基于WRF模拟的晋江市海陆风特征分析

随着沿海城市的快速发展,城市气候环境恶化,研究弱大气环流背景下的海陆风对改善城市环境具有重要意义。以晋江市为例,利用站点风要素观测数据,结合海陆风判别条件,提取并分析了两个典型海陆风日海陆风的基本特征;采用WRF与Noah陆面过程模式耦合,选用BEP多层城市冠层模型,对典型日进行了风场模拟。从模拟结果中分解出局地风,在验证海陆风现象的基础上,分析了海陆风特征的空间分布规律。结果显示:WRF模拟的逐小时局地风向时序与实测情况吻合较好,通过了信度为0.05的显著性检验,但局地风速模拟值与实测值存在显著差异,平均达到1 m/s。从WRF模拟结果提取的海、陆风起始和终止时间、持续时间与实际情况存在一定差别。两者持续时间在空间上的变化与各自起始时间的空间变化一致,且未明显出现随离岸距离增加,海陆风减弱的现象。上述结果表明,WRF能够较好地模拟海陆风日的风场特征,尽管对海、陆风速的模拟还存在一定的不确定性,但所得结论对晋江市城市规划和微环境改善有参考意义。

Analyzing the characteristics of sea-land breeze in Jinjiang based on WRF simulations

With the rapid development of coastal cities,the urban climate and environment have gradually become deteriorated.Therefore,it is urgent and important to assess the effects of sea-land breeze,which appears under weak atmospheric circulation,on improving the urban environment.In this paper,Jinjiang was taken as an example,which is a highly developed coastal city in Fujian Province,China.Based on the wind observations from distributed meteorological stations in Jinjiang,the characteristics of sea-land breeze in two different typical days were analyzed.Then,the weather research and forecasting (WRF) model,coupled with a land surface model (Noah) and an urban canopy model (BEP),was applied to simulate the wind fields over two days.Next,the local wind was decomposed from the simulation results and used to identify sea-land breezes in the Jinjiang area.Validation of sea-land breezes from the WRF simulations was conducted,and their spatial distribution were analyzed.The results showed that the simulated temporal series of hourly local wind directions were highly consistent with the observations without a significant difference at the 0.05 level,while the simulated local wind speed shows significant deviation from the observed data,with an average difference of about 1 m/s.At the same time,there were also some difference between the simulated and observed data in terms of the retrieved starting time,end time and duration for both sea and land breezes.The spatial distributions of the sea and land breezes over the two days were consistent with those of the starting time,and it was not apparent that the emergence of sea-land breezes could be suppressed merely due to distance from the shore.The above-mentioned results indicated that the WRF model is able to simulate sea-land breeze,and extract its characteristics accurately,although there remain some uncertainties in the simulated wind speed.The results also provide a reference to the planning of Jinjiang City,and suggestions to the improvement of its urban micro-environment.