Interannual Variability of Tropospheric Moisture and Temperature and Relationships to ENSO Using COSMIC-1 GNSS-RO Retrievals
Interannual Variability of Tropospheric Moisture and Temperature and Relationships to ENSO Using COSMIC-1 GNSS-RO Retrievals
复制标题
使用 COSMIC-1 GNSS-RO 反演对流层湿度和温度的年际变化及其与 ENSO 的关系
DOI：
10.1175/jcli-d-21-0884.1
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发表时间：
2022
影响因子：
4.9
通讯作者：
Braun, John J.
中科院分区：
文献类型：
--
作者：
Johnston, Benjamin R.;Randel, William J.;Braun, John J.
对流层湿度和温度的年际变化是地球气候的关键方面。本文利用12年的COSMIC-1(C_1)无线电掩星资料，对60°N到60°S之间的月平均比湿度(Q)和温度(T)变率进行了分析。在对流层下部/中层和对流层上部/下部平流层内，C_1的反演值分别与Q和T的先验值相对独立。热带年际变化以厄尔尼诺-南方涛动(ENSO)为主。在2009/10年和2015/16年厄尔尼诺事件以及2007/08年和2010/11年拉尼娜事件期间，分别观察到纬向平均数和纬度的系统性增加和减少。用线性回归方法分离出青藏高原的ENSO型，异常强度随高度的升高而增大，在对流层上层达到最大。上对流层异常从热带扩展到中纬度平流层下部，垂直结构与湿绝热响应相一致。将C1结果与NCAR的全大气社区气候模式(WACCM)进行比较，以评估模式在理想化设置下的行为。Q和T中的WACCM ENSO变化一般表现出与C_1一致的行为，但幅度较小。在研究期间，我们就主要的ENSO事件进行了个案研究。Q的空间变率与出射长波辐射(OLR)异常密切相关。例如，在2015/16年厄尔尼诺期间，中太平洋对流层Q值增加了100%以上，OLR值下降了50Wm−2以上，每一次事件在整个热带和中纬度都观察到了相当大的区域Q值和T值异常。
Interannual variability of tropospheric moisture and temperature are key aspects of Earth’s climate. In this study, monthly mean specific humidity (q) and temperature (T) variability is analyzed using 12 years of COSMIC-1 (C1) radio occultation retrievals between 60°N and 60°S, with a focus on the tropics. C1 retrievals are relatively independent of the a priori values forqandTwithin the lower/middle troposphere and upper troposphere/lower stratosphere, respectively. Tropical interannual variability is dominated by El Niño–Southern Oscillation (ENSO). Systematic increases and decreases in zonal meanqandTare observed during the 2009/10 and 2015/16 El Niño events and 2007/08 and 2010/11 La Niña events, respectively. ENSO patterns inqandTare isolated using linear regression, and anomaly magnitudes increase with altitude, reaching a maximum in the upper troposphere. Upper-troposphericqanomalies expand from the tropics into the midlatitude lower stratosphere, and theTvertical structure is consistent with a moist adiabatic response. C1 results are compared with NCAR’s Whole Atmosphere Community Climate Model (WACCM), forced by observed sea surface temperatures, to evaluate model behavior in an idealized setting. WACCM ENSO variations inqandTgenerally show consistent behavior with C1 with somewhat smaller magnitudes. Case studies are conducted for major ENSO events during the study period. The spatial variability ofqis closely aligned with outgoing longwave radiation (OLR) anomalies. For example, midtroposphericqincreases over 100% and OLR decreases over 50 W m−2over the central Pacific during the 2015/16 El Niño, and substantial regionalqandTanomalies are observed throughout the tropics and midlatitudes for each event.