How Close Are Leading Tropical Tropospheric Temperature Perturbations to Those under Convective Quasi Equilibrium?
How Close Are Leading Tropical Tropospheric Temperature Perturbations to Those under Convective Quasi Equilibrium?
复制标题
主要热带对流层温度扰动与对流准平衡状态下的温度扰动有多接近？
DOI：
10.1175/jas-d-21-0315.1
复制
发表时间：
2022
影响因子：
3.1
通讯作者：
Yu, Jia-Yuh
中科院分区：
文献类型：
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作者：
Li, Yi-Xian;Neelin, J. David;Kuo, Yi-Hung;Hsu, Huang-Hsiung;Yu, Jia-Yuh
在对流准平衡理论中，热带对流层温度扰动预计会遵循受对流约束的垂直廓线，这里称为A廓线，通常近似为湿对流层的扰动。一个理想化的A-配置文件的基础上，静态能量守恒和温度扰动来自夹带和nonentraining包裹计算之间的差异是适度的对流条件下，深对流大多发生时，低对流层接近饱和，从而最大限度地减少夹带对流层温度的影响。因此，简单的计算与伪绝热扰动的观察到的配置文件提供有用的基线A-配置文件。对流层温度（TEOF 1）的ERA-Interim和AIRS反演低于中性浮力（LNB）的水平的第一个模态进行了比较，这些A-配置文件。具有高LNB（通常高于400 hPa）的TEOF 1剖面与A剖面具有很高的垂直空间相关性（0.9），表明对流层温度扰动往往与准平衡假设一致，其中环境有利于深对流。低相关往往出现在低LNB的地区，不利于深对流。排除温度廓线与低LNB显着增加热带平均垂直空间相关性。LNB附近的温度扰动表现出负偏差的A-配置文件-对流冷顶现象-与更大的偏差为更高的LNB。在相关性较低的地区，600 hPa以下的距平距平呈S形，通常伴随着较干燥的对流层低层。这些研究结果在从每日到每月的广泛时间尺度上是稳健的，尽管垂直空间相关性和TEOF 1解释的方差在短时间尺度上趋于减少。
In convective quasi-equilibrium theory, tropical tropospheric temperature perturbations are expected to follow vertical profiles constrained by convection, referred to as A-profiles here, often approximated by perturbations of moist adiabats. Differences between an idealized A-profile based on moist-static energy conservation and temperature perturbations derived from entraining and nonentraining parcel computations are modest under convective conditions—deep convection mostly occurs when the lower troposphere is close to saturation, thus minimizing the impact of entrainment on tropospheric temperature. Simple calculations with pseudoadiabatic perturbations about the observed profile thus provide useful baseline A-profiles. The first EOF mode of tropospheric temperature (TEOF1) from the ERA-Interim and AIRS retrievals below the level of neutral buoyancy (LNB) is compared with these A-profiles. The TEOF1 profiles with high LNB, typically above 400 hPa, yield high vertical spatial correlation (∼0.9) with A-profiles, indicating that tropospheric temperature perturbations tend to be consistent with the quasi-equilibrium assumption where the environment is favorable to deep convection. Lower correlation tends to occur in regions with low climatological LNB, less favorable to deep convection. Excluding temperature profiles with low LNB significantly increases the tropical mean vertical spatial correlation. The temperature perturbations near LNB exhibit negative deviations from the A-profiles—the convective cold-top phenomenon—with greater deviation for higher LNB. In regions with lower correlation, the deviation from A-profile shows an S-like shape beneath 600 hPa, usually accompanied by a drier lower troposphere. These findings are robust across a wide range of time scales from daily to monthly, although the vertical spatial correlation and TEOF1 explained variance tend to decrease on short time scales.