Spatiotemporal Analysis of Diurnal Temperature Range: Effect of Urbanization, Cloud Cover, Solar Radiation, and Precipitation

Andri Pyrgou,Mattheos Santamouris,Iro Livada

doi:10.3390/cli7070089

Andri Pyrgou, Mattheos Santamouris + Show 1 more

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https://doi.org/10.3390/cli7070089

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Abstract

High daily temperatures in the Mediterranean and Europe have been documented in observation and modeling studies. Long-term temperature data, from 1988 to 2017, from a suburban station and an urban station in Nicosia, Cyprus have been analyzed, and the diurnal temperature range (DTR) trend was investigated. The seasonal Mann–Kendall test revealed a decreasing DTR trend of −0.24 °C/decade at the urban station and −0.36 °C/decade at the suburban station, which were attributed to an increase in the daily minimum temperature. Variations in precipitation, longwave radiation, ultraviolet-A (UVA), ultraviolet-B (UVB), cloud cover, water vapor, and urbanization were used to assess their possible relationship with regional DTR. The clustering of daytime and night-time data showed a strong relationship between the DTR and observed cloud cover, net longwave radiation, and precipitation. Clouds associated with smaller shortwave and net longwave radiation reduce the DTR by decreasing the surface solar radiation, while atmospheric absolute humidity denotes an increased daytime surface evaporative cooling and higher absorption of the short and longwave radiation. The intra-cluster variation could be reduced, and the inter-cluster variance increased by the addition of other meteorological parameters and anthropogenic sources that affect DTR in order to develop a quantitative basis for assessing DTR variations.

Highlights

The population in Europe (EU-28) reached 503 million according to Eurostat in 2011 [1], increasing by about 200 million people in a century
Dai et al [13] showed that clouds, soil moisture, and precipitation can reduce the surface diurnal temperature range (DTR) by over 50% compared with clear sky days, and that atmospheric water vapor has the ability to increase both the minimum and maximum daily temperatures [13]
The results show that a decreasing DTR of −0.24 ◦ C/decade at the urban station and −0.36 ◦ C/decade at the suburban station are both within the range of the earlier reported trends

Summary

Introduction

The population in Europe (EU-28) reached 503 million according to Eurostat in 2011 [1], increasing by about 200 million people in a century. The increase of population over the past century combined with intensive urbanization and industrialization have led to a continuing increase of CO2 emissions, local and global climate change, and an important increase in the ambient temperature [2]. Clouds may reduce the shortwave radiation reaching the surface, leading to a lower daily maximum temperature, and increase the minimum daily temperature by enhancing downward longwave radiation. Precipitation increases the level of soil moisture, enhances surface–air interactions that lead to larger evaporation, and results in a lower daily maximum temperature [13,14]. Dai et al [13] showed that clouds, soil moisture, and precipitation can reduce the surface DTR by over 50% compared with clear sky days, and that atmospheric water vapor has the ability to increase both the minimum and maximum daily temperatures [13]. Atmospheric greenhouse gases and water vapor may promote larger downward longwave radiation and increase the minimum daily temperature

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