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Project Progress

In this task we are modifying models developed for Earth System scientists to set the stage for experiments for that will model exoplanet biospheres.

Ent Dynamic Global Terrestrial Ecosystem Model (Ent DGTEM): Last year, we implemented a full carbon cycle in the Goddard Institute for Space Studies general circulation model (GISS GCM), in collaboration with Anastasia Romanou at GISS, who implemented the ocean biogeochemistry model of VPL Co-I Gregg into the ocean model of the GISS GCM. We are continuing evaluation and testing of the coupled carbon dynamics to achieve a balanced carbon cycle with seasonal dynamics and prescribed land vegetation cover. Evaluation includes comparing equilibrium behavior of carbon stocks and identifying climate biases with observed meteorology for the 20^th century versus coupled to the GISS GCM. To do this with realistic land vegetation cover, we have been developing a global vegetation structure dataset to utilize the latest MODIS products (land cover, leaf area index, albedo), as well as LiDAR from the Geoscience Laser Altimeter System aboard the Ice, Cloud, and Land Elevation Satellite (ICESat/GLAS) (vegetation height) to serve as both boundary conditions or as a performance evaluation dataset. This dataset rectifies errors in a previous researcher’s attempt to compile at global vegetation height structure dataset from ICESat/GLAS by performing corrections for areas of steep topography and using MODIS and climate data to classify pixels not observed by ICESat/GLAS. Global tests with this dataset will help constrain the carbon budget of the Earth and processes in the Ent model, setting the stage for experiments for exoplanet biosphere modeling.

NASA Ocean Biogeochemical Model (NOBM): The NOBM is a model previously developed at NASA GSFC and is now being integrated within two modeling systems: the GISS Model E and GMAO GEOS-5 Earth system models. NOBM has been successfully integrated into GISS Model E and has been used to simulate post-industrial carbon cycling. Efforts to integrate into GEOS-5 are nearly complete, and the model has been fully integrated under the protocols of the Earth System Modeling Framework. Results are promising but there are differences between the GMAO Earth System model and the standalone data-driven model that remain unresolved.