Effects of a new land surface parametrization scheme on thermal extremes in a Regional Climate Model
Authors: Pollinger Felix , Ziegler Katrin , Abel Daniel , Paeth Heiko 
Published: March 2020

&lt;p&gt;&lt;span&gt;The &lt;/span&gt;&lt;span&gt;EFRE project Big Data@Geo aims at providing high resolution &lt;/span&gt;&lt;span&gt;environmental &lt;/span&gt;&lt;span&gt; information for the Lower Franconian region in Bavaria, Germany, &lt;/span&gt;&lt;span&gt;including climate change simulations &lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt;uitable&lt;/span&gt; &lt;span&gt;and relevant for &lt;/span&gt;&lt;span&gt;adaptation. &lt;/span&gt;&lt;span&gt;Hence, it &lt;/span&gt;&lt;span&gt;i&lt;/span&gt;&lt;span&gt;s &lt;/span&gt;&lt;span&gt;a&lt;/span&gt;&lt;span&gt; crucial&lt;/span&gt;&lt;span&gt; tasks &lt;/span&gt;&lt;span&gt;within this &lt;/span&gt;&lt;span&gt;interdisciplinary&lt;/span&gt;&lt;span&gt; project to enhance the regional climate model REMO, both by substantially increasing the spatial resolution a&lt;/span&gt;&lt;span&gt;s well as by&lt;/span&gt;&lt;span&gt; including further processes i&lt;/span&gt;&lt;span&gt;n&lt;/span&gt;&lt;span&gt; the model, which must be resolved on this new spatial scale.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;For the first time, we &lt;/span&gt;&lt;span&gt;successfully &lt;/span&gt;&lt;span&gt;coupled REMO&amp;#8217;s version 2015 (REMO15) with a superior land sur&lt;/span&gt;&lt;span&gt;f&lt;/span&gt;&lt;span&gt;a&lt;/span&gt;&lt;span&gt;c&lt;/span&gt;&lt;span&gt;e parametri&lt;/span&gt;&lt;span&gt;z&lt;/span&gt;&lt;span&gt;ation scheme (iMOVE) based on JSBACH. &lt;/span&gt;&lt;span&gt;REMO15-iMOVE&amp;#8217;&lt;/span&gt;&lt;span&gt;s core &lt;/span&gt;&lt;span&gt;feature &lt;/span&gt;&lt;span&gt;is &lt;/span&gt;&lt;span&gt;the&lt;/span&gt; &lt;span&gt;interactive vegetation, &lt;/span&gt;&lt;span&gt;represented on subgrid level via discrete classes. &lt;/span&gt;&lt;span&gt;These plant functional types&lt;/span&gt;&lt;span&gt; do not only respond to atmospheric forcing but in turn also &lt;/span&gt;&lt;span&gt;affect numerous near-surface climate variables.&lt;/span&gt;&lt;span&gt; I&lt;/span&gt;&lt;span&gt;n contrast,&lt;/span&gt;&lt;span&gt; the standard version &lt;/span&gt;&lt;span&gt;of &lt;/span&gt;&lt;span&gt;REMO&lt;/span&gt;&lt;span&gt;15&lt;/span&gt;&lt;span&gt; employs an idealized, constant seasonal cycle.&lt;/span&gt; &lt;span&gt;P&lt;/span&gt;&lt;span&gt;reliminary &lt;/span&gt;&lt;span&gt;results &lt;/span&gt;&lt;span&gt;i&lt;/span&gt;&lt;span&gt;ndicate&lt;/span&gt;&lt;span&gt; that &lt;/span&gt;&lt;span&gt;REMO15-iMOVE vegetation's dynamic is in good agreement with &lt;/span&gt;&lt;span&gt;observational data &lt;/span&gt;&lt;span&gt;and hence the &lt;/span&gt;&lt;span&gt;atmosphere&amp;#8217;s &lt;/span&gt;&lt;span&gt;lower boundary conditions should be more realistic &lt;/span&gt;&lt;span&gt;than in R&lt;/span&gt;&lt;span&gt;EMO15&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;To estimate the effects of &lt;/span&gt;&lt;span&gt;t&lt;/span&gt;&lt;span&gt;he enhanced model&lt;/span&gt; &lt;span&gt;o&lt;/span&gt;&lt;span&gt;n&lt;/span&gt; &lt;span&gt;the simulation of &lt;/span&gt;&lt;span&gt;thermal extreme &lt;/span&gt;&lt;span&gt;events&lt;/span&gt;&lt;span&gt; typically &lt;/span&gt;&lt;span&gt;a&lt;/span&gt;&lt;span&gt;ffecting Lower Franconia, &lt;/span&gt;&lt;span&gt;w&lt;/span&gt;&lt;span&gt;e a&lt;/span&gt;&lt;span&gt;nalyze&lt;/span&gt;&lt;span&gt; for both versions &lt;/span&gt;&lt;span&gt;one&lt;/span&gt;&lt;span&gt; simulation &lt;/span&gt;&lt;span&gt;with&lt;/span&gt;&lt;span&gt; 0.1&amp;#176;x0.1&amp;#176; and &lt;/span&gt;&lt;span&gt;one with &lt;/span&gt;&lt;span&gt;0.44&amp;#176;x0.44&amp;#176; horizontal &lt;/span&gt;&lt;span&gt;resolution forced with ERA-Interim &lt;/span&gt;&lt;span&gt;for the decade 2000-2009&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;span&gt;We e&lt;/span&gt;&lt;span&gt;valuate &lt;/span&gt;&lt;span&gt;the occurrence of &lt;/span&gt;&lt;span&gt;extremely warm (&lt;/span&gt;&lt;span&gt;minimum temperature &lt;/span&gt;&lt;span&gt;of&lt;/span&gt;&lt;span&gt; 20.0&amp;#176;&lt;/span&gt;&lt;span&gt;C or above or &lt;/span&gt;&lt;span&gt;maximum temperature above 30.0&amp;#176;C) &lt;/span&gt;&lt;span&gt;and cold days &lt;/span&gt;&lt;span&gt;(&lt;/span&gt;&lt;span&gt;maximum temperature below 0.0&amp;#176;C) &lt;/span&gt;&lt;span&gt;as well as the spatio-temporal pattern of the European Heat Wave 2003 &lt;/span&gt;&lt;span&gt;in comparison t&lt;/span&gt;&lt;span&gt;o&lt;/span&gt;&lt;span&gt; E-OBS data&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;span&gt;W&lt;/span&gt;&lt;span&gt;hile &lt;/span&gt;&lt;span&gt;the spatial &lt;/span&gt;&lt;span&gt;resolution &lt;/span&gt;&lt;span&gt;is clearly the main factor affecting the &lt;/span&gt;&lt;span&gt;quality&lt;/span&gt;&lt;span&gt; of the simulation&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt;, &lt;/span&gt;&lt;span&gt;we also find significant &lt;/span&gt;&lt;span&gt;effects of the land surface scheme &lt;/span&gt;&lt;span&gt;on warm events&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;B&lt;/span&gt;&lt;span&gt;ased on these first results&lt;/span&gt;&lt;span&gt;, REMO15-iMOVE appears to be a capable and flexible &lt;/span&gt;&lt;span&gt;tool &lt;/span&gt;&lt;span&gt;for transient climate change simulations &lt;/span&gt;&lt;span&gt;as well as &lt;/span&gt;&lt;span&gt;for &lt;/span&gt;&lt;span&gt;studies focussing on thermal extremes&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/p&gt;