First ISCCP Regional Experiment (FIRE) Atlantic Stratocumulus Transition Experiment (ASTEX) SOFIA ARAT Fokker F27 Aircraft Flight Data

The scientific objective of SOFIA during ASTEX was the study of energy transfer (heat, humidity and momentum fluxes) between the sea surface and the atmospheric boundary layer at scales ranging from the local scale to the mesoscale (50 km). The general concept of the program was to develop a measurement strategy based on nested boxes in which instrumentation would be used to estimate and quantify fluxes. These instruments, from which flux estimates at different scales would be measured, were used in connection with satellite measurements to understand and, hence, to validate the satellite integration of fluxes, particularly in the presence of mesoscale oceanic and atmospheric structures responsible for spatial inhomogeneity of fluxes.

The FOKKER F27 aircraft with flux measurement package and the airborne Lidar Leandre was used during ASTEX. The FOKKER 27 ARAT capabilities were as follows:

• Turbulence measurements of wind, temperature and moisture. Fast response sensors located on a nose boom 5m long, which measured - attack and sideslip angles by mobile vanes and by a five hole probe (Rosemound 858). - true airspeed by a Pitot probe - temperature by a fast response INSU probe - humidity by a Lyman-alpha humidity meter
• Mean state sensors - Rosemount temperature probe - Reverse-flow temperature probe - General Eastern dew point sensor
• Aerosols and cloud microphysics - 1-D drop size measurements from 0-6000 microns by four Knollenberg sensors - 2-D sensor OAP 2DC for drop sizes between 25 and 800 microns
• Liquid water content - Johnson-Williams sensors
• Radiative measurements, up- and downward - Longwave (14-40 microns) Eppley radiometers - Shortwave (0.2-2.8 microns) Eppley radiometers - Radiances (7.8-14 microns) Barnes PRT5 radiometers
• Chemical measurements(isokinetic veins)
• Pointint backscatter lidar (Leandre)
• Directional reflectances meausrements (POLDER- Polarized Direct Reflectance)