Moist Thermodynamics of Convectively Coupled Waves over the Western Hemisphere
Moist Thermodynamics of Convectively Coupled Waves over the Western Hemisphere
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西半球对流耦合波的湿热力学
DOI：
10.1175/jcli-d-22-0435.1
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发表时间：
2023
影响因子：
4.9
通讯作者：
Adames, Ángel F.
中科院分区：
文献类型：
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作者：
Mayta, Víctor C.;Adames, Ángel F.
西半球的对流耦合波 (CCW) 根据其控制热力学进行分类。研究发现，只有热带低气压（TD；TD 波）满足被视为潮湿模式所需的标准，如早期研究中发现的类罗斯比波。在这种波中，水蒸气波动在热力学中比温度波动发挥更大的作用。只有在向东传播的惯性重力（EIG）波中，温度才控制热力学。温度和湿度在所有其他波浪中发挥着类似的作用，包括西半球的马登-朱利安振荡（MJO-W）。通过分析 ERA5 数据和 2014/15 年绿海亚马逊 (GoAmazon 2014/15) 实地活动观测和建模数据，研究了 CCW 的湿静态能量 (MSE) 预算。结果表明，MSE的垂直平流是西向惯性重力（WIG）波、开尔文波和MJO-W中柱状MSE传播的主要驱动力，而水平平流在罗斯贝重力（MRG）和TD混合波中起核心作用。结果还表明，云辐射加热和水平 MSE 平流控制着大多数 CCW 的维持。 ERA5 和 GoAmazon 之间存在重大分歧。在 GoAmazon 中，对流与柱 MSE 的变化联系更紧密，垂直 MSE 平流在 MSE 趋势中发挥着更突出的作用。这些结果以及 ERA5 数据中发现的大量预算残差表明，热带西半球的特定常规武器在重新分析中没有得到充分体现。 意义说明与全球其他地区相比，影响热带西半球降水的天气系统很少受到关注。在这项研究中，我们研究了影响该地区降水的对流耦合波的结构、传播和热力学。我们发现缓慢演变的热带系统是“湿度模式”，即通过云和辐射之间的相互作用维持高湿度和降水的移动区域。较快的波是表现出相对较大的温度波动的系统。垂直运动对于这些波浪中的降雨运动更为重要。最后，我们发现，再分析和观测对于亚马逊地区上空发生的波浪中不同过程的重要性存在分歧，这暗示了再分析如何代表该地区云的潜在缺陷。
Convectively coupled waves (CCWs) over the Western Hemisphere are classified based on their governing thermodynamics. It is found that only the tropical depressions (TDs; TD waves) satisfy the criteria necessary to be considered a moisture mode, as in the Rossby-like wave found in an earlier study. In this wave, water vapor fluctuations play a much greater role in the thermodynamics than temperature fluctuations. Only in the eastward-propagating inertio-gravity (EIG) wave does temperature govern the thermodynamics. Temperature and moisture play comparable roles in all the other waves, including the Madden–Julian oscillation over the Western Hemisphere (MJO-W). The moist static energy (MSE) budget of CCWs is investigated by analyzing ERA5 data and data from the 2014/15 observations and modeling of the Green Ocean Amazon (GoAmazon 2014/15) field campaign. Results reveal that vertical advection of MSE acts as a primary driver of the propagation of column MSE in westward inertio-gravity (WIG) wave, Kelvin wave, and MJO-W, while horizontal advection plays a central role in the mixed Rossby gravity (MRG) and TD wave. Results also suggest that cloud radiative heating and the horizontal MSE advection govern the maintenance of most of the CCWs. Major disagreements are found between ERA5 and GoAmazon. In GoAmazon, convection is more tightly coupled to variations in column MSE, and vertical MSE advection plays a more prominent role in the MSE tendency. These results along with substantial budget residuals found in ERA5 data suggest that CCWs over the tropical Western Hemisphere are not represented adequately in the reanalysis.Significance StatementIn comparison to other regions of the globe, the weather systems that affect precipitation in the tropical Western Hemisphere have received little attention. In this study, we investigate the structure, propagation, and thermodynamics of convectively coupled waves that impact precipitation in this region. We found that slowly evolving tropical systems are “moisture modes,” i.e., moving regions of high humidity and precipitation that are maintained by interactions between clouds and radiation. The faster waves are systems that exhibit relatively larger fluctuations in temperature. Vertical motions are more important for the movement of rainfall in these waves. Last, we found that reanalysis and observations disagree over the importance of different processes in the waves that occurred over the Amazon region, hinting at potential deficiencies on how the reanalysis represents clouds in this region.