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PACE-PAX Flightpaths
Reflectance from the PRISM instrument taken during the PACE-PAX Campaign
532 nm Lidar Backscatter Data from the HSRL instrument during the PACE-PAX Campaign

PACE-PAX

Plankton, Aerosol, Cloud, ocean Ecosystem Postlaunch Airborne eXperiment

Principal Investigator

Kirk Knobelspiesse

Data Centers

ASDC
LAADS DAAC

The Plankton, Aerosol, Cloud, ocean Ecosystem Postlaunch Airborne eXperiment (PACE-PAX) was a field campaign to gather data to support PACE mission validation. A secondary objective was help validate data from JAXA/ESA's Earth Cloud, Aerosol, and Radiation Explorer (EarthCARE) mission. 

PACE-PAX was conducted in September 2024 in Southern and Central California and nearby coastal regions. The team flew 81 hours on the NASA ER-2 operating out of the NASA Armstrong Flight Research Center and 60 flight hours on the CIRPAS Twin Otter from Marina Municipal Airport. A NOAA vessel, the R/V Shearwater, operated 16 day trips out of Santa Barbara, while a privately owned sailboat, the R/V Blissfully, conducted nine sorties out of Long Beach. Numerous other entities — many of which were members of the PACE Validation Science Team (PVST) — cooperated to make coincident observations. 

Ocean data are archived at the SeaWiFS Bio-optical Archive and Storage System (SeaBASS), DOI: 10.5067/SeaBASS/PACE-PAX/DATA001 

The field campaign overview is: Knobelspiesse, K. D., Cetinić, I., Cairns, B., Leblanc, S. E., Ueyama, R., and the PACE-PAX team: The NASA Plankton, Aerosol, Cloud, ocean Ecosystem mission Postlaunch Airborne eXperiment (PACE-PAX), Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2026-541, in review, 2026. 
Other related manuscripts are listed in the Publications section of this page.

The PACE-PAX mission website contains additional campaign documentation.

For more meteorology resources supporting PACE-PAX, please visit NASA Ames Airborne Science Meteorological Support for PACE-PAX.

PACE Imagery from the time of the PACE-PAX campaign
  • Provide sufficient data to validate narrow swath orbital observations 
  • Validate radiometric and polarimetric properties 
  • Focus on specific processes or phenomena (e.g., high-aerosol loads over land and ocean, multiple aerosol layers) 
PACE-PAX Timeline
Platform TypePlatformRelevant Instrument
Air-BasedER-2Airborne Hyper-Angular Rainbow Polarimeter 2 (AirHARP2)
High Spectral Resolution Lidar - 2 (HSRL-2)
Meteorology and Navigation Data
Merged PRISM/PICARD data
Portable Remote Imaging Spectrometer (PRISM) 
Pushbroom Imager for Cloud and Aerosol Research and Development (PICARD)
Research Scanning Polarimeter (RSP)
Spectro-Polarimeter for Exploration Airborne (SPEX Airborne)
AnalysisER-2
PRISM/PICARD		Merged PRISM/PICARD data (PACE/OCI proxy)
Air-BasedCIRPAS Twin Otter

Twin Otter Facility instruments:

  • Cloud and Aerosol Spectrometer (CAS)
  • Cloud Droplet Probe (CDP)
  • Cloud Imaging Probe (CIP)
  • Gerber Particulate Volume Monitor
  • GPS, attitude, winds, temperature, humidity, pressure
  • Heitronics KT 19.85 Pyrometer (downlooking)
  • HotWire Liquid Water Content (HW)
  • Passive-Cavity Aerosol Spectrometer Probe (PCASP)
  • SPN-1 Sunshine Pyranometer
  • Ultrafine Condensation Particle Counter

Langley Aerosol Research Group Experiment (LARGE) suite:

  • Aerodynamic Particle Sizer (APS)
  • Printed Optical Particle Spectrometer (POPS)
  • TSI-3563 Nephelometer
  • Tricolor Absorption Photometer (TAP)
  • Ultra-High Sensitivity Aerosol Spectrometer (UHSAS)
AnalysisIn-Situ Aerosol Retrieval Algorithm (ISARA)Merged CIRPAS Twin Otter In-Situ aerosol data for validation
Ground-BasedMarina Air Traffic Control Tower SiteAerodynamic Particle Sizer (APS)
Ultra-High Sensitivity Aerosol Spectrometer (UHSAS)
Spectral Aerosol Light Absorption Detector (SALAD)
Spectral aerosol Extinction instrument (SpEx)
Tricolor Absorption Photometer (TAP)
TSI-3563 Nephelometer
Ground-BasedAerosol Robotic Network (AERONET)1Cimel Sun Photometers
Water-BasedR/V Shearwater2Oceanographic instruments
Water-BasedR/V Blissfully2Oceanographic instruments

1Data available on the AERONET site.
2Data available at SeaBASS, DOI: 10.5067/SeaBASS/PACE-PAX/DATA001

Related Instruments

Langley Aerosol Research Group Experiment (LARGE) The Langley Aerosol Research Group Experiment (LARGE) measures in-situ aerosol micrphysical and optical properties.
Portable Remote Imaging Spectrometer (PRISM) PRISM is an airborne push-broom spectrometer that provides the necessary spectral, spatial, and temporal resolution to characterize events in coastal zones.
Pushbroom Imager for Cloud and Aerosol Research and Development (PICARD) PICARD provides visible near-infrared (VNIR) and short-wave infrared (SWIR) imagery to support atmospheric research and validate satellite retrievals.