Cloud properties over the Arctic based on regional climate model data and satellite observations for different sea ice conditions amg

The pres­ence of clouds in the Arctic regu­lates the surface energy budget (SEB) over the sea‐ice surface and the ice‐free ocean. Foll­owing several prev­ious field camp­aigns, the cloud‐radi­ation rela­tion­ship, incl­uding cloud vert­ical stru­cture and phase, has been eluc­ida­ted; however, mode­ling of this rela­tion­ship has matured slowly. In reco­gnit­ion of the recent decline in the Arctic sea‐ice extent, repr­esen­tat­ion of the cloud system in nume­rical models should cons­ider the effects of areas covered by sea ice and ice‐free areas. Using an in situ stat­ion­ary mete­orol­ogi­cal obse­rvat­ion data set obta­ined over the ice‐free Arctic Ocean by the Japa­nese Rese­arch Vessel Mirai (Sept­ember 2014), coor­dina­ted eval­uat­ion of six regi­onal climate models (RCMs) with nine model runs was perf­ormed by focu­sing on clouds and the SEB. The most rema­rka­ble find­ings were as follows: (1) reduced occu­rre­nce of unst­able stra­tifi­cat­ion with low‐level cloud water in all models in comp­ari­son to the obse­rvat­ions, (2) sign­ific­ant diff­eren­ces in cloud water repr­esen­tati­ons between single‐ and double‐moment cloud schemes, (3) exte­nsive diff­eren­ces in part­itio­ning of hydr­omet­eors incl­uding solid/liquid prec­ipit­ation, and (4) pron­oun­ced lower‐trop­osph­eric air temp­erat­ure biases. These issues are cons­ide­red as the main sources of SEB unce­rtai­nty over ice‐free areas of the Arctic Ocean. The results from a coupled RCM imply that the SEB is cons­trai­ned by both the atmo­sph­ere and the ocean (and sea ice) with cons­ider­able feed­back. Coor­dina­ted impr­ovem­ent of both stand‐alone atmo­sphe­ric and coupled RCMs would promote a more comp­rehe­nsive and impr­oved unde­rsta­nding of the Arctic air‐ice‐sea coupled system