JOYCE: Jülich Observatory for Cloud Evolution

Abstract

The Jülich Observatory for Cloud Evolution (JOYCE), located at Forschungszentrum Jülich in the most western part of Germany, is a recently established platform for cloud research. The main objective of JOYCE is to provide observations, which improve our understanding of the cloudy boundary layer in a midlatitude environment. Continuous and temporally highly resolved measurements that are specifically suited to characterize the diurnal cycle of water vapor, stability, and turbulence in the lower troposphere are performed with a special focus on atmosphere–surface interaction. In addition, instruments are set up to measure the micro- and macrophysical properties of clouds in detail and how they interact with different boundary layer processes and the large-scale synoptic situation. For this, JOYCE is equipped with an array of state-of-the-art active and passive remote sensing and in situ instruments, which are briefly described in this scientific overview. As an example, a 24-h time series of the evolution of a typical cumulus cloud-topped boundary layer is analyzed with respect to stability, turbulence, and cloud properties. Additionally, we present longer-term statistics, which can be used to elucidate the diurnal cycle of water vapor, drizzle formation through autoconversion, and warm versus cold rain precipitation formation. Both case studies and long-term observations are important for improving the representation of clouds in climate and numerical weather prediction models.

The HD(CP)<sup>2</sup> Observational Prototype Experiment (HOPE) – an overview

“…It is permanently installed at FZJ. Amongst other instruments (see Löhnert et al, 2015), JOYCE contributed to HOPE with observations of a continuously scanning 35 GHz cloud radar, a Doppler lidar, and three microwave radiometers (one continuously scanning, one vertically pointing, and one continuously obtaining temperature profiles) for the spatiotemporal characterization of humidity and liquid water fields and for provision of the line-of-sightintegrated amount of water vapour and liquid water (Rose et al, 2005). The observations at the supersite Jülich were supported by high-resolved measurements of the vertical profile of the atmospheric temperature and water vapour mixing ratio, both at daytime and at night, which have been performed with the multi-wavelength polarization Raman lidar system BASIL of the Università degli Studi della Basilicata (UniBas), Italy (Di Girolamo et al, 2009, and the lidar system ARL-2 of the Max Planck Institute for Meteorology (MPIM) .…”

“…As an example, a detailed depiction of IOP7 (25 April 2013) consisting of a turbulently driven boundary layer development topped with afternoon single cumulus clouds in the afternoon can be found in Löhnert et al (2015). There, it is demonstrated that a holistic view of the daily development of the boundary layer is only possible through the synergetic treatment of different ground-based remote sensors.…”

Evaluation of large-eddy simulations forced with mesoscale model output for a multi-week period during a measurement campaign

“…A qualitative comparison of cloud water and cloud rain produced by the LES with the Cloudnet product (Illingworth et al, 2007) at the LACROS site complemented with the weather overview archive produced during HOPE is presented. Note that Cloudnet is a composite measurement product, which is derived from ceilometers, cloud radar, microwave radiometers and output from the COSMO model (e.g., Löhnert et al, 2015). Figure 4a shows the Cloudnet target classification at LACROS.…”

Ground-based lidar and microwave radiometry synergy for high vertical resolution absolute humidity profiling

“…At the permanent supersite JOYCE (Löhnert et al, 2014), measurements by the University of Basilicata Raman lidar system (BASIL) and an MWR were carried out, and auxiliary data from other instruments are available.…”