نتایج جستجو برای: rain
تعداد نتایج: 17335 فیلتر نتایج به سال:
Rainfall forecasts compiled by the South African Weather Service (SAWS) are used daily by agriculture, industry, sportsmen and the general public. Because of the importance of the rainfall forecast, it is of considerable interest to know how reliable these forecasts are. The SAWS evaluates the rainfall forecasts issued by the Central Forecasting Office (CFO) on a daily basis. A hit score is det...
This paper presents the bit error rate (BER) upper bounds for trellis coded asymmetric 8PSK (TC-A8PSK) system using the Ka-band satellite in the rain fading environment. The probability density function (PDF) for the rain fading random variable can be theoretically derived by assuming that the rain attenuation can be approximated to a log-normal distribution and the rain fading parameters are c...
Understanding the causes of savanna–forest dynamics is vital as small but widespread changes in the extent of tropical forests can have major impacts on global climate, biodiversity and human well-being. Comparison of aerial photographs for 50 rain-forest patches in Kakadu National Park had previously revealed a landscape-wide monotonic expansion of rain-forest boundaries between 1964 and 2004....
Rain-water-harvesting is one of the means by which agricultural production can be increased to meet the growing food demands in all regions. The study indentified the factor affecting rain-water-harvesting technology adoption for irrigation and farmers practice in water harvesting against drought in lowland woreda, Eastern Hararghe, Oromia Region. Both primary and secondary data were collected ...
Amazonian rain forest-savanna boundaries are highly sensitive to climatic change and may also play an important role in rain forest speciation. However, their dynamics over millennial time scales are poorly understood. Here, we present late Quaternary pollen records from the southern margin of Amazonia, which show that the humid evergreen rain forests of eastern Bolivia have been expanding sout...
A radar image acquired by the C-band synthetic aperture radar (SAR) aboard the European Remote Sensing satellite ERS-2 over the coastal waters south of Singapore showing radar signatures of a strong tropical squall line (“Sumatra Squall”) is compared with coincident and collocated weather radar data. Squall line features such as the gust front, areas of updraft convergence, and rain areas are i...
The presence of rain in the sub-satellite track can significantly degrade altimeter measurements by causing an attenuation of the backscattered signal, a change in its path length through the atmosphere and a change in the mean square slope of the sea surface. This can cause errors, not only in the measurement of the satellite altitude, but also in the determination of wind speed and wave heigh...
This study focuses on improving the retrieval of rain from measured microwave brightness temperatures and the capability of the retrieved field to represent the mesoscale structure of a small intense hurricane. For this study, a database is constructed from collocated Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and the TRMM Microwave Imager (TMI) data resulting in about ...
In this paper, a novel method for rain rate estimation is researched by polarimetric phase shift of the Global Navigation Satellite System (GNSS). The physical process of GNSS signals propagating through rain-filled medium is investigated, by which the cause of polarimetric phase shift is explored. Then, a theoretical model between polarimetric phase shift ∆φ and rain rate R is established and ...
The visual appearance of rain is highly complex. Unlike the particles that cause other weather conditions such as haze and fog, rain drops are large and visible to the naked eye. Each drop refracts and reflects both scene radiance and environmental illumination towards an observer. As a result, a spatially distributed ensemble of drops moving at high velocities (rain) produces complex spatial a...
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