Relationships between Extratropical Precipitation Systems and UTLS Temperatures and Tropopause Height from GPM and GPS-RO

Benjamin R Johnston,Chuntao Liu,Feiqin Xie

doi:10.3390/atmos13020196

Abstract

This study characterizes the relationship between extratropical precipitation systems to changes in upper troposphere and lower stratosphere (UTLS) temperature and tropopause height within different environments. Precipitation features (PFs) observed by the Global Precipitation Measurement (GPM) satellite are collocated with GPS radio occultation (RO) temperature profiles from 2014 to 2017 and classified as non-deep stratospheric intrusion (non-DSI; related to convective instability) or deep stratospheric intrusion (DSI; related to strong dynamic effects on the tropopause). Non-DSI PFs introduce warming (up to 1 K) in the upper troposphere, transitioning to strong cooling (up to −3.5 K) around the lapse rate tropopause (LRT), and back to warming (up to 2.5 K, particularly over the ocean) in the lower stratosphere. UTLS temperature anomalies for DSI events are driven predominantly by large scale dynamics, with major cooling (up to −6 K) observed from the mid-troposphere to the LRT, which transitions to strong warming (up to 4 K) in the lower stratosphere. Small and deep non-DSI PFs typically result in a lower LRT (up to 0.4 km), whereas large but weaker PFs lead to a higher LRT with similar magnitudes. DSI events are associated with larger LRT height decreases, with anomalies of almost −2 km near the deepest PFs. These results suggest intricate relationships between precipitation systems and the UTLS temperature structure. Importantly, non-DSI PF temperature anomalies show patterns similar to tropical convection, which provides unification of previous tropical research with extratropical barotropic convective impacts to UTLS temperatures.

Highlights

The upper troposphere and lower stratosphere (UTLS) is a coupling region in the atmosphere, which is distinct in radiation, dynamics, chemistry, and microphysics [1,2]
This section focuses on extratropical Precipitation features (PFs) characteristics and UTLS temperature anomalies within ±5 km of the PF lapse rate tropopause (LRT) height
GPS-radio occultation (RO) temperature anomalies near both non-deep stratospheric intrusion (DSI) and DSI PFs are separated by their surface properties and further divided into subgroups based on PF size and depth (RD)

Summary

Introduction

The upper troposphere and lower stratosphere (UTLS) is a coupling region in the atmosphere, which is distinct in radiation, dynamics, chemistry, and microphysics [1,2]. A strong connectivity amongst these various processes makes the UTLS highly susceptible to climate change [3] and has attracted much research attention in recent decades. The WMO definition of the tropopause is based on lapse rate criteria (lapse rate tropopause or LRT) and is defined as “the lowest level at which the lapse rate decreases to 2 K km−1 or less, provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 K km−1” [8]. Regardless of tropopause definition, it has been suggested that changes in tropopause height can serve as a useful indicator of climate change [3,11]

Objectives

Methods

Results

Conclusion