![]() ![]() Specific elevation angles depend on the site and scanning mode of the Radar. ![]() Products from elevation angles at or below 3.5 degrees are available, and select sites may also scan at an additional low elevation angle, as low as -0.2 degrees. The same as N*R products defined above, except data values are actual reflectivity values instead of categories, data extends to further range, and additional elevations are available. Digital Base Reflectivity (NXQ, NYQ, NZQ, N0Q, NAQ, N1Q, NBQ, N2Q, N3Q/94) Sixteen possible data levels are also available. Four low elevation angles are available, with specific elevation angles depending on the scanning mode of the Radar. Scientists use these products to detect precipitation, evaluate storm structure, locate boundaries, and determine hail potential. Product Descriptionsīase Reflectivity (N0R, N1R, N2R, N3R/19 and N0Z/20)Ī display of echo intensity measured in decibels relative to Z (dBZ). ![]() Note: Missing 元 data for Hurricane Ian were recently reprocessed and restored to archive. Each copy includes state, county, and city background maps. Most 元 products are available as digital images, color hard copy, grayscale hard copy, or acetate overlay copy. Over 75 Level-III (元) products are routinely available from NCEI. A data file consists of a 24-byte volume scan header record followed by numerous 2,432-byte base data and message records. Data are stored in files that typically contain four, five, six, or ten minutes of base data depending on the volume coverage pattern. Additional categories include dual-polarization base data of differential reflectivity, correlation coefficient, and differential phase. Level-II (L2) data are grouped into three meteorological base quantities: reflectivity, mean radial velocity, and spectrum width. Request Offline Data NEXRAD Level-II (Base) Data This dataset is not currently available for direct download from NCEI, but is available by request from the offline archive. An inventory of events is available here. An event summary file with descriptive information is included for each case study. The data files have been aggregated by event and by hour for the archive with a total data volume of approximately 20 TB. The data files are in the native compressed file format as Time Series (TS) Archive. The number of case studies per year ranges from 1 to 33, with an average of approximately 10 per year. The period of record is from 2008 to present with additional data years planned. NEXRAD operational sites and test sites are used. It includes only the Level 1 data that has been used for algorithm development and verification by the ROC and its partners. Please click here here for "Method to Use").This dataset contains the Level-I (L1) raw radar event data recorded at Next Generation Radar (NEXRAD) sites and collected by the NOAA National Weather Service (NWS) Radar Operations Center (ROC) for specific radar case studies. ![]() :Please click the icon to access radar imagery with geographical information (Note: require geo-browser software supporting KML data format.The time of the radar image represents the time when the radar completes its scans.Please exercise care when viewing the image, as these signals may occasionally show up on the radar image. Weather radar may occasionally pick up reflected signals from sources other than rain, such as reflections from clouds, trees, buildings, birds, hills, sea waves and even distant land mass.For surface rainfall distribution over Hong Kong, please visit this link. Furthermore, the rainfall rate refers to the 3-km level, so that the rainfall reaching ground could be very different. Thus, the rainfall rate presented here is only an estimate. An empirical formula is used to convert the signal intensity into rainfall rate.For the latest rainfall recorded in various regions of Hong Kong, please click here.Generally speaking, the larger the raindrops are and the more their amount is, the stronger is the reflected signal. This signal intensity depends on a number of factors. Weather radar detects rain in the atmosphere by measuring the intensity of signals reflected from raindrops.64 km image updates once every 6 minutes 128 km and 256 km images update once every 12 minutes.The colour scale on the right indicates the magnitude of the rainfall rate. The image shows the rainfall rate at a height of 3 km above mean sea level, as observed by Hong Kong Observatory's weather radar.:Please click the icons to switch on/off terrain information. ![]()
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