Mark P. Esplin

Spectral measurements of high-temperature isotopic carbon dioxide in the 4.5- and 2.8-μm regions

High-resolution measurements have been made using the AFGL 2-m path difference Fourier transform spectrometer on isotopically enriched samples of carbon dioxide. Two regions were investigated: 2140–2320 and 3470–3770 cm−1. The samples were observed in absorption at temperatures up to 800 K. Observed line positions to high rotational levels were obtained for 15 parallel bands with Δv3 = 1 for the isotopic variants 13C16O2, 13C16O18O, and 13C16O17O in the 4.5-μm region and for 23 bands of the type Δv1 = 1, Δv3 = 1 for the species 12C16O2, 12C16O18O, and 12C18O2 in the 2.8-μm region.

Spectral measurements of high temperature isotopic carbon dioxide in the 4.3-μm region

Abstract High resolution (0.007 cm −1 ) spectral measurements in the 4.3-μm region have been performed using a Fourier transform spectrometer to observe in absorption two isotopically enriched samples of CO 2 which were heated to temperatures up to 800 K. One of these samples was enriched with 13 C and the other with 18 O. Observed line positions are tabulated which give line positions to an estimated accuracy of 0.0004 cm −1 for five bands of the three isotopes 13 C 16 O 2 , 12 C 16 O 18 O, and 12 C 18 O 2 as well as one band of 13 C 16 O 18 O. Spectroscopic constants are also reported for each observed band.

Spectral measurements of high temperature 13 C 16 O 2 and 13 C 16 O 18 O in the 4.3-μm region

High resolution (0.007-cm(-1)) spectral measurements of a hot (800 K) CO(2) sample consisting of 88% (13)C(16)O(2), 11% (13)C(16)O(18)O, and 1% various other isotopes were made in the 4.3-microm region using the Air Force Geophysics Laboratory Fourier transform spectrometer. Vibration-rotation constants which predict line positions to better than 0.001 cm(-1) are presented for several bands of these two isotopes.

A geosynchronous imaging Fourier transform spectrometer (GIFTS) for hyperspectral atmospheric remote sensing: instrument overview and preliminary performance results

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) was developed for the NASA New Millennium Program (NMP) Earth Observing-3 (EO-3) mission. This paper discusses the GIFTS measurement requirements and the technology utilized by the GIFTS sensor to provide the required system performance. Also presented are preliminary results from the recently completed calibration of the instrument. The GIFTS NMP mission challenge was to demonstrate new and emerging sensor and data processing technologies to make revolutionary improvements in meteorological observational capability and forecasting accuracy using atmospheric imaging and hyperspectral sounding methods. The GIFTS sensor is an imaging FTS with programmable spectral resolution and spatial scene selection, allowing radiometric accuracy and atmospheric sounding precision to be traded in near-real time for area coverage. System sensitivity is achieved through the use of a cryogenic Michelson interferometer and two large-area, IR focal plane detector arrays. Due to funding limitations, the GIFTS sensor module was completed as an engineering demonstration unit, which can be upgraded for flight qualification. Capability to meet the next generation geosynchronous sounding requirements has been successfully demonstrated through thermal vacuum testing and rigorous IR calibration activities.

High temperature, high resolution line position measurements of 12C16O2 in the 580 to 940 cm-1 region

Abstract More than 6500 P, Q and R branch spectral lines in the region 580–940 cm-1 have been identified and assigned to 43 vibration-rotation bands of the principal isotope of carbon dioxide, 12C16O2. The position of each line was measured and an uncertainty in the position of each line was estimated. The interferometric data used in this study were obtained from naturally occurring samples of carbon dioxide heated to 800 K, to yield data on high quantum-number rotational, vibrational and vibrational angular momentum states. Measurements were made for three different sample pressures: 5, 15 and 40 torr. Measurements at 15 and 40 torr permitted the observation of weak, high quantum-number vibrational transitions normally not observed at room temperature and high-quantum-number rotational transitions within the vibrational transitions. A maximum unapodized instrumental resolution of 0.0044 cm-1 was used. A weighted linear least-squares procedure was applied to the spectral lines of each vibrational transition to estimate rotational-vibrational molecular constants Gv, Bv, Dv and Hv which are reported here.

High temperature absorption measurements and modeling of CO2 for the 12 micron window region

Abstract High temperature absorption measurements were made for CO2 gas in Local Thermodynamic Equilibrium (LTE) with a hot cell and high resolution interferometer. The experimental data were compared to band-model and line-by-line model transmittance calculations using line parameters from the HITRAN and HITEMP data bases. The line-by-line calculations using HITEMP were in excellent agreement with experimental measurements, while the model calculations using the HITRAN data underpredicted the absorption by approx. 10%.

Preflight Assessment of the Cross-track Infrared Sounder (CrIS) Performance

The Cross-track Infrared Sounder (CrIS) is a part of the Crosstrack Infrared and Microwave Sounding Suite (CrIMSS) that will be used to produce accurate temperature, water vapor, and pressure profiles on the NPOESS Preparatory Project (NPP) and upcoming Joint Polar Satellite System (JPSS) operational missions. The NPP CrIS flight model has completed sensor qualification, characterization, and calibration and is now integrated with the NPP spacecraft in preparation for the launch. This paper reviews the CrIS performance during thermal vacuum tests, including the spacecraft integration test, and provides a comparison to the AIRS and IASI heritage sensors that it builds upon. The CrIS system consists of the instrument itself and ground-based scientific algorithms. The data reported in this paper was processed with the latest version of the CrIS science sensor data record (SDR) algorithm and thus reflects the performance of the CrIS SDR system. This paper includes the key test results for Noise Equivalent Differential Noise (NEdN), Radiometric Performance, and Spectral Accuracy. The CrIS sensor performance is outstanding and will meet the mission needs for the NPP /JPSS mission. NEdN is one of the key performance tests for the CrIS sensor. The overall NEdN performance for the CrIS in the LWIR, MWIR and SWIR spectral bands is excellent and is comparable or exceeds NEdN performance of AIRS and IASI. Also discussed is the Principal Component Analysis (PCA) approach developed to estimate contribution of random and spectrally correlated noise components to the total NEDN.

Modeled vs. actual performance of the geosynchronous imaging Fourier transform spectrometer (GIFTS)

The NASA Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) has been completed as an Engineering Demonstration Unit (EDU) and has recently finished thermal vacuum testing and calibration. The GIFTS EDU was designed to demonstrate new and emerging sensor and data processing technologies with the goal of making revolutionary improvements in meteorological observational capability and forecasting accuracy. The GIFTS EDU includes a cooled (150 K), imaging FTS designed to provide the radiometric accuracy and atmospheric sounding precision required to meet the next generation GOES sounder requirements. This paper discusses a GIFTS sensor response model and its validation during thermal vacuum testing and calibration. The GIFTS sensor response model presented here is a component-based simulation written in IDL with the model component characteristics updated as actual hardware has become available. We discuss our calibration approach, calibration hardware used, and preliminary system performance, including NESR, spectral radiance responsivity, and instrument line shape. A comparison of the model predictions and hardware performance provides useful insight into the fidelity of the design approach.

Preliminary Data on Variations ofOH Airglow During the Leonid 1999 Meteor Storm

As part of the 1999 Leonid MAC Campaign an extensive set of infrared (1.00 – 1.65 µm) airglow spectra and imaging data were collected from onboard the USAF FISTA aircraft. These data will permit a detailed study of the upper atmospheric conditions over a several day period centered on the Leonid meteor storm of 17/18 November, 1999 as well as during the meteor storm itself. We describe initial results of a spectral analysis that indicates a small but significant enhancement in the OH airglow emission during the peak of the storm but we cannot yet be certain of a cause and effect relationship. No similar systematic enhancement was observed in the O2 (1.27 µm) airglow emission recorded with the same instrument.

High resolution fourier spectroscopy of nitrous oxide at elevated temperatures

The Air Force Geophysics Laboratory high resolution interferometer has been used to measure the infrared absorption spectrum in the 8-μm region of a nitrous oxide sample heated to temperatures up to 800 K. A least-squares-fit was then used to obtain effective molecular constants for 18 rotation-vibration bands. These constants predict the position of spectral lines originating from excited rotational states with an accuracy considerably greater than previously available constants.