Urban heat island of the Moscow megacity: the long-term trends and new approaches for monitoring and research based on crowdsourcing data

Abstract

This paper reports on various aspects of the urban heat island (UHI) of the Moscow megacity – its spatial and temporal variability and linkages with human thermal comfort. Firstly, we analyze long-term trends of air temperature, UHI intensity and thermal stress indices based on meteorological observations over the period 1977-2018. We show that the city exhibits 40% higher rates of summertime climate warming than the countryside, as well as higher rates of human thermal comfort deterioration. Secondly, we present a new approach for spatially-resolving urban climate studies and real-time monitoring applications based on the usage of crowdsourced air temperature data from Netatmo citizen weather stations (CWSs). The CWSs provide uncertified and often misrepresentative data. However, their quality could be controlled by application of statistically-based algorithms. Additionally, we have experimentally evaluated uncertainties of the Netatmo temperature observations and regard them to be acceptable for UHI studies. Observations from more than 1500 CWSs as well as reference observations were used to analyze spatial patterns of the summertime nocturnal UHI. Both types of data shown an UHI covering the whole city and its suburbs, with a tendency of a temperature decrease with the distance from the city center. As a prototype a monitoring application, based on CWS data, we developed a web-service for real-time temperature mapping in Moscow, which is available at http://carto.geogr.msu.ru/mosclim/.