A Microphysics Guide to Cirrus -- Part II: Climatologies of Clouds and Humidity from Observations
Authors: Krämer Martina , Rolf Christian ,   Cirrus Guide II Team
Published: March 2020

&lt;p&gt;&lt;span&gt;This study presents airborne in-situ and satellite remote sensing climatologies &lt;/span&gt;&lt;span&gt;of &lt;/span&gt;&lt;span&gt; cirrus clouds and humidity. The climatologies serve as a guide to the properties of cirrus clouds, with the new in-situ data base providing detailed insights into boreal mid-latitudes and the tropics, while the satellite-borne data set offers a global overview.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;To this end, an extensive, quality checked data archive, the Cirrus Guide II in-situ data base, is created from airborne in-situ measurements during &lt;/span&gt;&lt;span&gt;150&lt;/span&gt;&lt;span&gt; flights &lt;/span&gt;&lt;span&gt;in &lt;/span&gt;&lt;span&gt;24&lt;/span&gt;&lt;span&gt; campaigns&lt;/span&gt;&lt;span&gt;. The archive contains meteorological parameters, &lt;/span&gt;&lt;span&gt;IWC, N&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;, R&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt; , RH&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt; and H&lt;/span&gt;&lt;sub&gt;&lt;span&gt;2&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;O&lt;/span&gt; &lt;span&gt;(&lt;/span&gt;&lt;span&gt;IWC: ice water content, N&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;: number concentration of ice crystals, R&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt; : ice crystal mean mass radius, RH&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;: relative humidity with respect to ice, H&lt;/span&gt;&lt;sub&gt;&lt;span&gt;2&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;O: water vapor mixing ratio&lt;/span&gt;&lt;span&gt;)&lt;/span&gt; &lt;span&gt;for &lt;/span&gt;&lt;span&gt;each of the flights. Depending on the specific parameter, the data base has extended by about a factor of &lt;/span&gt;&lt;span&gt;5-10&lt;/span&gt;&lt;span&gt; compared to the previous studies of Schiller et al. (&lt;/span&gt;&lt;span&gt;2008&lt;/span&gt;&lt;span&gt;), &lt;/span&gt;&lt;span&gt;JGR,&lt;/span&gt;&lt;span&gt; and Kr&amp;#228;mer et al. (&lt;/span&gt;&lt;span&gt;2009&lt;/span&gt;&lt;span&gt;), &lt;/span&gt;&lt;span&gt;ACP&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;An important step in completing the Cirrus Guide II is the provision of the global cirrus &lt;/span&gt;&lt;span&gt;N&lt;/span&gt;&lt;sub&gt;&lt;span&gt;ice&lt;/span&gt;&lt;/sub&gt;&lt;span&gt; climatology, derived by means of the retrieval algorithm DARDAR-Nice from &lt;/span&gt;&lt;span&gt;10&lt;/span&gt;&lt;span&gt; years of cirrus remote sensing observations from satellite. The in-situ data base has been used to evaluate and adjust the satellite observations. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;A specific highlight of the study is the in-situ observations of tropical tropopause layer (&lt;/span&gt;&lt;span&gt;TTL&lt;/span&gt;&lt;span&gt;) cirrus and humidity in the Asian monsoon anticyclone &lt;/span&gt;&lt;span&gt;and the&lt;/span&gt;&lt;span&gt; comparison to the surrounding tropics. &lt;/span&gt;&lt;/p&gt;