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

Abstract

Abstract. The HD(CP) 2 Observational Prototype Experiment (HOPE) was performed as a major 2-month field experiment in Jülich, Germany, in April and May 2013, followed by a smaller campaign in Melpitz, Germany, in September 2013. HOPE has been designed to provide an observational dataset for a critical evaluation of the new German community atmospheric icosahedral non-hydrostatic (ICON) model at the scale of the model simulations and further to provide information on land-surface-atmospheric boundary layer exchange, cloud and precipitation processes, as well as sub-grid variability and microphysical properties that are subject to parameterizations. HOPE focuses on the onset of clouds and precipitation in the convective atmospheric boundary layer. This paper summarizes the instrument set-ups, the intensive observation periods, and example results from both campaigns.HOPE-Jülich instrumentation included a radio sounding station, 4 Doppler lidars, 4 Raman lidars (3 of them providePublished by Copernicus Publications on behalf of the European Geosciences Union. temperature, 3 of them water vapour, and all of them particle backscatter data), 1 water vapour differential absorption lidar, 3 cloud radars, 5 microwave radiometers, 3 rain radars, 6 sky imagers, 99 pyranometers, and 5 sun photometers operated at different sites, some of them in synergy. The HOPEMelpitz campaign combined ground-based remote sensing of aerosols and clouds with helicopter-and balloon-based in situ observations in the atmospheric column and at the surface.HOPE provided an unprecedented collection of atmospheric dynamical, thermodynamical, and micro-and macrophysical properties of aerosols, clouds, and precipitation with high spatial and temporal resolution within a cube of approximately 10 × 10 × 10 km 3 . HOPE data will significantly contribute to our understanding of boundary layer dynamics and the formation of clouds and precipitation. The datasets have been made available through a dedicated data portal.First applications of HOPE data for model evaluation have shown a general agreement between observed and modelled boundary layer height, turbulence characteristics, and cloud coverage, but they also point to significant differences that deserve further investigations from both the observational and the modelling perspective.

Helicopter-borne observations of the continental background aerosol in combination with remote sensing and ground-based measurements

“…These were corroborated in the frame of the HD(CP) 2 Observational Prototype Experiment HOPE (Macke et al, 2017) at the central European research observatory Melpitz, Germany. In particular, lidar-based aerosol optical properties are compared to respective values obtained from airborne in situ measurements, based on modeled optical properties for the regional background aerosol under consideration of the hygroscopic growth of the aerosol particles.…”

“…hdcp2.eu). The project's aims have been to reduce uncertainties in the representation of cloud and precipitation in atmospheric models (detailed information for HOPE is given in Macke et al, 2017).…”

A parameterization of the heterogeneous hydrolysis of N<sub>2</sub>O<sub>5</sub> for mass-based aerosol models: improvement of particulate nitrate prediction

“…relative humidity, temperature, wind speed, wind direction) were simultaneously measured at Melpitz. More details about the HOPE campaign are given in Macke et al (2017).…”

“…We also incorporated NewN2O5 into the 3-D fully online coupled model COSMO-MUSCAT in order to investigate the improvement of particulate nitrate prediction. The measurements of the HOPE campaign (HD(CP) 2 Observational Prototype Experiment; Macke et al, 2017) at the Melpitz site (12.93 • E, 51.53 • N; 86 m a.s.l. ; a regional background observatory of central Europe) and three other stations of the German federal environmental agency (UBA) over Germany were used to validate the simulation results.…”

Clear-air lidar dark band

“…In this paper we illustrate measurements carried out in the frame of the High-Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP) 2 ) Observational Prototype Experiment (HOPE, Macke et al, 2017 the morning until 06:00 UTC and by the passage of a cold front shortly afterwards. The passage of the cold front was followed by a circulation change from a south-westerly to west/north-westerly marine flow, with the sky clearing up in the late morning and the onset of a strong convective activity.…”