Earth Sciences Division (ESD) Department of Energy (DOE) Lawrence Berkeley National Laboratory (LBNL)

Climate Sciences Core Capability: Greenhouse Gas

LBNL-Earth Sciences Division’s Climate Science Department is involved in a wide variety of measurements projects, including eddy covariance measurements, tower and aircraft observations, and high-precision concentration and isotopic measurements of CO2, CH4, CO, 13C, and 18O. These observations are combined with transport and simulation models to improve our capabilities in soil and plant analyses, land-surface modeling, and regional atmospheric budgets.

We use eddy covariance flux systems to characterize C, water, and energy fluxes, as well as to perform experiments to elucidate effects of management on ecosystem carbon and energy exchanges with the atmosphere. 

The LBNL-ARM carbon project has two portable eddy flux towers deployed in fields being converted to switchgrass and three permanent flux systems at the ARM central facility at 4m, 25m, and 60m.

We have developed a comprehensive suite of greenhouse gas measurements gathered from tower and aircraft platforms.  Data is submitted to the ARM, NOA, AmeriFlux, and Fluxnet Archives.

Carbon cycle data streams generated by the LBNL ARM Carbon Project. All data are archived regularly and publicly available. In the past two years (to May 1, 2009), more than 120 scientists have downloaded our data from the ARM archives and 2,000 from AmeriFlux. CF = Central Facility.

Carbon Cycle Measurements

Progress: data streams and archiving

Precision CO2 system (PGS)

Operating since July 2001 at the CF. Continuous measurement at 2, 4, 25, and 60 m (each height every 15 minutes). Data archived monthly.

Precision CO system (CO)

Operating since May 2005. Continuous measurement at 60 m.

Data archived every 6 months.

CO2 isotopes (13CO2, C18OO),

Operating since 2001 at the CF. Regular sampling is a weekly diel.

Data archived every 3 months.

Radon (Rn)

Continuous measurement at 60 m (30 minute intervals) since 2006

Data archived monthly.

CO2, water, and energy flux at Central Facility.

Operating at the CF since 2001 at 60 m, since 2002 at 4 and 25 m.

Continuous measurement (30 minute intervals). Data archived weekly.

CO2, water, and energy flux, portables

Conducting intensive observation periods (IOP) around ARM SGP, 2001–2008. Data archived for each IOP.

Airborne continuous CO2 system

Operating since June 2007. Data archived for CLASIC IOP.

Data archived for non-CLASIC every 6 months.

NOAA-ESRL flasks for carbon cycle network (CO2, CO, CH4, N2O, H2, SF6, 13CO2 and C18OO)

Operating since January 2003 at the CF. Weekly sampling from 60 m.

Operating since September 2002 on aircraft. Collecting at 12 heights 1,500–17,500 feet above sea level since March 2006. Data archived monthly.

Radiocarbon (14C): CF tower and airborne

Operating since June 2007 at the CF and on aircraft. Periodic sampling for campaigns. Data available upon request

We are recognized for our expertise in obtaining high-precision concentration measurements of CO2, CH4, CO, and CO2 isotopes (13C and 18O). Cessna 206 and Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter planes provide continuous CO2 and CO concentrations (CO and CH4 from NASA’s Argus). Our capabilities include National Oceanic and Atmospheric–Earth System Research Laboratory (NOAA–ESRL) 12-flask samplers, flasks for high-precision 14CO2, and large volume samples for radon concentration. Land-surface fluxes of energy, water, and CO2 are modeled at 250 m resolution and aggregated to 10 km using a land-surface model (ISOLSM), Moderate Resolution Imaging Spectroradiometer (MODIS) data, and Mesonet meteorological forcing.

Our research approach applies a combination of field and laboratory experiments to investigate soil carbon cycling and storage. Facilities are available for density fractionation and chemical analysis of whole soils and specialized laboratory equipment to support our advanced analytical techniques – pH meter, shaker table, wrist action shaker, sonifier and bench top mixer, floor-mounted centrifuge, high-precision centrifuge with temperature control, chemical fume hoods, and analytical balances. 

We are able to perform high precision concentration measurements of CO2, CH4, CO, 13C, and 18O.  Facilities are available for density fractionation and chemical analysis of whole soils. Available laboratory equipment includes analytical balances, DI water dispenser, pH meter, shaker table, wrist action shaker, sonifier and bench top mixer, a floor-mounted centrifuge with four-place swinging bucket rotor and a high-precision centrifuge with temperature control equipped with a four-place swinging bucket rotor and a 24-place fixed angle (25º) rotor, chemical fume hoods, magnetic stirrer/hotplates, and chemical storage and sample preparation areas.

Vacuum lines are designed to separate complex gas mixtures (e.g., whole air samples) and extraction of water from plant and soil material for isotopic analyses.  Instruments include a muffle furnace used for combustion of solid phase samples, a roller mill and SPEX-Certiprep 8000M mixer mill for homogenizing sample material, a stereo-microscope, three drying ovens, a freeze dryer, refrigerators and freezers, and an ultramicrobalance.  We have an LI-6400 portable infra-red gas analyzer for photosynthesis and respiration and a system for measuring 13CO2 in soil respiration.

CO2, water, and energy fluxes in SGP are spatially heterogeneous and show strong interannual and seasonal variability. The relationships of these variations to climate, land-cover type, and vegetation status are complex, yet critical for estimating regional C budgets, surface forcing for SCMs, and as priors and tests for regional and global climate models. We are engaged in several model development tasks and have an array of applications for our models and ACRF observations such as exploring drought signals (including 18O and 13C as tracers of land-surface exchanges); producing forcing fields for cloud experiments at SGP and improving land-surface forcing in SCMs; and investigating PBL dynamics.

Using both bottom-up (distributed ecosystem models) and top-down (based on atmospheric measurements) approaches, regional-scale surface fluxes are estimated and then used to test our land-surface model output against our site-level eddy covariance data. These results are incorporated into NACP synthesis products and land-surface forcing for Single Column Models (SCMs) and GCMs. The results of our regional estimates for surface energy budgets are submitted for SCM modeling analyses. We are moving our stable isotope modules, plant physiology, and climate forcing inputs to the CLM framework, which we have coupled to the mesoscale climate model WRF. The coupled CLM-WRF model is used to explore the role of climate variability (e.g., droughts, cloud properties, radiation regime) on surface exchanges and the atmospheric 18O and 13C signal of regional-scale ecosystem water stress.

To perform regional modeling experiments, we have developed (and made available on the ARM archive) 10 km climate and vegetation forcing data derived from the >120 Mesonet and EF stations, NEXRAD precipitation measurements, and satellite data. Using this forcing data and our distributed model, we have characterized the impact of model resolution on estimates of carbon sources and sinks, as well as on LH and SH (Riley et al., 2009). Predicting net ecosystem CO2 fluxes requires characterization of the land surface at very high resolution, while latent and sensible heat-flux predictions are more robust across model spatial resolution.