Ice supersaturated regions: properties and validation of ERA-Interim reanalysis with IAGOS in situ water vapor measurements

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Abstract
<jats:p> &amp;lt;p&amp;gt;Cirrus clouds and their potential formation regions, so-called ice-supersaturated regions (ISSRs) occur frequently in the tropopause region.&amp;amp;#160;It is assumed that ISSRs and cirrus clouds&amp;amp;#160;can change the tropopause structure by diabatic processes, driven by latent heating due to phase transitions and interaction with radiation.&amp;amp;#160;These effects may also alter the distribution of potential vorticity (PV) in the upper troposphere, thus leading to changes in large scale dynamics and stratosphere-to-troposphere exchange.&amp;amp;#160;&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;The measurement of water vapour at the tropopause level is not trivial. Beside radiosonde data the most important in-situ dataset is provided by in-service passenger airplanes.&amp;amp;#160;The European Research Infrastructure &amp;amp;#8217;In-service Aircraft for a Global Observing System&amp;amp;#8217; (IAGOS) (Petzold et al., 2015) provides long-term in-situ measurements on board commercial passenger aircraft. Along its flight track every aircraft is monitoring the chemical composition of the surrounding air and atmospheric state parameters by compact instruments.&amp;amp;#160;Especially in the upper troposphere/lowermost stratosphere (UTLS) these&amp;amp;#160;measurements&amp;amp;#160;are&amp;amp;#160;very valuable as most flight tracks are situated in heights between&amp;amp;#160;9&amp;amp;#160;to&amp;amp;#160;13 km, depending on the actual weather conditions,&amp;amp;#160;seasons and geographic region.&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;However, for many research questions a three-dimensional picture&amp;amp;#160;including a&amp;amp;#160;sufficient&amp;amp;#160;temporal resolution of the water vapour fields in the UTLS region&amp;amp;#160;is&amp;amp;#160;required.&amp;amp;#160;Hence, in our study we use the&amp;amp;#160;in-situ data from IAGOS&amp;amp;#160;to quantify the quality of the&amp;amp;#160;established and often used ERA-Interim data set. The underlying IFS-model of this reanalysis data&amp;amp;#160;allows explicitly&amp;amp;#160;ice-supersaturation&amp;amp;#160;in cloud free conditions&amp;amp;#160;and is therefore&amp;amp;#160;suitable for comparison.&amp;amp;#160;For instance,&amp;amp;#160;we&amp;amp;#160;compare&amp;amp;#160;properties&amp;amp;#160;such as&amp;amp;#160;the seasonal cycle of the vertical distribution&amp;amp;#160;of water vapour mixing ratio, relative humidity&amp;amp;#160;and the fraction of ice-supersaturated regions.&amp;amp;#160;&amp;lt;/p&amp;gt; </jats:p>
Autoren
  • Philipp Reutter
  • Patrick Neis
  • Susanne Rohs
  • Bastien Sauvage
  • Peter Spichtinger
  • Andreas Petzold
DOI
10.5194/egusphere-egu2020-9301
Buchtitel
Copernicus GmbH
Datum der Veröffentlichung
2020
Status
Published
Herausgeber URL
http://dx.doi.org/10.5194/egusphere-egu2020-9301
Datum der Datenerfassung
2020
Titel
Ice supersaturated regions: properties and validation of ERA-Interim reanalysis with IAGOS in situ water vapor measurements

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