Daily and Seasonal Dynamics of Surface Temperature in the Volgograd City

Abstract

The research purpose is to reveal the features of daily and seasonal dynamics of surface temperature in the city of Volgograd (using the example of the year 2018, which was typical in terms of climatic characteristics) and to find out whether its seasonal course depends on characteristics of the underlying surface of the urban area. Materials and methods. The choice of year for the study required analyzing a 20-year course of air temperatures in Volgograd. Availability of continuous data on temperatures of the underlying surface has also been taken into account. Determining the temperature of the urban surface has been carried out by processing images of the warm half of the year obtained using MOD11A2 information product (8-day raster composites of day and night temperatures with a resolution of about 1 km). Geo-informational processing of the images has been conducted in the QGIS program. Based on the Global Land Cover (GLC) data, the main types of underlying surface in the territory of Volgograd have been identified. Results and discussion. The share of sealed soils makes 38,2 %. A map of average annual surface temperatures in Volgograd has been compiled. The map refl ects the main features of spatial distribution of positive and negative thermal anomalies. It has been revealed that seasonal variation of the daily, daytime and nighttime average temperatures of the underlying surface and the surface air layer in Volgograd represents a parabola facing downward branches with a maximum falling on the period from June 26 to July 6. The course of average daily air temperatures repeats the seasonal course of the city surface temperature (r = 0,99). Conclusions. Mapping based on MODIS data with a resolution of 1 km lets reveal the spatial distribution of large positive and negative anomalies in the city and its environs. The significant variability in the values of average daily temperature of the underlying surface in the areas with a high proportion of water bodies, wetlands and a low degree of soil coverage has been revealed.