Advanced Data Analysis Techniques for Active Microwave Occultation Experiments

主动微波掩星实验的先进数据分析技术

• 批准号: 0139511
• 负责人: Benjamin Herman
• 金额: --
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-15 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0139511&HistoricalAwards=false
• 关键词: Advanced; Data; Analysis; Techniques; Active

This grant advances methods of atmospheric sounding based on measurement and interpretation of GPS signals received by low earth orbiting (LEO) satellites. Because of refraction, radio signals follow a slightly bent path and have a slightly reduced speed when they propagate through the earth's atmosphere from a GPS transmitting satellite to a LEO receiver. From the amount of bending and the excess time delay can be inferred the vertical profile of the radio refractivity of the atmosphere. The refractivity is related to the electron density in the ionosphere and to the temperature, pressure, and water vapor content of the neutral atmosphere. Atmospheric sounding using the occultation technique separates the different contributions to the refractive index to determine both the electron density profile in the high atmosphere and the profiles of temperature and humidity in the lower atmosphere.The project is divided into two main parts. The first is concerned with solving certain problems in using the existing system of GPS satellites to monitor profiles of temperature, humidity, and electron density. It includes (1) developing corrections for the effects of the ionosphere on measurements in the lower atmosphere; (2) studying the effects of multipath propagation in the lower troposphere; (3) extending the profiling down to the boundary layer; (4) assimilating radio occultation data into weather forecasting models. The second part of the project is aimed at developing an advanced sounding system in which an array of as many as six LEO satellites will be equipped for both transmitting and receiving signals at frequencies within selected water vapor and ozone absorption bands (so-called crosslink experiments). Measuring the amplitudes and phases of such signals enables the determination of profiles of temperature, water vapor, and ozone from radio occultations. This research lays the groundwork for new methods of atmospheric sounding that will have important application in numerical weather prediction models and, through the detection of long-term trends, in climate studies.

该赠款改进了基于低地球轨道 (LEO) 卫星接收到的 GPS 信号的测量和解释的大气探测方法。 由于折射，无线电信号在通过地球大气层从 GPS 发射卫星传播到 LEO 接收器时会遵循稍微弯曲的路径，并且速度会略有降低。 从弯曲量和额外的时间延迟可以推断出大气无线电折射的垂直剖面。 折射率与电离层中的电子密度以及中性大气的温度、压力和水蒸气含量有关。 使用掩星技术的大气探测分离了对折射率的不同贡献，以确定高层大气中的电子密度分布以及低层大气中的温度和湿度分布。该项目分为两个主要部分。 第一个涉及解决使用现有GPS卫星系统监测温度、湿度和电子密度分布的某些问题。 它包括 (1) 对电离层对低层大气测量的影响进行修正； (2) 研究对流层低层多径传播的影响； (3) 将剖面延伸至边界层； (4)将射电掩星数据同化到天气预报模型中。 该项目的第二部分旨在开发先进的探测系统，其中将配备多达六颗低地球轨道卫星的阵列，用于以选定的水蒸气和臭氧吸收频带内的频率发射和接收信号（所谓的交联实验） ）。 测量此类信号的幅度和相位可以根据射电掩星确定温度、水蒸气和臭氧的分布。 这项研究为新的大气探测方法奠定了基础，这些方法将在数值天气预报模型中发挥重要作用，并通过检测长期趋势在气候研究中发挥重要作用。