Abstract

Despite the fact that tropospheric temperature inversions are thought to be an important feature of climate as well as a significant factor affecting air quality, low-level cloud formation, and the radiation budget of the Earth, a quantitative assessment of their representation in atmospheric reanalyses is yet missing. Here, we provide new evidence of the occurrence of low-tropospheric temperature inversions and associated uncertainties in their parameters existing among reanalyses produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) and upper-air soundings for Europe covering the period 2001–2010. The reanalyses utilized here include (1) surface-input reanalyses represented by ERA-20C and CERA-20C as well as (2) full-input reanalyses represented by ERA-Interim and ERA5. The upper-air soundings were derived from the Integrated Global Radiosonde Archive (IGRA), version 2. The data consists mainly of air temperature and geopotential height from the model levels (ModLev) and pressure levels (PresLev) of ECMWF reanalyses. The results show that the frequency of surface-based inversions (SBI) and elevated inversions (EI) is largely in agreement among the reanalyses. The quality of their representation depends, however, on the inversion type, season, and region. Over the vast majority of IGRA upper-air stations, SBI frequency is overestimated and EI frequency is underestimated by ECMWF reanalyses. Substantially larger uncertainties arise from the selection between the data of ModLev and PresLev of the reanalyses—the differences in the frequency of the temperature inversions are particularly large for summertime SBI suggesting that PresLev are not capable of resolving the main features of shallow and weak SBI.

Highlights

  • Atmospheric reanalyses, which are spatially and temporally coherent datasets providing a synthesized estimate of the past and current state of the Earth’s atmosphere, have recently become widely used both in climate and environmental research as well as outside scientific applications (Gregow et al 2016, Hersbach et al 2018)

  • Methods for the inter-comparison of temperature inversions’ parameters derived from European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses and upper air soundings While a general view on the frequency of surface-based inversions (SBI) and elevated inversions (EI) is provided on maps created separately for ECMWF reanalyses and upper-air soundings, a more comprehensive comparison of SBI and EI parameters was performed for the ten Integrated Global Radiosonde Archive (IGRA) upper-air stations indicated in table 2—shaded rows

  • Across mainland Europe, the frequency of summertime SBI identified by applying the data from model levels (ModLev) is about 30% higher as that obtained by applying data from pressure levels (PresLev)

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Summary

July 2020

Angelika Palarz1, Jürg Luterbacher2,3, Zbigniew Ustrnul1, Elena Xoplaki2 and Daniel Celinski-Mysław1 Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Keywords: temperature inversions, lower-tropospheric stability, ECMWF reanalyses, upper-air soundings, data evaluation

Introduction
ECMWF reanalyses and upper air soundings
Methods for the identification of temperature inversions
Frequency of low-tropospheric temperature inversions
Parameters of low-tropospheric temperature inversions
Discussion and conclusions
Full Text
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