The diurnal cycle of precipitation over the Maritime Continent in a high-resolution atmospheric model
The diurnal cycle of precipitation over the Maritime Continent in a high-resolution atmospheric model
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DOI：
10.1002/qj.809
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发表时间：
2011-04-01
影响因子：
8.9
通讯作者：
Lister, Grenville M. S.
中科院分区：
文献类型：
--
作者：
Love, Barnaby S.;Matthews, Adrian J.;Lister, Grenville M. S.
在热带暖池中心的印度尼西亚群岛海洋大陆上，气候模式的平均降水量可能会出现系统性误差。这些通常可以追溯到对日周期的错误模拟，并通过行星波传播导致全球气候的错误。在这里，我们研究模拟的日周期在海洋大陆的一系列高分辨率集成的英国气象局大气模型，水平分辨率为40和12公里（对流参数化）和4公里（对流明确解决），作为级联项目的一部分。在这些模式中，垂直加热廓线的岛屿的变化，从对流廓线与对流层中部的最大值在下午早些时候到一个更层状的廓线与对流层上部加热和对流层中部冷却后。对流加热廓线迫使第一个内部模式的重力波，迅速传播离岸深暖异常背后的下降流波前抑制对流在下午早些时候离岸。层状加热剖面迫使重力波与高阶垂直模式，传播缓慢离岸下午晚些时候。这种模式在对流层中部有一个负的，不稳定的温度异常。加上两种模式的波前之间的会聚区，为近海对流创造了有利条件。在4公里的显式对流模式，离岸对流强烈响应这种重力波强迫，与观测结果一致，支持在海洋大陆的昼夜循环的重力波对流范例。然而，在较低分辨率模式的对流响应是不太连贯的，导致在日周期和平均降水的错误。因此，为了改善气候模式模拟，重力波强迫的敏感性应该是未来对流参数化方案的一个因素。版权所有（C）2011皇家气象学会
Climate models can exhibit systematic errors in their mean precipitation over the Maritime Continent of the Indonesian archipelago at the heart of the tropical warm pool. These can often be traced back to an erroneous simulation of the diurnal cycle, and can lead to errors in global climate, through planetary wave propagation. Here, we examine the simulation of the diurnal cycle over the Maritime Continent in a series of high-resolution integrations of the UK Met Office atmospheric model, with horizontal resolutions of 40 and 12 km (where the convection is parametrised) and 4 km (where the convection is explicitly resolved), as part of the Cascade project. In these models, the vertical heating profile over the islands changes from a convective profile with a mid-tropospheric maximum in the early afternoon to a more stratiform profile with upper-tropospheric heating and mid-tropospheric cooling later. The convective heating profile forces a first internal mode gravity wave that propagates rapidly offshore; the deep warm anomalies behind its downwelling wavefront suppress convection offshore during early afternoon. The stratiform heating profile forces a gravity wave with a higher-order vertical mode that propagates slowly offshore later in the afternoon. This mode has a negative, destabilising temperature anomaly in the mid-troposphere. Together with the convergence zone between the wave fronts of the two modes, favourable conditions are created for offshore convection. In the 4 km explicit convection model, the offshore convection responds strongly to this gravity wave forcing, in agreement with observations, supporting a gravity wave-convection paradigm for the diurnal cycle over the Maritime Continent. However, the convective response in the lower-resolution models is much less coherent, leading to errors in the diurnal cycle and mean precipitation. Hence, to improve climate model simulations, sensitivity to gravity wave forcing should be a factor in future convective parametrisation schemes. Copyright (C) 2011 Royal Meteorological Society