Extended Abstract (276K)P2.25
Analysis of Convective Clouds and Turbulent Boundary Layers Using Hyperspectral Data
Kristopher M. Bedka, CIMSS/Univ. of Wisconsin, Madison, WI; and J. R. Mecikalski and W. F. Feltz
The focus of this research is to demonstrate new techniques in the analysis of convectively generated clouds and convective boundary layer (CBL) turbulence using high spectral resolution (i.e. hyperspectral) data. Atmospheric convection has been studied using simulated hyperspectral data for the future Geostationary Imaging Fourier Transform Spectrometer (GIFTS) instrument, as recently produced at UW-CIMSS. Data from the GIFTS instrument will be an invaluable resource in the analysis of convective clouds due to its combined high temporal (5-10 min), spectral (~1 cm-1), and spatial (1-4 km) resolutions, much more than is now achievable with currently operational geostationary weather satellites. The GIFTS instrument will improve the observation of all three basic atmospheric state variables (temperature, moisture, and wind velocity). Convective boundary layer research has been performed using high spectral and temporal resolution (40 s) Atmospheric Emitted Radiance Interferometer (AERI) data. Profiles of temperature and moisture every 40 s from AERI data have only recently become available, and allow for unique analyses of CBL turbulent structures.
Simulated GIFTS data was used to demonstrate the utility of the GIFTS instrument in the analysis of convective clouds, including the assessment of the timing/location of convective initiation (i.e. first detection of precipitation at the surface from cumulus clouds) and the characterization of existing convective storms (e.g. cloud top microphysical phase, cloud top height, cloud motion). Simulated GIFTS data cubes were developed from a MM5 numerical model simulation of convective storms that occurred on June 12th, 2002 during the IHOP experiment. Techniques used to study these storms are based on existing techniques developed with the GOES (~6.7 - 11 µm difference) and MODIS (~8.5 - 11 µm difference) instruments. Results show the extraordinary sensitivity of these band-differencing techniques to selected wavelength. This sensitivity is caused by the marked difference in spectral resolution between existing instruments (e.g., GOES) and GIFTS. Work is also being performed to determine the critical band difference thresholds and time rates-of-change in cloud top brightness temperatures that are important for assessing the timing/location of convective initiation. This presentation will summarize the convective cloud analyses using simulated GIFTS data.
New high temporal resolution (40 s) AERI data has been used to assess the spacing and thermodynamic characteristics of CBL roll structures, as present during the CRYSTAL-FACE experiment (one day for which 40 s AERI data are available). These data, collected within a nearly stationary sea breeze front in Southeast Florida on July 29th, 2002, revealed the presence of periodic moisture and temperature fluctuations as the CBL deepened through strong solar heating. Spectral and simple statistical analyses have indicated that a 15 to 20 min periodicity existed in these moisture/temperature fluctuations, which correspond well the passage of CBL rolls over the AERI instrument site in GOES-08 satellite imagery. This presentation will also highlight this analysis technique and the corresponding results.
Poster Session 2, IIPS Poster Session II
Wednesday, 14 January 2004, 2:30 PM-4:00 PM, Room 4AB
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