caa a22 4500 60547219X CHVBK 20210128100337.0 cr unu---uuuuu 210128e20150701xx s 000 0 eng 10.1007/s00382-014-2352-9 doi (NATIONALLICENCE)springer-10.1007/s00382-014-2352-9 Contribution of the North Atlantic subtropical high to regional climate model (RCM) skill in simulating southeastern United States summer precipitation [Elektronische Daten] [Laifang Li, Wenhong Li, Jiming Jin] This study assesses the skill of advanced regional climate models (RCMs) in simulating southeastern United States (SE US) summer precipitation and explores the physical mechanisms responsible for the simulation skill at a process level. Analysis of the RCM output for the North American Regional Climate Change Assessment Program indicates that the RCM simulations of summer precipitation show the largest biases and a remarkable spread over the SE US compared to other regions in the contiguous US. The causes of such a spread are investigated by performing simulations using the Weather Research and Forecasting (WRF) model, a next-generation RCM developed by the US National Center for Atmospheric Research. The results show that the simulated biases in SE US summer precipitation are due mainly to the misrepresentation of the modeled North Atlantic subtropical high (NASH) western ridge. In the WRF simulations, the NASH western ridge shifts 7° northwestward when compared to that in the reanalysis ensemble, leading to a dry bias in the simulated summer precipitation according to the relationship between the NASH western ridge and summer precipitation over the southeast. Experiments utilizing the four dimensional data assimilation technique further suggest that the improved representation of the circulation patterns (i.e., wind fields) associated with the NASH western ridge substantially reduces the bias in the simulated SE US summer precipitation. Our analysis of circulation dynamics indicates that the NASH western ridge in the WRF simulations is significantly influenced by the simulated planetary boundary layer (PBL) processes over the Gulf of Mexico. Specifically, a decrease (increase) in the simulated PBL height tends to stabilize (destabilize) the lower troposphere over the Gulf of Mexico, and thus inhibits (favors) the onset and/or development of convection. Such changes in tropical convection induce a tropical-extratropical teleconnection pattern, which modulates the circulation along the NASH western ridge in the WRF simulations and contributes to the modeled precipitation biases over the SE US. In conclusion, our study demonstrates that the NASH western ridge is an important factor responsible for the RCM skill in simulating SE US summer precipitation. Furthermore, the improvements in the PBL parameterizations for the Gulf of Mexico might help advance RCM skill in representing the NASH western ridge circulation and summer precipitation over the SE US. Springer-Verlag Berlin Heidelberg, 2014 Southeastern US summer precipitation nationallicence North Atlantic subtropical high western ridge nationallicence North American Regional Climate Change Assessment Program (NARCCAP) nationallicence Weather Research and Forecasting (WRF) model nationallicence Li Laifang Earth and Ocean Sciences, Nicholas School of the Environment and Earth Sciences, Duke University, 321C Old Chem. Bldg, P.O. Box 90227, 27708, Durham, NC, USA aut Li Wenhong Earth and Ocean Sciences, Nicholas School of the Environment and Earth Sciences, Duke University, 321C Old Chem. Bldg, P.O. Box 90227, 27708, Durham, NC, USA aut Jin Jiming Department of Watershed Sciences, Utah State University, 84322, Logan, UT, USA aut Climate Dynamics Springer Berlin Heidelberg 45/1-2(2015-07-01), 477-491 0930-7575 45:1-2<477 2015 45 382 https://doi.org/10.1007/s00382-014-2352-9 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-014-2352-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Li Laifang Earth and Ocean Sciences, Nicholas School of the Environment and Earth Sciences, Duke University, 321C Old Chem. Bldg, P.O. Box 90227, 27708, Durham, NC, USA aut NATIONALLICENCE 700 1- Li Wenhong Earth and Ocean Sciences, Nicholas School of the Environment and Earth Sciences, Duke University, 321C Old Chem. Bldg, P.O. Box 90227, 27708, Durham, NC, USA aut NATIONALLICENCE 700 1- Jin Jiming Department of Watershed Sciences, Utah State University, 84322, Logan, UT, USA aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/1-2(2015-07-01), 477-491 0930-7575 45:1-2<477 2015 45 382