Researchers found and explained CAM5 missing cloud occurrences.
Ice clouds, often appearing at high altitudes, have a large impact on the Earth’s radiation budget. More reliable model simulation of ice cloud occurrence can greatly improve the quality of weather prediction and climate projection. The research team investigated whether the global climate model CAM5 can realistically simulate the macro- and microphysical properties of ice clouds.
The team found that further improvements are needed to understand sub-grid relative humidity (RH) variability and ice nucleation and growth in the model.
The research team evaluated the cloud properties simulated by CAM5 using aircraft measurements from the HIAPER Pole-to-Pole Observations (HIPPO) campaign. The model was nudged towards reanalysis data, so that the model data can be collocated with flight tracks and directly compared with the observations. The model reproduces 79.8?% of observed cloud occurrences inside model grid boxes and even higher (94.3%) for ice clouds (T≤-40°C). The missing cloud occurrences in the model are primarily ascribed to the fact that the model cannot account for the high spatial variability of observed relative humidity (RH). Furthermore, model RH biases are mostly attributed to the discrepancies in water vapor, rather than temperature. At the micro-scale of ice clouds, the model captures the observed increase of ice crystal mean sizes with temperature, albeit with smaller sizes than the observations.
Contacts (BER PM)
Earth System Modeling Program
Pacific Northwest National Laboratory
The U.S. Department of Energy Office of Science, Biological and Environmental Research supported this research as part of the Accelerated Climate Modeling for Energy (ACME) project of the Earth System Modeling (ESM) program.
Wu, C., X. Liu, M. Diao, K. Zhang, A. Gettelman, Z. Lu, J.E. Penner, Z. Lin. "Direct Comparisons of Ice Cloud Macro- and Microphysical Properties Simulated by the Community Atmosphere Model Version 5 with HIPPO Aircraft Observations." Atmos. Chem. Phys., 17, 4731-4749 (2017). [DOI:10.5194/acp-17-4731-2017]
BER Highlight: Evaluating Climate Simulations against Aircraft Measurements
SC-23.1 Climate and Environmental Sciences Division, BER
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]
List all highlights (possible long download time)