A5023917476- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Atmospheric chemistry and aerosols
- Hydrocarbon exploration and reservoir analysis
- Climate variability and models
- Methane Hydrates and Related Phenomena
- Geochemistry and Geologic Mapping
- Air Quality and Health Impacts
- Synthetic Aperture Radar (SAR) Applications and Techniques
- CO2 Sequestration and Geologic Interactions
- Precipitation Measurement and Analysis
- Climate Change Policy and Economics
- Catalysis and Oxidation Reactions
- Meteorological Phenomena and Simulations
- Tropical and Extratropical Cyclones Research
- Constructed Wetlands for Wastewater Treatment
- Cryospheric studies and observations
- Carbon Dioxide Capture Technologies
- Vehicle emissions and performance
- Soil Moisture and Remote Sensing
- Spectroscopy and Laser Applications
- Water Treatment and Disinfection
- Wastewater Treatment and Nitrogen Removal
- Climate change and permafrost
Universities Space Research Association
2012-2020
Goddard Space Flight Center
1987-2020
Research Institute for Sustainability at GFZ
2019-2020
NOAA Air Resources Laboratory
2012
Environmental Defense Fund
2004-2011
Harvard University
2002-2004
Planetary Science Institute
2002-2004
A much-cited bar chart provided by the Intergovernmental Panel on Climate Change displays climate impact, as expressed radiative forcing in watts per meter squared, of individual chemical species. The organization reflects history atmospheric chemistry, which investigators typically focused a single species interest. However, changes pollutant emissions and concentrations are symptom, not cause , primary driver anthropogenic change: human activity. In this paper, we suggest organizing...
Methane has exhibited significant interannual variability with a slowdown in its growth rate beginning the 1980s. We use 3‐D chemical transport model accounting for interannually varying emissions, transport, and sinks to analyze trends CH 4 from 1988 1997. Variations sources were based on meteorological country‐level socioeconomic data. An inverse method was used optimize strengths of base year, 1994. present best‐guess budget along sensitivity tests. The analysis suggests that sum...
Abstract. The tropical tropopause layer (TTL) is the transition region between well-mixed convective troposphere and radiatively controlled stratosphere with air masses showing chemical dynamical properties of both regions. representation TTL in meteorological reanalysis data sets important for studying complex interactions circulation, convection, trace gases, clouds, radiation. In this paper, we present evaluation climatological long-term temperature characteristics ERA-Interim, ERA5,...
Abstract Observations taken over the last few decades indicate that dramatic changes are occurring in Arctic‐Boreal Zone (ABZ), which having significant impacts on ABZ inhabitants, infrastructure, flora and fauna, economies. While suitable for detecting overall change, current capability is inadequate systematic monitoring improving process‐based large‐scale understanding of integrated components ABZ, includes cryosphere, biosphere, hydrosphere, atmosphere. Such knowledge will lead to...
Abstract. The precise contribution of the two major sinks for anthropogenic CO2 emissions, terrestrial vegetation and ocean, their location year-to-year variability are not well understood. Top-down estimates spatiotemporal variations in emissions uptake expected to benefit from increasing measurement density brought by recent situ remote observations. We uniquely apply a batch Bayesian synthesis inversion at relatively high resolution surface observations bias-corrected GOSAT satellite...
Abstract. The 13C isotopic ratio of methane, δ13C CH4, provides additional constraints on the CH4 budget to complement from observations. interpretation observations is complicated, however, by uncertainties in methane sink. reaction with Cl highly fractionating, increasing relative abundance 13CH4, but there currently no consensus strength tropospheric Global model simulations halogen chemistry differ strongly one another terms both magnitude and its geographic distribution. This study...
The tropical tropopause is a transition layer between the troposphere and stratosphere that influences global climate atmospheric chemistry. Several studies have reported multidecadal cooling suggested correlation observed temperature stratospheric water vapor. Our more rigorous examination of observations shows trends greater uncertainty than previously may not be statistically significant. We used two approaches to remove time‐varying bias effects from cold‐point estimated radiosonde...
Aircraft observations of Asian outflow from the Transport and Chemical Evolution Over Pacific (TRACE‐P) aircraft mission over NW (March April 2001) show large CH 4 enhancements relative to background, as well strong ‐C 2 H 6 ‐CO correlations that provide signatures regional sources. We apply a global chemical transport model simulation system for TRACE‐P period interpret these in terms sources explore particular unique constraints correlations. use priori source inventory constrained with...
Relatively little attention has been paid to integrating gaseous N2O generated by wastewater treatment into overall reactive nitrogen (Nr) pollution reduction. We propose that there is potential for substantial reductions in emissions through the addition of denitrification processes existing nitrifying plants (WWTPs), which are designed lower ammonia levels but currently do not reduce Nr. In providing benefit reducing total concentrations effluent, this kind WWTP upgrade demonstrated energy...
We estimated the global abundance of OH for years 1988–1994 by interpreting observations methyl chloroform (MCF) from two networks using an inverse technique and a 3‐D chemical transport model driven assimilated meteorology. Our inversion approach optimized both emissions MCF OH. Because priori overestimate latitudinal gradient concentration in standard setup, lowers sink due to Optimized are about 10% lower than published inventories on average between 1988 1994, decrease suggested implies...
A recent study of 1979–2010 tropical tropospheric temperature trends in climate model simulations and satellite microwave sounding unit (MSU) observations concluded that, although both showed greater warming the upper than lower troposphere, vertical amplification was exaggerated most models. We repeat that analysis trends, difference trend ratios using five radiosonde datasets. Some, but not all, comparisons support notion models exceeds observed. However, larger ranges compared with those...
Abstract. We present the Efficient CH4–CO–OH (ECCOH) chemistry module that allows for simulation of methane, carbon monoxide, and hydroxyl radical (CH4–CO–OH) system, within a climate model, cycle or Earth system model. The computational efficiency many multi-decadal sensitivity simulations which primarily determines global atmospheric oxidizing capacity. This capability is important capturing nonlinear feedbacks understanding perturbations to CO, OH, concomitant impacts on climate....
A unique set of data collected for a soil moisture experiment has been used to evaluate three radar backscatter roughness models. The were by the NASA Space Shuttle flight 41G (SIR-B) synthetic aperture (SAR) in an intensively farmed area near Fresno, California. SIR-B swath included large number bare dry fields with variety surface roughnesses. small perturbation model gave best results, particularly when definite periodic row structure omitted. standard deviation heights appears be good...
Atmospheric carbon dioxide (CO2) inversions for estimating natural fluxes typically do not allow adjustment of fossil fuel CO2 emissions, despite significant uncertainties in emission inventories and inadequacies the specification international bunker emissions inversions. Also, most place release from combustion biospheric sources entirely at surface. However, a non-negligible portion actually occurs form reduced species, which are eventually oxidized to downwind. Omission this 'chemical...
A two‐dimensional model is used to evaluate the impact of stratospheric chlorine on δ 13 C CH 4 at surface and analyze sensitivity different chemical transport processes. It found that Cl depends relative strength lower upper branches circulation, which emphasize regions differing rates methane fractionation. estimated increase in concentrations associated with human activity has contributed most 0.54‰ 2‰ observed over past century. follows growth importance heavier sources (associated, for...
Abstract. Top–down estimates of the spatiotemporal variations in emissions and uptake CO2 will benefit from increasing measurement density brought by recent future additions to suite situ remote platforms. In particular, planned NASA Active Sensing Emissions over Nights, Days, Seasons (ASCENDS) satellite mission provide greater coverage cloudy regions, at high latitudes, night than passive systems, as well precision accuracy. a novel approach quantifying ability column measurements constrain...
Abstract. We present the Efficient CH4-CO-OH chemistry module (ECCOH) that allows for simulation of methane, carbon monoxide and hydroxyl radical (CH4-CO-OH) system, within a climate model, cycle or earth system model. The computational efficiency many multi-decadal sensitivity simulations which primarily determines global atmospheric oxidizing capacity. This capability is important capturing nonlinear feedbacks understanding perturbations to CO OH concomitant impacts on climate. implemented...
Abstract. The 13C isotopic ratio of methane, δ13C CH4, provides additional constraints on the CH4 budget to complement from observations. interpretation observations is complicated, however, by uncertainties in methane sink. reaction with Cl highly fractionating, increasing relative abundance 13CH4, but there currently no consensus strength tropospheric We use a set GEOS global model simulations different predicted fields test sensitivity diversity output chemical transport models. find that...
Abstract. Top-down estimates of the spatiotemporal variations in emissions and uptake CO2 will benefit from increasing measurement density brought by recent future additions to suite situ remote platforms. In particular, planned NASA Active Sensing Emissions over Nights, Days, Seasons (ASCENDS) satellite mission provide greater coverage cloudy regions, at high latitudes, night than passive systems, as well precision accuracy. a novel approach quantifying ability column measurements constrain...
Abstract. The precise contribution of the two major sinks for anthropogenic CO2 emissions, terrestrial vegetation and ocean, their location year-to-year variability are not well understood. Top-down estimates spatiotemporal variations in emissions uptake expected to benefit from increasing measurement density brought by recent situ remote observations. We uniquely apply a batch Bayesian synthesis inversion at relatively high resolution surface observations bias-corrected GOSAT satellite...
Abstract. The tropical tropopause layer (TTL) is the transition region between well mixed, convective troposphere and radiatively controlled stratosphere with air masses showing chemical dynamical properties of both regions. representation TTL in meteorological reanalysis data sets important for studying complex interactions circulation, convection, trace gases, clouds radiation. In this paper, we present evaluation characteristics that has been performed as part SPARC (Stratosphere–...