Effects of a new land surface parametrization scheme on thermal extremes in a Regional Climate Model

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