# Presentation: 146941

## AmeriFlux Data Assimilation System (ADAS) and its Application at the Missouri Ozark AmeriFlux Site (MOFLUX)

**AmeriFlux Data Assimilation System (ADAS) and its Application at the Missouri Ozark AmeriFlux Site (MOFLUX)**

- ADAS Developers:
- L. Gu, Qing Liu, Mac Post, Tom Boden, Oak Ridge National Laboratory (ORNL)
- Suzanne Lenhart, University of Tennessee / ORNL

- Acknowledgement:** **This project is supported by U.S. Department of Energy, Office of Science, Biological and Environmental Research Program, Environmental Science Division, Terrestrial Carbon Program.

- MOFLUX Investigators:
- ORNL: L. Gu, B. Yang, P. Hanson, S. Wullschleger, J. Riggs, D. Sluss
- University of Missouri – Columbia: S. Pallardy, K. Hosman
- ATDD/NOAA: T. Meyers, M. Heuer

**What is ADAS?**
-    A data assimilation system that integrates a comprehensive land surface model (the Fluxes and Pools Integrated Simulator, FAPIS) with diverse observations of biophysical and biogeochemical fluxes and ecosystem states measured at AmeriFlux sites. ADAS generates synthetic, value-added products (reanalysis dataset) that are spatially consistent and temporally complete for the AmeriFlux network to support NACP regional initiatives, ecosystem process studies, and assimilative land surface modeling.

**Major ADAS Functions**

- Synthetic data products
- 	- Uniform and complete ecosystem level net fluxes, including carbon dioxide, water vapor, sensible heat, net radiation, terrestrial radiation and momentum.
- 	- Contributions to net fluxes from ecosystem components, including gross primary production, leaf respiration, stem respiration, soil respiration, transpiration, soil evaporation, intercepted rainfall re-evaporation, biomass heat storage, metabolic heat storage, sensible heat flux from canopy, sensible heat flux from soil, etc.
- 	- Fundamental ecosystem parameters, including biochemical parameters (Vcmax, Jmax, TPU, etc), stomatal conductance parameters, LAI, etc.
- A platform for development and testing of new effective and efficient methodologies for complex optimization.
- A next generation land surface model that integrates forward simulation and intensive and extensive observational networks to support weather prediction and climate modeling.

**ADAS Methodology**

-  Types of observations assimilated (if available):
-  CO2 flux
-  Water vapor flux
-  Sensible heat flux
-  Terrestrial radiation
-  Canopy reflectances
-  Soil respiration
-  Momentum flux
-  Soil temperature
-  Soil moisture
-  Any site biochemical / biogeochemical parameters

-  Integrated prognostic simulation and assimilation

-  Automatic switch between prognostic simulation and assimilation

**ADAS Library of Optimization Methods**

**ADAS Forward Model FAPIS Structures**

- Canopy vertical structure: Any number of layers
- Leaf grouping: Sunlit / shaded leaves and dry / wet leaves for photosynthesis and energy balance
- Solar radiative transfer: Photon transport equations / two stream radiative transfer model
- Longwave radiative transfer: Longwave radiative transfer matrix method
- Turbulence transfer / scalar profile: Localized near field (LNF) theory
- Leaf photosynthesis: Farquhar biochemical model
- Stomatal conductance: Ball – Berry - Leuning model / Buckley – Farquhar model
- Leaf energy balance: Quartic equation without thermal equilibrium assumption
- Soil vertical structure: Any number of soil layers
- Soil moisture dynamics: Richards equation
- Soil temperature dynamics: Heat diffusion equation

**Examples of ADAS Synthetic Products for the MOFLUX Site**