Initialization and validation of a simulation of cirrus using FIRE-II data
- Naval Research Lab., Monterey, CA (United States)
- NASA/Ames Research Center, Moffet Field, CA (United States)
- NASA/Langley Research Center, Hampton, VA (United States); and others
Observations from a wide variety of instruments and platforms are used to validate many different aspects of a three-dimensional mesoscale simulation of the dynamics, cloud microphysics, and radiative transfer of a cirrus cloud system observed on 26 November 1991 during the second cirrus field program of the First International Satellite Cloud Climatology Program (ISCCP) Regional Experiment (FIRE-II) located in southeastern Kansas. The simulation was made with a mesoscale dynamical model utilizing a simplified bulk water cloud scheme and a spectral model of radiative transfer. Expressions for cirrus optical properties for solar and infrared wavelength intervals as functions of ice water content and effective particle radius are modified for the midlatitude cirrus observed during FIRE-II and are shown to compare favorably with explicit size-resolving calculations of the optical properties. Rawinsonde, Raman lidar, and satellite data are evaluated and combined to produce a time-height cross section of humidity at the central FIRE-II site for model verification. Due to the wide spacing of rawinsondes and their infrequent release, important moisture features go undetected and are absent in the conventional analyses. The upper-tropospheric humidities used for the initial conditions were generally less than 50% of those inferred from satellite data, yet over the course of a 24-h simulation the model produced a distribution that closely resembles the large-scale features of the satellite analysis. The simulated distribution and concentration of ice compares favorably with data from radar, lidar satellite, and aircraft. Direct comparison is made between the radiative transfer simulation and data from broadband and spectral sensors and inferred quantities such as cloud albedo, optical depth, and top-of-the-atmosphere 11-{mu}m brightness temperature, and the 6.7-{mu}m brightness temperature. 49 refs., 26 figs., 1 tab.
- DOE Contract Number:
- AI05-90ER61074
- OSTI ID:
- 466625
- Journal Information:
- Journal of the Atmospheric Sciences, Vol. 53, Issue 23; Other Information: PBD: 1 Dec 1996
- Country of Publication:
- United States
- Language:
- English
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