Biophysical parameters and extreme air temperature indices in the Cerrado-Amazonia transition

Abstract

This paper aimed to evaluate the changes in biophysical parameters and trends in annual extremes of air temperature in Sinop, Mato Grosso, Brazil, using data from automatic weather stations (AWS) installed in rural and urban areas of the municipality. Changes in land use, surface albedo, radiation balance (Rn), sensible heat (H), and latent heat (LE) were estimated from Landsat 5 and Landsat 8 satellite images obtained in 2007, 2011 and 2017. With RClimDex software, the trends in six extreme indices of annual maximum and minimum temperatures were calculated with least-squares calibration and statistical significance assessed by Fisher test at a significance level (α) equal to 0.05. Through the years changes in land use and biophysical parameters like increase of albedo and reduction of Rn were observed in the rural area, while at the urban station (UFMT Sinop) the inversion of LE and H partition was observed. The extreme indices indicated an increasing tendency towards extreme temperatures in the urban area, with significant changes occurring in the indices TNx, DTR, Tn90p, and Tx90p. In the last decade, with the expansion of the urban area of Sinop, Mato Grosso - Brazil, fluctuations in trends of temperature extreme indices were observed, and are attributed to changes in land use and biophysical parameters.

Keywords:
Albedo; Radiation; Heat flux; Climate changes; Soil use