Dr. Robert B. Chatfield Profile

Dr. Robert B. Chatfield

at NASA Ames Research Ctr

SPIE Involvement:

Author

Publications (4)

Proceedings Article | 10 October 2019 Presentation + Paper

TEMPO Green Paper: Chemistry, physics, and meteorology experiments with the Tropospheric Emissions: monitoring of pollution instrument

K. Chance, X. Liu, C. Chan Miller, G. González Abad, G. Huang, C. Nowlan, A. Souri, R. Suleiman, K. Sun, H. Wang, L. Zhu, P. Zoogman, J. Al-Saadi, J. -C. Antuña-Marrero, J. Carr, R. Chatfield, M. Chin, R. Cohen, D. Edwards, J. Fishman, D. Flittner, J. Geddes, M. Grutter, J. Herman, D. Jacob, S. Janz, J. Joiner, J. Kim, N. Krotkov, B. Lefer, R. Martin, O. Mayol-Bracero, A. Naeger, M. Newchurch, G. Pfister, K. Pickering, R. Pierce, C. Rivera Cárdenas, A. Saiz-Lopez, W. Simpson, E. Spinei, R. J. Spurr, J. Szykman, O. Torres, J. Wang

Proceedings Volume 11151, 111510B (2019) https://doi.org/10.1117/12.2534883

KEYWORDS: Pollution, Aerosols, Clouds, Atmospheric modeling, Ozone, Satellites, Chemistry, Agriculture, Ultraviolet radiation, Soil science

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Proceedings Article | 1 September 2006 Paper

Tropospheric infrared mapping spectrometers (TIMS) for air quality measurements

John Kumer, John Mergenthaler, Aidan Roche, Richard Rairden, Robert Chatfield

Proceedings Volume 6299, 629908 (2006) https://doi.org/10.1117/12.680925

KEYWORDS: Short wave infrared radiation, Mid-IR, Long wavelength infrared, Infrared radiation, Spectral resolution, Atmospheric modeling, Spectrometers, Sensors, Absorption, Calibration

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Proceedings Article | 21 October 2005 Paper

Infrared mapping spectrometer to provide vertical information on atmospheric CH₄

Jack Kumer, John Mergenthaler, Aidan Roche, David Crain, Larrabee Strow, Robert Chatfield

Proceedings Volume 5978, 59781X (2005) https://doi.org/10.1117/12.627729

KEYWORDS: Short wave infrared radiation, Satellites, Knowledge management, Spectroscopy, Reflectivity, Infrared spectroscopy, Sensors, Molecules, Ocean optics, Diffraction

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Precise measurements of CH₄ in a column of near surface air, and in partial columns above this, would be very valuable in identifying sources/sinks of atmospheric CH₄, and its transport. For this purpose we have proposed a grating mapping spectrometer (GMS) for deployment as an Instrument of Opportunity (IOO) on the NPOESS that acquires data in the 2990 to 3050 cm^-1 spectral region. It will provide measurements of CH₄ absorption of sunlight in the weaker CH₄ features in the region, and of thermal emission in the stronger CH₄ features in the region. It is the combination of the two that provides the vertical information. The IOO will acquire spectra on a crosstrack swath centered on nadir, and with 1/2 width of 55 degrees on each side of nadir (about 2800 km full width swath on the ground for a nominal 828 km satellite altitude). This with footprints that are about 3.1 km on a side at nadir. The small footprint facilitates cloud screening, and identification of CH₄ source hotspots. A capability to project the slit to nadir along the direction from satellite to sun will be utilized for over the ocean viewing in order to facilitate measurements in solar glitter. It will obtain spectra with resolution n < 0.58 cm^-1 and sample spacing < 0.17 cm^-1. Based on the spectral characteristics and currently achievable very low-noise we do a linear error analysis (Rodgers, [1]) for the simultaneous retrieval of multi-column CH₄, humidity, and surface parameters and ¹³CH₄ total column. We show that useful multi-column CH₄ retrievals can be obtained, with good near surface sensitivity in sunlit conditions. We also show the ¹³CH₄ column can be retrieved with precision better than 3%. Retrieval of ¹³CH₄ column in the earth's atmosphere is analogous in difficulty to retrieval of the major CH₄ isotope column in the Martian atmosphere by a similar GMS deployed on a Mars orbiter. We show that H₂O vertical information can be retrieved from these measurements and discuss the potential for ethane column retrieval.

Proceedings Article | 21 October 2005 Paper

Proposed NPOESS IOO to provide enhanced information on atmospheric CH₄, CO, and CO₂, and to mitigate effects of CO₂ SWIR non-LTE

Jack Kumer, John Mergenthaler, Aidan Roche, David Crain, Larrabee Strow, Robert Chatfield

Proceedings Volume 5978, 59780E (2005) https://doi.org/10.1117/12.627722

KEYWORDS: Short wave infrared radiation, Spectral resolution, Reflectivity, Clouds, Calibration, Temperature metrology, Troposphere, Data modeling, Satellites, Carbon monoxide

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Measurements of the column CH₄, CO and CO₂ are high priorities of the NPOESS Pre-Planned Product Improvement (P3I) data sets. Risk reduction for existing NPOESS instruments, including mitigation of daytime CO₂ SWIR non-LTE effects, is also a high priority. We have proposed an NPOESS Instrument Of Opportunity (IOO) to address these priorities. It consists of two grating mapping spectrometers (GMSs). One that would acquire measurements with high spectral resolution Δv < 0.13 cm^-1 of CH₄, CO and H₂O absorption lines in reflected sunlight in the VSWIR region 4281 to 4301 cm^-1, and another for measurements with Δv < 0.30 cm^-1 in the SWIR region 2355 to 2430 cm^-1. The IOO will acquire spectra on a crosstrack swath from nadir to 55 degrees (about 1400 km on the ground) on footprints that are about 1.55 and 3.1 km on a side at nadir for the two GMS, respectively. The small footprint facilitates cloud screening, and identification of pollution hotspots. We use linear error analysis (LEA, based on the Rodgers [1] paper) to estimate the proposed IOO's performance. The LEA indicates that the IOO should be able to provide CH₄ and CO column retrieval over sunlit land (and from ocean glitter when it is viewed) that satisfies or exceeds NPOESS P3I Environmental Data Records (EDRs) requirements in all aspects except refresh where the IOO would provide every two days vs the once per day requirement. Further, it shows the VSWIR IOO data when used in combination with the NPOESS Cross Track Infrared Sounder (CrIS) [2] data should provide: (a) CO profile data with sensitivity to CO in near surface air that is enhanced compared to that in the current TERRA-MOPITT, ACQUA-AIRS and AURA-TES data sets because these are limited to thermal infrared measurements that lack sensitivity to CO in near surface air layer where there is little contrast between the air temperature and the ground surface temperature, (b) CH₄ profile with sensitivity in the near surface air layer that is crucial for identifying CH₄ sources/sinks (c) and significant improvement in the CrIS retrieved humidity in the near surface layer of air. We show the SWIR IOO data can be used for CO₂ column retrieval with near surface air layer sensitivity in the daytime. And also that in combination with CrIS SWIR data facilitates CO₂ SWIR non-LTE mitigation that is required for advanced sounding quality temperature profile (TP) retrieval from CO₂ SWIR data in daytime conditions. This provides risk reduction in case of degradation in the CrIS LWIR region data.

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