Accession Number:

ADA526975

Title:

Space-Based Measurements of Stratospheric Mountain Waves by CRISTA. 1. Sensitivity, Analysis Method, and a Case Study

Descriptive Note:

Journal article

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH

Report Date:

2002-01-01

Pagination or Media Count:

24.0

Abstract:

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere CRISTA instrument measured stratospheric temperatures and trace species concentrations with high precision and spatial resolution during two missions. The measuring technique is infrared limb-sounding of optically thin emissions. In a general approach, we investigate the applicability of the technique to measure gravity waves GWs in the retrieved temperature data. It is shown that GWs with wavelengths of the order of 100-200 km horizontally can be detected. The results are applicable to any instrument using the same technique. We discuss additional constraints inherent to the CRISTA instrument. The vertical field of view and the influence of the sampling and retrieval imply that waves with vertical wavelengths 3-5 km or larger can be retrieved. Global distributions of GW fluctuations were extracted from temperature data measured by CRISTA using Maximum Entropy Method MEM and Harmonic Analysis HA, yielding height profiles of vertical wavelength and peak amplitude for fluctuations in each scanned profile. The method is discussed and compared to Fourier transform analyses and standard deviations. Analysis of data from the first mission reveals large GW amplitudes in the stratosphere over southernmost South America. These waves obey the dispersion relation for linear two-dimensional mountain waves MWs. The horizontal structure on 6 November 1994 is compared to temperature fields calculated by the Pennsylvania State University PSUNational Center for Atmospheric Research NCAR mesoscale model MM5. It is demonstrated that precise knowledge of the instruments sensitivity is essential. Particularly good agreement is found at the southern tip of South America where the MM5 accurately reproduces the amplitudes and phases of a large-scale wave with 400 km horizontal wavelength. Targeted ray-tracing simulations allow us to interpret some of the observed wave features. A companion paper will d

Subject Categories:

  • Atmospheric Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE