Regional Earth System Model Research Articles

Hot spots of vegetation‐climate feedbacks under future greenhouse forcing in Europe

We performed simulations of future biophysical vegetation‐climate feedbacks with a regional Earth System Model, RCA‐GUESS, interactively coupling a regional climate model and a process‐based model of vegetation dynamics and biogeochemistry. Simulated variations in leaf area index and in the relative coverage of evergreen forest, deciduous forest, and open land vegetation in response to simulated climate influence atmospheric state via variations in albedo, surface roughness, and the partitioning of the land‐atmosphere heat flux into latent and sensible components. The model was applied on a ∼50 × 50 km grid over Europe under a future climate scenario. Three potential “hot spots” of vegetation‐climate feedbacks could be identified. In the Scandinavian Mountains, reduced albedo resulting from the snow‐masking effect of forest expansion enhanced the winter warming trend. In central Europe, the stimulation of photosynthesis and plant growth by “CO2 fertilization” mitigated warming, through a negative evapotranspiration feedback associated with increased vegetation cover and leaf area index. In southern Europe, increased summer dryness restricted plant growth and survival, causing a positive warming feedback through reduced evapotranspiration. Our results suggest that vegetation‐climate feedbacks over the European study area will be rather modest compared to the radiative forcing of increased global CO2 concentrations but may modify warming projections locally, regionally, and seasonally, compared with results from traditional “off‐line” regional climate models lacking a representation of the relevant feedback mechanisms.

Regional Climate Modeling: Progress, Challenges, and Prospects

Regional climate modeling with regional climate models (RCMs) has matured over the past decade and allows for meaningful utilization in a broad spectrum of applications. In this paper, latest progresses in regional climate modeling studies are reviewed, including RCM development, applications of RCMs to dynamical downscaling for climate change assessment, seasonal climate predictions and climate process studies, and the study of regional climate predictability. Challenges and potential directions of future research in this important area are discussed, with the focus on those to which less attention has been given previously, such as the importance of ensemble simulations, further development and improvement of regional climate modeling approach, modeling extreme climate events and sub-daily variation of clouds and precipitation, model evaluation and diagnostics, applications of RCMs to climate process studies and seasonal predictions, and development of regional earth system models. It is believed that with both the demonstrated credibility of RCMs’ capability in reproducing not only monthly to seasonal mean climate and interannual variability but also the extreme climate events when driven by good quality reanalysis and the continuous improvements in the skill of global general circulation models (GCMs) in simulating large-scale atmospheric circulation, regional climate modeling will remain an important dynamicalmore » downscaling tool for providing the needed information for assessing climate change impacts and seasonal climate predictions, and a powerful tool for improving our understanding of regional climate processes. An internationally coordinated effort can be developed with different focuses by different groups to advance regional climate modeling studies. It is also recognized that since the final quality of the results from nested RCMs depends in part on the realism of the large-scale forcing provided by GCMs, the reduction of errors and improvement in physics parameterizations in both GCMs and RCMs remain a priority for climate modeling community.« less

Perspectives for regional earth system modeling

The recent development of regional climate models which can potentially produce long-term (multi-year to multi-decadal) simulations at high spatial resolution (5–50 km), opens a range of possibilities for interactive coupling with ecosystem, hydrology, ocean-sea-ice and chemistry models on the regional scale. Such coupling offers two primary advantages: (1) It is accomplished at scales more consistent with regional processes and available models; (2) It allows the explicit description of fine scale interactions between different Earth System components. A discussion of available models, strategies for coupling and issues which would especially benefit from an integrated regional modeling approach is presented.