摘要
本文利用WRF模式对2014年5月25日发生在海南的一次海风过程进行了数值模拟,通过地形敏感性试验,探讨了海南岛地形对局地海风环流结构的影响。结果表明:控制试验(CNTL)海风于15时左右达到强盛。无地形试验(FLAT)中,水平方向上,海风持续时间缩短,南、北、西向海风向内陆传播距离变短1~5km,海风强度减弱1m/s左右,海风动能及辐合强度在沿海地区及西南山区存在大值衰减区;垂直方向上,海风碰撞位置向西、北方向移动,高空回流高度降低,海风厚度减小,垂直环流强度减弱2~6m2/s2,海风锋附近的垂直速度减小10cm/s以上。谷风对海风同相叠加作用的消失也使得海风强度减弱。其主要影响机制为:在动力方面,由山脉屏障作用引起的海风强迫抬升、绕流等增强作用消失;在热力方面,地表吸收净辐射减少,导致其向大气中释放的感热、潜热通量等各项均减少约9%,这种改变造成了海陆之间温度、气压差的减小,最终造成了海风的减弱。此外,通过两组削山试验,发现海拔高度降低区辐合范围、强度及动能均减小,同时海风垂直环流结构也相应发生改变,其中移去黎母山脉(RMLM)对海风环流结构的影响大于移去五指山脉(RMWZ)。
One sea breeze circulation process over the Hainan Island is simulated by the WRF model on 25 May, 2014. The impact of topography on the sea breeze circulation is studied by changing the terrain height. The results show that the land-sea thermal difference, which is the trigger mechanism of sea breeze, reaches its top at 15：00 LST in CNTL experiment. In FLAT experiment, the main variations are embodied in two aspects, one is in the horizomal direction： the duration of the sea breeze becomes shorter, and the propagation distance of sea breeze reduces about 1-5 km. At the same time, the intensity of sea breeze weakens more than 1 m/s. Meanwhile, the kinetic energy of sea breeze exists great attenuation area in the coastal and southwest region, and the corresponding range of sea breeze convergence zone narrows down and the sea breeze convergence line also moves to the coastal regions. The other is in the vertical direction： the impacted location of different directions of sea breeze moves to the west and north, the backflow in high altitude and sea breeze thickness become lower. The intensity of the vertical circulation around sea breeze front reduces more than 10 cm/s. Moreover, the effect which the valley wind strengthens the sea breeze disappears. Its Influence mechanism can be summarized as the following two parts, in the dynamical aspect, the updraft and flow caused by mountains disappeared. In the thermal aspect, net radiation absorbed by the earth＇s surface decreases, which causes the releasing of sensible heat flux and latent heat flux decline about 9%, respectively. Ultimately, land-sea thermal difference and the corresponding air pressure difference all get smaller than CNTL, which weakens the basic character- istics of the sea breeze circulation. In addition, the results of the two experiments which only part of the mountains is removed show that the kinetic energy and convergence zone of sea breeze become weaker in the corresponding regions, and the structure of the vertical circulation also chan
出处
《海洋学报》
CAS
CSCD
北大核心
2017年第3期24-43,共20页
基金
公益性行业(气象)科研专项经费项目(GYHY201306009)
关键词
热带岛屿
复杂地形
海风结构
海风辐合
tropical island
complex topography
sea breeze structure
sea breeze convergence
