نتایج جستجو برای: rain
تعداد نتایج: 17335 فیلتر نتایج به سال:
Short Title: Spatial-Temporal Statistics of Rain. Abstract Rain rate near the ground can be interpreted as a collection of random variables forming a random field parameterised by three coordinates: two spatial coordinates and one temporal. Interest among the radio propagation community has been focused on the first order statistics of these random variables, principally on the average annual p...
By definition, steady rain should have a nearly constant rainfall rate. Thus far, however, the criteria for determining when rain is steady remain qualitative and arbitrary. The authors suggest a definition for steadiness that can be used to quantify the elusive notion of natural variability. In particular, the logical criteria for steadiness imply statistical stationarity and lack of correlati...
The visual effects of rain are complex. Rain removal is a very useful technique in applications such as security surveillance, video editing, vision based navigation, and video indexing/retrieval. Rain produces sharp intensity variation in images and videos, which put down the performance of outdoor vision systems. These intensity variations depend on different parameters, such as the camera pr...
Accurate rain estimation from radar measurements has been a difficult task due to the variation of raindrop size distribution (DSD), lack of accurate axis ratio model, measurement error, clutter, and so forth. Previously, rain estimation from weather radars has been largely dependent upon empirical relations such as R-Z relations. The development of polarimetric radar makes accurate rain DSD re...
Satellite remote sensing of rain is important for quantifying the hydrological cycle, atmospheric energy budget, and cloud and precipitation processes; however, radar retrievals of rain rate are sensitive to assumptions about the raindrop size distribution. The upcoming EarthCARE satellite will feature a 94 GHz Doppler radar alongside lidar and radiometer instruments, presenting opportunities f...
The primary mission of the SeaWinds scatterometer on the QuikSCAT satellite is to infer surface wind vector from ocean backscatter measurements. Occasionally the backscatter measurements are contaminated by the presence of rain; therefore a reliable method of identifying rain is needed. Fortunately, the SeaWinds scatterometer simultaneously obtains active (scattering) and passive (emission) mea...
Rain over the oceans causes attenuation of communication and radar signals for satellites and backscatter to satellite radars. To determine the attenuation and backscatter, one must know the height of the rain in a storm, and must be able to find it from a satellite measurement likely to be available. Microwave radiometers on satellites can provide estimates of rain rates, and therefore relatin...
Since many years Doppler radar profilers are known as valuable tools to retrieve profiles of rain rate and further rain parameters (e.g. Wakasugi et al. (1986)). Applying well established relations for terminal fall velocity, shape and backscatter cross section of rain drops allows to derive rain rate without empirical assumptions. For calculating the backscatter cross section, the flattening o...
Statistics of 1 minute rain rate has a major impact in the design of satellite communication systems at frequencies above 10 GHz. The effect of rain causes serious degradation of radio signals at frequencies above about 10 GHz; therefore, models for the prediction of statistics of excess path attenuation needed for the design of communication propagation paths requires a statistical description...
Millimeter wave band is still under exploited compared to the microwave band and it can be a potential frequency band for resolving the spectrum congestion. Therefore, millimeter-wave networks are undergoing intensive development to meet the necessity for high speed wireless data transmission. However, millimeter-wave band is largely affected by attenuation due to rain. While calculating link b...
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