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首页> 外文学位 >Using National Weather Service (NWS) forecasts and Model Output Statistics (MOS) to forecast evapotranspiration.
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Using National Weather Service (NWS) forecasts and Model Output Statistics (MOS) to forecast evapotranspiration.

机译：使用国家气象局（NWS）预报和模型输出统计（MOS）预报蒸散量。

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摘要

Competition for water is increasing because of increased demand and reduced supply due to drought in the Great Plains for the past 5 yrs. Availability of water and its economic use are dominant factors governing irrigation and food production. If irrigators apply all available water, they may overuse water without adding benefit to the crop. A better understanding of the water requirement of a crop can yield greater benefits if irrigators can use just the needed amount of water which will protect yield while reducing water use. This better understanding can be achieved through estimating crop water use. Evapotranspiration (ET) helps in understanding crop water use. ET will help irrigators determine their potential water requirement and prevent them from over-irrigating or under-irrigating and improve the quality of the yield.;All over the world, ET has been calculated from weather data acquired from weather stations or from lysimeters. Usually, current or archived weather data is used to calculate ET. Various weather parameters (temperature, wind, relative humidity, solar radiation) and methods (Hargreaves--Samani, classic Penman, etc.) are used to calculate ET with the help of computer models for different types of crops. But little effort has been made to forecast ET, which in turn will help irrigation scheduling.;In this study, we have made an effort to forecast evapotranspiration for different crops. This information can be used by irrigators and agronomists, and others to schedule irrigation and for other purposes, such as tracking soil moisture.;Although many methods are available to calculate ET, we have used the FAO Penman-Monteith method (Allen et al., 1998) to estimate forecast ET because this method is the most accepted method to calculate ET. This method uses temperature, relative humidity, wind speed and solar radiation as its variables to calculate ET.;A computer application is developed to forecast ET for 1-3 days in advance. Daily ET values are estimated for three locations in South Dakota, Brookings, Pierre and Caputa, to compare the forecast ET to daily estimated ET from the weather data. If we can forecast ET for these three stations successfully, then ET can be evaluated for any other station in the state or for that matter in the country. The forecast weather information was used from National Weather Service (NWS) and Model Output Statistics (MOS) to evaluate forecast evapotranspiration. Forecasted temperature, relative humidity and wind speed are the required forecasted variables to be taken from NWS and MOS. As solar radiation is not readily available in these forecasts, we use three types of solar radiation to determine the best one for forecasting ET, a constant solar radiation, solar radiation from M-H model (Mahmood and Hubbard, 2002) and solar radiation from sky cover percentage forecast, in the Penman-Monteith method.;This application absorbs forecasted weather information from NWS and MOS using PHP scripting language and is stored in a MySql database. This stored information is extracted using a PHP program with forecasts being calculated using three different types of solar radiation methods. These programs run three times a day for NWS data and once a day for MOS data to make use of forecasts which are updated several times a day.;Forecasted ET values from both the sources are compared to estimated ET from automatic weather station data to determine the statistical accuracy of these estimates using a regression trend line in MS-Excel.
机译：由于过去五年来大平原的干旱导致需求增加和供应减少，因此水资源竞争日趋激烈。水的可利用性及其经济利用是控制灌溉和粮食生产的主要因素。如果灌溉者使用所有可用的水，他们可能会过度使用水而不会增加作物的收益。如果灌溉者仅使用所需量的水，既可以保护产量又可以减少用水量，那么对作物的需水量有了更好的了解会产生更大的收益。可以通过估算作物用水来获得更好的理解。蒸发蒸腾（ET）有助于了解作物用水。 ET将帮助灌溉者确定其潜在的需水量，并防止其过度灌溉或灌溉不足，并提高产量。在世界范围内，ET都是根据从气象站或测渗仪获得的天气数据计算得出的。通常，使用当前或存档的天气数据来计算ET。借助多种天气参数（温度，风，相对湿度，太阳辐射）和方法（Hargreaves-Samani，经典Penman等），借助计算机模型针对不同类型的农作物计算ET。但是，很少有努力来预测ET，这反过来将有助于灌溉计划。；在这项研究中，我们已经做出了努力来预测不同作物的蒸散量。灌溉者和农艺师以及其他人可以使用此信息来安排灌溉时间以及用于其他目的，例如跟踪土壤湿度。;尽管有许多方法可以计算ET，但我们使用了FAO Penman-Monteith方法（Allen等。 （1998年），因为这种方法是计算ET的最广泛接受的方法，因此可以估算预测ET。该方法利用温度，相对湿度，风速和太阳辐射作为变量来计算ET。;开发了计算机应用程序来提前1-3天预测ET。估计南达科他州，布鲁金斯，皮埃尔和卡普塔三个地点的每日ET值，以便将天气预报的ET与根据天气数据得出的每日ET进行比较。如果我们可以成功预测这三个站的ET，则可以评估该州或该国其他任何站的ET。国家气象局（NWS）和模型输出统计（MOS）使用了预报天气信息来评估预报蒸散量。预测温度，相对湿度和风速是需要从NWS和MOS获取的预测变量。由于在这些预测中太阳辐射不易获得，因此我们使用三种类型的太阳辐射来确定用于预测ET的最佳方法：恒定太阳辐射，MH模型的太阳辐射（Mahmood和Hubbard，2002年）和天空覆盖的太阳辐射百分比预报，采用Penman-Monteith方法。该应用程序使用PHP脚本语言从NWS和MOS吸收天气预报信息，并将其存储在MySql数据库中。使用PHP程序提取此存储的信息，并使用三种不同类型的太阳辐射方法来计算预测。这些程序针对NWS数据每天运行3次，对于MOS数据每天运行一次，以利用每天更新几次的预测。;将两个来源的预测ET值与自动气象站数据的估计ET进行比较，以确定使用MS-Excel中的回归趋势线估算这些估计值的统计准确性。

著录项

  • 作者

    Kandula, Sumana.;

  • 作者单位

    South Dakota State University.;

  • 授予单位 South Dakota State University.;
  • 学科 Atmospheric Sciences.;Computer Science.
  • 学位 M.S.
  • 年度 2007
  • 页码 120 p.
  • 总页数 120
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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