Concept of the JOYCE Core Facility

The Juelich Observatory for Cloud Evolution (JOYCE) has become an established site for ground-based remote sensing with a special focus on radar and passive microwave observations. JOYCE is a cooperation of the University of Bonn, the University of Cologne and the Research Center Jülich. Currently, JOYCE is transformed into a Core Facility (JOYCE - CF) of the German Research Foundation (DFG, Deutsche Forschungsgemeinschaft) to ensure long-term high quality observations.

As major instrumentation a set of two polarimetric X-band radars located in 40 km distance from each other operate at 9.3 GHz. They can be combined with a microwave profiler, two cloud radars operating at 94 GHz and 35 GHz, an infrared spectrometer, a Doppler wind lidar and two ceilometers. All instruments are located within a radius of 10 m in close distance to one of the polarimetric X-band radars. This setup ensures optimal and simultaneous monitoring of the development of the microphysical and macrophysical quantities of clouds and precipitation. The instrument platform also offers a base for additional instrumentation for measurement campaigns and additional long-term observations. The set of remote sensing measurements together with the additional instrumentation enables a wide opportunity for instrument synergies.

JOYCE – CF offers a centralized access to instruments, operational data sets and observation platforms. The instrumentation is generally operated using standardized measurements routines for long-term observations with continuous procedures and observables. Targeted intensive measurement campaigns will be performed where JOYCE-CF also welcomes additional installations and campaign requests from external users.

The two polarimetric X-band radars deliver a volume scan in a five minutes schedule, consisting of Plan-Position-Indicators (PPIs), a Range-Height-Indicator (RHI) and a vertical scan. Both radars cover an area with 100 km radius in 1 deg and < 100 m bin size. This close distance supports instrument synergies of the radars and other local instrumentation. Within all scan-procedures the polarimetric information as reflectivity in horizontal and vertical polarization, differential reflectivity, cross-correlation coefficient, differential phase shift and Doppler velocity is stored an archived. These measurements deliver a base for local surface rain rates and a 3D radar composite with hydrometeor classification. Additionally the radars can be compared with a gauge network, microwave backhaul links and a stormchase-trailer mounted with a laser distrometer, a ceilometer, multi weather sensor, micro rain radar, hemispheric camera and a GPS sensor. The passive remote sensing observations give a base for higher level products like cloud classification, boundary layer height and hydrometeor classifications. Cloud radars provide deeper insights in microphysical processes and multi sensor observations give additional benefits to cloud and precipitation observations. This set of calibrated measurements will be distributed in a central database as level one and higher level products.

The large variety of cloud and precipitation observations and their environment will provide users with a solid database to investigate various research questions. Already today, the observations are widely used in different research projects to investigate microphysical processes, evaluate atmospheric models, improve model parametrizations and evaluate satellite data.

As the precipitation in central Europe is mostly characterized by stratiform precipitation about 750 mm per year single significant extreme events can cause large destructions and are still challenging. E.g. at the 20 June 2013 a supercell caused high surface precipitation, which leaded to floods in the city center of Bonn. At the 9 June 2014 a supercell caused hail damages and was followed by a mesoscale convective system at the same day, which lead to large destructions by downbursts, precipitation and lightning. A strong supercell at the 5 July 2015 caused large hail (> 6 cm) and many damages on cars, roofs and plants. In May and June 2016 a set of strong supercells in whole Germany caused severe local floodings and landslides. These few extreme events are exploited on in their micro- and macrophysical processes. But also the stratiform events can be used to evaluate Quasi-Vertical-Profiles (QVPs) and give detailed information about developments. This information is used for model evaluations.

This presentation will provide an overview of the instrumentation and the developed products in order to demonstrate the large variety of measurements and their synergy potential. Specifically, the holistic view of a precipitation cell compiled from the different measurement instruments will illustrate the possibilities of JOYCE – CF.