Editing IPCC:AR6/WGI/Chapter-10 (section)

==== 10.6.4.3 Observational Issues ====

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The Mediterranean region spans a wide variety of countries and economies. This has led to large differences in the existence and availability of observational records, with the southern part of the area being sparsely covered by meteorological stations (Figure 10.20b). Consequently, basin-wide, homogeneous, quality controlled observational datasets are lacking, especially before the advent of substantial satellite observations in the 1970s. Observational uncertainties exist also for those regions that are covered by high quality networks such as European Climate Assessment &amp; Dataset (ECA&amp;D; [[#Flaounas--2012|Flaounas et al., 2012]] ).

Large differences of up to 7°C between the CRU and UDEL datasets have been found especially over mountainous areas, such as the [[IPCC:Wg1:Chapter:Atlas|Atlas]] in Morocco ( [[#Zittis--2017|Zittis and Hadjinicolaou, 2017]] ; [[#Strobach--2019|Strobach and Bel, 2019]] ). Bucchignani et al. (2016a, b) compared three different datasets (CRU, UDEL, and MERRA) with the available ground observations and found that although the geographical distribution of the bias is qualitatively similar for the three datasets, differences exist, with the absolute bias being generally lower in Modern-Era Retrospective Analysis for Research and Applications (MERRA) especially over North Africa during the summer and winter season. There is ''high confidence'' that the sparse monitoring network in parts of the Mediterranean region strongly increases the uncertainty across different gridded datasets ( [[#10.2.2.3|Section 10.2.2.3]] , Figure 10.20b,c).

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