A5084676642- Atmospheric and Environmental Gas Dynamics
- Climate variability and models
- Atmospheric chemistry and aerosols
- Meteorological Phenomena and Simulations
- Atmospheric Ozone and Climate
- Plant Water Relations and Carbon Dynamics
- Genetics, Bioinformatics, and Biomedical Research
- Methane Hydrates and Related Phenomena
- Hydrocarbon exploration and reservoir analysis
- Carbon Dioxide Capture Technologies
- Cryospheric studies and observations
- Climate Change Policy and Economics
- Gothic Literature and Media Analysis
- Archaeology and Natural History
- CO2 Sequestration and Geologic Interactions
- Geology and Paleoclimatology Research
- American Environmental and Regional History
- Climate change and permafrost
- Hydrology and Watershed Management Studies
- Global Energy and Sustainability Research
- Remote Sensing in Agriculture
- Spectroscopy and Laser Applications
- Vehicle emissions and performance
- Environmental Impact and Sustainability
- Soil Moisture and Remote Sensing
Colorado State University
2012-2023
Cooperative Institute for Research in Environmental Sciences
2020
University of Colorado Colorado Springs
2019
Office of Science
2016
National Oceanic and Atmospheric Administration
1999-2007
Purdue University West Lafayette
2007
Laboratoire des Sciences du Climat et de l'Environnement
2007
Tohoku University
2007
Heidelberg University
1999
University of Victoria
1995-1999
Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, momentum across land-atmosphere interface to be specified. These are calculated by submodels called land surface parameterizations. Over last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations global soil-vegetation-atmosphere transfer system as advances in plant physiological hydrological...
The Common Land Model (CLM) was developed for community use by a grassroots collaboration of scientists who have an interest in making general land model available public and further development. major characteristics include enough unevenly spaced layers to adequately represent soil temperature moisture, multilayer parameterization snow processes; explicit treatment the mass liquid water ice their phase change within system; runoff following TOPMODEL concept; canopy photo...
Measurements of midday vertical atmospheric CO 2 distributions reveal annual-mean gradients that are inconsistent with models estimate a large transfer terrestrial carbon from tropical to northern latitudes. The three most closely reproduce the observed weaker uptake –1.5 petagrams per year (Pg C –1 ) and emission +0.1 Pg compared previous consensus estimates –2.4 +1.8 , respectively. This suggests industrial emissions plays smaller role than previously thought that, after subtracting...
Monthly CO 2 fluxes are estimated across 1988–2003 for 22 emission regions using data from 78 measurement sites. The same inversion (method, priors, data) is performed with 13 different atmospheric transport models, and the spread in results taken as a measure of model error. Interannual variability (IAV) winds not modeled, so any IAV measurements attributed to fluxes. When both this error random estimation errors considered, flux obtained statistically significant at P ≤ 0.05 when grouped...
Abstract This paper overviews the short‐term (biophysical) and long‐term (out to around 100 year timescales; biogeochemical biogeographical) influences of land surface on weather climate. From our review literature, evidence is convincing that terrestrial ecosystem dynamics these timescales significantly influence atmospheric processes. In studies past possible future climate change, are as important changes in composition, ocean circulation, ice sheet extent, orbit perturbations.
The TransCom 3 experiment was begun to explore the estimation of carbon sources and sinks via inversion simulated tracer transport. We build upon previous work by presenting seasonal inverse results which provide estimates flux for 11 land ocean regions using 12 atmospheric transport models. monthly fluxes represent mean cycle 1992 1996 time period. spread among model is larger than average their estimated uncertainty in northern extratropics vice versa tropical regions. In regions, largest...
Precision requirements are determined for space‐based column‐averaged CO 2 dry air mole fraction data. These result from an assessment of spatial and temporal gradients in the relationship between precision surface flux uncertainties inferred inversions data, effects biases on fidelity inversions. Observational system simulation experiments synthesis inversion modeling demonstrate that Orbiting Carbon Observatory mission design sampling strategy provide means to achieve these data requirements.
The ability to reliably estimate CO 2 fluxes from current in situ atmospheric measurements and future satellite is dependent on transport model performance at synoptic shorter timescales. TransCom continuous experiment was designed evaluate the of forward simulations hourly, daily, timescales, we focus latter two this paper. Twenty‐five models or variants submitted hourly time series nine predetermined tracers (seven for ) 280 locations. We extracted synoptic‐scale variability daily averaged...
The Amazon Basin is crucial to global circulatory and carbon patterns due the large areal extent flux magnitude. Biogeophysical models have had difficulty reproducing annual cycle of net ecosystem exchange (NEE) in some regions Amazon, generally simulating uptake during wet season efflux seasonal drought. In reality, opposite occurs. Observational modeling studies identified several mechanisms that explain observed cycle, including: (1) deep soil columns can store water amount, (2) ability...
We show that transport differences between two commonly used global chemical models, GEOS-Chem and TM5, lead to systematic space-time in modeled distributions of carbon dioxide sulfur hexafluoride. The distribution suggests inconsistencies the simulated by most likely due representation vertical motion. further demonstrate these result surface CO
Abstract Carbonyl sulfide (COS) is an atmospheric trace gas that participates in some key reactions of the carbon cycle and thus holds great promise for studies processes. Global monitoring networks sampling programs provide concurrent data on COS CO 2 concentrations free troposphere boundary layer over vegetated areas. Here we present a modeling framework interpreting these illustrate what measurements might tell us about We implemented mechanistic empirical descriptions leaf soil uptake...
Spatial and temporal variations of atmospheric CO2 concentrations contain information about surface sources sinks, which can be quantitatively interpreted through tracer transport inversion. Previous inversion calculations obtained differing results due to different data, methods models used. To isolate the uncertainty, we have conducted a set annual mean experiments in 17 or model variants were used calculate regional carbon sinks from same data with standardized method. Simulated is...
The Community Land Model version 3 (CLM3.0) simulates land‐atmosphere exchanges in response to climatic forcings. CLM3.0 has known biases the surface energy partitioning as a result of deficiencies its hydrological and biophysical parameterizations. Such models, however, need be robust for multidecadal global climate simulations. FLUXNET now provides an extensive data source carbon, water investigating land processes, it encompasses range ecosystem‐climate interactions. Data from 15 sites...
We present a data assimilation system to estimate surface fluxes of CO 2 and other trace gases from observations their atmospheric abundances. The is based on ensemble methods under development for Numerical Weather Prediction (NWP) the first its kind be used flux estimation. was developed overcome computational limitations encountered when large number are unknown fluxes. approach attractive because it returns an approximation covariance, does not need adjoint model or linearization...
We present a detailed investigation of the gross 12 C and 13 exchanges between atmosphere biosphere their influence on δ variations in atmosphere. The photosynthetic discrimination Δ against is derived from biophysical model coupled to general circulation [ Sellers et al. , 1996a], where stomatal conductance carbon assimilation are determined simultaneously with ambient climate. respired calculated by biogeochemical Potter 1993; Randerson 1996] as sum contributions compartments varying ages....
The isotope 18 O in CO 2 is of particular interest studying the global carbon cycle because it sensitive to processes by which land biosphere absorbs and respires . Carbon dioxide water exchange isotopically both leaves soils, character atmospheric strongly influenced biota, should constrain gross primary productivity total respiration ecosystems. In this study we calculate surface fluxes for vegetation soils using SiB2 model coupled with Colorado State University general circulation model....
Biogeochemical models must include a broad variety of biological and physical processes to test our understanding the terrestrial carbon cycle predict ecosystem biomass fluxes. We combine photosynthesis biophysical calculations in Simple Biosphere model, Version 2.5 (SiB2.5) with biogeochemistry from Carnegie‐Ames‐Stanford Approach (CASA) model create SiBCASA, hybrid capable estimating fluxes diurnal decadal timescales. add dynamic allocation Gross Primary Productivity growth maintenance...
The exchange of carbon dioxide (CO2) between the atmosphere and terrestrial ecosystems due to photosynthesis respiration has been simulated using a new version simple biosphere model (SiB2) Colorado State University (CSU) general circulation (GCM). Parameters associated with extent seasonality vegetation were derived from satellite observations. fluxes calculated at GCM time step 6 min, so that diurnal cycle is well resolved. Annual net primary productivity by coupled agrees previous...
Predicting the global carbon and water cycle requires a realistic representation of vegetation phenology in climate models. However most prognostic models are not yet suited for applications, diagnostic satellite data can be uncertain lack predictive power. We present framework assimilation Fraction Photosynthetically Active Radiation absorbed by (FPAR) Leaf Area Index (LAI) from MODerate Resolution Imaging Spectroradiometer (MODIS) to constrain empirical temperature, light, moisture...
The African continent has a large and growing role in the global carbon cycle, with potentially important climate change implications. However, sparse observation network around means that Africa is one of weakest links our understanding cycle. Here, we combine data from regional inventories as well forward inverse model analyses to appraise what known about Africa's continental-scale dynamics. With low fossil emissions productivity largely compensates respiration, land conversion primary...
Carbon dioxide concentrations due to fossil fuel burning and CO 2 exchange with the terrestrial biosphere have been modeled 12 different three‐dimensional atmospheric transport models. The models include both on‐line off‐line types use a variety of advection algorithms subgrid scale parameterizations. A range model resolutions is also represented. distributions show large responses. For experiment using source, annual mean meridional gradient at surface varies by factor 2. This suggests...