Signs of climate variability in double tropopause global distribution from radio occultation data

IF 5.2 1区 地球科学 Q1 ENVIRONMENTAL SCIENCES
Alejandro de la Torre, Peter Alexander, Torsten Schmidt, Andrea K. Steiner, Florian Ladstädter, Rodrigo Hierro, Pablo Llamedo
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Abstract

Abstract. In a standard atmosphere, there is a single lapse rate tropopause (in what follows, tropopause) that separates the troposphere below from the stratosphere above. However, in certain situations, such as in regions of strong vertical wind shear or associated with certain weather phenomena, a second tropopause layer may form above the standard tropopause. The presence of a double tropopause (DT) can have implications for atmospheric and climate studies, as it may be associated with dynamic and complex weather patterns. Based on 14 years of temperature profiles retrieved by GNSS radio occultation and the resulting DT, a possible relationship between the spatio-temporal distribution of the relative number of DT to simple tropopauses (NDT) (or dependent variable) and a set of monthly climate indices (or features) is explored with a focus on the methodological approach. A cluster analysis is applied to geographically associate the DT occurrences with the climate indices. Then a multivariate linear regression is constructed using a progression of different models to identify the relevant features for the occurrence of DTs. On a global scale, from a hierarchical cluster analysis six sub-regions with different location and spread characteristics are identified. In addition to the condition of linearity in the residuals, the performance of each model in the train and test populations is evaluated to discard possible overfitting. The required conditions of non-collinearity, stationarity and cross-correlation between the features and the relative number of NDT after the removal of the climatological mean for each month (NDT’) are checked. Mean squared errors, adjusted coefficient of determination (adjusted R2) and number of degrees of freedom (F-statistic) parameters are evaluated for each model obtained. Taking into account the constraints of the present analysis, the most relevant climatic indices for the distribution of NDT' are identified.
从无线电掩星数据看双对流层顶全球分布的气候变异迹象
摘要在标准大气中,有一个单一的失效率对流层顶(以下简称 "对流层顶")将下面的对流层和上面的平流层分开。然而,在某些情况下,例如在强垂直风切变区域或与某些天气现象相关的区域,在标准对流层顶之上可能会形成第二个对流层顶层。双对流层顶(DT)的出现对大气和气候研究有影响,因为它可能与动态和复杂的天气模式有关。根据全球导航卫星系统无线电掩星检索到的 14 年温度剖面图和由此产生的双对流层顶,探讨了双对流层顶与简单对流层顶相对数量(或因变量)的时空分布与一系列月气候指数(或特征)之间可能存在的关系,重点是方法学方法。采用聚类分析将 DT 出现的地理位置与气候指数联系起来。然后,利用一系列不同的模型构建多元线性回归,以确定出现 DTs 的相关特征。在全球范围内,通过分层聚类分析,确定了六个具有不同位置和分布特征的子区域。除了残差的线性条件外,还对每个模型在训练群和测试群中的性能进行了评估,以排除可能的过拟合。对各特征之间的非共线性、静止性和交叉相关性以及去除各月气候平均值后的无损检测相对数量("无损检测")等必要条件进行检查。对获得的每个模型的均方误差、调整后的判定系数(调整后 R2)和自由度数(F 统计量)参数进行评估。考虑到本次分析的限制因素,确定了与 NDT'分布最相关的气候指数。
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来源期刊
Atmospheric Chemistry and Physics
Atmospheric Chemistry and Physics 地学-气象与大气科学
CiteScore
10.70
自引率
20.60%
发文量
702
审稿时长
6 months
期刊介绍: Atmospheric Chemistry and Physics (ACP) is a not-for-profit international scientific journal dedicated to the publication and public discussion of high-quality studies investigating the Earth''s atmosphere and the underlying chemical and physical processes. It covers the altitude range from the land and ocean surface up to the turbopause, including the troposphere, stratosphere, and mesosphere. The main subject areas comprise atmospheric modelling, field measurements, remote sensing, and laboratory studies of gases, aerosols, clouds and precipitation, isotopes, radiation, dynamics, biosphere interactions, and hydrosphere interactions. The journal scope is focused on studies with general implications for atmospheric science rather than investigations that are primarily of local or technical interest.
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