Imaging Gravity Waves in Lower Stratospheric AMSU-A Radiances. Part 2: Validation Case Study
Abstract
Two-dimensional radiance maps from Channel 9 (approx. 60-90 hPa) of the Advanced Microwave Sounding Unit (AMSU-A), acquired over southern Scandinavia on 14 January 2003, show plane-wave-like oscillations with a wavelength lambda(sub h) of approx. 400-500 km and peak brightness temperature amplitudes of up to 0.9 K. The wave-like pattern is observed in AMSU-A radiances from 8 overpasses of this region by 4 different satellites, revealing a growth in the disturbance amplitude from 00:00 UTC to 12:00 UTC and a change in its horizontal structure between 12:00 UTC and 20:00 UTC. Forecast and hindcast runs for 14 January 2003 using high resolution global and regional numerical weather prediction (NWP) models generate a lower stratospheric mountain wave over southern Scandinavia with peak 90 hPa temperature amplitudes of approx. 5-7K at 12:00 UTC and a similar horizontal wavelength, packet width, phase structure, and time evolution to the disturbance observed in AMSU-A radiances. The wave's vertical wavelength is approx. 12 km. These NWP fields are validated against radiosonde wind and temperature profiles and airborne lidar profiles of temperature and aerosol backscatter ratios acquired from the NASA DC-8 during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). Both the amplitude and phase of the stratospheric mountain wave in the various NWP fields agree well with localized perturbation features in these suborbital measurements. In particular, we show that this wave formed the type II polar stratospheric clouds measured by the DC-8 lidar. To compare directly with the AMSU-A data, we convert these validated NWP temperature fields into swath-scanned brightness temperatures using three-dimensional Channel 9 weighting functions and the actual AMSU-A scan patterns from each of the 8 overpasses of this region.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 14, 2006
- Accession Number
- ADA524941
Entities
People
- A. Stephens
- B. N. Lawrence
- C. A. Hostetler
- Dufei Wu
- J. F. Burris
- James D. Doyle
- John P. McCormack
- L. Coy
- Stephen D. Eckermann
- T. F. Hogan
- T. J. Mcgee
Organizations
- United States Naval Research Laboratory