elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Privacy Policy | Contact | Deutsch
Fontsize: [-] Text [+]

A Distribution Law for Relative Humidity in the Upper Troposphere and Lower Stratosphere Derived from Three Years of MOZAIC Measurements

Gierens, K. and Schumann, U. and Helten, M. and Smit, H. and Marenco, A. (1999) A Distribution Law for Relative Humidity in the Upper Troposphere and Lower Stratosphere Derived from Three Years of MOZAIC Measurements. Annales Geophysicae, 17, pp. 1218-1226.

[img]
Preview
PDF
171kB

Official URL: http://www.ann-geophys.net/17/1218/1999/

Abstract

Data from three years of MOZAIC measurements made it possible to determine a distribution law for the relative humidity in the upper troposphere and lower stratosphere. Data amounting to 13.5% of the total were obtained in regions with ice supersaturation. Troposphere and stratosphere are distinguished by an ozone concentration of 130 ppbv as threshold. The probability of measuring a certain amount of ice supersaturation in the troposphere decreases exponentially with the degree of ice supersaturation. The probability of measuring a certain relative humidity in the stratosphere (both with respect to water and ice) decreases exponentially with the relative humidity. A stochastic model that naturally leads to the exponential distribution is provided. Mean supersaturation in the troposphere is about 15%, whereas ice nucleation requires 30% supersaturation on the average. This explains the frequency of regions in which aircraft induce persistent contrails but which are otherwise free of clouds. Ice supersaturated regions are 3-4 K colder and contain more than 50% more vapour than other regions in the upper troposphere. The stratospheric air masses sampled are dry, as expected, having mean relative humidity over water of 12% and over ice of 23%, respectively. However, 2% of the stratospheric data indicate ice supersaturation. As the MOZAIC measurements have been obtained on commercial flights mainly between Europe and North America, the data do not provide a complete global picture, but the exponential character of the distribution laws found is probably valid globally. Since water vapour is the most important greenhouse gas and since it might enhance the anthropogenic greenhouse effects via positive feedback mechanisms, it is important to represent its distribution correctly in climate models. The discovery of the distribution law of the relative humidity makes possible simple tests to show whether the hydrological cycle in climate models is represented in an adequate way or not.

Item URL in elib:https://elib.dlr.de/9117/
Document Type:Article
Title:A Distribution Law for Relative Humidity in the Upper Troposphere and Lower Stratosphere Derived from Three Years of MOZAIC Measurements
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Gierens, K.UNSPECIFIEDUNSPECIFIED
Schumann, U.UNSPECIFIEDUNSPECIFIED
Helten, M.ICG2, FZ JülichUNSPECIFIED
Smit, H.ICG2, FZ JülichUNSPECIFIED
Marenco, A.CNRS, Toulouse, FUNSPECIFIED
Date:1999
Journal or Publication Title:Annales Geophysicae
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:17
Page Range:pp. 1218-1226
Status:Published
Keywords:atmospheric composition and structure, troposphere - composition and chemistry
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Deposited By: DLR-Beauftragter, elib
Deposited On:24 Jan 2008
Last Modified:31 Jul 2019 19:14

Repository Staff Only: item control page

Browse
Search
Help & Contact
Information
electronic library is running on EPrints 3.3.12
Copyright © 2008-2017 German Aerospace Center (DLR). All rights reserved.