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Quantitative Precipitation Forecast
The quantitative precipitation forecast (abbreviated QPF) is the expected amount of melted precipitation accumulated over a specified time period over a specified area. A QPF will be created when precipitation amounts reaching a minimum threshold are expected during the forecast's valid period. Valid periods of precipitation forecasts are normally synoptic hours such as 00:00, 06:00, 12:00 and 18:00 GMT. Terrain is considered in QPFs by use of topography or based upon climatological precipitation patterns from observations with fine detail. Starting in the mid-to-late 1990s, QPFs were used within hydrologic forecast models to simulate impact to rivers throughout the United States. Forecast models show significant sensitivity to humidity levels within the planetary boundary layer, or in the lowest levels of the atmosphere, which decreases with height. QPF can be generated on a quantitative, forecasting amounts, or a qualitative, forecasting the probability of a specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Centers For Environmental Prediction
The United States National Centers for Environmental Prediction (NCEP) delivers national and global weather, water, climate, and space weather guidance, forecasts, warnings, and analyses to government agencies and private users. The centers form part of the National Weather Service. NCEP consists of nine centers: # Aviation Weather Center provides aviation warnings and forecasts of hazardous flight conditions at all levels within domestic and international air space. # Climate Prediction Center monitors and forecasts short-term climate fluctuations and provides information on the effects climate patterns can have on the nation. # Environmental Modeling Center develops and improves numerical weather, climate, hydrological and ocean prediction through a broad program in partnership with the research community. # National Hurricane Center provides forecasts of the movement and strength of tropical weather systems and issues watches and warnings for the North Atlantic and the E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type I And Type II Errors
Type I error, or a false positive, is the erroneous rejection of a true null hypothesis in statistical hypothesis testing. A type II error, or a false negative, is the erroneous failure in bringing about appropriate rejection of a false null hypothesis. Type I errors can be thought of as errors of commission, in which the status quo is erroneously rejected in favour of new, misleading information. Type II errors can be thought of as errors of omission, in which a misleading status quo is allowed to remain due to failures in identifying it as such. For example, if the assumption that people are ''innocent until proven guilty'' were taken as a null hypothesis, then proving an innocent person as guilty would constitute a Type I error, while failing to prove a guilty person as guilty would constitute a Type II error. If the null hypothesis were inverted, such that people were by default presumed to be ''guilty until proven innocent'', then proving a guilty person's innocence would ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Power
In frequentist statistics, power is the probability of detecting a given effect (if that effect actually exists) using a given test in a given context. In typical use, it is a function of the specific test that is used (including the choice of test statistic and significance level), the sample size (more data tends to provide more power), and the effect size (effects or correlations that are large relative to the variability of the data tend to provide more power). More formally, in the case of a simple hypothesis test with two hypotheses, the power of the test is the probability that the test correctly rejects the null hypothesis (H_0) when the alternative hypothesis (H_1) is true. It is commonly denoted by 1-\beta, where \beta is the probability of making a type II error (a false negative) conditional on there being a true effect or association. Background Statistical testing uses data from samples to assess, or make inferences about, a statistical population. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intersection (set Theory)
In set theory, the intersection of two Set (mathematics), sets A and B, denoted by A \cap B, is the set containing all elements of A that also belong to B or equivalently, all elements of B that also belong to A. Notation and terminology Intersection is written using the symbol "\cap" between the terms; that is, in infix notation. For example: \\cap\=\ \\cap\=\varnothing \Z\cap\N=\N \\cap\N=\ The intersection of more than two sets (generalized intersection) can be written as: \bigcap_^n A_i which is similar to capital-sigma notation. For an explanation of the symbols used in this article, refer to the table of mathematical symbols. Definition The intersection of two sets A and B, denoted by A \cap B, is the set of all objects that are members of both the sets A and B. In symbols: A \cap B = \. That is, x is an element of the intersection A \cap B if and only if x is both an element of A and an element of B. For example: * The intersection of the sets and is . * The n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systematic Bias
Systematic may refer to: Science * Short for systematic error * Systematic fault In engineering, a fault is a defect or problem in a system that causes it to fail or act abnormally. An example of this is the Windows fault screen, commonly referred to as the Blue Screen of Death (BSoD). The system actively monitors kernel-mod ... * Systematic bias, errors that are introduced by an inaccuracy inherent to the system Economy * Systematic trading, a way of defining trade goals, risk controls and rules that can make investment and trading decisions in a methodical way * Systematic Paris-Region: French business cluster devoted to complex systems Music * Systematic (band), American hard rock band * Systematic Chaos, a 2007 album by Dream Theater Others * Systematic SitaWare, a Danish software company; see See also * Systematics (other) * Systemic (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Radar
A weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation (meteorology), precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather. During Radar in World War II, World War II, radar operators discovered that weather was causing echoes on their screens, masking potential enemy targets. Techniques were developed to filter them, but scientists began to study the phenomenon. Soon after the war, military surplus, surplus radars were used to detect precipitation. Since then, weather radar has evolved and is used by national weather services, research departments in universities, and in television stations' weather d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rain Gauge
A rain gauge (also known as udometer, ombrometer, pluviometer and hyetometer) is an instrument used by meteorologists and Hydrology, hydrologists to gather and measure the amount of liquid precipitation in a predefined area, over a set period of time. It is used to determine the depth of precipitation (usually in mm) that occurs over a unit area and measure rainfall amount. History People living in India and the Ancient Greece, Ancient Greeks began to record rainfall around 400 to 500 BCE.Ian Strangeways, A History of rain gauges, TerraData, 2010 In India the readings were correlated against expected growth. In the Arthashastra, used for example in Magadha (Mahajanapada), Magadha, precise standards were set as to grain production. Each state storehouse was equipped with a rain gauge to classify land for taxation purposes. Rainfall measurement was also mentioned in the Jewish text in Palestine. In 1247, the Song (Chinese surname), Song Chinese mathematician and inventor Qin Jiushao ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Meteorological Society
The American Meteorological Society (AMS) is a scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance the atmospheric and related sciences, technologies, specifications, applications and services for the benefit of society. Background Founded on December 29, 1919, by Charles F. Brooks, at a meeting of the American Association for the Advancement of Science in St. Louis, and incorporated on January 21, 1920, the American Meteorological Society has a membership of more than 13,000 weather, water, and climate scientists, professionals, researchers, educators, students, and enthusiasts. AMS publishes 12 atmospheric and related oceanic and hydrologic journals (in print and online), sponsors as many as twelve conferences annually, and administers professional certification programs and awards. The AMS Policy and Education programs promote scientific kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bureau Of Meteorology
The Bureau of Meteorology (BOM or BoM) is an executive agency of the Government of Australia, Australian Government that is responsible for providing Weather forecasting, weather forecasts and Meteorology, meteorological services to Australia and neighbouring countries. It was established in 1906 under the Meteorology Act (Cth), and brought together the States and territories of Australia, state meteorological services that existed before then. The states officially transferred their weather recording responsibilities to the Bureau of Meteorology on 1 January 1908. History The Bureau of Meteorology was established on 1 January 1908 following the passage of the ''Meteorology Act 1906''. Prior to Federation of Australia, Federation in 1901, each colony had had its own meteorological service, with all but two colonies also having a subsection devoted to astronomy. In August 1905, federal home affairs minister Littleton Groom surveyed state governments for their willingness to cede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Probability Of Precipitation
Probability of precipitation (PoP) is a commonly used term referring to the likelihood of precipitation falling in a particular area over a defined period of time, which is commonly a day, half day, or hour. The PoP measure is meaningless unless it is associated with an interval of time. Forecasts commonly use PoP defined over 12-hour periods (PoP12), though 6-hour periods (PoP6) and other measures are also published. A "daytime" PoP12 means from 6 am to 6 pm. Probabilities are often calculated by ensemble forecasting and represents the number of simulations that show rain occurred. PoPs are generally not statistically independent. A good example of an event that has a strongly dependent hour-to-hour PoP is a hurricane. In that case, there may be a 1 in 5 chance of the hurricane hitting a given stretch of coast, but if it does arrive there will be rain for several hours, with the effect that a one-hour PoP for the same region and period would be similar: about 1 in 5. Localized ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
