通过WRF(Weather Research and Forecasting)模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式,结合激光雷达资料,进行数值模拟,定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市...通过WRF(Weather Research and Forecasting)模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式,结合激光雷达资料,进行数值模拟,定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市边界层的特征。夜间,气溶胶在低层起到保温作用,高云使得保温作用得到加强,地表增温达1.5K。中高层,气溶胶降低所在气层温度,高云使得降温幅度减少,降温达0.2～0.7K。白天,高云和气溶胶减少到达地面的太阳短波辐射,导致低层温度降低,地表降温达1.3K。中高层,气溶胶加热所在的气层,高云使得这一增温幅度减少,在500m处增温最大,达0.85K。无论白天还是夜间,气溶胶的辐射效应都会抵消一部分形成山谷风的热力条件,使得中低层的风速减少,这种影响在白天显得尤为明显。高云的存在使得这种抵消得到少量的补偿。展开更多
In this paper, the process of oasis-desert circulation (ODC) is simulated by MM5V3.5 model through designing an ideal oasis-desert scheme and assuming that initial atmosphere is at rest (V= 0). The findings showed tha...In this paper, the process of oasis-desert circulation (ODC) is simulated by MM5V3.5 model through designing an ideal oasis-desert scheme and assuming that initial atmosphere is at rest (V= 0). The findings showed that the key of forming special oasis boundary structure is the difference of energy and water between oasis and desert. The evaporation of oasis surface consumes heat energy, and the low temperature of oasis causes an oasis breeze circulation (OBC), which drives an ODC with a downdraft over the oasis and an updraft over the desert. Later, the cold, dry and stable boundary over oasis is gradually formed, on the contrary, the atmospheric boundary over desert on the edge of oasis is hot, humid and unstable and its height is about 600 hPa. The updraft over the desert forms a wet ring that acts as a vertical wall weakening the low-level moisture exchange between the oasis and desert. The downdraft of OBC increases the atmospheric stability that reduces the oasis evaporation. The low-level outflow from the oasis (into the desert) prevents the dry, hot air flowing from the desert into the oasis. Thus an oasis self-preservation mechanism may be formed due to OBC. The horizontal area influenced by oasis is twice as oasis area and the vertical range is four times as oasis. The ODC is strong in the daytime and reaches the strongest at 17:00, and the influenced area is the largest at 20:00.展开更多
生成满足大气边界层风场特性的入口湍流是开展结构风效应大涡模拟的关键问题之一。该文的主要目的是验证并探讨两类主要的大气边界层大涡模拟入口湍流生成方法的合理性与可行性。采用CDRFG(Consistent Discretizing Random Flow Generat...生成满足大气边界层风场特性的入口湍流是开展结构风效应大涡模拟的关键问题之一。该文的主要目的是验证并探讨两类主要的大气边界层大涡模拟入口湍流生成方法的合理性与可行性。采用CDRFG(Consistent Discretizing Random Flow Generation)方法和被动模拟法生成大气边界层风场,从统计特性、流场结构和计算效率等方面进行对比分析,比较不同网格系统下的数值模拟结果,提出结构风效应大涡模拟的网格划分策略。结果表明:相比于CDRFG方法,被动模拟法生成的流场结构更加合理,但无法预先考虑脉动风场的空间相关性,且需要较高的计算成本和先验的流场信息。计算域的网格分辨率对于统计特性和流场结构的模拟精度具有重要影响,而目标区域的网格分辨率应依据控制工程结构风致响应的主要频带范围确定。展开更多
文摘通过WRF(Weather Research and Forecasting)模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式,结合激光雷达资料,进行数值模拟,定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市边界层的特征。夜间,气溶胶在低层起到保温作用,高云使得保温作用得到加强,地表增温达1.5K。中高层,气溶胶降低所在气层温度,高云使得降温幅度减少,降温达0.2～0.7K。白天,高云和气溶胶减少到达地面的太阳短波辐射,导致低层温度降低,地表降温达1.3K。中高层,气溶胶加热所在的气层,高云使得这一增温幅度减少,在500m处增温最大,达0.85K。无论白天还是夜间,气溶胶的辐射效应都会抵消一部分形成山谷风的热力条件,使得中低层的风速减少,这种影响在白天显得尤为明显。高云的存在使得这种抵消得到少量的补偿。
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KZCX3-SW-329 and KZCX1-09)the National Natural Science Foundation of China(Grant No.40233035).
文摘In this paper, the process of oasis-desert circulation (ODC) is simulated by MM5V3.5 model through designing an ideal oasis-desert scheme and assuming that initial atmosphere is at rest (V= 0). The findings showed that the key of forming special oasis boundary structure is the difference of energy and water between oasis and desert. The evaporation of oasis surface consumes heat energy, and the low temperature of oasis causes an oasis breeze circulation (OBC), which drives an ODC with a downdraft over the oasis and an updraft over the desert. Later, the cold, dry and stable boundary over oasis is gradually formed, on the contrary, the atmospheric boundary over desert on the edge of oasis is hot, humid and unstable and its height is about 600 hPa. The updraft over the desert forms a wet ring that acts as a vertical wall weakening the low-level moisture exchange between the oasis and desert. The downdraft of OBC increases the atmospheric stability that reduces the oasis evaporation. The low-level outflow from the oasis (into the desert) prevents the dry, hot air flowing from the desert into the oasis. Thus an oasis self-preservation mechanism may be formed due to OBC. The horizontal area influenced by oasis is twice as oasis area and the vertical range is four times as oasis. The ODC is strong in the daytime and reaches the strongest at 17:00, and the influenced area is the largest at 20:00.
文摘生成满足大气边界层风场特性的入口湍流是开展结构风效应大涡模拟的关键问题之一。该文的主要目的是验证并探讨两类主要的大气边界层大涡模拟入口湍流生成方法的合理性与可行性。采用CDRFG(Consistent Discretizing Random Flow Generation)方法和被动模拟法生成大气边界层风场,从统计特性、流场结构和计算效率等方面进行对比分析,比较不同网格系统下的数值模拟结果,提出结构风效应大涡模拟的网格划分策略。结果表明:相比于CDRFG方法,被动模拟法生成的流场结构更加合理,但无法预先考虑脉动风场的空间相关性,且需要较高的计算成本和先验的流场信息。计算域的网格分辨率对于统计特性和流场结构的模拟精度具有重要影响,而目标区域的网格分辨率应依据控制工程结构风致响应的主要频带范围确定。
