Abstract
Four state-of-the-science numerical weather prediction (NWP) models were used to perform mountain wave (MW)-resolving hindcasts over the Drake Passage of a 10-day period in 2010 with numerous observed MW cases. The Integrated Forecast System (IFS) and the Icosahedral Nonhydrostatic (ICON) model were run at Dx ≈ 9 and 13 km globally. The Weather Research and Forecasting (WRF) Model and the Met Office Unified Model (UM) were both configured with a Dx 5 3-km regional domain. All domains had tops near 1 Pa (z ≈ 80 km). These deep domains allowed quantitative validation against Atmospheric Infrared Sounder (AIRS) observations, accounting for observation time, viewing geometry, and radiative transfer. All models reproduced observed middle-atmosphere MWs with remarkable skill. Increased horizontal resolution improved validations. Still, all models underrepresented observed MW amplitudes, even after accounting for model effective resolution and instrument noise, suggesting even at Dx ≈ 3-km resolution, small-scale MWs are underresolved and/or overdiffused. MW drag parameterizations are still necessary in NWP models at current operational resolutions of Dx ≈ 10 km. Upper GW sponge layers in the operationally configured models significantly, artificially reduced MW amplitudes in the upper stratosphere and mesosphere. In the IFS, parameterized GW drags partly compensated this deficiency, but still, total drags were ≈6 times smaller than that resolved at Dx ≈ 3 km. Meridionally propagating MWs significantly enhance zonal drag over the Drake Passage. Interestingly, drag associated with meridional fluxes of zonal momentum (i.e., u ̗y ̗) were important; not accounting for these terms results in a drag in the wrong direction at and below the polar night jet. SIGNIFICANCE STATEMENT: This study had three purposes: to quantitatively evaluate how well four state-of-the-science weather models could reproduce observed mountain waves (MWs) in the middle atmosphere, to compare the simulated MWs within the models, and to quantitatively evaluate two MW parameterizations in a widely used climate model. These models reproduced observed MWs with remarkable skill. Still, MW parameterizations are necessary in current Dx ≈ 10-km resolution global weather models. Even Dx ≈ 3-km resolution does not appear to be high enough to represent all momentum-fluxing MW scales. Meridionally propagating MWs can significantly influence zonal winds over the Drake Passage. Parameterizations that handle horizontal propagation may need to consider horizontal fluxes of horizontal momentum in order to get the direction of their forcing correct.
Original language | English |
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Pages (from-to) | 909-932 |
Number of pages | 24 |
Journal | Journal of the Atmospheric Sciences |
Volume | 79 |
Issue number | 4 |
Early online date | 16 Mar 2022 |
DOIs | |
Publication status | Published - 1 Apr 2022 |
Bibliographical note
Funding Information:Acknowledgments. Numerous institutions and funding agencies supported this international, collaborative work. CGK was supported both by an Advanced Study Program postdoctoral fellowship at NCAR and by the NSF (NSF Grant 2004512). MJA was supported by NASA Grants 80NSSC18K0069 and 80NSSC17K0169. LH was supported by NASA Grants 80NSSC18K0768 and 80NSSC17K0169. PSˇ was supported by Project CZ.02.2.69/0.0/0.0/19_074/0016231 (International mobility of researchers at Charles University MSCA-IF III). CW was supported by a Royal Society Research fellowship (UF160545). KS was supported by JST, CREST Grant JPMJCR1663, Japan. SG was supported by the German Federal Ministry for Education and Research (01LG1907, WASCLIM, ROMIC program). ME was supported by the German Research Foundation (DFG) Grant ER 474/4-2 and by the German Federal Ministry of Education and Research (BMBF) Grant 01LG1905C (QUBICC, ROMIC). The International Space Science Institute (ISSI) and the Stratosphere–troposphere Processes And their Role in Climate (SPARC) project both supported a meeting and travel for this group. High-performance computing was performed on the Cheyenne supercomputer (ark:/85065/d7wd3xhc) with support provided by NCAR’s Computational and Information systems Laboratory, sponsored by the National Science Foundation. The ICON simulations were performed with computing time granted by the John von Neumann Institute for Computing (NIC) and performed on the JURECA supercomputer (Krause and Thörnig 2018) at the Jülich Supercomputing Center (JSC). Additionally, this work used JASMIN, the U.K. collaborative data analysis facility. Finally, David Gill, Jimy Dudhia, Jordan Powers, Kevin Manning, and Joe Klemp, all within MMM at NCAR, were essential in getting WRF to run in the deep configuration presented here.
Keywords
- Dynamics
- Forcing
- Gravity waves
- Instrumentation/sensors
- Mesoscale processes
- Middle atmosphere
- Model comparison
- Model errors
- Model evaluation/performance
- Momentum
- Mountain waves
- Orographic effects
- Parameterization
- Regional models
- Satellite observations
- Spectral analysis/models/distribution
- Stratosphere-troposphere coupling
- Subgrid-scale processes
ASJC Scopus subject areas
- Atmospheric Science