Project: Aerosol Comparisons between Observations and Models - The AeroCom-project (https://aerocom.met.no/) is an open international initiative of scientists interested in the advancement of the understanding of the global aerosol and its impact on climate. A large number of observations (including MODIS, POLDER, MISR, AVHHR, SEAWIFS, TOMS, AERONET, surface concentrations and other observations of relevance) and results from more than 20 global models have been assembled to document and compare state of the art modeling of the global aerosol. A common protocol has been established and models are asked to participate in the AeroCom experiments. Results are documented via interactive websites which give access to 2D fields and standard comparisons to observations. Regular workshops are held to discuss findings, joint publications and future directions. Summary: This experiment contains the model output from a series of sensitivity simulations, called "rain", carried out with the global aerosol-climate model ECHAM6-HAM2 (model version ECHAM6.1-HAM2.2-MOZ0.9). The simulations were performed within the scope of the AeroCom project (https://aerocom.met.no/). In general, the "rain" sensitivity study aims to provide a process-based observational constraint on the cloud lifetime effect by examining the parameterized precipitation stemming from warm rain. Aerosol (precursor) emission estimates of the year 2000 from the AEROCOM-II ACCMIP dataset were used as forcing. Details can be found in the associated publication of Mülmenstädt et al., (2020). The sensitivity simulations aim at investigating the effect of changing the autoconversion tuning factor (gamma) and the critical effective radius (rc) in the parameterization of autoconversion (see Fig.3 and Eq. 3 in Mülmenstädt et al., (2020). The respective setting of these parameters is indicated in the dataset group name (e.g. AeroCom ECHAM6-HAM2 warm rain sensitivity simulation gamma${x_gamma} rc${x_rc}. In the default setting of ECHAM6-HAM2, gamma is 4 and rc is -1. rc=-1 is used for simulations where no critical impact radius is applied. In addition to microphysical variables, the model output includes simulated radar reflections from CloudSat created with the satellite simulator COSP (Cloud Feedback Model Intercomparison Project Observational Simulator Package, see Bodas-Salcedo et al., (2011)). The radar reflectivities are outputted on so-called subcolumns to include information on the subgrid variability of hydrometeors. The model output is provided as global fields on a reduced Gaussian Grid (N48) with 3-hourly temporal resolution and covers the period January 2000 to December 2004. The dataset is well suited for evaluating the sensitivity of warm rain parameterization in ECHAM6-HAM2. The data publication is standardized according to the ATMODAT Standard (v3.0) (Ganske et al. 2021). The data standardization was funded within the framework of “Forschungsvorhaben zur Entwicklung und Erprobung von Kurationskriterien und Qualitätsstandards von Forschungsdaten” by the German Federal Ministry of Education and Research (BMBF; FKZ: 16QK02B).
