Avaliação da umidade do solo no estado do Ceará utilizando dados In Situ e estimados pelo satélite SMOS/SENSOR MIRAS

Abstract

Soil moisture is an important parameter that influences the hydrology of a region. Through it, it is possible to better manage water use and understand drought and flood events. The state of Ceará, located in the Northeast of Brazil, has its territory predominantly located in the semiarid region and suffers from drought due to high temperatures and precipitation concentrated in a few months of the year. Thus, this study sought to compare soil moisture data from the SMOS (Soil Moisture and Ocean Salinity)/MIRAS (Microwave Imaging Radiometer with Aperture Synthesis) satellite, which provides data with high temporal and spatial resolution, with data from in situ stations in the cities of Catarina, Crato, Forquilha, Guaraciaba do Norte, General Sampaio, Jaguaribe, Mauriti, Pentecoste, Quixeramobim and Umari, located in the state of Ceará. The methodology consisted of comparing daily data from in situ sensors of 10 CEMADEM stations with remote sensors from the SMOS satellite, using Pearson's r correlation coefficient, BIAS and RMSE. The time series graphs showed a similar behavior between the soil moisture values estimated by the SMOS satellite, with those collected by the in situ and precipitation stations. Of the 10 stations analyzed, 2 were discarded (Catarina and Umari) from the statistical analysis, as they presented values between 0.20 and 0.50 m3.m-3 of soil moisture during the dry season of the region, which strongly indicates a lack of calibration of the in situ monitoring equipment. Of the 8 stations, 5 were classified as having a strong correlation by Pearson's r coefficient, while 3 were classified as moderate. Through BIAS, it was possible to determine that SMOS underestimated the soil moisture data for 6 of the 8 analysis stations. By RMSE, the values varied between 0.04 and 0.06, attesting to the good accuracy of the data estimated by SMOS.