Value Added in Regional Climate Modeling: Should One Aim to Improve on the Large Scales as Well?

摘要: Expectations various regional climate modelers have expressed as to the impact on large scales are recalled. While some authors do mention possibility of improvement also at (e.g., Giorgi, J Phys IV France 139:101–118, 2006), majority clearly accepts view “downscaling” an effort in which driver global model hoped be preserved much possible and only small improved compared those model. Many find it even desirable use so-called “large-scale nudging” order help achieve this objective. Mesinger et al. (Limited area predictability: can “upscaling” take place? Research activities atmospheric oceanic modeling, WMO, Geneva, CAS/JSC WGNE Rep. No. 32, 5.30-5.31, 2002; see Mesinger, The Eta model: design, history, performance, what lessons we learned? In: Symposium 50th anniversary operational numerical weather prediction, University Maryland, College Park, MD, 14–17 June 2004, Preprints CD-ROM, 20pp, 2004) however argued that NWP results NCEP strongly suggest improvements been taking place more often than not. In addition, there was a four-month nine-member ensemble result Fennessy Altshuler early 2000s, published recently (Veljovic Meteorol Z 19:237–246, 2010), RCM achieved dramatic over its AGCM hindcasting precipitation difference central United States between “flood year” 1993 “drought 1988; not believe could without significant scales. If indeed is so generalized, then large-scale nudging would unnecessary but may harmful result. It holds for models while others. case, why question obvious importance. Given claims made modeling impossible any models, hard evidence specific desirable. preceding additional points discussed well detail given, summarizing perhaps first comprehensive direct tests issue 2010). Additional shown regarding choice lateral boundary conditions (LBC) scheme, pointing advantage (Mesinger, Contrib Atmos 50:200–210, 1977) conventional costlier relaxation scheme. As posed, summarized show driving by ECMWF 32-day members tended not, giving support our tenet improving efforts possible. We furthermore argue pursuing objective should beneficial smaller well.