摘要
太湖微气候条件及局地热环境的研究对于太湖周边城市地区可持续发展以及大气宏观调控具有重要意义。为了更准确模拟太湖湖-气交换,将CLM4-LISSS浅水湖泊陆面过程参数化方案耦合进入WRF中的Noah陆面过程模型。采用太湖湖上平台及岸边陆上测站观测的数据,评估了CLM4-LISSS浅水湖泊过程方案对太湖区域近地层气象条件的模拟性能。并基于耦合模型模拟研究了太湖对周边城市区域热环境的影响。结果表明,CLM4-LISSS湖泊陆面过程方案模拟的湖表面温度能反映真实温度的变化趋势。两种陆面过程方案在2 m气温的模拟值也存在一定的差异。CLM4-LISSS与Noah方案计算所得湖上2 m气温的模拟值与观测值的平均均方根误差分别为1.77和2.22℃,平均相关系数分别为0.88和0.84;模拟10 m风速的平均均方根误差分别为1.93和2.78 m/s,平均相关系数为0.72和0.68。太湖对周边城市热环境存在明显的影响。8月太湖对周边地区15时(北京时)近地层平均降温0.5—0.7℃,影响范围达60 km。06时太湖导致周边近地层平均升温达0.7—1℃,影响范围达50 km。湖风带来的冷空气抑制了城市热岛的垂直运动,在高温天气下使得苏州、无锡和常州城市地区昼间边界层下降高度可达300、400和100 m。无锡地区边界层内气温最高降幅可达0.5—0.7℃。通过选取无锡地区2015年8月28日高温小风天气作为背景条件,分析该地区湖风对城市热岛环流的影响机制。结果表明湖风能够破坏无锡地区的热岛环流结构,改变近地面热量和水汽的分布,抑制城市热岛的垂直发展,并影响至整个无锡地区。局地热力环流的变化对于局地气候以及污染物质的输送与扩散有可能产生重要影响,准确的湖泊陆面过程参数化方案对于天气预报、空气污染模拟,以及气候模拟研究等均具有重要意义。
Previous studies have shown that Lake Taihu's microclimate condition and local thermal environment play an impor- tant role in sustainable development of the surrounding cities and atmospheric macro-control. In order to more precisely simu- late the lake-air interaction in Lake Taihu, the CLM4-LISSS shallow lake land-surface process parameterization scheme is cou- pled with the Noah land-surface process model in WRF in the present study. The performance of CLM4-LISSS shallow lake process scheme on the simulation of near-surface meteorological conditions in the region of Lake Taihu is evaluated using obser- vations from the lake platforms and the observational stations in the land. Furthermore, on the basis of the coupled model sim- ulation, the effect of Lake Taihu on the thermal environment in the surrounding cities is analyzed in the present study. The re- suits are as follows. The lake surface temperature simulated by CLM4-LISSS lake surface process scheme can realistically re- flect the variational trend of observed temperature. Differences are found in the simulated 2 m air temperature by the two land surface schemes. The Root Mean Square Error (RMSE) of 2 m air temperature between CLM4-LISSSS simulation and observa- tions is 1.77~C, which is better than that between Noah simulation and observations (2.22℃). The correlation coefficients be- tween observations and simulations by the two schemes are 0.88 (CLM4-LISSS) and 0.84 (Noah), respectively. The RMSEs of 10 m wind speed and correlation coefficients between observations and simulations by the two schemes are 1.93 m/s and 0.72 (CLM4-LISSS) and 2.78 m/s and 0.68 (Noah), respectively. Lake Taihu has a significant impact on the thermal envi- ronment of the surrounding cities. Near-surface temperature can be decreased by 0.5 - 0.7℃ averagely at 15:00 BT in August due to the lake effects and the influence range of the lake is up to 60 km. Near-surface temperature can be increased by 0.7 - 1 ℃ averagely at 06:00 BT in August and the influence range of the lake is up to 50 km. The cold air brought by the lake breeze suppresses the vertical motion induced by the urban heat island effect. Under the control of hot weather, average planetary boundary layer (PBL) heights over the urban areas of Suzhou, Wuxi and Changzhou can be decreased by 300, 400 and 100 m, respectively during the daytime. The maximum temperature decrease within the PBL in the region of Wuxi can reach up to 0.5 - 0.7℃. The result indicates that the lake breeze can disrupt the heat island circulation structure in the region of Wuxi, change the distribution of near-surface heat and water vapor fluxes, restrain the vertical expansion of urban heat island and affect the entire region of Wuxi. The change in local thermal circulation may have a great impact on local climate and the transport and dispersion of pollutants. Accurate parameterization scheme of lake surface process is significant for weather fore cast and air quality simulation and climate study.
出处
《气象学报》
CAS
CSCD
北大核心
2017年第4期645-660,共16页
Acta Meteorologica Sinica
基金
国家自然科学基金面上项目(41275024
41505005)
江苏省自然科学青年项目(BK20150900)
江苏高校优势学科建设工程项目(PAPD)
中国科学院大气物理研究所大气边界层物理与大气化学国家重点实验室开放课题(LAPC-KF-2014-09)
关键词
WRF模式
浅水湖泊陆面过程
城市热环境
参数化方案耦合
WRF model, Shallow lake surface process, Urban thermal environment, Coupling of parameterization schemes