface geopotential height, a spectral fit has been used slightly to modify the original Gaussian grid-point values of orography.A series of experiments has been performed in order to assess the impact of the reference atmosphere on ECMWF medium- range forecasts at the r     

Weather categorization — a useful tool for assessing climatic trends

Summary A computer-assisted weather categorization was applied to meteorological time series measured at the Mileovka Observatory (a mountain station) and Prague-Klementinum (an inner city site). Groups of winter days (December, January and February) with extreme mean temperatures were examined with respect to their frequency of occurrence and presence of any trends in the period 1941–1988. In general, frequencies of cold categories exhibited a decreasing trend, and frequencies of warm categories tended to increase. In both series a prominent negative trend in temperature amplitude was detected within warm clusters, related to a statistically insignificant decline in the maximum temperature and an increase in the minimum temperature. Additional analysis indicates that changes in circulation patterns occurred over the region during the period investigated, namely strengthening of zonal circulation in winter.With 6 Figures     

Simulation of Pollutant Transport in Complex Terrain with a Numerical Weather Prediction–Particle Dispersion Model Combination

A new scaling approach, based on the convective velocity obtained from the sun-exposed eastern slopes and thus suited for steep and narrow Alpine valleys, is investigated with respect to pollutant dispersion. The capability of the new method is demonstrated with the operational emergency response system of MeteoSwiss, which consists of the COSMO (COnsortium for Small-scale MOdelling) numerical weather prediction model coupled with a Lagrangian particle dispersion model (LPDM). The new scaling approach is introduced to the interface between COSMO and LPDM, and is compared to results of a classical similarity theory approach and to the operational coupling type, which uses the turbulent kinetic energy (TKE) from the COSMO model directly. For the validation of the modelling system, the TRANSALP-89 tracer experiment is used, which was conducted in highly complex terrain in southern Switzerland. The ability of the COSMO model to simulate the valley wind system is assessed with several meteorological surface stations, and the dispersion simulation is evaluated with the measurements from 25 surface samplers. The sensitivity of the modelling system towards the soil moisture, horizontal grid resolution, and boundary-layer height determination is investigated, and it is shown that, if the flow field is correctly reproduced, the new scaling approach improves the tracer concentration simulation when compared to classical coupling methods.     

Is Strange Weather in the Air? A Study of U.S. National Network News Coverage of Extreme Weather Events

This paper asks whether extreme weather events are becoming more discernible. It uses the Vanderbilt University Television News Archives to determine if annual coverage given to heat waves, droughts, hurricanes and floods has increased on the network news between 1968 and 1996. An index of extreme weather events shows a clear trend toward increased coverage, especially since 1988. However, the different types of extreme events do not receive equal coverage: for example, annual peaks for droughts contain about twice as many stories as the peaks for heat waves. The data further reveal that there is no association between coverage of climate change and the overall coverage of extreme events. While extreme events have attracted more stories in the U.S., there has been no increase in the coverage devoted to extreme events in foreign countries. The possible effects of shifts in TV coverage on the public salience and understanding of climate change are discussed.     

Atmospheric modulation of surface heat fluxes at Ocean Weather Station P on a decadal time‐scale

Abstract

A 30‐year record (1951–1980) of surface heat fluxes at Ocean Weather Station P in the northeastern Pacific Ocean (50°N, 145°W) was examined for differences in the interdecadal variation between fail and winter. During the latter part of the 1950s and the early 1960s, the winter surface heat flux from the ocean to the atmosphere diminished significantly whereas the fall heat flux increased slightly This difference in the modulation of the winter heat flux from the fall heat flux during this period appears to be caused by the presence of an atmospheric circulation anomaly resembling that of the Pacific/North America (PNA) low‐frequency variability mode during the winter season.     

A Digitized Weather Radar in Gansu Province and a Simple Radar-Raingauge Comparison

An on-line computer processing system was added to the LanzhouInstitute’sX-bandradar.Thepotentlal of digitized weather radar isdiscussed and a preliminary examination of the rain-measuring capabilityof the radar-computer system is made.     

Machine Learning of Weather Forecasting Rules from Large Meteorological Data Bases

Discovery of useful forecasting rules from observational weather data is an outstanding interesting topic.The traditional methods of acquiring forecasting knowledge are manual analysis and investigation performed by human scientists.This paper presents the experimental results of an automatic machine learning system which derives forecasting rules from real observational data.We tested the system on the two large real data sets from the areas of centra! China and Victoria of Australia.The experimental results show that the forecasting rules discovered by the system are very competitive to human experts.The forecasting accuracy rates are 86.4% and 78% of the two data sets respectively     

CAWS600 Automatic Weather Station

The CAWS600 automatic weather station was granted the use license by the China Meteorological Administration in September 2001. It is the first project whose products have put to use in CAMS and from which we obtain good social and economic benefits. The CAWS600 automatic weather station series and the corresponding sensors, such as temperature, humidity, radiation, etc., sensors, accompanying the finalization of the automatic weather station (AWS), also passed the product finalization successively and obtained the use licenses. Presently, these products have been released into the market and have had a certain market share. The recent years have seen a continuous increase in sales and in application fields. The new-type airport     

New Generation Weather Warning System

It is a national high-tech application project, whose purpose is to issue warning before local, short time severe weather approaching. The system adopts the digital transmitting mode to transmit meteorological graph, image, word and voice messages, collects data and controls data transmission automatically with computers. The transmitter uses the FM mode to send messages with the working frequency being 140 -150 MHz. At the receiving terminals, users can receive graph, image and word messages through desktop computers, portable computers, and handhold PCs and receive voice messages by FM radios.     

Progresses of Researches on Numerical Weather Prediction in China： 1999-2002

The recent progresses in the research and development of (NWP) in China are reviewed in this paper. The most impressive achievements are the development of direct assimilation of satellite irradiances with a 3DVAR (three-dimentional variational) data assimilation system and a non-hydrostatic model with a semi-Lagrangian semi-implicit scheme. Progresses have also been made in model physics and model application to precipitation and environmental forecasts. Some scientific issues of great importance for further development are discussed.     

MAX Weather系统简介及应用

介绍了气象图文包装系统MAX Weather的主要功能,从系统的界面管理、素材管理、性能和设计框架等方面与Weather Central作出对比,以《佛山气象》晚间节目的设计思路和制作过程为例,引出MAX Weather系统的新特性及在节目制作过程中的应用技巧,针对节目业务化运行分析了优缺点。     

Weather extremes and street life in India—Implications of Fuzzy Cognitive Mapping as a new tool for semi-quantitative impact assessment and ranking of adaptation measures

The potential impacts of progressing climate change are alarming. Some adverse consequences are now unavoidable and adaptation measures are increasingly needful. This poses enormous challenges for emerging megacities in the Global South, which barely manage in current weather conditions. This paper introduces Fuzzy Cognitive Mapping as a new tool for structured, semi-quantitative assessments of climate change impacts and adaptation measures.Fuzzy Cognitive Mapping is used to evaluate differences in sensitivities to heatwaves and rainstorms across socio-economic groups and for the ranking of useful adaptation options, based on 188 individual interviews to the impacts of extreme weather events in Hyderabad, India. The results of this multi-stakeholder assessment indicate that rainstorms affect low-income residents more than heatwaves, while the opposite is true for medium-income respondents. The latter are also less seriously affected by extreme weather in general. Profession, though, not income determines the kind of impact that people feel most affected by. Individual characteristics like age and gender do not significantly explain differences in the data, but religion does. This is because, in Hyderabad, Muslims live in the older, less serviced and more affected parts of the city. However, semi-quantitative scenario analyses suggest that, under future climate change, many parts of the city will become increasingly exposed to the effects of extreme weather. Planned investments in urban infrastructure will be seriously challenged by climate change and preventive adaptation measures are urgently needed to at least maintain the current level of quality of life. Investments in the health infrastructure appear to be most effective in reducing the impact of heatwaves and investments in the traffic infrastructure most effective in reducing the impact of rainstorms. However, looking at heat and rain events together—which is realistic as they are both projected to increase and often occur in the same year—reveals that investments in water infrastructure and management have greatest potential to reduce impacts across all localities and on all social groups, particularly the lower-income classes. This is because first-order impacts caused by inadequate water infrastructure often give rise to second- or third-order impacts. Addressing the root cause is the most effective way to break cause-and-effect chains and prevent proliferation of negative consequences. Similar studies are suggested in other cities in order to support adaptation mainstreaming in complex urban environments. Fuzzy Cognitive Mapping proved a useful, semi-quantitative tool for climate change impact and adaptation assessments.     

An Experiment on the Air Flow Structure in a Meso- βHail System Using a Single New Generation Weather Radar

Based on data from the China new-generation weather radar (CINRAD), a comprehensive study of a meso-βhail system occurring in central Gansu on 30 May 2005 is performed as regards the evolution of reflectivity intensity and radial velocity as well as variations in the retrieved horizontal wind structure and height of echo zone base. The following results are that: 1) the hail system has a lifecycle of 3.5 h,experiencing the genesis of new cells and decay of old ones, together with the merging of multiple cells, and each cell has its own flow field and the connection of such elds favors the merging and intensi cation of cells, and cells 4 and 8 are responsible for hailfall; 2) the hail system is produced in a large-scale background consisting of a NWW environmental wind, low-level warm, and high-level cold advection, with the hail system depending on joint e ects of northwest, northeast, easterly, and southeast winds for its evolution, and the flow field is marked by cyclonic convergence at low, jets at middle, and anticyclonic divergence at higher levels; and 3) the horizontal resolution is 2 km during the retrieval experiment with horizontal winds, which is unable for us to investigate the flow structure of a cell inside the system but successful analysis is made of formation causes, dynamic structure, and behaviors of the hail system.     

‘A Case Study on a Polar Cold Air Outbreak over Fram Strait using a Mesoscale Weather Prediction Model’

The mesoscale weather prediction model ’Lokal-Modell’ (LM) of the Deutscher Wetterdienst is applied to the situation of an Arctic cold air outbreak in the Fram Strait region in April 1998. Observations are available from a flight along 5⁰E carried out during the ARTIST campaign. Initial and time-dependent boundary data for the simulation are taken from a larger scale operational model system. Using the standard configuration of LM, the simulation reproduced the propagation of cold air and the characteristic structure of the atmospheric boundary layer (ABL) in fair agreement with the observations. However, a detailed comparison revealed three basic problems. Firstly, there is evidence that the available data on sea-ice conditions were insufficient approximations to the true state for several reasons. A modification of the sea-ice data towards observations revealed that parts of the discrepancies were due to the original sea-ice data. Secondly, a control run with the model in its standard configuration shows an insufficient warming of the ABL downstream of the ice edge due to underestimation of surface heat fluxes. A simple modification of the approach for the scalar roughness length resulted in the strongest benefit, while comparative studies showed only a slight sensitivity to different types of parametrisation of turbulent mixing or the inclusion of an additional moist convection parametrisation. Thirdly, in all the simulations the deepening of the convective ABL downstream of the ice edge is weaker than observed. This may be partly due to the thermal stratification above the ABL in the analysis data, which is more stable than observed; but it may also be a hint to the fact that processes near the inversion are insufficiently parametrised in mesoscale models with resolutions as used in LM. The simulated cloud layer in the convective ABL is similar to that observed with respect to condensate content, a sharply defined cloud top, a diffuse lower bound, and continuous light precipitation.     

Weather peculiarities of the 2007–2008 cold season in the Northern Caspian Sea

Weather patterns of the cold season in the studied region of the Caspian Sea are quite complicated; ice processes here represent an actual threat for hydrotechnical and other engineering constructions located both on the coast and the Northern Caspian Sea shelf, as well as for the navigation in the ice covered sea. Analysis of the materials obtained from the researches performed in November 2007–March 2008 showed that weather patterns of the 2007–2008 cold season in the Northern Caspian Sea formed under the influence of synoptic processes differed from the multiyear norm. The unusually high frequency of anticyclonic processes (especially, the Siberian anticyclone) defined the low monthly average air temperature in January that was 2–5°C below the climatologic norm over the entire Northern Caspian water area.     

Research on the Formation Mechanism and the Prediction Theory of Hazardous Weather over China

Themid-termassessmentmeetingoftheprojectwasheldinBeijingfrom28to29December2000.Theassessingexpertsinclude:AcademicianTaoShiyan,AcademicianLiZechun,AcademicianZhouXiuji,AcademicianWuGuoxiong,AcademicianChouJifan,ProfessorYanHong,ProfessorDingYihui,Professo…     

A Trend towards a Stable Warm and Windless State of the Surface Weather Conditions in Northern and Northeastern China during 1961–2014

This study investigates the trends in the mean state and the day-to-day variability(DDV) of the surface weather conditions over northern and northeastern China(NNEC) during 1961–2014 using CN05.1 observational data. In this study, we show that the surface temperature(wind speed) has increased(decreased) over NNEC and that the DDV of the surface temperatures and wind speeds has decreased, indicating a trend towards a stable warm and windless state of the surface weather conditions over NNEC. This finding implies a trend towards more persistent hot and windless episodes, which threaten human health and aggravate environmental problems. The trends are also examined in reanalysis data. Both the ERA-40 and the NCEP data show an increasing(decreasing) trend in the mean state of the surface temperatures(wind speeds). However, the reanalysis data show a consistent decreasing trend in the DDV of the surface weather conditions only in the spring. The underlying reason for the decreased DDV of the surface weather conditions is further analyzed, focusing on the spring season. Essentially,the decreased DDV of the surface weather conditions can be attributed to a decrease in synoptic-scale wave activity, which is caused by a decrease in the baroclinic instability. There is a contrasting change in the baroclinic instability over East Asia, showing a decreasing(increasing) trend north(south) of 40°N. This contrasting change in the baroclinic instability is primarily caused by a tropospheric cooling zone over East Asia at approximately 40°N, which influences the meridional temperature gradient over East Asia.