A scheme to detect sand/dust weather applying meteorological radars

Sandy dust weather occur frequently in arid and semi-arid areas. It is important to actually detect the sandy dust grain concentration or the visibility of the sandy dust weather for weather forecasting. In this paper, based on numerical calculation of the effective detection distance of different radar detecting the sandy-dust weather with different strength, a scheme to detect sand/dust weather applying existed meteorological radar stations is proposed in this paper. The scheme can be efficient to detect sandy dust weather, for it makes a good supplement to the current deficiencies in detecting sandy dust weather and it’s a cost-saving detection way by using the existed meteorological radars. In addition, the effect of charges carried by sand/dust grains and the relative humidity on the effective detection distance of radar is also investigated, and it shows that these effects will not change the proposed scheme. It will be promising to detect the sandy dust weather in the way of disastrous weather precaution by using this scheme.

An unusual case of abnormal propagation of micro-wave caused by Nor'wester

An unusual type of radar echo was noticed on the of PPI scope of a 3 cm meteorological radar at Dum Dam airport on 3 April 1957 after the passage of a nor'wester squall. It has been shown that conditions were favourable for the formation of radio duct at that time and this echo was probably due to existence of this duct.

Towards the Next Generation Operational Meteorological Radar

This article summarizes research and risk reduction that will inform acquisition decisions regarding NOAA’s future national operational weather radar network. A key alternative being evaluated is polarimetric phased-array radar (PAR). Research indicates PAR can plausibly achieve fast, adaptive volumetric scanning, with associated benefits for severe-weather warning performance. We assess these benefits using storm observations and analyses, observing system simulation experiments, and real radar-data assimilation studies. Changes in the number and/or locations of radars in the future network could improve coverage at low altitude. Analysis of benefits that might be so realized indicates the possibility for additional improvement in severe-weather and flash-flood warning performance, with associated reduction in casualties. Simulations are used to evaluate techniques for rapid volumetric scanning and assess data quality characteristics of PAR. Finally, we describe progress in developing methods to compensate for polarimetric variable estimate biases introduced by electronic beam-steering. A research-to-operations (R2O) strategy for the PAR alternative for the WSR-88D replacement network is presented.

Meteorological radiolocator as a tool to improve meteorological information for aviation

The paper deals with meteorological radar as a tool to improve meteorological information for aviation. The first theoretical part is devoted to the history of weather forecasting and its gradual improvement. The part describes the current state of the problem in the Slovak Republic and in the world. The next part characterizes the meteorological radar, what it is used for and what is its essence. The following is the division of radars, characteristics of the radar network in Europe and the radar network in Slovakia. In the last theoretical part, attention was paid to the merged maps, their individual products - Maximum, CAPPI 2 km, EchoTop and 1h total precipitation. The last part consists in a practical representation and description of individual maps of the cold, warm and occlusive front over the territory of the Slovak Republic. These maps show how the radar captured the weather, SYNOP reports were also used, which provide a more detailed weather forecast, maps of dangerous phenomena for aviation and maps from the OPERA network.

Condições de tempo severo e formação de tornado em Brasília-DF: um estudo de caso

Os danos ambientais e estruturais causados por uma tempestade severa e tornado associado na área do Aeroporto Internacional de Brasília (DF) no dia 01 de outubro de 2014 motivaram a realização desta pesquisa. A ocorrência do tornado de intensidade F0 (escala Fujita), um fenômeno pouco frequente no Centro-Oeste do Brasil, evidencia a importância de estudos que possibilitem compreender melhor os padrões atmosféricos que favorecem o desenvolvimento de sistemas convectivos severos na região. O objetivo deste trabalho foi identificar fatores ambientais potencialmente favoráveis à manutenção ou dissipação da convecção profunda. A técnica estatística da Análise de Componentes Principais (ACP), dados meteorológicos de superfície e de ar superior e imagens de um radar meteorológico banda-S localizado no Gama-DF foram os principais recursos disponíveis para esta pesquisa. Os resultados indicam que a coexistência de alta instabilidade potencial, temperaturas elevadas e ventos intensos foi determinante para a evolução da tempestade severa. Os índices de instabilidade analisados apresentam valores que diferem consideravelmente dos limiares normalmente utilizados como indicadores da formação de tornados. Linhas de instabilidade em forma de arco (“bow echoes”) detectadas pelo radar meteorológico durante o período de chuva intensa com danos em superfície são os indícios mais fortes do tornado que atingiu a região. Registros fotográficos de linhas de transmissão de energia elétrica, telhados, árvores e carros danificados pelo vento (95 km/h) também são relevantes na caracterização do fenômeno.Severe weather conditions and tornado formation in Brasília-DF: a case study A B S T R A C TThe environmental and structural damages caused by a severe storm and associated tornado in the area of the International Airport of Brasília (DF) on 01 October 2014 motivated this research. The occurrence of the F0 intensity tornado (Fujita scale), an infrequent phenomenon in Central-West Brazil, highlights the importance of studies that allow a better understanding of the atmospheric patterns that favor the development of severe convective systems in the region. In this context, the objective in this work was to identify environmental factors that are potentially favorable to the maintenance or dissipation of deep convection. The statistical technique of Principal Component Analysis (PCA), meteorological surface and upper air data and Gama-DF S-band meteorological radar images were the main resources available for this research. The results indicate that the coexistence of high instability potential, high temperatures and strong winds was fundamental for the severe storm evolution. The instability indices show values that differ considerably from the limits normally used as indicative of tornado formation. Arc-shaped squall lines (“bow echoes”) detected by the meteorological radar during the intense rainfall period with surface damages are the strongest signatures of the tornado that hit the region. Photographic evidences of damages on transmission lines of electricity, roofs, trees and cars caused by the winds (95 km/h) are also relevant in the phenomenon characterization.Keywords: tornado, bow echo, squall line, Principal Component Analysis.