ABOVECLOUD

Azores: Above-Cloud Radiation Budget near Graciosa Island

15 April 2010 - 15 September 2010

Lead Scientist: Mark Miller

Observatory: AMF, GRW

The scientific focus is to measure the cloud-top downwelling radiative fluxes in coincidence with trace gas measurements made at Pico Observatory, Pico Island Azores. To enhance measurement capabilities in the vicinity of Graciosa and to take advantage of a unique opportunity to measure cloud transmittance in the marine, instruments associated with the ARM Ancillary Facility will be deployed at the Pico Observatory during May through September of 2010. Of particular interest are broadband longwave and shortwave radiometers and a shadow-band radiometer. Conditions at Pico include high wind velocities, but the operators of the Pico Observatory (Detlev Helmig, University of Colorado) are experienced and their experience necessary to determine a deployable instrument configuration. Measurement of cloud-top radiation budget in marine stratocumulus will enable calculation of solar transmittance as a function of cloud microphysical structure and above inversion air mass source. Such a strategy can be used to address uncertainties in aerosol indirect effects, which carry the largest uncertainties of all forcings in the latest IPCC report. Marine stratocumulus are poorly simulated in climate models, so these observations will also contribute to improved understanding of this climatologically significant cloud genera.