Abstract
Abstract. In this study the shortwave cloud radiative effect (SWCRE) over ocean calculated by the ECHAM 5 climate model is evaluated for the cloud property input derived from ship based measurements and satellite based estimates and compared to ship based radiation measurements. The ship observations yield cloud fraction, liquid water path from a microwave radiometer, cloud bottom height as well as temperature and humidity profiles from radiosonde ascents. Level-2 products of the Satellite Application Facility on Climate Monitoring (CM~SAF) from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) have been used to characterize clouds. Within a closure study six different experiments have been defined to find the optimal set of measurements to calculate downward shortwave radiation (DSR) and the SWCRE from the model, and their results have been evaluated under seven different synoptic situations. Four of these experiments are defined to investigate the advantage of including the satellite-based cloud droplet effective radius as additional cloud property. The modeled SWCRE based on satellite retrieved cloud properties has a comparable accuracy to the modeled SWCRE based on ship data. For several cases, an improvement through introducing the satellite-based estimate of effective radius as additional information to the ship based data was found. Due to their different measuring characteristics, however, each dataset shows best results for different atmospheric conditions.
Highlights
Clouds strongly influence the energy budget of the Earth’s atmosphere
In this study the shortwave cloud radiative effect (SWCRE) over ocean calculated by the ECHAM 5 climate model is evaluated for the cloud property input derived from ship based measurements and satellite based estimates and compared to ship based radiation measurements
Within a closure study six different experiments have been defined to find the optimal set of measurements to calculate downward shortwave radiation (DSR) and the SWCRE from the model, and their results have been evaluated under seven different synoptic situations
Summary
Clouds strongly influence the energy budget of the Earth’s atmosphere. Because of their high degree of temporal and spatial variability, and the complexity of cloud processes, it remains challenging to model and predict the effect of clouds on the energy budget. The cloud radiative effect (CRE), defined as the difference between the net radiative fluxes of the cloudy and cloud-free atmosphere, is often not represented satisfactorily The reason for this is its dependence on a large number of cloud parameters and their highly variable distribution. These parameters include the vertical profiles of ice and liquid water, effective radius (re), and cloud droplet number concentration (CDNC). To evaluate this source of uncertainty in GCMs, it is important to identify those situations in which the model can reproduce the CRE well and badly. Over ocean which covers nearly 2/3 of the Earth, ground-based measurements of cloud properties and radiative fluxes are sparse
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
