Fourier-Ray Modeling of Short-Wavelength Trapped Lee Waves Observed in Infrared Satellite Imagery Near Jan Mayen

• Main Authors: Eckermann, Stephen D., Broutman, Dave, Ma, Jun, Lindeman, John
• Other Authors: NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
• Format: Text
• Language: English
• Published: 2006
• Subjects: Theoretical Mathematics; Photography; *SATELLITE IMAGERY; *FOURIER ANALYSIS; *WAVES; *SHORT WAVELENGTHS; TOPOGRAPHY; CLEAR AIR TURBULENCE; FLOW; RADIOSONDES; RADIOMETERS; GEOSTROPHIC WIND; NORTH ATLANTIC OCEAN; OROGRAPHY; HIGH RESOLUTION; TRAPPING(CHARGED PARTICLES); WEATHER; ALGORITHMS; REPRINTS; *FOURIER-RAY MODELING; *LEE WAVES; INFRARED SATELLITE IMAGERY; MOUNTAIN WAVES; JAN MAYEN; AVHRR-3(ADVANCED VERY HIGH RESOLUTION RADIOMETER VERSION 3); LIPPS-HEMLER OROGRAPHIC FLOW MODELS; RVSM(REDUCED VERTICAL SEPARATION MINIMA); NWP(NUMERICAL WEATHER PREDICTION); MWFM(MOUNTAINWAVE FORECAST MODEL); Jan Mayen; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA523741; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA523741

A time-dependent generalization of a Fourier-ray method is presented and tested for fast numerical computation of high-resolution nonhydrostatic mountain-wave fields. The method is used to model mountain waves from Jan Mayen on 25 January 2000, a period when wavelike cloud banding was observed long distances downstream of the island by the Advanced Very High Resolution Radiometer Version 3 (AVHRR-3). Surface weather patterns show intensifying surface geostrophic winds over the island at 1200 UTC caused by rapid eastward passage of a compact low pressure system. The 1200 UTC wind profiles over the island increase with height to a jet maximum of approximately 60-70 m s(exp -1), yielding Scorer parameters that indicate vertical trapping of any short wavelength mountain waves. Separate Fourier-ray solutions were computed using high-resolution Jan Mayen orography and 1200 UTC vertical profiles of winds and temperatures over the island from a radiosonde sounding and an analysis system. The radiosonde-based simulations produce a purely diverging trapped wave solution that reproduces the salient features in the AVHRR-3 imagery. Differences in simulated wave patterns governed by the radiosonde and analysis profiles are explained in terms of resonant modes and are corroborated by spatial ray-group trajectories computed for wavenumbers along the resonant mode curves. Output from a nonlinear Lipps-Hemler orographic flow model also compares well with the Fourier-ray solution horizontally. Differences in vertical cross sections are ascribed to the Fourier-ray model's current omission of tunneling of trapped wave energy through evanescent layers. Published in Monthly Weather Review, v143 p2830-2848, Oct 2006.