Southeast Australia experienced intensive and geographically extensive wildfires during the 2019–2020 summer season^1,2. The fires released substantial amounts of carbon dioxide into the atmosphere³. However, existing emission estimates based on fire inventories are uncertain⁴, and vary by up to a factor of four for this event. Here we constrain emission estimates with the help of satellite observations of carbon monoxide⁵, an analytical Bayesian inversion⁶ and observed ratios between emitted carbon dioxide and carbon monoxide⁷. We estimate emissions of carbon dioxide to be 715 teragrams (range 517–867) from November 2019 to January 2020. This is more than twice the estimate derived by five different fire inventories^8–12, and broadly consistent with estimates based on a bottom-up bootstrap analysis of this fire episode¹³. Although fires occur regularly in the savannas in northern Australia, the recent episodes were extremely large in scale and intensity, burning unusually large areas of eucalyptus forest in the southeast¹³. The fires were driven partly by climate change^14,15, making better-constrained emission estimates particularly important. This is because the build-up of atmospheric carbon dioxide may become increasingly dependent on fire-driven climate–carbon feedbacks, as highlighted by this event¹⁶.

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Production of oil and natural gas in North America is at an all-time high due to the development and use of horizontal drilling and hydraulic fracturing. Methane emissions associated with this industrial activity are a concern because of the contribution to climate radiative forcing. We present new measurements from the space-based TROPOspheric Monitoring Instrument (TROPOMI) launched in 2017 that show methane enhancements over production regions in the United States. In the Uintah Basin in Utah, TROPOMI methane columns correlated with in-situ measurements, and the highest columns were observed over the deepest parts of the basin, consistent with the accumulation of emissions underneath inversions. In the Permian Basin in Texas and New Mexico, methane columns showed maxima over regions with the highest natural gas production and were correlated with nitrogen-dioxide columns at a ratio that is consistent with results from in-situ airborne measurements. The improved detail provided by TROPOMI will likely enable the timely monitoring from space of methane emissions associated with oil and natural gas production.

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On 13 October 2017 the European Sentinel 5 Precursor was successfully launched, with on board the TROPOMI (TROPOspheric Monitoring Instrument). TROPOMI is an imaging spectrometer developed by The Netherlands and ESA for monitoring the atmospheric composition, for air quality climate and ozone layer monitoring. The launch of TROPOMI marks the start of operational atmospheric composition measurements from space within the European Copernicus programme, the largest Earth observation programme in the world. After one month of instrument checkout, the first light of TROPOMI was received in November 2017. During the commissioning phase the TROPOMI instrument settings were optimized. This included an increase in the spatial sampling from 7x7 to 3.5x7 km2(across track x along track), for most of the TROPOMI spectral bands. The S5P commissioning phase was completed half a year after launch and on 30 April 2018 the routine operations were started. The first batch of data products was publicly released on 11 July 2018. By the time of the AGU fall meeting, almost all the data products must have been released. TROPOMI has provided very exciting results during its first year in orbit. Very remarkable are the plumes of short-lived gases like NO2, which can extend several tens of kilometers from the source. These plumes were predicted by air quality models; however it requires the spatial resolution of TROPOMI to see them from space. Also, the CO maps have attracted a lot of attention. Because of the high sensitivity for the entire vertical column, both the sources as well as the transport of CO are clearly visible in the TROPOMI data. The high spatial resolution of the TROPOMI data also poses new challenges. More than for the previous satellite sensors, the need for accurate modelling of the surface reflectance becomes clear. Also, the 3D effects of clouds are now more prominent. All these aspects are also important for the upcoming geostationary missions within the CEOS air quality constellation. In this presentation an overview will be given of the status of the mission, including the in-orbit calibration and the data products. Specific results will be highlighted that illustrate the new capabilities of TROPOMI and also the challenges that need to be addressed in future updates of the data products.@en

The Measurements of Pollution in the Troposphere (MOPITT) instrument is the only satellite-borne sensor in operation that uses both thermal (TIR) and nearinfrared (NIR) channels to estimate CO profiles. With more than 15 years (2000 to present) of validated multispectral observations, MOPITT provides the unique capability to separate CO in the lowermost troposphere (LMT, surface to 3 km (∼ 700 hPa)) from the free-tropospheric abundance. To extend this record, a new, hyper-spectral approach is presented here that will provide CO data products exceeding the capabilities of MOPITT by combining the shortwavelength infrared (SWIR, equivalent to the MOPITT NIR) channels from the TROPOspheric Monitoring Instrument (TROPOMI) to be launched aboard the European Sentinel 5 Precursor (S5p) satellite in 2016 and the TIR channels from the Cross-track Infrared Sounder (CrIS) aboard the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. We apply the MUlti-SpEctra, MUlti-SpEcies, Multi-SEnsors (MUSES) retrieval algorithm to quantify the potential of this joint CO product. CO profiles are retrieved from a single-footprint, full-spectral-resolution CrIS transect over Africa on 27-28 August 2013 coincident with significant biomass burning. Comparisons of collocated CrIS and MOPITT CO observations for the LMT show a mean difference of 2.8 ± 24.9 ppb, which is well within the estimated measurement uncertainty of both sensors. The estimated degrees of freedom (DOF) for CO signals from synergistic CrIS-TROPOMI retrievals are approximately 0.9 in the LMT and 1.3 above the LMT, which indicates that the LMT CO can be distinguished from the free troposphere, similar to MOPITT multispectral observations (0.8 in the LMT, and 1.1 above the LMT). In addition to increased sensitivity, the combined retrievals reduce measurement uncertainty, with ∼15% error reduction in the LMT. With a daily global coverage and a combined spatial footprint of 14 km, the joint CrIS-TROPOMI measurements have the potential to extend and improve upon the MOPITT multispectral CO data records for the coming decade.

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