期刊名称：Journal of Advances in Modeling Earth Systems
电子版ISSN：1942-2466
出版年度：2018
卷号：10
期号：10
页码：2527-2547
DOI：10.1029/2018MS001417
出版社：John Wiley & Sons, Ltd.
摘要：The accuracy with which parametrizations of orographic blocking and orographic gravity wave drag (OGWD) are able to reproduce the explicitly resolved impacts on flow over complex terrain is investigated in two models: the Met Office Unified Model (MetUM) and the European Centre for Medium‐Range Weather Forecasts Integrated Forecasting System (ECMWF IFS). To this end, global and limited area short‐range forecast experiments across a range of horizontal resolutions, and their model errors relative to analyses, are assessed over two complex mountainous regions: the Himalayas and the Middle East. The impact of resolved orography on the circulation is deduced by taking the difference between high‐resolution experiments with a high (4 to 9 km) and low‐resolution (125 to 150 km) orography. This is then compared with the impact of parametrized orographic drag, deduced from global low‐resolution experiments with and without parametrized orographic drag. At resolutions ranging from tens to hundreds of kilometres, both the MetUM and ECMWF IFS exhibit too strong zonal winds relative to analyses in the lower stratosphere in the region of maximum resolved orographic gravity wave breaking, indicative of some deficiency in the parametrization of OGWD. Diagnosis of the parametrized physics and resolved dynamics tendencies across a range of OGWD parameter values reveal that this error is partly due to the manner in which the resolved dynamics interacts with the parametrized OGWD. This work introduces a method for quantifying the impacts of resolved versus parametrized orographic drag in models and highlights the importance of physics‐dynamics interactions.
关键词：orographic drag;gravity wave drag;high‐resolution simulations;physics‐dynamics coupling;systematic model error;parametrized processes
