We present an overview of the initial data products of TEMPO during its commissioning and early nominal operation and preliminary comparison with correlative satellite and ground-based observations.

TEMPO is NASA’s first Earth Venture Instrument (EVI) and first host payload. It measures hourly daytime atmospheric pollution over North America from Mexico City to the Canadian oil sands, and from the Atlantic to the Pacific, at high spatiotemporal resolution (~10 km² at boresight) from the geostationary (GEO) orbit. It uses UV/visible spectroscopy (293-493 nm, 538-741 nm) to measure O₃ profiles including lower tropospheric O₃ and columns of NO₂, H₂CO, SO₂, C₂H₂O₂, H₂O, BrO, IO, as well as clouds aerosols, and UVB. TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry and captures the inherent high variability in the diurnal cycle of emissions and chemistry. The TEMPO instrument was built by Ball in 2018. It was integrated into the host commercial communication satellite Intelsat 40e (IS-40e) by Maxar. IS-40e was successfully launched on April 7 by a SpaceX Falcon 9 rocket on to the GEO orbit at 91°W. The TEMPO Instrument powered up for the first time on orbit in early June to start its commissioning. After a month of dry out and activation, TEMPO first light of solar and earth measurements occurred on July 31-August 2. Nominal operation started on 19 October 2023 after the commissioning phase and the post-launch acceptance review. Science data products are archived and distributed at NASA’s ASDC and will be released to the public in approximately February 2024 for L1b and in April 2024 for L2/3. TEMPO is part of a geostationary constellation to measure air quality along with GEMS (launched in Feb. 2020) over Asia and Sentinel-4 (to launch in 2024) over Europe.

How to cite: Liu, X., Chance, K., Suleiman, R., Houck, J., Davis, J., Gonzalez Abad, G., Nowlan, C., Wang, H., Chong, H., and Hou, W. and the TEMPO Team: A New Era of Air Quality Monitoring from Space overNorth America with TEMPO: Commissioning and Early Nominal Operation Results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14173, https://doi.org/10.5194/egusphere-egu24-14173, 2024.

Together with the geostationary imagers over Southeast Asia (GEMS), North America (TEMPO) and Europe (Sentinel 4), TROPOMI and its follow-on low Earth orbit missions will establish the global air quality satellite constellation. The role of the low Earth orbit sensors in this constellation is twofold: firstly to provide the global coverage, including regions that cannot or will not be covered by the geostationary imagers, and secondly to facilitate cross-comparisons of the geostationary imagers, thereby serving as a travelling standard.

With the availability of the GEMS data and the expected release of the TEMPO data, the development of novel methods to intercompare the geostationary and low Earth orbit data is timely. When comparing data from geostationary and low Earth orbit data, one important aspect to overcome is the difference in the Sun-satellite geometry of the observations for an area on Earth. When comparing measured radiances under different geometries, complex corrections are required, for example to deal with the directionality of the surface reflectance. The uncertainties of such corrections may be larger than the expected difference in the radiance between the geostationary and low Earth orbit observations.

As the GEMS field of view includes the sub-satellite point at the equator, there is the unique opportunity for direct comparison when the TROPOMI nadir observations cover this point. In this case, observations of GEMS and TROPOMI with the same the same viewing geometry are available within maximum 30 minutes of each other. The time difference can be accounted for by interpolation, and/or by including a larger geographic area on the Earth in the intercomparison. As the orbital repeat cycle of TROPOMI is 227 orbits, there is an opportunity for direct comparisons approximately every 16 days. Such comparisons can include comparisons of the Level 1B radiances, reflectances, or fitted quantities such as slant column densities for different gases.

In this contribution we will demonstrate the method using case studies of direct comparisons of radiance, reflectances and NO₂ slant columns, as well as comparisons for different seasons.

How to cite: Veefkind, P., Leune, B., van Geffen, J., and Hong, H.: Comparing TROPOMI and GEMS Observations for the Same Sun-Satellite Geometry , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10909, https://doi.org/10.5194/egusphere-egu24-10909, 2024.

Nitrogen oxides (NOx = NO + NO₂) are among the most important pollutants in the atmosphere. They impact tropospheric ozone chemistry, contribute to particle formation and adversely affect human health.

The monitoring of NO₂ is mainly performed by surface in-situ networks. Satellite observations can contribute by providing a large-scale picture and covering regions without in-situ observations. The satellite instruments traditionally used for NO₂ retrieval (GOME, SCIAMACHY, OMI, TROPOMI) operate on low-earth orbiting platforms, providing global coverage but only one or two measurements per day. The Korean GEMS instrument, launched in February 2020, is the first in a series of geostationary observation platforms allowing hourly measurements of NO₂ from space.

Based on the work performed in preparation for the European S4 satellite, a tropospheric NO₂ retrieval for GEMS has been developed at IUP-UB. This product focuses on achieving low noise and high accuracy by optimising the fitting window and including corrections for instrument polarisation sensitivity and scene inhomogeneity. Stratospheric correction is performed using different approaches to investigate the impact on the tropospheric columns. For the airmass factors, cloud correction is applied using cloud fractions derived after correction for calibration issues in GEMS irradiance measurements. The resulting tropospheric columns for the first three years of GEMS operation show excellent agreement with the operational TROPOMI NO₂ product at the time of TROPOMI overpass. They also exhibit systematic and variable daily patterns, which depend on season and location.

How to cite: Richter, A., Lange, K., Burrows, J. P., Boesch, H., Kim, S.-W., Seo, S., Kim, K.-M., Hong, H., Lee, H., and Park, J.: The GEMS IUP-UB tropospheric NO2 product – sensitivity studies and first results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10221, https://doi.org/10.5194/egusphere-egu24-10221, 2024.

The atmospheric composition instrument (ACX) on NOAA's GeoXO mission will enhance NOAA's air quality monitoring capabilities by providing hourly high-resolution observations of air pollutants over North America, like its predecessor, NASA's TEMPO mission. We are developing and implementing an advanced algorithm for accurate NO₂ retrieval from GeoXO ACX. Applying this algorithm to GEMS and TEMPO, we demonstrate in this presentation the success of rapid production of high-quality NO₂ data soon after the mission starts to collect Earthview measurements. We describe the technique for instrument characterization and identification of instrument artifacts for improving retrieval precisions, and the soft calibration approach for removing systematic biases in NO₂ retrieval. Using TROPOMI as a transfer standard, we show consistent NO₂ slant columns are retrieved from GEMS and TEMPO using the GeoXO ACX NO₂ algorithm.

How to cite: Yang, K., Kondragunta, S., and Wei, Z.: Application of the GeoXO ACX NO2 Algorithm to GEMS and TEMPO and Intercomparisons with TROPOMI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6093, https://doi.org/10.5194/egusphere-egu24-6093, 2024.

Nitrogen oxides play an important role in many atmospheric chemistry processes in both the stratosphere and troposphere. In this context, over the past few decades, NO₂ column measurements have been provided from polar sun-synchronous low-earth orbit (LEO) satellite instruments. These space-borne remote sensing measurements have contributed to our understanding of the global distribution of tropospheric NO₂ levels, their changes over time and estimates of emissions. However, the LEO instruments only observe NO₂ once per day at a specific local time, limiting the monitoring of diurnal variation in NO₂ due to variations in emissions and chemical reactions throughout the day. To address the shortcomings of the current atmospheric composition monitoring by LEO and to capture the diurnal variation of air quality processes at the local scale, the Geostationary Air Quality (Geo-AQ) constellation mission, consisting of three geostationary satellite sensors (i.e. Geostationary Environment Monitoring Spectrometer (GEMS) for Asia, Tropospheric Emissions: Monitoring of Pollution (TEMPO) for North America, and Sentinel-4 (S4) for Europe), has been launched.

In this study, we present a tropospheric NO₂ retrieval algorithm designed for geostationary satellites using GEMS measurements. The GEMS NO₂ retrieval algorithm is based on a heritage of NO₂ retrieval from previous LEO satellites, following a common approach consisting of three steps: (1) the spectral retrieval of total NO₂ slant columns using Differential Optical Absorption Spectroscopy (DOAS) technique, (2) the separation of slant columns into stratospheric and tropospheric contributions, and (3) the conversion of tropospheric slant columns to tropospheric vertical columns using air mass factors. However, to account for the characteristics of the geostationary satellite, such as hourly sampling, limited geographical coverage, and larger zenith angles, we developed and implemented a number of improvements in the DLR GEMS NO₂ retrieval algorithm. To estimate the stratospheric contribution and describe the diurnal variation of stratospheric fields, an improved stratosphere-troposphere separation approach was developed using the CAMS global forecast (IFS cycle 48r1) data and evaluated by comparing it to results obtained using the STREAM scheme. For the improved tropospheric AMF calculation, sensitivity tests were performed using different surface reflectance and cloud products. Notably, a cloud correction using cloud parameters from the DLR Optical Cloud Recognition Algorithm (OCRA) based on Loyola et al. (2018) improves the tropospheric NO₂ column retrievals for clear-sky scenes.

Our GEMS tropospheric NO₂ retrieval results show good agreement with various reference datasets including ground-based and satellite measurements. Furthermore, the hourly sampling and high spatial resolution of GEMS tropospheric NO₂ columns demonstrate the capability for a detailed analysis of the diurnal evolution of NO₂ burden and emission strengths over Asia from space.

How to cite: Seo, S., Valks, P., Heue, K.-P., Lutz, R., Hedelt, P., Loyola, D., Lee, H., and Kim, J.: Tropospheric NO2 column retrieval from the Geostationary Environment Monitoring Spectrometer (GEMS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6208, https://doi.org/10.5194/egusphere-egu24-6208, 2024.

Nitrogen oxides are key gas components of emissions from fossil-fuel combustion, are known to degrade air quality and have adverse health effects. Diurnal NO₂ observations are crucial for enhancing our understanding of NOx emissions, lifetime, and chemistry. Geostationary Environment Monitoring Spectrometer (GEMS) has been providing hourly observations NO₂ columns over Asia since November 2020. The latest NO₂ version 3 products have significantly improved with updated air mass factors (AMFs) and the separation of stratospheric and tropospheric columns. To identify the dependency of the distribution on the time of the day, we investigated hourly tropospheric NO₂ cycles of cities over Asia using GEMS measurements for the first time. The cities show similar diurnal concentration patterns with peaks in the morning and troughs in the afternoon, although the amplitude and specific times vary by city. The reduction rate of NO₂ was influenced by the temporal dependence of the spatial distribution within and around cities. We also observed distinct NO₂ diurnal patterns in certain industrial areas and cities where NOx emissions are thought to be controlled. To explain the location-dependent variations of the tropospheric NO₂ columns, we compared the diurnal NO₂ cycles obtained from the GEMS measurement with WRF-Chem models for some cities. In addition, estimated top-down NOx emissions from GEMS measurements are presented in comparison with bottom-up emission inventory, showing a smaller difference compared to the top-down emission from TROPOMI measurements. It is expected that hourly top-down NOx emissions using GEMS measurements can provide a useful information in improving the future performance of air quality modeling.

How to cite: Lee, H., Park, J., Hong, H., Kim, J., Lee, H.-J., Jung, Y., Roozendael, M. V., Fayt, C., Park, R., Kim, S., Ahn, M.-H., Jacob, D. J., Kim, D., Choi, W., Lee, W.-J., Lee, D.-W., Wagner, T., Richter, A., Krotkov, N. A., and Lamsal, L. N.: Diurnal characteristics of the NO2 columns observed over Asia from Geostationary Environment Monitoring Spectrometer (GEMS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17722, https://doi.org/10.5194/egusphere-egu24-17722, 2024.

Nitrogen dioxide (NO₂) is one of the most important air pollutants in the troposphere. NO₂ can be retrieved by differential optical absorption spectroscopy measurements, which can be performed from various platforms.

Measurements from low earth satellites in sun-synchronous orbits provide a global overview and have already contributed valuable insights into understanding NO₂. The latest instrument, TROPOMI, with its high spatial resolution of 3.5 x 5.5 km², has given new opportunities to disentangle and analyze NO_x sources. However, instruments in low-earth orbits usually provide only one measurement per day at each location.

To achieve diurnal cycles of trace gases, instruments on geostationary satellites are needed. The Korean instrument GEMS on GK2B, launched in February 2020, is the first instrument in geostationary orbit, delivering hourly daytime observations of NO₂ with a spatial resolution of 3.5 x 8 km² over a large part of Asia.

In this study, one year of tropospheric NO₂ vertical column densities (VCDs) of the operational GEMS product are compared to the scientific GEMS IUP-UB NO₂ VCD product, the operational TROPOMI NO₂ VCD product, and ground-based DOAS measurements in Korea. The diurnal variation of NO₂ observed by GEMS is compared to the diurnal variation observed at several ground-based MAX-DOAS stations located in different pollution regimes in Korea. The large variety of observed diurnal cycles are interpreted regarding potential influencing factors. In this respect, the ERA5 10 m wind data provide valuable insights into the influence of transport effects on the tropospheric NO₂ VCD depending on station location and seasonality.

How to cite: Lange, K., Richter, A., Bösch, T., Zilker, B., Burrows, J. P., Bösch, H., Merlaud, A., Fayt, C., Friedrich, M. M., Van Roozendale, M., Ziegler, S., Ripperger-Lukosiunaite, S., Wagner, T., Kim, D., Chang, L.-S., Hong, H., Bae, K., Song, C.-K., and Lee, H.: Validation of GEMS tropospheric NO2 with the GEMS IUP-UB NO2 product, the TROPOMI NO2 product, and ground-based DOAS measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10891, https://doi.org/10.5194/egusphere-egu24-10891, 2024.

Sulfur dioxide emissions (SO₂) from coal-fired power plants are known as a major contributor to air pollution. SO₂ emitted into the atmosphere forms sulfate aerosols, leading to acid rain and causing damage to forests. Moreover, exposure to SO₂ in humans can cause eye irritation and affect respiratory health. This study presents the column density variations of anthropogenic SO₂ over Asia using the Geostationary Environment Monitoring Spectrometer (GEMS) onboard the Geostationary Korea Multi-Purpose Satellite-2B (GEO-KOMPSAT-2B). We investigated the diurnal variations of SO₂ emissions from anthropogenic sources, such as coal-fired power plants in India. Retrieved SO₂ columns from GEMS were compared with low-orbit satellites In the GEMS observation area, there was a tendency of low sensitivity in SO₂ retrieval due to scattering by air molecules in the high geometry region, particularly at a high viewing zenith angle (VZA), resulting in high uncertainty in SO₂ retrieval. We discuss these tendencies in detail through an investigation of SO₂ retrieval sensitivity based on concentration and geometry.

How to cite: Park, J., Lee, H., Hong, H., and Kim, J.: Diurnal variations of anthropogenic sulfur dioxide over Asia observed from GEMS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15371, https://doi.org/10.5194/egusphere-egu24-15371, 2024.

Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO₂) retrieved from sun-synchronous satellite instruments have provided abundant NO₂ data for environmental studies, but such data are limited by retrieval uncertainties and insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEMS) launched in February 2020 monitors NO­₂ at an unprecedented hourly resolution during the daytime. Here we present a research product for tropospheric NO₂ VCDs, referred to as POMINO-GEMS. We develop a hybrid retrieval method combining GEMS, TROPOMI and GEOS-CF data to generate hourly tropospheric NO₂ slant column densities (SCDs). We then derive tropospheric NO₂ air mass factors (AMFs) with explicit corrections for surface reflectance anisotropy and aerosol optical effects, through parallelized pixel-by-pixel radiative transfer calculations. Prerequisite cloud parameters are retrieved with the O₂-O₂ algorithm by using ancillary parameters consistent with those used in NO₂ AMF calculations.

Initial retrieval of POMINO-GEMS tropospheric NO₂ VCDs for June–August 2021 exhibits strong hotspot signals over megacities and distinctive diurnal variations over polluted and clean areas. POMINO-GEMS NO₂ VCDs agree with the POMINO-TROPOMI v1.2.2 product (R = 0.98, and NMB = 4.9%) over East Asia, with slight differences associated with satellite viewing geometries and cloud and aerosol properties affecting the NO₂ retrieval. POMINO-GEMS also shows good agreement with OMNO2 v4 (R = 0.87, and NMB = −16.8%) and GOME-2 GDP 4.8 (R = 0.83, and NMB = −1.5%) NO₂ products. POMINO-GEMS shows small biases against ground-based MAX-DOAS NO₂ VCD data at nine sites (NMB = –11.1%) with modest or high correlation in diurnal variation at six urban and suburban sites (R from 0.60 to 0.96). The spatiotemporal variation of POMINO-GEMS correlates well with mobile-car MAX-DOAS measurements in the Three Rivers’ Source region on the Tibetan Plateau (R = 0.81). Surface NO₂ concentrations estimated from POMINO-GEMS VCDs are consistent with measurements from the Ministry of Ecology and Environment of China for spatiotemporal variation (R = 0.78, and NMB = –26.3%) as well as diurnal variation at all, urban, suburban and rural sites (R ≥ 0.96). POMINO-GEMS data will be made freely available for users to study the spatiotemporal variations, sources and impacts of NO₂.

How to cite: Zhang, Y., Lin, J., Kim, J., Lee, H., Park, J., Hong, H., Van Roozendael, M., Hendrick, F., Wang, T., Wang, P., He, Q., Qin, K., Choi, Y., Kanaya, Y., Xu, J., Xie, P., Tian, X., Zhang, S., Wang, S., and Cheng, S. and the Yuhang Zhang: A research product for tropospheric NO2 columns fromGeostationary Environment Monitoring Spectrometerbased on Peking University OMI NO2 algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2169, https://doi.org/10.5194/egusphere-egu24-2169, 2024.

NOAA’s Geostationary Operational Environmental Satellites (GOES) – R Series is now six years into its operational life with GOES-16 serving as GOES East, GOES-18 serving as GOES West, and GOES-17 in on-orbit storage.  The last GOES-R Series satellite (GOES-U) will launch in late April 2024.  Together the GOES-R satellites watch more than half the globe – from the west coast of Africa to New Zealand, and from Antarctica to the Arctic Ocean and will continue operations into the 2030s.

To ensure the continuity of these critical observations, NOAA has initiated the mission that will follow GOES-R, the Geostationary Extended Observations (GeoXO) program.  GeoXO will expand the weather-centric mission of GOES-R's imagers and lightning mappers by adding a hyperspectral IR sounder (GXS).  GeoXO will expand beyond the weather mission by including hyperspectral sensors that measure atmospheric composition and ocean colour.    

The first GeoXO launch is targeted for 2032 and the series is expected to be operational into the 2050s. This presentation provides a status on GOES-R operations and will also discuss GeoXO requirements, instrument status and  user readiness.

How to cite: Heidinger, A., Lindsey, D., Joiner, J., and Sullivan, P.: NOAA's Plans for its GEO Program from Today to 2050, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11150, https://doi.org/10.5194/egusphere-egu24-11150, 2024.

The Copernicus Sentinel-4/UVN mission is Europe's contribution to the virtual constellation of air quality related sensors in geostationary orbit. It is planned to be launched in 2025 on board EUMETSAT’s Meteosat Third Generation – Sounder (MTG-S) platform and complement the Korean GEMS and American TEMPO instruments which are already in orbit over Asia and North America, respectively.

Following the space segment development and in-orbit commissioning under ESA responsibility, EUMETSAT will be responsible for operations, data processing and continuous calibration/validation of the Copernicus Sentinel-4 instruments and the derived operational products. The state-of-the-art UVN sounder onboard the MTG-S satellite covers the UV to NIR spectral range to provide hourly high spatial resolution measurements of several trace gas and aerosol concentrations and vertical profiles, crucial for monitoring atmospheric pollution. Other instruments (e.g., the Infrared Sounder, Lightning Imager and Flexible Combined Imager) onboard the MTG platforms will provide complementary information about temperature, clouds, and atmospheric constituents like water vapour.

In this presentation, we will cover the progress achieved at EUMETSAT for the Sentinel-4 UVN mission with respect to the readiness of the ground segment including the in-orbit calibration key data (CKD) generation. We will put forward the in-flight measurement sequences and manoeuvres that are meant to secure the quality of the generated L1 and L2 data. We will show the results of the system validation test performed with the EUMETSAT ground segment and Telespazio after the successful mechanical integration of the instrument onto the platform in September 2023. We will also present the ongoing preparation and planned activities concerning the development of tools and facilities for monitoring and operational validation.

How to cite: Kumar, V., Rüthrich, F., Garcia, S. G., Gu, M., Pandey, P., Taberner, M., Lindstrot, R., Dobber, M., Grandell, J., Ahlers, B., Veihelmann, B., Courreges-Lacoste, G. B., and Bojkov, B.: The Copernicus Sentinel-4 UVN mission: status and ongoing activities at EUMETSAT  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15076, https://doi.org/10.5194/egusphere-egu24-15076, 2024.

In the next few decades a large increase in population is expected to occur on the African continent, leading to a doubling of the current population, which will reach 2.5 billion by 2050. At the same time, Africa is experiencing substantial economic growth. As a result, air pollution and greenhouse gas emissions will increase considerably with significant health impacts to people in Africa. In the decades ahead, Africa’s contribution to climate change and air pollution will become increasingly important. The time has come to determine the evolving role of Africa in global environmental change.  

We are building an Atmospheric Composition Virtual Constellation, as envisioned by the Committee on Earth Observation Satellites (CEOS), by adding to our polar satellites,  geostationary satellites in the Northern Hemisphere : GEMS over Asia (launch 2022); TEMPO over the USA (launch 2023) and Sentinel 4 over Europe to be launched in the 2024 timeframe. However, there are currently no geostationary satellites envisioned over Africa and South-America, where we expect the largest increase in emissions in the decades to come.

In this paper the scientific need for geostationary satellite measurements over Africa will be described, partly based on several recent research achievements related to Africa using space observations and modeling approaches, as well as first assessments using the GEMS data over Asia, and TEMPO over the USA. Our ambition is to develop an integrated community effort to better characterize air quality and climate-related processes on the African continent. 

How to cite: Levelt, P., Marais, E. A., Worden, H., Tang, W., Martinez-Alonso, S., Edwards, D., Eskes, H., Veefkind, P., Brown, S., Gameli Hodoli, C., Felix Hughes, A., Lefer, B., Sheldon, D., and Westervelt, D.: Investigating expanding air pollution and climate change on the African continent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13470, https://doi.org/10.5194/egusphere-egu24-13470, 2024.

The Geostationary Extended Observations (GeoXO) satellite system is the intended successor to the GOES-R Series from NOAA, and it is planned to begin operating in the early 2030s. This next generation system will be outfitted with an Atmospheric Composition Instrument (ACX) that will provide hourly observations of tropospheric trace gases and aerosols including pollutants associated with poor health; the highest priority factors for air quality monitoring in this new system include some of the pollutants most hazardous to human health such as ozone (O₃), particulate matter (PM), and nitrogen dioxide (NO₂). GeoXO will be a geostationary satellite with multiple overpasses of the United States per day in contrast to the TROPOspheric Monitoring Instrument (TROPOMI) on board the sun-synchronous polar-orbiting Sentinel-5P satellite. This satellite – launched by the European Space Agency – overpasses each place on Earth 1-2 times per day around 1:30 PM.

In this project, we evaluate the influence that GeoXO remote sensing capabilities could have for assessing air pollution-related health impacts in the United States. We do this by comparing the health effects associated with predicted NO₂ exposure at TROPOMI overpass times to predicted NO₂ exposure during daylight hours. To conduct this comparison, we develop a land-use regression (LUR) model that predicts hourly surface-level NO₂ data per month in the United States using monthly oversampled TROPOMI NO₂ columns, static land-use data including roads, population density, built environment and elevation differential, and hourly meteorological reanalysis data of temperature, boundary layer height, precipitation, and total liquid water column amount. We fuse these variables using different regression techniques including both a lasso and multi-layer perceptron regression to predict monthly surface-level NO₂ during daylight hours.

We compare the predicted hourly surface-level NO₂ to NO₂ derived just at TROPOMI overpass time – approximately 1:30 PM – to quantify how geostationary observations could better reveal how populations are exposed to pollutants like NO₂ than exposures that are reliant on data from a single overpass time. We additionally investigate the health disparity introduced from this assumption by estimating the new pediatric asthma cases and premature mortality associated with hourly daylight NO₂ exposure versus NO₂ exposure from just a single overpass time. Additionally, we discuss how data from the new TEMPO instrument – that was launched by NASA in 2023 – will influence and improve this TROPOMI-derived LUR.

How to cite: Nawaz, O., Anenberg, S., Goldberg, D., Kerr, G., and Kondragunta, S.: Development of a Land-Use Regression of Hourly Surface NO2 in preparation for GeoXO Atmospheric Composition Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11978, https://doi.org/10.5194/egusphere-egu24-11978, 2024.

TEMPO (Tropospheric Emissions: Monitoring Pollution) is a geostationary ultraviolet and visible spectrometer to monitor major air pollutants over north America.   The instrument was launched in April 2023 and the L1b data were available since October 17, 2023.   The sensor’s coverage of the O₂B band (688nm) enables us to retrieve aerosol layer height (ALH).  At National Oceanic and Atmospheric Administration (NOAA) in the United States, we developed an algorithm to retrieve aerosol optical depth, aerosol type, and aerosol layer height from the TEMPO data.   Our approach involves the creation of a 0.05x0.05 degree database of surface reflectances for various bands, accounting for solar-satellite geometry.   To retrieve AOD, AOD and surface reflectance are varied until a solution is found that gives a minimum residual between derived and prescribed spectral surface reflectance ratio between blue and red bands. The surface reflectances at the O₂B band are derived from retrievals of other bands using the surface reflectance ratio database. The ALH is determined by minimizing differences between the measured 688/670 bands' top-of-atmosphere (TOA) reflectance ratio and the calculated ratio.

The retrieval algorithm was tested using the August-September 2020 TROPOMI data as a proxy over CONUS region where heavy smoke was observed.  The results show good AOD retrieval performance compared to ground-based Aerosol Robotic Network (AERONET) AOD:  the retrieved AOD has a correlation of 0.68, a bias of 0.11 and RMSE of 0.37 with respect to AERONET AOD.   Comparing to CALIOP ALH, the retrieved ALH has a correlation of 0.67, a bias of 0.91 km and an RMSE of 2.59 km.  Preliminary AOD retrieval from TEMPO data also demonstrates favorable agreement with AOD from the ABI instrument onboard GOES-East.

Disclaimer: The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce.

How to cite: Zhang, H., Kondragunta, S., and Ciren, P.: TEMPO Aerosol Retrieval Algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11547, https://doi.org/10.5194/egusphere-egu24-11547, 2024.

Since the launch of the Sentinel 5P satellite, NO₂ observations have become available with a resolution of 3.5x5 km, which allows for the monitoring of NOx emissions at the scale of city districts and industrial facilities. For Europe, emissions are annually reported for country totals and large industrial facilities and these are made publicly available via the European Environmental Agency . Satellite observations can provide independent and more timely information on NOx and NH₃ emissions. A new version of the inversion algorithm DECSO (Daily Emissions Constraint by Satellite Observations) has been developed for deriving NOx and NH₃ emissions for Europe on a daily basis, averaged to monthly mean maps. These are based on observations of TROPOMI (Sentinel 5p) and CrIS. In a newly developed post-processing step anthropogenic NOx emissions are separated from soil NOx emissions. These satellite-derived emissions from DECSO have been compared for industrial locations, cities and country totals to the officially reported European emissions and spatial-temporal disaggregated emission inventories like CAMS. In addition, a branch of DECSO is developed to derive hourly NOx emissions. This new approach has been demonstrated for a high latitude region (around 70 degree North) in summer time, when multiple orbits of Sentinel 5P cover the same location on a single day.

How to cite: van der A, R., Ding, J., and Eskes, H.: NOx emissions over Europe from Sentinel 5P and towards Sentinel 4, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16468, https://doi.org/10.5194/egusphere-egu24-16468, 2024.

The advent of new satellite technologies has ushered in a promising era for trace gas and aerosol observations, offering advanced data quality and temporal resolution. Low Earth Orbit (LEO) satellites have markedly heightened our ability to generate accurate air quality forecasts. The Geo-Ring, comprising the geostationary satellites of GEMS over East Asia, TEMPO over North America and the imminent Copernicus Sentinel-4 over Europe, promises to unlock unprecedented possibilities in atmospheric monitoring.

The Horizon Europe CAMEO (CAMS EvOlution) project coordinated by the European Centre for Medium-Range Weather Forecasts (ECMWF) is dedicated to upgrading the quality and efficiency of the Copernicus Atmosphere Monitoring Service (CAMS). By integrating new satellite retrievals of atmospheric composition into the Integrated Forecast System (IFS), CAMEO aims to augment the data assimilation and inversion capabilities of the global and regional CAMS production system, thereby improving the quality of atmospheric composition analyses and forecasts.

During the initial year of CAMEO, the IFS was prepared to assimilate geostationary data alongside polar orbiting retrievals. This integration aims to optimise air quality modeling and provide a more accurate depiction of the diurnal cycle of O3, a pivotal component of atmospheric composition. The assimilation of a substantial volume of geostationary air quality data into the CAMS system poses challenges, necessitating the further development of the super observation software. Following updates to the IFS model and additional technical improvements, experiments were conducted using IFS version CY48R1 and the more recent CY49R1 to monitor and evaluate the Near Real-Time v.2. GEMS NO2 and O3 observations from April to December 2023.

Preliminary results reveal a notable positive bias in the GEMS NO2 tropospheric column data, consistently exceeding the model's first-guess and TROPOMI satellite observations. In urban and populated areas like Beijing, while similarities in structures and patterns of NO2 data between GEMS and TROPOMI are identified, significant discrepancies persist. The GEMS NO2 data also exhibit noticeable noise attributed to factors such as stratospheric correction, cloud treatment, and unspecified measurement errors. In the case of O3, GEMS demonstrates better performance than NO2 when compared to TROPOMI and the model's first guess, with no significant bias identified. Nonetheless, the current data version features large O3 gaps due to quality control measures. These findings offer crucial insights for refining the assimilation of geostationary air quality data, thereby enhancing forecasting and monitoring of atmospheric composition in CAMS. Upcoming releases, such as v.3. GEMS data, are anticipated to address the identified data issues, further amending the usefulness of the GEMS data for air quality applications. 

How to cite: Paschalidi, Z., Inness, A., Flemming, J., and Ribas, R.: Integrating Geostationary Satellite Data for Advanced Air Quality Modeling: Evaluating GEMS NRT Observations within the ECMWF’s IFS system for the HE CAMEO Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19066, https://doi.org/10.5194/egusphere-egu24-19066, 2024.

The North American component of the Geo-Ring for Air Quality, the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument, began collecting measurements on August 2, 2023. Multiple airborne field-intensives were conducted over the US during this TEMPO first-light period, including the NOAA Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) and Coastal Urban Plume Dynamics Study (CUPiDS) campaigns, coordinated with the NASA Synergistic TEMPO Air Quality Sciences (STAQS) campaign. The North American cities targeted included New York City, Los Angeles, Chicago, and Toronto. Here, we present an overview of the AEROMMA / CUPiDS collected summer 2023 datasets, relevant for calibration and validation activities of TEMPO, including for ozone (O3), nitrogen dioxide (NO2), formaldehyde (CH2O), sulfur dioxide (SO2), aerosol optical depth (AOD), and aerosol layer height (ALH). Ground-based lidar and airborne in-situ vertical profiling by the NASA DC-8 and NOAA Twin Otter aircraft are available for evaluating TEMPO Level 2 O3 profile products (tropospheric and 0-2 km column retrievals). Airborne measurements of NO2 (photolytic conversion of NO2 into NO followed by laser-induced fluorescence, cavity enhanced spectroscopy, and multi-axis differential optical absorption spectroscopy (MAX-DOAS)) are available for evaluating TEMPO Level 2 NO2 vertical column density products. Airborne measurements of formaldehyde and glyoxal (in-situ and MAX-DOAS remote sensing) can be evaluated similarly as other volatile organic compounds (VOCs). Lastly, a wide array of aircraft-based in-situ measurements of composition, size distribution, optical properties can be utilized to derive aerosol optical depth (AOD) and aerosol extinction profiles for evaluating TEMPO AOD and ALH products, along with TROPOMI and stereoscopic aerosol layer height products from GOES-16/18. Preliminary evaluation of TEMPO NO2 will be presented as an initial calibration / validation test case, employing best practices to facilitate direct comparisons between airborne data with TEMPO Level 2 observations.

How to cite: McDonald, B., Cooper, O., Warneke, C., Schwantes, R., Rollins, A., Baidar, S., and Brown, S. and the AEROMMA / CUPiDS cal/val team: Overview of Airborne Field Campaigns under TEMPO for Calibration and Validation of Trace Gas and Aerosol Products, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14053, https://doi.org/10.5194/egusphere-egu24-14053, 2024.