Satellite and radiosonde measurements of atmospheric humidity

• Main Author: Kottayil, Ajil
• Format: Master Thesis
• Language: English
• Published: Luleå tekniska universitet, Rymdteknik 2012
• Subjects: Aerospace Engineering; Rymd- och flygteknik; Chalmers; Kiruna; Luleå
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17792

This licentiate thesis is based on two papers which are related to the study ofatmospheric humidity. The first paper mainly focuses on a non linear method forretrieving atmospheric humidity from infrared sounder satellite measurements basedon fuzzy clustering which could potentially improve the retrieval accuracy. The mainaim of this study was to provide a better first guess humidity profile for physicalretrieval algorithms which can further improve retrieval accuracy. This method hasbeen compared against linear and non linear regression retrievals which are the gen-erally used methods to get the first guess profile. The results reveal that the retrievalaccuracy is better for the new method as compared to the conventional methods.Generally, the accuracy of the humidity measurements of radiosonde is poor in theupper troposphere (UT) and is worse for day time measurements due to solar heatingof the humidity sensor. Several methods have been developed to correct the humiditymeasurements of radiosondes in the UT. The second paper presents a detailed analysisof the implications of these corrections and depicts how important they are for satellitevalidation. The corrections have been applied separately for daytime and nighttimeradiosonde measurements and their effects have been quantified by comparing againstthe coinciding satellite measurements in the infrared and microwave spectral rangeused for humidity measurements. Godkänd; 2012; 20111213 (ajikot); LICENTIATSEMINARIUM Ämnesområde: Rymdteknik/Space Engineering Examinator: Professor Stefan Buehler, Institutionen för system- och rymdteknik, Luleå tekniska universitet Diskutant: Docent Patrick Eriksson, Institutionen för rymd- och geovetenskap, Chalmers tekniska högskola, Göteborg Tid: Fredag den 3 februari 2012 kl 10.00 Plats: Sal C, Rymdcampus Kiruna, Luleå tekniska universitet