COPS

Convective and Orographically-induced Precipitation Study (COPS)

2 April 2007 - 31 December 2007

Lead Scientist: Volker Wulfmeyer

Observatory: AMF , FKB

The ARM Mobile Facility (AMF) was deployed and operated in the Black Forest area during the Convective and Orographically-induced Precipitation Study (COPS) in summer 2007. The COPS region can be characterized by significant orographic precipitation with most of the summertime precipitation being convective. Due to major problems in predicting this type of precipitation, the area was chosen as a natural laboratory for convection during the intensive observational period of the German priority program on Quantitative Precipitation Forecasting (PWP) funded for a six-year period by the German Research Foundation (DFG). The aim was to identify the reasons of deficiencies in QPF and to improve the skill of mesoscale model forecasts with respect to precipitation. During the COPS field campaign, large efforts were put on observing the four-dimensional state of the atmosphere from the pre-convective environment, to the initiation of convection to the formation of clouds, to the development and decay of precipitation. For this purpose, measurements from several super sites (similar to the AMF) within an area of about 100 x 100 km2 were combined with satellite and radar data. At the super sites, a number of new scanning remote sensing instruments (cloud radar, lidar, microwave radiometer) were deployed. To transfer the COPS results to a larger scale, a General Observations Period (GOP) of the PQP covered the area of central Europe and the full year 2007. Here, close cooperation with the CloudNET project (stations Cabauw, Chilbolton, and Lindenberg) took place to derive a set of cloud microphysical parameters using novel synergetic algorithms and to compare those with numerical modeling results. For an improved connection between COPS and the GOP, researchers performed continuous measurements of the AMF for nine months at a special observation site in the COPS area where initiation of convection and cloud formation can often be expected. As COPS and the GOP have an open data policy, these data are available for all collaborators. The following science questions were investigated by combining the AMF, COPS, GOP and CloudNET data:

• What are the processes responsible for the formation and evolution of convective clouds in orographic terrain?
• What are the microphysical properties of orographically induced clouds and how do these depend on dynamics, thermodynamics, and aerosol microphysics?
• How can convective clouds in orographic terrain be represented in atmospheric models based on AMF, COPS, and GOP data?

To answer these science questions, the observations (ground-based, air- and satellite-borne) were strongly linked with atmospheric models ranging from detailed cloud microphysical models over state-of-the-art mesoscale models used in short-range weather prediction to general circulation models. Using this set of tools, researchers investigated how representative the observations were of an atmospheric column by the AMF and the other CloudNET stations for a model grid box (from about 2 to 200 km) in orographic terrain. The PQP program was coordinated with other international research programs such as the MAP Forest Demonstration Project (FDP) and THORPEX of the World Weather Research Program (WWRP). A strong collaboration between modelers, instrument principal investigators, weather services within international research programs and organizations were established. Consequently, the PQP community provided and studied unique data sets of observations and model results for addressing the science questions above.

The AMF helped scientists collect data about orographic precipitation, which is common in the Black Forest, particularly in the summertime.