Study of Microwave Radiometer Temperature Profiles for Use in Calculating Relative Humidity
Student: Stanford Carter
Howard University, Washington, D.C.
Degree Level: Bachelor of Science
Internship Site: NASA Goddard Space Flight Center, Greenbelt, Maryland
Mentor: Dr. Daniel Ramirez
Abstract: Hygroscopic growth is one of the most fundamental properties of atmospheric aerosols. By absorbing or evaporating water, an aerosol particle changes its size, morphology, phase, chemical composition and reactivity, and other parameters such as its refractive index. Because of this, extensive research is being done on aerosol particle hygroscopic growth at NASA. This research is important to the understanding of aerosol effects on climate change. Currently, the operation of radiosondes is the most common technique used to characterize vertical profiles of temperature, water vapor mixing ratio and relative humidity. However, radiosondes are launched only two to three times a day because of the high cost of each one. The attempted solution to this problem is utilizing a Microwave Radiometer (MWR). Microwave radiometry allows for continuous retrievals of temperature profiles by measuring brightness and sky temperature at different zenith elevations. The focus of this study is the sensitivity of Relative Humidity Profiles obtained from both instruments. This will be accomplished by using temperature profiles from the MWR and radiosonde. The result of these comparisons will allow for the study of the sensitivity of the Relative Humidity profile obtained by radiosonde and those combining temperature profiles from the MWR and the Water Vapor mixing ratio from the radiosonde. These Relative Humidity profiles will then be compared to Relative Humidity profiles from the radiosonde. The data used in this study was acquired from the Howard University Beltsville Campus during the Discover AQ campaign in the summer of 2011. The result of this project will be used as a baseline for evaluating uncertainties in the retrieval of aerosol hygroscopic growth by means of Lidar measurement.
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