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Rapid identification of anomalous methane sources in oil/gas fields could enable corrective action to fight climate change. The GHGSat-D satellite instrument measuring atmospheric methane with 50-meter spatial resolution was launched in 2016 to demonstrate space-based monitoring of methane point sources. Here we report the GHGSat-D discovery of an anomalously large, persistent methane source (10–43 metric tons per hour, detected in over 50% of observations) at a gas compressor station in Central Asia, together with additional sources (4–32 metric tons per hour) nearby. The TROPOMI satellite instrument confirms the magnitude of these large emissions going back to at least November 2017. We estimate that these sources released 142 ± 34 metric kilotons of methane to the atmosphere from February 2018 through January 2019, comparable to the 4-month total emission from the well-documented Aliso Canyon blowout.

We quantify the impact of atmospheric transport and limited marine boundary layer sampling on changes in global and regional methane burdens estimate using tracer transport model simulations with annually repeating methane emissions and sinks but varying atmospheric transport patterns. We find the 1σ error due to this transport and sampling effect on annual global methane increases to be 1.11A ppb/year and on zonal growth rates to be 3.8A ppb/year, indicating that it becomes more critical at smaller spatiotemporal scales. We also find that the trends in inter-hemispheric and inter-polar difference of methane are significantly influenced by the effect. Contrary to a negligible trend in the inter-hemispheric difference of measurements, we find, after adjusting for the transport and sampling, a trend of 0.37A A±A 0.06A ppb/year. This is consistent with the emission trend from a 3-D inversion of the measurements, suggesting a faster increase in emissions in the Northern Hemisphere than in the Southern Hemisphere. © 2019. The Authors.

One of the unanswered questions of climate change is how the biospheric uptake of carbon responds to events such as droughts and floods. Especially, semiarid regions have received interest recently, as they can respond very rapidly to changing environmental conditions. Here we report on a large enhanced carbon sink over Australia from the end of 2010 to early 2012 detected using the Greenhouse Gases Observing SATellite (GOSAT). This enhanced sink coincides with the strong La Nina episode, accompanied by record-breaking amounts of precipitation. This precipitation led to an enhanced growth of vegetation, resulting in large increases in biospheric carbon uptake in line with increased levels of vegetation fluorescence. An inversion based on the satellite retrievals confirms this strong anomaly in the sink of roughly 0.77 0.10PgCyr(-1) or 1.5 0.2PgC in total for the April 2010 to December 2011 period, which corresponds to 25% of the multiyear annual average gross primary production of the Australian biosphere.

Column-averaged dry air mole fractions of carbon dioxide (XCO2) measured by the Greenhouse Gases Observing Satellite (GOSAT) reveal significant interannual variation (IAV) of CO2uptake during the Northern Hemisphere summer between 2009 and 2010. The XCO2drawdown in 2010 is shallower than in 2009 by 2.4 ppm and 3.0 ppm over North America and Eurasia, respectively. Reduced carbon uptake in the summer of 2010 is most likely due to the heat wave in Eurasia driving biospheric fluxes and fire emissions. A joint inversion of GOSAT and surface data estimates an integrated biospheric and fire emission anomaly in April-September of 0.89 ±0.20 PgC over Eurasia. In contrast, inversions of surface measurements alone fail to replicate the observed XCO2IAV and underestimate emission IAV over Eurasia. This shows the value of GOSAT XCO2in constraining the response of land-atmosphere exchange of CO2 to climate events. © 2013 American Geophysical Union. All Rights Reserved.

Skylight reflectivity and polarisation spectra across the ultraviolet (UV) and visible (VIS) wavelength range show abundant features coinciding with solar Fraunhofer lines. Although the appearance of these features in reflectivity spectra has been shown to be caused by rotational Raman scattering by atmospheric molecules, quantitative modelling of this so-called Ring effect as observed in polarisation spectra of scattered sunlight is still lacking. Accurate modelling of UV-VIS radiances and polarisation at high-spectral resolution has, however, become increasingly important because of the increased use of high-spectral resolution spectrophotometers, that are often highly polarisation sensitive. In this paper, we present high-spectral resolution skylight polarisation spectra and show that the Ring effect in these spectra can be simulated using a radiative transfer program that includes rotational Raman scattering up to the second order of scattering.

High-spectral resolution polarisation measurements of the clear daylight sky reveal an unexpected rich spectral fine-structure in the polarisation super-imposed on the more familiar broad-band continuum. This polarisation spectrum shows the spectral fingerprints of scattering and absorption processes which is illustrated with radiative transfer calculations. In particular, radiative transfer calculations suggest the potential of high-spectral resolution polarimetry within absorption bands for remote sensing of aerosol vertical distribution, which is relevant to the Earth's radiation budget and ozone hole chemistry. In addition, the presence of spectral fine-structure in the polarisation of skylight also has relevance to radiance measurements performed with polarisation sensitive spectrometers, such as the space-based GOME instrument.

[1] The column-average dry air mole fractions of atmospheric carbon dioxide and methane and are inferred from observations of backscattered sunlight conducted by the Greenhouse gases Observing SATellite (GOSAT). Comparing the first year of GOSAT retrievals over land with colocated ground-based observations of the Total Carbon Column Observing Network (TCCON), we find an average difference (bias) of −0.05% and −0.30% for and with a station-to-station variability (standard deviation of the bias) of 0.37% and 0.26% among the 6 considered TCCON sites. The root-mean square deviation of the bias-corrected satellite retrievals from colocated TCCON observations amounts to 2.8 ppm for and 0.015 ppm for Without any data averaging, the GOSAT records reproduce general source/sink patterns such as the seasonal cycle of suggesting the use of the satellite retrievals for constraining surface fluxes.

Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state-of-the-art atmospheric chemistry models have been intercompared and synthesized as part of a wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing “optimistic,” “likely,” and “pessimistic” options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5% decrease, through a 6% increase, to a 15% increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25%. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of -50, 180, and 300 mW m-2, compared to a CO2 forcing over the same time period of 800–1100 mW m-2. These values indicate the importance of air pollution emissions in short- to medium-term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere-troposphere exchange. This level of climate change also reduces the methane lifetime by around 4%. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000, and 550 Tg(O3) yr-1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O3)) is 10% larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10% shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NO x production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere-troposphere exchange; biomass burning; and water vapor concentrations.