Evaluation of the consistency of station-based soil moisture measurements with hydrological model and remote sensing observations over Turkey

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2015

Öğrenci: BURAK BULUT

Danışman: MUSTAFA TUĞRUL YILMAZ

Özet:

Soil moisture is a critical parameter for many subjects like climate, drought, water and energy balance, weather prediction; yet the number of studies involving soil moisture has been limited in Turkey. Soil moisture parameter can be obtained using several different methods. Among the values obtained via different methods, station-based observations have the greatest potential to provide the most accurate soil moisture information, even though station based observations have the representativeness errors over large areas. Additionally, validations of satellite- and hydrological model-based soil moisture estimates are only possible through evaluation against station-based measurements. Soil moisture observations have been made by Turkish State Meteorological Service (TSMS) at 149 different stations since 2007. On the other hand these datasets have not been used in any study before as their accuracy has not been assessed before. In this study, evaluation of the stations is made by classifying the time-series as “reliable” or “not reliable” depending on their consistency against the station-based precipitation data after applying quality control of data. Soil moisture observations later are compared with both satellite- (ASCAT, LPRM) and hydrological model-based (API, NOAH) soil moisture values. As a result of intercomparison Pearson correlation coefficient (R) between stations and other sources were found as respectively 0.751 for NOAH, 0.638 for API, 0.720 for LPRM and 0.634 for ASCAT. In addition to these values, RMSE values of overall 68 stations were found as follows, NOAH 0.035, API 0.048, LPRM 0.040 and ASCAT 0.046. These results are later inter-compared against the results of similar studies structured on evaluation of station-, satellite-, and model-based studies. Results show station-based soil moisture observations over Turkey showed significant correlation and accuracy results and ability to be used for future studies.