Climate Research Group
The Climate Research Group
The Climate Research Group is made up of staff from the Rossby Centre at SMHI in Sweden. The Rossby Centre pursues research on climate processes and the behaviour of the climate system. The principal tools are the global and regional climate models developed within the research unit. The Rossby Centre has a broad history using satellite data for intercomparison of climate models. For ESA Cloud CCI they will exploit the Cloud CCI environmental climate variables (ECV) in regional and global climate models and also deliver the Climate Assessment Report.
The task will take place in the period from October 2012 to September 2013 and include
- the use of the cloud ECV products (cloud cover, cloud top height and temperature, liquid and ice water path) for evaluating EC-EARTH global coupled climate simulations and arctic climate simulations using the Regional Climate Model from Rossby Centre called RCA,
- the use of the ESA Cloud CCI products to investigate the benefits of increased model resolution for cloud simulation using EC-EARTH Atmosphere only experiments, and
- the documentation of the results in the Climate Assessment Report.
The evaluation will be done for monthly means, but also comparisons for higher temporal resolutions and other statistics will be performed. Example of simulated monthly cloud cover from an EC-EARTH run with prescribed sea surface temperature (SST) and sea ice as well as the cloud cover of ERA-Interim for July 2006 are shown in the figures.
The Regional Climate Model Evaluation Group
The regional climate model evaluation will be carried out by the Institute for Atmospheric and Climate Science of the ETH Zurich. This Work Pack (WP 073) of the ESA Cloud CCI Option 7 evaluates the applicability of ESA Cloud CCI products for assessing the representation of summer convection in km-scale climate and weather simulations. The specific aims are to compare the simulated diurnal cycle of cloud cover (CC), cloud top height (CTH), and cloud top temperature (CTT) over the European Alps and adjacent regions with the cloud properties derived from polar satellite sensors as part of ESA Cloud CCI. In addition, the project is linked to comparisons of cloud properties from geostationary sensors with a higher temporal resolution.
The detailed knowledge of the diurnally resolved cloud evolution enables the evaluation of key processes governing the diurnal cycle of convection over mountainous terrain (e.g. timing of the initiation of moist convection, transition from shallow to deep convection). Such observations can only be obtained from the satellite sensors. In this respect, the ESA Cloud CCI project provides a novel source of verification data, since few other observational methods provide the required spatial and temporal resolution. However, the tools and validation metrics to apply to the data and to properly include its uncertainty in climate and weather model verification have yet to be developed. This for instance includes the generation of synthetic satellite data out of the Consortium for Small-scale Modeling (COSMO) model in the climate mode (COSMO-CLM) by use of the RTTOV radiative transfer model (Figure). In addition, Top-of-the-Atmosphere (ToA) radiative fluxes from Geostationary Earth Radiation Budget (GERB) measurements will facilitate the interpretation of regional-scale model biases.
The proposed work will focus on two tasks:
- Comparison of ESA Cloud CCI parameters to 12 km resolution regional clomate models (RCMs) using parameterized convection
- Demonstration of the added value of cloud-resolving climate simulations with respect to RCMs using parameterized convection using the ESA Cloud CCI products.
The following picture shows the synthetic satellite radiances from two different setups in the COSMO-CLM model and satellite radiances from Spinning enhanced visible and infrared imager (SEVIRI) on Meteosat Second Generation (MSG) at 10.8 m brightness temperature at 12 UTC on 12 July 2006.