天津地区夏季海陆风对城市热岛日变化特征影响的观测分析

Observational analysis of influence of sea-land breeze on diurnal characteristics of urban heat island in Tianjin during summer

摘要:

应用2008年天津市14个自动气象站逐小时观测资料、北京站探空资料和天津站6 h一次的地面常规观测资料,分析了2008年天津地区夏季海陆风对城市热岛日变化特征的影响。结果表明:在大气层结稳定条件下,海陆风日与非海陆风日相比,天津市热岛强度的日变化幅度增大,海风能使城市降温,削弱城市热岛强度,推迟夜间热岛的出现时间,而陆风能使夜间热岛显著增强;天津市热岛强度与海风向内陆传播的距离有密切关系,在海陆风日,当天气尺度地转风与离岸风的方向一致时,海风的传播距离较近,而当天气尺度地转风与向岸风方向一致时,海风的传播距离较远,当海风只能到达津南、东丽或宁河站时,天津市热岛强度增幅最大,随着海风传播距离的增加,热岛强度的总体增幅减小。

Abstract:

Based on the hourly observations of 14 automatic weather stations in Tianjin,the Beijing radiosounding data,and the 6-hourly surface conventional observation data in Tianjin during summer 2008,this paper studies the relationship between the sea-land breeze and the diurnal characteristics of urban heat island in Tianjin.Results show that,under the atmospheric stable stratification condition,the diurnal variation of urban heat island intensity in Tianjin increases on the sea-land breeze days compared to the non sea-land breeze days.The sea breeze can cool the city,reduce the urban heat island intensity,and delay the appearance of the urban heat island in the nighttime,while the land breeze can significantly enhance the urban heat island intensity at night.We also find that the urban heat island intensity is closely related to the distance of sea breeze propagating.On the sea breeze days,when the synoptic scale geostrophic winds are in the same direction with the offshore wind,the sea breeze can only spread short distance;when the synoptic scale geostrophic winds are in the same direction with the onshore wind,the sea breeze can propagate farther;when the sea breeze can only reach Jinnan,Dongli or Ninghe stations,the urban heat island intensity in Tianjin has the maximum increase;with the increasing of sea breeze propagating distance,the overall increase rate of urban heat island intensity decreases.