Numerical Simulation of Cirrus Clouds - Fire Case Study and Sensitivity Analysis
Abstract
The October 28, 1986 FIRE (First ISCCP Regional Experiment) case was simulated using the Regional Atmospheric Modeling System. This three dimensional, mesoscale model was applied in non-hydrostatic and nested-grid mode using explicit, bulk microphysics and radiation. The simulation resulted in very good agreement between observed and model predicted dynamic and cloud fields. We verified cloud height, thickness, areal extent and microphysical composition against GOES satellite imagery, lidar, and aircraft measurements taken during the FIRE Cirrus IFO (Intensive Field Observation). The simulated cirrus lifecycle is examined to determine possible formation, maintenance and dissipation mechanisms. Sensitivity simulations were run to determine long and short wave radiative forcing. Also, a simulation was run with no condensate to examine cloud feedbacks on the environment. Cloud top generation zones, fallstreaks, and layering were simulated. Longwave radiation appeared to be instrumental in developing weak convective activity in the lower layer thereby increasing it's optical depth. Cloud top cooling and cloud base heating affected the flow around the cloud. Secondarily, the effects of three upper boundary conditions on cirrus clouds were studied in a synoptic setting.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 12, 1991
- Accession Number
- ADA242902
Entities
People
- Scot T. Heckman
Organizations
- Colorado State University