Effects of Sea Breeze on Urban Areas Using Computation Fluid Dynamic—A Case Study of the Range of Cooling and Humidity Effects in Sendai, Japan

Shiyi Peng,Hironori Watanabe,Yusuke Kon

doi:10.3390/su14031074

Abstract

Sea breezes have a significant influence on the urban environment of coastal cities. Therefore, the study of the sea breeze cooling range and its relationship with specific humidity is of great significance for improving the urban environment of coastal cities. This study aims to reproduce the climate of Sendai using the regional Weather Research and Forecasting (WRF) model, clarify the influence range of sea breezes in Sendai, and create an urban environmental climate map. The results revealed a strong correlation between the measured temperatures and the calculated results, and that the cooling effect range of sea breezes was mainly concentrated in the coastal area. In addition, the temperature rise mitigation effect changed over time, and although the maximum mitigation effect range affected a part of the urban area, it did not reach the inland area. In comparison, the specific humidity increased over time from the coastal area to the inland area. It was found that sea breezes mainly affected a part of the urban area and coastal areas in terms of temperature, but affected inland areas in terms of specific humidity. The results show that the range of the cooling effect of sea breezes on temperature was only concentrated within 5 km of the coast; in terms of moderating the temperature rise, there was an effect within the area ~7 km from the coast. In terms of humidity, the effect of sea breezes occurred approximately 1 h later than the effect of temperature.

Highlights

IntroductionAccording to the statistics of the United Nations (2019), it is estimated that by 2050, approximately 68% of the world’s population will live in cities
Academic Editor: Luigi AldieriAccording to the statistics of the United Nations (2019), it is estimated that by 2050, approximately 68% of the world’s population will live in cities
The “KLIMA-ATLAS” is a series of map sets based on the characteristics of cities, which can provide insight on the current situation of the urban thermal environment and air quality

Summary

Introduction

According to the statistics of the United Nations (2019), it is estimated that by 2050, approximately 68% of the world’s population will live in cities. Due to the industrialization that has taken place since the last century, the extensive emissions of CO2 have become the major source of anthropogenic greenhouse gas. This is the main trigger that contributes to global warming [7]. In the summer of 2018, there were approximately 90,000 heatstroke patients in Japanese metropolitan areas [9]. Improving the heat island effect has become a key challenge to achieve urban sustainability [11]

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