Vertical Structure of Radiative Heating Rates of the MJO during DYNAMO
Vertical Structure of Radiative Heating Rates of the MJO during DYNAMO
复制标题
DYNAMO 期间 MJO 辐射加热速率的垂直结构
作者：
K. M. Shell;S. Szoeke;Michael Makiyama;Zhe Feng
本文介绍了DYNAMO/ARM MJO调查实验期间与MJO有关的热带印度洋地区辐射加热率的垂直结构。利用太平洋西北国家实验室联合遥感检索（CombRet）数据测定了马尔代夫Gan岛（0.69°S, 73.15°E）活跃期、抑制期和扰动期的平均升温速率和变率。CombRet产品的TOA和地表通量与配置的3小时CERES SYN1deg Ed4A卫星检索结果进行了比较。通量在时间上的相关系数在0.9左右，但CombRet时间平均OLR要大15 W m−2。先前的研究表明，由于低空云层的信号衰减和仪器灵敏度随高度的降低，CombRet对高云的采样不足。然而，CombRet和CERES的平均OLR在所有OLR值上都是不同的，而不仅仅是广泛高云对应的最低OLR值。中程OLR的差异峰值，提示降水，高耸的积云对流云，而不是层状卷云。厚云的云顶高度的低偏差是CombRet高估OLR的主要原因。CombRet数据用于生成复合短波和长波大气加热速率剖面，作为局部OLR的函数。尽管CombRet中存在与OLR没有直接关系的相当大的变率，但使用OLR作为插值生成的平均升温速率复合材料的时高结构在季节内时间尺度上广泛代表了热带对流变率。
The vertical structure of radiative heating rates over the region of the tropical Indian Ocean associated with the MJO during the DYNAMO/ARM MJO Investigation Experiment is presented. The mean and variability of heating rates during active, suppressed, and disturbed phases are determined from the Pacific Northwest National Laboratory Combined Remote Sensing Retrieval (CombRet) from Gan Island, Maldives (0.69°S, 73.15°E). TOA and surface fluxes from the CombRet product are compared with collocated 3-hourly CERES SYN1deg Ed4A satellite retrievals. The fluxes are correlated in time with correlation coefficients around 0.9, yet CombRet time-mean OLR is 15 W m−2 larger. Previous work has suggested that CombRet undersamples high clouds, due to signal attenuation by low-level clouds and reduced instrument sensitivity with altitude. However, mean OLR differs between CombRet and CERES for all values of OLR, not just the lowest values corresponding to widespread high clouds. The discrepancy peaks for midrange OLR, suggestive of precipitating, towering cumulus convective clouds, rather than stratiform cirrus clouds. Low biases in the cloud-top height of thick clouds substantially contribute to the overestimate of OLR by CombRet. CombRet data are used to generate composite shortwave and longwave atmospheric heating rate profiles as a function of the local OLR. Although there is considerable variability in CombRet not directly related to OLR, the time–height structure of mean heating rate composites generated using OLR as the interpolant is broadly representative of tropical convective variability on intraseasonal time scales.