PIRS: Pyro-Atmosphere Infrared Sounder


PIRS will demonstrate a new hyperspectral infrared sounder for airborne campaigns dedicated to monitoring wildfires. Projected to be 3x lighter than current IR sounders, this instrument will be especially useful during pre- and active-fire stages, providing wildfire managers with 3D measurements of atmospheric thermodynamic conditions at high resolution. Equipped with novel optical components, the instrument will have flexible spatial resolution and a wide swath, making it ideal for instantaneously mapping fire weather conditions across active burn sites.

Science Area

Fire meteorology studies how meteorological conditions influence fire initiation and development and how wildfires can alter atmospheric circulation and provide feedback to fire development. It is also a key factor determining the transport of air pollution produced by wildfires, which can travel hundreds of miles from its original source. Observing fire meteorology in real time is difficult, and new instruments dedicated to the task will be a tremendous asset to wildfire managers monitoring active burns and pre-burn conditions.


PIRS will use new grating spectrometer optics and detector technology to achieve major size reductions. With a spatial resolution of ~15-470 m and wide swath (20 km at 8.5 km altitude), PIRS will perform the following measurements: 3D soundings of temperature and specific humidity in the atmosphere; carbon monoxide distribution for monitoring the transport of polluted air; and, estimates of fire radiative power at a resolution of 15 m. PIRS will also investigate the atmospheric thermodynamic conditions that initiate pyrocumulonimbus clouds for hazard mitigation during fire suppression activities.


  • All-refractive optics assembly both produces better image quality over a wide field of view and reduces the overall size of the instrument.
  • Novel immersion grating spectrometer splits light into 640 spectral channels, from 4.08-5.13 μm, allowing PIRS to monitor a diverse collection of atmospheric targets.
  • HOT-BIRD focal plane array operates reliably at temperatures as high as 115 degrees kelvin. This it better suited for collecting infrared measurements from aircraft without large cryocoolers when compared to traditional hyperspectral infrared sounders.

Principal Investigator

Sun Wong photoSun Wong is an atmospheric physicist and a weather and climate scientist. He is the PIRS project’s principal investigator and science lead. He received his PhD in physics in Columbia University in 1999, and has been a research scientist in the Atmospheric Physics and Weather Group at Jet Propulsion Laboratory (JPL) of California Institute of Technology since 2009. He is also a member of the Atmospheric Infrared Sounder team at JPL.

Sun is assisted at JPL by co-investigators Thomas Pagano (lead engineer), Alex Soibel (task manager and electronic engineer), Dean Johnson (thermal engineer), Brian Monacelli (optics engineer), Roger Chao (flight manager), Robert Wilson (retrieval scientist), Mathias Schreier (retrieval scientist), and at Sierra Lobo Inc. by Megan Gibson (mechanical engineer) for the PIRS project.

Selected Publications

Pagano, T. S. et al. (2019), CubeSat Infrared Atmospheric Sounder technology development status, J. Appl. Remote Sens., vol 13, no. 3, 032512, Sep. 2019, doi: 10.1117/1.JRS.13.032512

Pagano, T. S., D. Johnson, J. Mcguire, M. Schwochert and D. Z. Ting (2022), Technology Maturation Efforts for the Next Generation of Grating Spectrometer Hyperspectral Infrared Sounders,” in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, doi: 10.1109/JSTARS.2022.3165168.

Wong, S., E. J. Fetzer, M. Schreier, G. Manipon, E. F. Fishbein, B. H, Kahn, Q. Yue, and F. W. Irion (2015), Cloud-induced uncertainties in AIRS and ECMWF temperature and specific humidity, J. Geophys. Res., 120, doi:10.1002/2014JD022440.