Orals: Wed, 30 Apr | Room -2.15
Following its launch from Kennedy Space Center in February 2024, NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission has been revolutionizing our understanding of Earth’s systems. The observatory hosts three cutting-edge instruments: the Ocean Color Instrument (OCI), a hyperspectral radiometer, and two multi-angular polarimeters, SpexOne and HARP2. Together, these instruments are collecting unprecedented data on our living oceans, atmospheric aerosols and clouds, and land.
PACE extends NASA’s legacy of over 20 years of global satellite observation while initiating an advanced suite of climate-relevant data records. For the first time, daily global measurements are enabling improved predictions of fisheries dynamics, the emergence of harmful algal blooms, and other critical factors impacting commercial and recreational industries. Furthermore, PACE provides key insights into cloud properties and aerosols—tiny airborne particles that influence air quality and regulate Earth's energy balance by absorbing and reflecting sunlight.
Since its launch, the PACE science team, in collaboration with the broader scientific community, has focused on implementing, testing, and validating mission data products. Performance assessments through the PACE Validation Science Team (PVST) and field campaigns, such as the Post-launch Airborne eXperiment (PACE-PAX), have been pivotal in refining data quality and enhancing the mission’s scientific outcomes.
This presentation provides an overview of the current status of PACE science products, highlighting key achievements, ongoing validation efforts, and future goals aimed at maximizing the mission’s contributions to Earth science.
How to cite: Ibrahim, A., Werdell, J., Cetinic, I., Franz, B., Cairns, B., Craig, S., Hasekamp, O., Mannino, A., Martin, V., Meister, G., and Sayer, A.: NASA’s PACE Mission Status Updates: Advancing Science and Data Products, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12978, https://doi.org/10.5194/egusphere-egu25-12978, 2025.
The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, successfully launched on February 8, 2024, with aims to advance our understanding of global ocean ecology, biogeochemistry, atmospheric aerosols, and clouds. PACE features cutting-edge instruments, including the Ocean Color Instrument (OCI), a hyperspectral scanning radiometer, and two Multi-Angle Polarimeters (MAPs): the UMBC Hyper-Angular Rainbow Polarimeter (HARP2) and the SRON Spectro-Polarimeter for Planetary EXploration one (SPEXone). These instruments offer valuable data for simultaneous retrievals of aerosol, cloud, and surface properties.
This talk will focus on simultaneous aerosol and ocean retrievals derived from PACE MAP measurements, emphasizing data products, uncertainties, and validation. The retrieved products encompass aerosol properties such as complex refractive index, effective radius and variance, layer height, optical depth, and single-scattering albedo, as well as oceanic and surface properties. To streamline operational processing, we have incorporated deep neural network-based radiative transfer models into the PACE polarimetric retrieval algorithms via the FastMAPOL framework. Preliminary validation against in-situ measurements will be presented, along with potential applications of MAP data, including the study of ocean color bidirectional reflectance signals and multi-angle cloud masking.
How to cite: Gao, M., Knobelspiesse, K., Franz, B., Zhai, P., Aryal, K., Sayer, A., Ibrahim, A., and Werdell, J.: Simultaneous aerosol and ocean retrievals from PACE multi-angle polarimeters: data products and validation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7777, https://doi.org/10.5194/egusphere-egu25-7777, 2025.
Long-term, global ocean-color observations are needed for biogeochemistry and climate applications and require integration across multiple satellite sensors. This study proposes a methodology for cross-calibrating polar-orbiting ocean-color sensors using a geostationary reference sensor. The geostationary sensor serves as an intermediary, offering numerous coincidences in time and geometry with polar-orbiting sensors, particularly over oceanic regions where radiance levels are typical for ocean-color remote sensing. The methodology is applied to cross-calibrate current ocean-color sensors, including the recently launched OCI, using AHI, a sensor expected to remain stable over short cross-calibration intervals. Accuracy is evaluated based on radiometric noise, acquisition time differences, solar and viewing geometry variations, and spectral band mismatch uncertainties. Cross-calibration coefficients derived from suitable imagery provide a foundation for consistent, normalized calibration of polar-orbiting sensors, enabling the generation of reliable long-term ocean-color products from multiple satellites.
How to cite: Tan, J. and Frouin, R.: Cross-Calibration of Polar-Orbiting Satellite Ocean-Color Sensors Using a Geostationary Reference Sensor, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20712, https://doi.org/10.5194/egusphere-egu25-20712, 2025.
Improving future climate predictions requires enhancing the current meteorological numerical models for which a better understanding of the roles that clouds and aerosols (and their interactions) play in Earth’s weather and climate is crucial. Along these lines, the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) successfully launched the Earth Cloud, Aerosol, and Radiation Explorer (EarthCARE) satellite in May 2024. This satellite mission aims to advance the studies of global aerosol and cloud properties via novel active and passive spaceborne observations. EarthCARE carries four instruments: the ATmospheric LIDar (ATLID), the Cloud Profiling Radar (CPR), the Multi-Spectral Imager (MSI), and the Broadband Radiometer (BBR). Of particular interest to this work are the CPR observations providing significant observations of clouds’ vertical structure, including the first ever in-cloud Doppler Velocity profiles from space.
As part of ESA’s global calibration/validation initiative, the EarthCARE Commissioning Calibration/Validation Campaign in Ottawa (ECALOT) took place in Canada from October 2024 to January 2025. ECALOT collected essential airborne and surface observations to calibrate and validate key EarthCARE products. These include CPR and ATLID Level 1 and Level 2 products, composite and synergy products, as well as EarthCARE’s scene construction algorithm and radiation products. ECALOT successfully observed fall and winter weather conditions with dedicated flights targeted to sample relevant weather underflying the EarthCARE path. The National Research Council Canada’s (NRC) Convair-580 aircraft, equipped with W- and X- band radars (NAWX), 355nm Lidars, and a full array of state-of-the-art in-situ cloud microphysics and aerosol probes, provided critical independent observations to support EarthCARE validation efforts. These observations were complemented by surface-based sites deployed by Environment and Climate Change Canada and McGill University near Ottawa airport and two Climate Sentinels network stations operated by McGill University and Université du Québec à Montréal in the Montreal region.
In this presentation, we will provide an initial evaluation of EarthCARE’s CPR performance during the ECALOT campaign. A comprehensive analysis of the cloud vertical structure as seen by the CPR and NAWX observations and an intercomparison of vertical cross sections of reflectivity and Doppler velocity will be presented. In addition, an assessment of the behavior of CPR under stratiform and convective conditions will be provided.
How to cite: Borque, P., Nguyen, C., Qu, Z., Kollias, P., Puigdomenech, B., Ranjbar, K., Bala, K., Bliankinshtein, N., Nichman, L., Boodoo, S., and Donaldson, N.: First comparison between EarthCARE’s CPR and airborne W-band cloud radar observations during ECALOT campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14131, https://doi.org/10.5194/egusphere-egu25-14131, 2025.
The ESA-JAXA EarthCARE satellite mission, launched in May 2024, delivers vertical profiles of aerosols, clouds, and precipitation properties together with radiative fluxes, utilizing an instrumental suite of a high spectral resolution lidar (ATLID), a Doppler cloud radar (CPR), a multi-spectral imager (MSI), and a broadband radiometer (BBR). The simultaneous measurements will be utilized to improve our understanding of aerosol-cloud interactions (ACI) and their radiative effects and to assess the representation of clouds, precipitation, aerosols, radiative fluxes, and heating rates in weather and climate models [1]. Due to the multi-sensor complexity/diversity and the innovation of its standalone and synergistic products, the EarthCARE mission has several validation challenges and strong sub-orbital synergies are needed to address Cal/Val and science objectives.
The Mediterranean basin provides a complex aerosol-cloud environment for the exploitation EarthCARE's capabilities. For the validation of the EarthCARE products in the Mediterranean, the ACROSS validation activity will be implemented, which would increase synergies towards achieving the following objectives: (i) validate EarthCARE aerosol and cloud products using state-of-the-art ground-based and airborne facilities, (ii) implement science studies targeting radiative closures, ACI, and data assimilation experiments, (iii) and provide information for harmonizing and bridging past and future missions, to deliver Climate Data Records on aerosols and clouds.
The rationale for ACROSS is based on lessons learned from the JATAC campaign in the Atlantic [2]. Following the JATAC example, we target to implement 3 Intensive Observational Periods, including large-scale field experiments in the Mediterranean. The suborbital component follows the ASKOS [3] example. It includes (i) ACTRΙS Aerosol and Cloud remote sensing facilities and high-precision radiation measurements (Potenza site in Italy, Limassol Cyprus, as well as Pyrgos, Thessaloniki, and PANGEA sites in Greece), (ii) radiation measurements for closure studies, (iii) UAV and aircraft in-situ flights collocated with the remote sensing measurements. ACROSS activities will be clustered with the ARCHIMEDES experimental activities in the Mediterranean, foreseen between late 2026 and late 2027. ACROSS seeks synergies with airborne activities. To this end, the first synergistic measurements were collected during the PERCUSION campaign in November 2024, during which HALO underpass two EarthCARE tracks close to the Thessaloniki and PANGEA sites. More airborne activities are envisioned in the Mediterranean area for Spring/September 2025/2026.
ACROSS is a collaborative effort between NOA, DLR, the University of Nova Gorica, CyI, INOE, FMI, CNR-IMAA, PMOD, ERATOSTHENES CoE, CUT, and TROPOS. ACROSS is supported by ACTRIS RI and the dataset collected will support assimilation experiments and science activities in the framework of the PANGEA4CalVal, ATMO-ACCESS, and CERTAINTY EC projects and collaborations within.
References:
[1] Wehr T. et al., https://doi.org/10.5194/amt-16-3581-2023, 2023.
[2] Fehr, T., et al., https://doi.org/10.5194/egusphere-egu23-7249, 2023.
[3] Marinou, E. Et al., https://doi.org/10.3390/environsciproc2023026200, 2023.
Acknowledgments: This research was financially supported by the PANGEA4CalVal project (Grant Agreement 101079201) funded by the European Union, and the CERTAINTY project (Grant Agreement 101137680) funded by the Horizon Europe program. Part of the wok was financed through the Core Program within the Romanian National Research Development and Innovation Plan 2022-2027, carried out with the support of MCID, project no. PN 23 05.
How to cite: Marinou, E. and the ACROSS team: ACROSS Mediterranean activities for EarthCARE validation and exploitation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9811, https://doi.org/10.5194/egusphere-egu25-9811, 2025.
The PICARD (Pushbroom Imager for Cloud and Aerosol Research and Development) instrument, developed by the NASA Ames Research Center in partnership with Brandywine Photonics, LLC, is an airborne imager consisting of dual Offner spectrometers and an all-reflective telescope with a 50° full field-of-view (FOV). The instrument operates over a wavelength range of 400 – 2400 nm in more than 200 bands. PICARD has already flown multiple engineering flights on NASA ER-2 high altitude aircraft, the most recent during 2023 Western Diversity Time Series (WDTS) spring campaign where near co-incident measurements with spaceborne sensors such as MODIS and VIIRS were obtained including those over railroad valley (RRV) calibration site. In addition, PICARD has recently flown during the 2024 Plankton, Aerosol, Cloud, Ocean Ecosystem Postlaunch Airborne eXperiment (PACE-PAX) field campaign to gather data for the validation of the recently launched PACE mission. A recent analysis comparing PICARD measurements with RadCalNet dataset from RRV revealed excellent agreement for most of the bands except in the UV and blue region, where PICARD generally under reported. To better characterize these bands and improve this under reporting, detailed PICARD spectroradiometric characterization measurements were collected at Goddard Laser for Absolute Measurement of Radiance (GLAMR) laboratory at Goddard Space Flight Center (GSFC) in February 2024. The initial analysis of this characterization suggested that this under-report during flight is due to a stray light sensitivity inherent in the low signal-to-noise (SNR) bands of array spectroradiometers. Correcting for the GLAMR measured stray light reconciles the under report. In addition, poor SNR bands in SWIR atmospheric absorptions are recovered when corrected for stray light. In this presentation, we will share findings from our recent PICARD spectroradiometric characterization over GLAMR including updated results comparing PICARD flight radiances with RadCalNet at RRV.
How to cite: Shrestha, A., Ellis, T., Domingues, R., Hoffmann, G., Su, H., Jacobson, J., Meyer, K., Barsi, J., and Platnick, S.: Spectroradiometric and Stray light characterization of the Pushbroom Imager for Cloud and Aerosol Research and Development (PICARD) Airborne Imager, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7050, https://doi.org/10.5194/egusphere-egu25-7050, 2025.
The Plankton, Aerosol, Cloud, Ocean Ecosystem Postlaunch Airborne eXperiment (PACE-PAX) is a multi-platform, multi-instrument field campaign designed to validate NASA’s PACE mission. Two research aircraft participated in this month-long campaign: the CIRPAS Twin Otter, conducting in situ observations of aerosols and clouds, and NASA’s high-altitude research aircraft ER-2, equipped with remote sensing instruments. Among these instruments is SPEX airborne, an airborne proxy for the Dutch SPEXone instrument onboard PACE. SPEX airborne, like SPEXone, is a multi-angle spectropolarimeter for wavelengths between 400 and 780 nm, designed to characterize aerosols in the Earth’s atmosphere. It has nine viewing angles (nadir, ±14°, ±28°, ±42°, and ±56°) and an across-track swath of about 2.1 km at nadir at nominal ER-2 flight altitudes. SPEX airborne radiance and polarization data are formatted identically to SPEXone data, enabling the use of the same RemoTAP algorithm to retrieve aerosol properties such as aerosol optical depth, size distributions, refractive index, layer height, and composition. During multiple flights, totaling over 80 flight hours, the ER-2 frequently flew under PACE and ESA’s EarthCARE satellite, as well as over the Twin Otter, calibration sites, and aerosol ground stations, facilitating extensive data comparisons. In this presentation, we present preliminary validation of publicly released SPEX airborne level-1 data and collocate these with SPEXone observations. Additionally, we present validation of SPEX airborne aerosol retrievals against AERONET stations and other instruments deployed during PACE-PAX. The RemoTAP aerosol retrievals from SPEX airborne data emphasize the key role of PACE-PAX in confirming aerosol properties derived from SPEXone.
How to cite: Simon, B., Mens, J., Smit, M., Fu, G., Rietjens, J., Grim, M., Vonsée, T., Talsma, J., Wolfs, R., Hasekamp, O., and van Diedenhoven, B.: Aerosol Validation in NASA's PACE mission: Deployment of the SPEX Airborne Polarimeter in the PACE-PAX Field campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11760, https://doi.org/10.5194/egusphere-egu25-11760, 2025.
The Hyper Angular Rainbow Polarimeter 2 (HARP2), developed at UMBC, is a state-of-the-art wide field-of-view polarimeter capable of measuring total and polarized radiances with fine angular resolution (≥2 degrees) and high polarization accuracy in four spectral channels (440, 550, 670, 870 nm). HARP2 was successfully launched in February 2024 aboard NASA’s Plankton Aerosol Cloud and ocean Ecosystem (PACE) satellite and has since been collecting critical science data on Earth’s atmospheric, oceanic, and surface properties. In September 2024, UMBC’s AirHARP2, an advanced airborne polarimeter closely resembling the orbital HARP2, participated in the PACE Postlaunch Airborne eXperiment (PAX). This campaign provides a unique opportunity to validate radiometric and polarimetric measurements and derived science products from the PACE satellite by conducting direct cross-platform comparisons using co-located scenes. This study focuses on the retrieval comparisons of liquid water cloud microphysical properties from HARP2 and AirHARP2 during PACE-PAX using a novel look-up-table retrieval algorithm that leverages the geometric features of the polarized cloudbow to infer the cloud droplet size distribution. The retrievals will be performed using a novel look-up-table retrieval algorithm that uses the geometric parameters of the polarized cloudbow to retrieve the cloud droplet size distribution. With AirHARP2’s Level-1C grid resolution (~120 m) approximately 42 times finer than HARP2’s (~5 km), we will also examine the impact of spatial resolution on retrieval performance. The results will be further validated by cross-comparisons with official cloud products from the Ocean Color Instrument, the primary instrument aboard PACE.
How to cite: Smith, R., Xu, X., McBride, B., and Martins, V.: Liquid Water Cloud Retrievals from HARP2 and AirHARP2 Measurements from the PACE-PAX Validation Campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20586, https://doi.org/10.5194/egusphere-egu25-20586, 2025.
The success of Earth Science space-borne missions relies on the availability of optical field measurements, as well as a solid validation plan to assess and verify the in-orbit quality of the data products. Since the late 1990s, NASA’s SeaBASS has served the ocean color community as the primary repository for in situ radiometric and pigment observations, facilitating robust product validation across multiple missions. The PACE science data validation program is responsible for making sure data products meet mission-specified requirements and for assessing uncertainties across various water types, cloud conditions, and aerosol distributions. In addition to SeaBASS, the PACE validation plan includes 24 PACE Validation Science Teams and a targeted field campaign called PACE-PAX. Nonetheless, an ongoing challenge remains the limited number of matchups between in situ and satellite measurements due to cloud cover, data quality issues, and other constraints. Here, we discuss the limitations and challenges of ocean color validation and present the current PACE validation plan, data sources, and early validation results.
How to cite: Soto Ramos, I. M., Allen, J., Cetinić, I., Ibrahim, A., Proctor, C. W., Knobelspiesse, K. D., and Werdell, J.: PACE Observatory validation plan, data sources, and results , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14414, https://doi.org/10.5194/egusphere-egu25-14414, 2025.
Launched in February 2024 and serving data to the public as of April 2024, the NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite provides a novel set of hyperspectral and polarimetric Earth observation (EO) capabilities across aquatic, terrestrial, and atmospheric domains-- an interdisciplinary span not matched by other EO missions. With these observations, PACE data can support multiple applications areas such as water resource management, public health and air quality, climate science, terrestrial and agricultural, post-disaster monitoring, and more. The PACE Applications Program has the primary goal of fostering and accelerating the translation of PACE’s advanced data into actionable applications that benefit society. To achieve this, we support bridging of researchers and applied end users through programming such as the PACE Community of Practice, Early Adopters Program, and information-sharing and co-production activities such as workshops and focus sessions. In this presentation we describe the interdisciplinary applications capabilities of PACE and opportunities for you to engage with our program.
How to cite: McKibben, S. M. and Caplan, S.: PACE Applications Program: Putting PACE remote sensing data to work for societal benefit across the Earth System , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13336, https://doi.org/10.5194/egusphere-egu25-13336, 2025.
Although “land” is not included the acronym for NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite, the mission is actively supporting terrestrial science. Two new global, daily product suites were recently released using land data from PACE’s Ocean Color Instrument (OCI). The first, termed SFREFL, is a hyperspectral collection of surface reflectances from the ultraviolet into the shortwave infrared. SFREFL currently employs L2gen for atmospheric correction, ensuring continuity with heritage missions processed by the Ocean Biology Processing Group. ISOFIT is also being considered for use as a standard surface reflectance algorithm. Both algorithms make PACE terrestrial data directly applicable to future hyperspectral missions like SBG, and ease collaboration with current missions producing similar products. The second suite, LANDVI, includes 10 vegetation indices: 6 multispectral (NDVI, EVI, NDWI, NDII, CCI, and NDSI) and 4 which are hyperspectral-enabled, or narrowband (PRI, Car, CIRE, and mARI). Narrowband indices leverage OCI’s unique capabilities to provide previously uncharacterized insights into the status of terrestrial ecosystems across the globe. Having been in production for several months, preliminary results from both SFREFL and LANDVI will be presented here. The integration of these terrestrial products as outputs from PACE positions the mission as pivotal for global environmental monitoring and establishes it as an important part of the terrestrial hyperspectral data record.
How to cite: Caplan, S., Mannino, A., McKibben, M., Huemmrich, F., Knobelspiesse, K., Werdell, J., Gao, M., Hasekamp, O., and Fu, G.: From PACE to PLACE: Results from the First Months of Land Data Products, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12925, https://doi.org/10.5194/egusphere-egu25-12925, 2025.
Over the past year, the Hyper-Angular Rainbow Polarimeter (HARP2) multi-angle imaging polarimeter instrument on the NASA Plankton Aerosol Cloud ocean Ecosystem (PACE) mission observed the entire Earth every two days. HARP2 measures total and polarized radiances over four spectral channels (440/550/670/870 nm), at up to 90 distinct viewing directions, and over a 114° field-of-view (1550 km cross-track swath). This large volume of daily information requires new approaches to on-orbit operations, data processing, calibration, and science. In this work, we celebrate and recap the first year of HARP2 on PACE – from pre-launch to on-orbit calibration (solar/lunar/vicarious), exciting new and synergistic science products for cloud, aerosol, and ocean properties, and co-located intercomparisons with OCI, SPEXone, and AirHARP2 underflights during the recent NASA PACE-PAX field campaign. We close with a look ahead to HARP2 as a pathfinder for upcoming polarimetry missions.
How to cite: McBride, B., Martins, J. V., Xu, X., Puthukkudy, A., Fernandez-Borda, R., Sienkiewicz, N., Smith, R., Gao, M., van Diedenhoven, B., Stamnes, S., Knobelspiesse, K., Sayer, A., Rajapakshe, C., Franz, B., Patt, F., Arillo, C., Cairns, B., Werdell, J., and Remer, L.: The First Year of the Hyper-Angular Rainbow Polarimeter (HARP2) on the NASA PACE mission: Performance, Science, and Synergy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14437, https://doi.org/10.5194/egusphere-egu25-14437, 2025.
With the launch of EPS-SG in 2025, a new era for a long-term operational Near-Real-Time provision of aerosol product is starting. If most of the potential for such a new remote sensing polarimetry has been demonstrated since 1996 with the 3 POLDER and PARASOL missions, the recent advance in term of retrieval but also analysis and exploitation of the data reveal more and more the potential. Indeed, polarimeters allow the observation of aerosols with a significantly improved information content which will feed the retrieval. On top of the aerosol optical thickness classically retrieved, an additional set of parameters characterizing the aerosol properties can now be derived. This specificity of polarimeters requires a more demanding effort in term of validation. We will overview the different aspects to be considered for the validation, describe the methodology for most of the parameters, and focus on some examples.
How to cite: Fougnie, B., Jafariserajehlou, S., and Huerta Valcarce, D.: Validation of Aerosol Products from Polarimetric Sensors – Application to PARASOL and 3MI, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15557, https://doi.org/10.5194/egusphere-egu25-15557, 2025.
NASA's Plankton, Aerosol, Clouds, and Ocean Ecosystems (PACE) Mission, launched a year ago, provides data on ocean color, aerosols, clouds, and land surfaces through its three advanced sensors. Some of these data products rely on established "heritage" algorithms, ensuring continuity with previous and ongoing missions, while others are novel, leveraging recent algorithmic advancements and PACE's unique measurement capabilities. To validate PACE's data products, the PACE Postlaunch Airborne eXperiment (PACE-PAX) was conducted in September 2024 in California. This campaign featured coordinated operations involving multiple aircraft, ocean vessels, and surface-based instruments, particularly timed with PACE satellite overpasses. Additionally, PACE-PAX supported similar activities for ESA's EarthCARE (Cloud, Aerosol, and Radiation Explorer) Mission. This presentation highlights the campaign's achievements, discusses the current status of the data, and outlines future plans for utilizing this valuable dataset.
How to cite: Cetinic, I., Knobelspiesse, K., Cairns, B., and Werdell, J.: PACE Mission validation with the PACE-PAX field campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13069, https://doi.org/10.5194/egusphere-egu25-13069, 2025.
The sensitivities of cloud properties to changes in the climate and to anthropogenic aerosol emissions are crucial for understanding Earth’s climate but remain highly uncertain. Global cloud observations from satellites are needed to advance our knowledge on processes related to the formation and evolution of clouds and precipitation. While long term satellite data records of cloud microphysical properties exist, largely obtained by multi-spectral imagers, they are known to be substantially biased or failing in particular situations, such as in regions of broken and/or mixed-phase clouds. The cloud products provided by NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, which was launched on 8 February 2024, have several advantages over past missions. PACE caries the Ocean Color Instrument (OCI), which is a multi-spectral imager, the Hyper-angular Rainbow Polarimeter (HARP-2) and the Spectropolarimeter for Planetary Exploration (SPEXone). Advanced, pixel-level cloud microphysical products are produced from the polarimeters, including cloud top phase and full droplet size distributions, while collocated retrievals are provided by OCI using more traditional methods. Instrument-synergy products include liquid water path and droplet number concentrations. We present first global advanced cloud products from PACE. We present validation using airborne campaigns that indicates that the polarimetry products are much less affected by the presence of broken and mixed-phase clouds than OCI observations, consistent with previous studies using simulations and observations. These observations provide new insights on the microphysical properties of global clouds, including their drop size distribution width and bi-modality which may be linked to precipitation formation. Furthermore, we show that the polarimeter retrievals along with OCI’s unique combination of three commonly-used shortwave infrared wavelength bands allows to assess some of the biases in traditional bi-spectral retrievals in unprecedented detail and on a global scale. We show that the biases in bi-spectral results depend on cloud structure and on the wavelength used for the droplet size retrievals. The PACE data provides crucial information to reduce biases in traditional bi-spectral cloud retrievals by essentially all multi-spectral imagers in the program of record that result from, e.g., sub-pixel cloudiness, mixed-phase cases and 3D radiative transfer effects. We make recommendations on how biases in bi-spectral results may be mitigated.
How to cite: van Diedenhoven, B., Rajapakshe, C., Wasilewski, A., Sayer, A., Cairns, B., Hasekamp, O., Knobelspiesse, K., Alexandrov, M., Miller, D., Sinclair, K., McBride, B., and Martins, V.: Advanced cloud products from NASA’s PACE mission, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8313, https://doi.org/10.5194/egusphere-egu25-8313, 2025.
Accurate measurements of in-water inherent optical properties (IOPs) such as absorption and backscattering, along with coincident in-situ and satellite-measured radiometry, are key to refining and calibrating algorithms used by hyperspectral satellite missions such as NASA PACE to derive ocean color data products. The accuracy of hyperspectral ocean color products, such as phytoplankton community composition, is therefore linked to the accuracy of in-situ IOP measurements. However, current instrumentation for in-situ absorption and backscattering measurements has been limited to either single- or multi-spectral wavelengths or to hyperspectral wavelengths that do not entirely meet the wavelength range and resolution requirements of PACE and other hyperspectral remote sensing missions. Advancements in instrumentation are therefore necessary to expand the range, resolution, and sensitivity of in-situ absorption and backscattering measurements to support these missions and the development and distribution of accurate ocean color data products. Additionally, advancements in hyperspectral absorption and backscattering sensors can offer new insights into studying particulate and dissolved materials in the ocean in support of biogeochemistry research.
We have recently developed and commercialized submersible hyperspectral absorption (Hyper-a) and backscattering (Hyper-bb) instruments to meet the needs of current (e.g., PACE) and future (e.g., GLIMR, SBG) hyperspectral remote sensing missions. The Hyper-bb is a single-angle backscatter sensor that utilizes a broadband LED source, scanning linear variable filter assembly, and sensitive photomultiplier tube detector. The Hyper-a is an absorption sensor that utilizes a xenon flash lamp, dual spectrometers (signal and reference), and a pump-through Lambertian integrating cavity that reduces measurement uncertainty due to scattering errors characteristic in a reflective tube design. Both sensors are designed to enable user calibration, reducing cost and downtime typically associated with sending the instrument back for factory calibration.
We will present details related to the development of these two hyperspectral instruments as well as their engineering specifications and recent test results from laboratory studies and field work.
How to cite: Simon, K., Slade, W., Strait, C., Tonizzo, A., Twardowski, M., Leeuw, T., Pottsmith, C., Chandrasiri, R., and Mikkelsen, O.: In-Situ Hyperspectral Absorption and Backscattering Sensors for Ocean Color and Biogeochemistry Research, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7774, https://doi.org/10.5194/egusphere-egu25-7774, 2025.
System vicarious calibration (SVC) of satellite ocean-color sensors involves comparing retrievals of water-leaving radiance (Lw) with in-situ measurements at the time of overpass and adjusting the calibration coefficients to ensure agreement between retrieved and measured quantities. This approach is designed to reduce uncertainties associated with purely radiometric calibration techniques, which lack the accuracy required for science applications, and to minimize biases introduced by atmospheric correction. For the recently launched PACE Ocean Color Instrument (OCI), the methodology utilizes hyperspectral Lw measurements from HyperNav radiometer systems deployed at various locations (Crete, Moorea, Puerto Rico, Hawaii) and from the Marine Optical Buoy (MOBY) near Lanai. Match-ups are rigorously selected based on criteria for atmospheric, surface, water, and geometry conditions. Top-of-atmosphere (TOA) radiance derived from onboard calibration techniques is compared to TOA radiance calculated from in-situ Lw measurements, resulting in calibration adjustment gains. The application of these adjusted gains to OCI imagery in diverse oceanic regions demonstrates more realistic values for water reflectance, enhancing the accuracy of retrieved ocean color data for scientific analyses.
How to cite: Frouin, R., Tan, J., Barnard, A., Bailess, A., Boss, E., Haëntjens, N., Banks, A., Chamberlain, P., and Mazloff, M.: System Vicarious Calibration of the PACE Ocean Color Instrument, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20694, https://doi.org/10.5194/egusphere-egu25-20694, 2025.
Because the evaporation duct profile is difficult to measure, different empirical surface layer models have been developed to compute the average refractivity profile near the ocean surface using four bulk measurements: pressure, temperature, humidity, wind speed at a single height (e.g., the ship’s bridge), and sea surface temperature (SST). Although these parameters can be conveniently measured using standard equipment, the measurement accuracy is usually influenced by inherent factors, such as the movement of the ship or the heat island effect. To analyze the heat island effect of ship-based bulk measurements for evaporation duct estimation, an open cruise observation over the Tropical Eastern Indian Ocean from 23 Aug 2024 to 14 Oct 2024 is used. The ship weather station measurements and the corresponding evaporation duct profiles, computed by the NPS evaporation duct model, are compared with 48 low-altitude rocketsonde profiles, which sample a high vertical resolution of air temperature, air humidity, air pressure, and wind parameters. The sensors for air temperature, humidity, pressure, and wind vector are deployed at 13.4 m above the mean sea level, and the SST is measured by an infrared thermometer. The results show that the mean air temperature and relative humidity of the ship measurements are 1.03 K and 4.07% higher than the rocketsonde measurements at the same altitude (i.e., 13.4 m), and the evaporation duct height and strength computed from the ship-based measurements are 1.98 m and 10.07 M-units lower than those from the rocketsonde measurements.
How to cite: Zhao, X., Wang, Y., Yang, P., Chen, Y., and Wei, C.: Heat-island-effect of ship-based bulk measurements for evaporation duct estimation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7979, https://doi.org/10.5194/egusphere-egu25-7979, 2025.
In May 2024 the EarthCARE satellite mission EarthCARE was launched. For the first time, the satellite combines a high spectral resolution lidar and a cloud radar with doppler capability as key instruments on one single platform. In addition, it is equipped with a multi spectral imager and a broadband radiometer. This unique combination makes EarthCARE the most complex satellite mission to study aerosol, clouds, precipitation, and radiation. To fully use these new and advanced data for science applications, a careful validation of the measurements and data products is required. We have implemented an EarthCARE-like payload onboard the German research aircraft HALO (High Altitude and LOng range) to prepare and validate the EarthCARE data. This instrumentation was flown during PERCUSION (Persistent EarthCARE underflight studies of the ITCZ and organized convection) as a contribution to ORCESTRA (Organized Convection and EarthCARE Studies over the Tropical Atlantic).
ORCESTRA is a network of different campaigns conducted to better understand the organized tropical convection at the mesoscale, e.g. including the interaction of convective organization with tropical waves and air-sea interaction, and the impact of convective organization on the Earth’s climate and radiation budget. In addition, ORCESTRA helps to validate satellite remote sensing (especially EarthCARE). To achieve these objectives, ORCESTRA combines several sub-campaigns taking place on the Cape Verde Islands and Barbados in August and September 2024.
One of the campaigns within ORCESTRA is the PERCUSION campaign. PERCUSION aims to test factors hypothesized to influence the organization of deep maritime convection in the tropics and the influence of convective organization on its larger-scale environment. One focus of PERCUSION was to establish confidence in the EarthCARE measurements and products. For this purpose, we conducted one EarthCARE underpass within each research flight HALO measurements were performed during the EarthCARE commissioning phase in August 2024 out of Sal, Cape Verde, and out of Barbados in September 2024. In addition, we performed flights out of Oberpfaffenhofen, Germany in November 2024 for validation of conditions that could not be captured in the two first campaign parts. Altogether, 33 EarthCARE underpasses were carried out in different aerosol and cloud situations. Some of the flights were coordinated with in-situ measurements onboard other aircrafts (e.g. the French ATR42), with shipborne measurements onboard the German research vessel METEOR, or with ground-based radar and lidar measurements at Mindelo (Cape Verde), Barbados, and the ACTRIS stations Antikythera, Leipzig, Lindenberg and Munich. Four underpasses under NASA’s PACE mission were also performed.
In our presentation we will give an overview of ORCESTRA with the main focus on PERCUSION. We will present the HALO PERCUSION measurements and will show first comparisons of HALO lidar and radar and EarthCARE lidar and radar measurements.
How to cite: Gross, S., Ewald, F., Wirth, M., Ehrlich, A., Hirsch, L., Krüger, K., Luebke, A., Mayer, B., Rosenburg, S., Volkmer, L., Wendisch, M., Windmiller, J., and Stevens, B.: HALO airborne measurements; PERCUSION’s contribution to EarthCARE validation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6148, https://doi.org/10.5194/egusphere-egu25-6148, 2025.
How to cite: Chen, B., Wu, A., Hui, W., Rao, P., Feng, X., Chen, F., Han, C., Ying, Q., Wu, Y., Liu, M., Moss, D., and Qian, Z.: Radiometric Calibration using Artificial Intelligence: Constituting Uniform Observing Systems for Infrared Satellites, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8293, https://doi.org/10.5194/egusphere-egu25-8293, 2025.
