Regional climate projections and associated climate services in the southwest Indian ocean basin
Authors: Leroux Marie Dominique , Bonnardot François , Kotomangazafy Stephason , Veerabadren Philippe , Ridhoine Abdoul Oikil , Somot Samuel , Alias Antoinette , Chauvin Fabrice 
Published: March 2021

&lt;p&gt;&lt;span&gt;&lt;span&gt;In the former Cordex program,&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; regional climate models &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;were run over&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; Africa and&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; only covered &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;the &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;western part of the South &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;Indian Ocean &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;at&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;a coarse&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; 50-km &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;resolution while a 12-km resolution was used for Europe&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;A 50-km resolution &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;is &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;in&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;sufficient for island territories as small &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;and steep &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;as those in the Indian Ocean. Yet this &lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;area is especially vulnerable to natural catastrophes related to the effects of climate change: it is the third region in the world most affected by extreme climatic events. &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;The need for climate services over that populated area &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;has now become a&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; critical &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;issue. &lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;&lt;span&gt;Both dynamical and statistical downscaling from a few ongoing CMIP6 simulations&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;were &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;therefore&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;used to obtain regional climate information on a large area of the southwest Indian Ocean that includes most of the inhabited countries from the coasts of Mozambique (33&amp;#176;E) to 74&amp;#176;E as well as the main area of tropical cyclone genesis [2-28&amp;#176;S]. The&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;limited area model&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; ALADIN&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;was &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;implemented&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;in its climate version &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;at 12-km resolution and the first runs were coupled by outputs from &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;one of &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;the &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;CMIP6&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; Earth Simulation &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;Coupled &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;Model&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;s named&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; CNRM-ESM2-&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;1&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;&lt;span&gt;We&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; will present the numerical and statistical tools used for this regional climate study as well as the first projections obtained for ssp126 (RCP2.6), &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;ssp245 (RCP4,5)&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; and ssp585 (RCP8.5) scenarios &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;over the 20&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;15&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;-2100 period&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;R&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;esults &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;will be illustrated &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;for the southwest Indian ocean basin as well as &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;for &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;the main islands of the&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; IOC&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; member countries: &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;Mad&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;agascar, Reunion, Mauritius, Seychelles, and Comoros where observations over the 1981-2010 period were used for model bias correction using the quantile-quantile matching method. For climate uncertainty representativeness, the 20&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;15&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;-2100 evolution of both ALADIN and CNRM-ESM2-&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;1&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; temperature and precipitation averages over our region will be compared to that of the other available CMIP6 simulations.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;&lt;span&gt;This &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;work is part of the &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;BRIO (Building Resilience in the Indian Ocean) &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;project&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;which&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;aims at &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;support&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;ing&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;the &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;Indian Ocean Commission &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;(&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;IOC&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;)&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; member countries &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;in&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; the implementation of &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;their adaptation policies&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; with &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;respect to &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;climate change &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;(regarding water resources, health and other issues). &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;Th&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;is&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; project will &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;provid&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;e&lt;/span&gt;&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;&lt;span&gt;a set of high quality climate-related data on a free-access online regional portal &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;as well as&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; c&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;limate services. &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;It is&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt; funded by the Agence Fran&amp;#231;aise de D&amp;#233;veloppement (AFD), through the Adapt&amp;#8217;Action Facility, in cooperation with the IOC.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;