Stanley P. Sander1, Jean-Francois Blavier1, Yen-Hung Wu1, Daniel Preston1, Clare Wong1, Thomas Pongetti1, Yuk L. Yung2, and the CLARS and PanFTS Teams

1NASA Jet Propulsion Laboratory, California Institute of Technology2Division of Geological and Planetary Sciences, California Institute of Technology

copyright 2019, California Institute of Technology

Development and Field Validation of the PanFTS Instrument for Geostationary Measurements of

GHGs, Trace Gases and SIF

GEO Air Quality Constellation (2022)TEMPO (NASA/EVI-1), Sentinel-4 (ESA), GEMS (Korea)

• GeoCarb mission has been selected by NASA for geostationary observations of CO2, CH4 and CO for carbon cycle studies in the Western Hemisphere.

Geostationary Imaging Fourier Transform Spectrometer: Hourly Sampling of Trace Gases

From geostationary orbit PanFTS can map all of North and South America hourly with high resolution measurements (temporal, spatial, and spectral) that capture rapidly evolving tropospheric

concentrations with planetary boundary layer sensitivity

Spectra in every pixel captures rapidly evolving tropospheric

chemistry

500 km x 500 km scene is imaged onto a 128x128 pixel (or larger) focal plane array which provides a 2.7x2.7 km nadir GSD and records spectra in every pixel for 60 seconds per scene

3

4

O3

NO2

SO2

CO

H2COCHOCHOCH4

NH3

O2

CO2

N2O

Chappius

PanFTSPanFTS EMEMInfrared Visible UVUV

Earth Spectrum (Tropical noon, albedo 0.8)Wavelength (µm)

PanFTSPanFTS BBBB

Passive Vertical Profiling of Trace Gases Using Panspectral Observations

Wide spectral coverage and high spectral resolution enables tropospheric profiling of multiple species with boundary layer visibility

AIRS IASIOMI

AIRS TES IASI GOSATOMI

SCIAMACHYPanFTS has the measurement capabilities of several satellite instruments combined

Panspectral (UV IR) enables :• Retrievals of multiple chemical families

O2, O3, O4 H2O, HDO NO2, NH3, N2OCO, CO2, HCHO, CH4, CH3OH, (CHO)2SO2, BrO, AOD, SSA, AAOD, Temp.

D. Fu et al

IR onlyIR + UV UV only

a priori

PanFTS joint retrieval of O3 in UV and IR reduces uncertainty in profile retrievals (Fu et al.)

PanFTS EM Flight Like Optical Design

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Adjustable Stationary

Mirror

UV-NIR Interferometer Beam Splitter

UV-NIR Interferometer Compensator

Piezo Actuator

PiezoActuator

Bipod Struts (designed for precision alignment and thermal stability)

LWIRInterferometer

Bench

Input Beam Splitter

UV-VisInterferometer Bench

Input Beam Splitter Bench

Metrology Beam

Launcher

Adjustable Stationary

Mirror

LWIR OPDM Mirror

UV-NIROPDM Mirror

Input Beam Fold Mirror

UV-NIR Dichroic

LWIR Focusing Optics (aka LWIR camera) NIR Focusing Optics

(aka NIR camera)

UV Focusing Optics (aka UV camera)

Panchromatic Fourier Transform Spectrometer (PanFTS):Engineering Model for Geostationary Chemical Imaging

• Spectral Coverage:0.3-10 µm

• 2 Dynamically Aligned Plane Mirror Michelson InterferometersMOPD = 10 cm

• 3 Cameras: 128x128 focal plane arrays with in-pixel digitization

• 2.7 km nadir ground sampling/pixel from geostationary orbit PanFTS Engineering Model being inserted into JPL’s 10-foot

thermal-vacuum chamber for environmental testing in vacuum at -100 °C.

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Composite Bench Test Results:TIR through UV

1 µm10 µm 3 µm 0.3 µmWavelength (µm)

Update slides using this picture instead.

AzimuthalScan

FTIR Spectrometer 2. Basin

1.7 km a.s.l.

Spectral bands:CO2 (1.6 um)CH4 (1.7 um) N2O (2.3 um)CO (2.3 um) O2 (1.27 um)

Fu et al. AMT, 2014

Two measurement modes:

California Laboratory for Atmospheric Remote Sensing(CLARS)

1. Direct sun (Spectralon)

Sample Chemical Images (CH4, CO2, O2) from CLARSEach pixel is derived from a high resolution NIR spectrum

First operational demonstration of Imaging FTS in a Simulated Geostationary Environment

INCR

EASI

NG

SLA

NT

COLU

MN

DEN

SITY

VISIBLE O2

CH4 CO2

Hill in foreground

LA Basin in background

PanFTS Images of Solar Induced Fluorescence from Vegetation Visible B/W Image Broadband NIR Image

SIF Image

• 128x128 image derived from 0.5 cm-1

Fraunhofer spectra• High SIF features are

from grassy rings around horse racing track.

Hot Spots in XCH4:XCO2 Excess Ratio Reveal CH4 SourcesIn the Los Angeles Basin

Period: 09/2011-10/2013

• Scholl Canyon landfill• NG pipeline

• Puente Hills landfill• Fracking sites

Dairy farms

XCH4 Maps from Aliso Canyon Natural Gas Well Blowout (2015)

Geostationary Observations Provide High Temporal (hourly) and Spatial (2-4 km GSD) Resolution for Process Studies

LEAK START

Summary• The geostationary vantage point is complementary to other

orbits and permits long-duration observations for process studies with diurnal temporal and km-spatial resolution.

• Fourier transform spectrometers are ideally suited for geostationary observations, providing chemical imaging with high spectral and spatial resolution over a very large spectral range (0.3-10 µm) for passive profiling of trace gases.

• A prototype imaging FTS, PanFTS, has demonstrated these concepts using Mt. Wilson for simulated geostationary observations over a megacity.