Methane is the second most important anthropogenic greenhouse gas and, although the global budget is relatively well constrained, partitioning among sources remains highly uncertain. SCIAMACHY from its vantage point in space offers the... more
Methane is the second most important anthropogenic greenhouse gas and, although the global budget is relatively well constrained, partitioning among sources remains highly uncertain. SCIAMACHY from its vantage point in space offers the unique opportunity to sense methane globally with high sensitivity towards the surface. Recent retrievals of methane column averaged mixing ratios using short wave infrared nadir spectra obtained
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The SCIAMACHY near-infrared satellite instrument shows enhanced carbon monoxide (CO) columns over Australia during its biomass-burning (BB) season in local Spring. Chemistry-transport model simulations using the new independent... more
The SCIAMACHY near-infrared satellite instrument shows enhanced carbon monoxide (CO) columns over Australia during its biomass-burning (BB) season in local Spring. Chemistry-transport model simulations using the new independent satellite-based GFEDv2 biomass-burning emission data base show a similar temporal and spatial CO distribution, indicating that the observed enhancements are due to biomass burning. It is shown that the new GFEDv2 data
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Methane is an important greenhouse gas in the Earth's atmosphere, with an estimated contribution of 18% to the present-day radiative forcing caused by long-lived greenhouse gases. The future contribution of methane to climate change... more
Methane is an important greenhouse gas in the Earth's atmosphere, with an estimated contribution of 18% to the present-day radiative forcing caused by long-lived greenhouse gases. The future contribution of methane to climate change is very difficult to predict, as illustrated by the fact that the current level of methane is already significantly outside the envelope of scenarios that were formulated about a decade ago. Methane emissions in the tropics are an important term in the global uncertainty budget, and therefore key to improving our understanding of the global concentration evolution of methane. The SCIAMACHY satellite instrument has provided us a new view on atmospheric methane, greatly expanding the measurement coverage particularly in the tropics. It provided interesting new pieces of the puzzle of the global methane budget, however, the question remains how they fit together. In this study, several bottom-up inventories have been compiled of methane emissions from r...
Active mission concepts can provide column-integrated atmospheric CO2 concentration (XCO2) measurements day and night over all seasons. Compared to passive mission concepts, the signal is less affected by atmospheric aerosol loading and... more
Active mission concepts can provide column-integrated atmospheric CO2 concentration (XCO2) measurements day and night over all seasons. Compared to passive mission concepts, the signal is less affected by atmospheric aerosol loading and cloud cover. XCO2 Observations provide an indirect constraint on the processes governing the terrestrial carbon, water, and energy cycles. Assimilation of XCO2 into a model of the terrestrial biosphere can extend the scope of the observational information beyond the observational period and to quantities beyond the net exchange flux. The procedure is thus suited to retrieve a suite of higher level products. We apply quantitative network design techniques to assess the constraint provided by an active CO2 mission such as ASCENDS in the Carbon Cycle Data Assimilation System (CCDAS). The system links the observations to the terrestrial vegetation model BETHY via the fine resolution version of the atmospheric transport model TM3. In the modelling process...
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ABSTRACT A reanalysis of global CH4 emissions over the period 2003-2010 has been performed based on the TM5-4DVAR inverse modeling system. We use CH4 satellite retrievals from the Scanning Imaging Absorption Spectrometer for Atmospheric... more
ABSTRACT A reanalysis of global CH4 emissions over the period 2003-2010 has been performed based on the TM5-4DVAR inverse modeling system. We use CH4 satellite retrievals from the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instrument onboard Envisat, together with high-accuracy surface observations from the NOAA Earth System Research Laboratory global cooperative air sampling network. Using climatological OH fields, derived global total emissions for the period 2007-2010 are ~20 Tg CH4/yr higher than 2003-2005. Most of this increase is attributed to the tropics (~10-15 Tg CH4/yr) and mid-latitudes of the northern hemisphere (~5-10 Tg CH4/yr). No significant trend and only small inter-annual variability is attributed to the Arctic latitudes. Various sensitivity experiments have been performed investigating the impact of the SCIAMACHY observations (compared to inversions using only surface observations), satellite bias correction, OH fields, and a priori emission inventories on the derived trends and inter-annual variability of CH4 emissions.
Recently, precise retrievals of atmospheric methane (CH4) from the space-borne spectrometer SCIAMACHY on board ENVISAT have been reported (Frankenberg et al., 2005). We have made comparisons between these observations and simulations with... more
Recently, precise retrievals of atmospheric methane (CH4) from the space-borne spectrometer SCIAMACHY on board ENVISAT have been reported (Frankenberg et al., 2005). We have made comparisons between these observations and simulations with the chemistry--transport model TM4. A good agreement is found regarding most large-scale features in the CH4 distribution, but concentrations in tropical Africa and America appear to be underestimated
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We use the Carbon Cycle Data Assimilation System in quantitative network design mode and evaluate observational networks consisting of various types of in situ observations as well as a space mission.
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Methane is an important greenhouse gas that is emitted from multiple natural and anthropogenic sources. Atmospheric methane concentrations have varied on a number of timescales in the past, but what has caused these variations is not... more
Methane is an important greenhouse gas that is emitted from multiple natural and anthropogenic sources. Atmospheric methane concentrations have varied on a number of timescales in the past, but what has caused these variations is not always well understood. The different sources and sinks of methane have specific isotopic signatures, and the isotopic composition of methane can therefore help to identify the environmental drivers of variations in atmospheric methane concentrations. Here we present high-resolution carbon isotope data (δ(13)C content) for methane from two ice cores from Greenland for the past two millennia. We find that the δ(13)C content underwent pronounced centennial-scale variations between 100 BC and AD 1600. With the help of two-box model calculations, we show that the centennial-scale variations in isotope ratios can be attributed to changes in pyrogenic and biogenic sources. We find correlations between these source changes and both natural climate variability--such as the Medieval Climate Anomaly and the Little Ice Age--and changes in human population and land use, such as the decline of the Roman empire and the Han dynasty, and the population expansion during the medieval period.
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Nonmethane hydrocarbons (NMHC) play an important role in global scale tropospheric photochemistry. The representation of NMHC chemistry in three-dimensional tropospheric chemistry transport models requires a highly parameterized... more
Nonmethane hydrocarbons (NMHC) play an important role in global scale tropospheric photochemistry. The representation of NMHC chemistry in three-dimensional tropospheric chemistry transport models requires a highly parameterized description of only the most important ...
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Both a bulk-analytical and a micro-analytical technique were used to determine lead in standard particles and natural aerosols. The localization of lead within standard particles was successfully studied. Both techniques were able to... more
Both a bulk-analytical and a micro-analytical technique were used to determine lead in standard particles and natural aerosols. The localization of lead within standard particles was successfully studied. Both techniques were able to discriminate between particles which were coated with lead and particles with a homogeneous lead(II) distribution.Total lead present in aerosols was successfully quantitatively determined with Differential Pulse Anodic
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ABSTRACT Long term trends of atmospheric carbon dioxide column concentrations were analyzed from ground-based solar absorption Fourier transform infrared (FTIR) instruments in Bremen, Germany and in Ny-Alesund, Spitzbergen. The column... more
ABSTRACT Long term trends of atmospheric carbon dioxide column concentrations were analyzed from ground-based solar absorption Fourier transform infrared (FTIR) instruments in Bremen, Germany and in Ny-Alesund, Spitzbergen. The column average volume mixing ratio of the observations were then compared to the Stochastic Time Inverted Lagrangian Transport (STILT) model and CarbonTracker. Comparisons of atmospheric carbon dioxide anomalies between the FTIR data and the models show more reasonable agreement in Bremen than in Ny-Alesund. The reasons for which come from the larger diurnal variations in Ny-Alesund as a result of smaller measured intensities and the lack of vegetation in Ny-Alesund that the model may have over estimated. With the better agreement of the models in Bremen to the measurements, a "clear sky" bias was pin pointed as models see increased carbon dioxide during frontal zone conditions - a meteorological condition when FTIRs often cannot measure. The spatial heterogeneity of carbon dioxide was also assessed for Bremen by varying the horizontal resolutions of the STILT model from a fine to a coarse scale. The model outputs from these resolutions were then compared to STILT results with the highest resolution as well as to the FTIR data. From the standard deviation of differences among these datasets we can conclude that column concentrations are not sensitive to small-scale local carbon dioxide emission sources, although the FTIR being situated in an urban setting.
... Thermal infrared in-struments, on the contrary, reach a better global coverage, because theperformance in the near infrared is reduced ... All prior flux uncertainties are assumed to be uncorrelated in time. ... The instrument scans... more
... Thermal infrared in-struments, on the contrary, reach a better global coverage, because theperformance in the near infrared is reduced ... All prior flux uncertainties are assumed to be uncorrelated in time. ... The instrument scans in across-track direction resulting in a 960 km swath. ...
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Research Interests: Case Study and Methane
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OCO and GOSAT will likely bring a wealth of accurate total column CO2 measurements that will allow the estimation of CO2 sources and sinks from space. Meanwhile even more advanced measurement concepts are being investigated for the next... more
OCO and GOSAT will likely bring a wealth of accurate total column CO2 measurements that will allow the estimation of CO2 sources and sinks from space. Meanwhile even more advanced measurement concepts are being investigated for the next generation of instruments, such as the CO2 lidar A-SCOPE. Despite numerous attempts to simulate the benefit of remote sensing for the quantification