C. Gerbig

Mesoscale covariance of transport and CO2 fluxes: Evidence from observations and simulations using the WRF‐VPRM coupled atmosphere‐biosphere model

[1]xa0We developed a modeling system which combines a mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, with a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration (VPRM). The WRF-VPRM modeling system was designed to realistically simulate high-resolution atmospheric CO2 concentration fields. In the system, WRF takes into account anthropogenic and biospheric CO2 fluxes and realistic initial and boundary conditions for CO2 from a global model. The system uses several “tagged” tracers for CO2 fields from different sources. VPRM uses meteorological fields from WRF and high-resolution satellite indices to simulate biospheric CO2 fluxes with realistic spatiotemporal patterns. Here we present results from the application of the model for interpretation of measurements made within the CarboEurope Regional Experiment Strategy (CERES). Simulated fields of meteorological variables and CO2 were compared against ground-based and airborne observations. In particular, the characterization by aircraft measurements turned out to be crucial for the model evaluation. The comparison revealed that the model is able to capture the main observed features in the CO2 distribution reasonably well. The simulations showed that daytime CO2 measurements made at coastal stations can be strongly affected by land breeze and subsequent sea breeze transport of CO2 respired from the vegetation during the previous night, which can lead to wrong estimates when such data are used in inverse studies. The results also show that WRF-VPRM is an effective modeling tool for addressing the near-field variability of CO2 fluxes and concentrations for observing stations around the globe.

Atmospheric CO2 modeling at the regional scale: Application to the CarboEurope Regional Experiment

[1]xa0The CarboEurope Regional Experiment Strategy (CERES) experiment took place in May and June 2005 in France and offers a comprehensive database on atmospheric CO2 and boundary layer processes at the regional scale. One “golden” day of CERES is interpreted with the mesoscale atmospheric model Meso-NH coupled on-line with the Interactions between Soil, Biosphere and Atmosphere, CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. The rapid diurnal cycle of carbon coupled with water and energy fluxes is parameterized including, e.g., plant assimilation, respiration, anthropogenic emissions, and sea fluxes. During the analyzed day, frequent vertical profiles and aircraft transects revealed high spatial and temporal variabilities of CO2 concentrations within the boundary layer at the regional scale: a 10-ppm gradient of CO2-mixing ratio is observed during the day by the aircraft measurements. The Meso-NH model proved able to simulate very well the CO2 concentration variability as well as the spatial and temporal evolution of the surface fluxes and the boundary layer in the domain. The model is used to explain the CO2 variability as a result of two complementary processes: (1) the regional heterogeneity of CO2 surface fluxes related to the land cover (e.g., winter crops versus a pine forest) and (2) the variability of mesoscale circulation across the boundary layer: development of the sea breeze in the western part of the domain and dominating wind flow in the eastern part of the domain.

Continuing global significance of emissions of Montreal Protocol-restricted halocarbons in the United States and Canada

[1]xa0Contemporary emissions of six restricted, ozone-depleting halocarbons, chlorofluorocarbon-11 (CFC-11, CCl3F), CFC-12 (CCl2F2), CFC-113 (CCl2FCClF2), methyl chloroform (CH3CCl3), carbon tetrachloride (CCl4), and Halon-1211 (CBrClF2), and two nonregulated trace gases, chloroform (CHCl3) and sulfur hexafluoride (SF6), are estimated for the United States and Canada. The estimates derive from 900 to 2900 in situ measurements of each of these gases within and above the planetary boundary layer over the United States and Canada as part of the 2003 CO2 Budget and Regional Airborne–North America (COBRA-NA) study. Air masses polluted by anthropogenic sources, identified by concurrently elevated levels of carbon monoxide (CO), SF6, and CHCl3, were sampled over a wide geographical range of these two countries. For each polluted air mass, we calculated emission ratios of halocarbons to CO and employed the Stochastic Time-Inverted Lagrangian Transport (STILT) model to determine the footprint associated with the air mass. Gridded CO emission estimates were then mapped onto the footprints and combined with measured emission ratios to generate footprint-weighted halocarbon flux estimates. We present statistically significant linear relationships between halocarbon fluxes (excluding CCl4) and footprint-weighted population densities, with slopes representative of per capita emission rates. These rates indicate that contemporary emissions of five restricted halocarbons (excluding CCl4) in the United States and Canada continue to account for significant fractions (7–40%) of global emissions.

Quantifying the impact of the North American monsoon and deep midlatitude convection on the subtropical lowermost stratosphere using in situ measurements

[1]xa0The chemical composition of the lowermost stratosphere exhibits both spatial and temporal variability depending upon the relative strength of (1) isentropic transport from the tropical tropopause layer (TTL), (2) diabatic descent from the midlatitude and northern midlatitude stratosphere followed by equatorward isentropic transport, and (3) diabatic ascent from the troposphere through convection. In situ measurements made in the lowermost stratosphere over Florida illustrate the additional impact of equatorward flow around the monsoon anticyclone. This flow carries, along with older stratospheric air, the distinct signature of deep midlatitude convection. We use simultaneous in situ measurements of water vapor (H2O), ozone (O3), total odd nitrogen (NOy), carbon dioxide (CO2), and carbon monoxide (CO) in the framework of a simple box model to quantify the composition of the air sampled in the lowermost stratosphere during the mission on the basis of tracer mixing ratios ascribed to the source regions for these transport pathways. The results show that in the summer, convection has a significant impact on the composition of air in the lowermost stratosphere, being the dominant source of water vapor up to the 380 K isentrope. The implications of these results extend from the potential for heterogeneous ozone loss resulting from the increased frequency and lifetime of cirrus near the local tropopause, to air with increased water vapor that as part of the equatorward flow associated with the North American monsoon can become part of the general circulation.

Transport in the subtropical lowermost stratosphere during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment

[1]xa0We use in situ measurements of water vapor (H2O), ozone (O3), carbon dioxide (CO2), carbon monoxide (CO), nitric oxide (NO), and total reactive nitrogen (NOy) obtained during the CRYSTAL-FACE campaign in July 2002 to study summertime transport in the subtropical lowermost stratosphere. We use an objective methodology to distinguish the latitudinal origin of the sampled air masses despite the influence of convection, and we calculate backward trajectories to elucidate their recent geographical history. The methodology consists of exploring the statistical behavior of the data by performing multivariate clustering and agglomerative hierarchical clustering calculations and projecting cluster groups onto principal component space to identify air masses of like composition and hence presumed origin. The statistically derived cluster groups are then examined in physical space using tracer-tracer correlation plots. Interpretation of the principal component analysis suggests that the variability in the data is accounted for primarily by the mean age of air in the stratosphere, followed by the age of the convective influence, and last by the extent of convective influence, potentially related to the latitude of convective injection (Dessler and Sherwood, 2004). We find that high-latitude stratospheric air is the dominant source region during the beginning of the campaign while tropical air is the dominant source region during the rest of the campaign. Influence of convection from both local and nonlocal events is frequently observed. The identification of air mass origin is confirmed with backward trajectories, and the behavior of the trajectories is associated with the North American monsoon circulation.

Corrigendum to "A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements" published in Atmos. Chem. Phys., 14, 3991–4012, 2014

S. Houweling1,2, M. Krol1,2,3, P. Bergamaschi4, C. Frankenberg5, E. J. Dlugokencky6, I. Morino7, J. Notholt8, V. Sherlock9, D. Wunch10, V. Beck11, C. Gerbig11, H. Chen12,13, E. A. Kort14, T. Rockmann2, and I. Aben1 1SRON Netherlands Institute for Space Research, Utrecht, the Netherlands 2Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands 3Department of Meteorology and Air Quality (MAQ), Wageningen University and Research Centre, Wageningen, the Netherlands 4European Commission Joint Research Centre, Institute for Environment and Sustainability, Ispra (Va), Italy 5Jet Propulsion Laboratory, Pasadena, CA, USA 6NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA 7Center for Global Environmental Research, National Institute for Environmental Studies (NIES) Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan 8Institute of Environmental Physics, University of Bremen, Bremen, Germany 9National Institute of Water and Atmospheric Research (NIWA), P.O. Box 14-901, Wellington, New Zealand 10Caltech, Pasadena, CA, USA 11Max Planck Institute for Biogeochemistry, Jena, Germany 12Center for Isotope Research (CIO), University of Groningen, the Netherlands 13CIRES, University of Colorado, Boulder, CO, USA 14Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, USA

A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements (vol 14, pg 3991, 2014)

S. Houweling1,2, M. Krol1,2,3, P. Bergamaschi4, C. Frankenberg5, E. J. Dlugokencky6, I. Morino7, J. Notholt8, V. Sherlock9, D. Wunch10, V. Beck11, C. Gerbig11, H. Chen12,13, E. A. Kort14, T. Rockmann2, and I. Aben1 1SRON Netherlands Institute for Space Research, Utrecht, the Netherlands 2Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands 3Department of Meteorology and Air Quality (MAQ), Wageningen University and Research Centre, Wageningen, the Netherlands 4European Commission Joint Research Centre, Institute for Environment and Sustainability, Ispra (Va), Italy 5Jet Propulsion Laboratory, Pasadena, CA, USA 6NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA 7Center for Global Environmental Research, National Institute for Environmental Studies (NIES) Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan 8Institute of Environmental Physics, University of Bremen, Bremen, Germany 9National Institute of Water and Atmospheric Research (NIWA), P.O. Box 14-901, Wellington, New Zealand 10Caltech, Pasadena, CA, USA 11Max Planck Institute for Biogeochemistry, Jena, Germany 12Center for Isotope Research (CIO), University of Groningen, the Netherlands 13CIRES, University of Colorado, Boulder, CO, USA 14Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, USA

Erratum: A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements (Atmospheric Chemistry and Physics (2014) 14 (3991-4012))

S. Houweling1,2, M. Krol1,2,3, P. Bergamaschi4, C. Frankenberg5, E. J. Dlugokencky6, I. Morino7, J. Notholt8, V. Sherlock9, D. Wunch10, V. Beck11, C. Gerbig11, H. Chen12,13, E. A. Kort14, T. Rockmann2, and I. Aben1 1SRON Netherlands Institute for Space Research, Utrecht, the Netherlands 2Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands 3Department of Meteorology and Air Quality (MAQ), Wageningen University and Research Centre, Wageningen, the Netherlands 4European Commission Joint Research Centre, Institute for Environment and Sustainability, Ispra (Va), Italy 5Jet Propulsion Laboratory, Pasadena, CA, USA 6NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA 7Center for Global Environmental Research, National Institute for Environmental Studies (NIES) Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan 8Institute of Environmental Physics, University of Bremen, Bremen, Germany 9National Institute of Water and Atmospheric Research (NIWA), P.O. Box 14-901, Wellington, New Zealand 10Caltech, Pasadena, CA, USA 11Max Planck Institute for Biogeochemistry, Jena, Germany 12Center for Isotope Research (CIO), University of Groningen, the Netherlands 13CIRES, University of Colorado, Boulder, CO, USA 14Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, USA