Dejian Fu

Global phosgene observations from the Atmospheric Chemistry Experiment (ACE) mission

Author Institution: Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada; NASA Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, USA

Infrared and near infrared emission spectra of SbH and SbD

The XR ground state vibration–rotation spectrum of SbH and the near infrared spectra of the bR–XR transitions of SbH and SbD have been measured at high resolution by Fourier transform spectroscopy. The SbH and SbD radicals were generated in a tube furnace with a D.C. discharge of a flowing mixture of argon, hydrogen (or deuterium), and antimony vapor. In the infrared region, the 1–0 and 2–1 bands of the three components (0, 1e, and 1f) as well as the 0 + component of the 3–2 band were observed for SbH and SbH. In the near infrared region, the 0–0, 1–1, and 2–2 bands of the bR–XR system of both SbH and SbD as well as the 3–3 band of SbD were observed. Except for a few lines, the antimony isotopic shift was not resolved for these electronic spectra. The present data set was combined with the available ground state data on SbD and aD data for SbH and SbD from previous work, and a least-squares fit was performed for each of the four isotopologues: SbH, SbH, SbD, and SbD. Improved spectroscopic constants were obtained for the observed vibrational levels of the XR , aD, and bR states of these four isotopologues. In addition, all the above data were also fitted simultaneously to a multi-isotopologue Dunham model, which yielded Dunham constants and Born–Oppenheimer breakdown parameters for these three electronic states. Interestingly, we found that Born–Oppenheimer breakdown corrections were also required for some of the spin–spin and spin–rotation parameters of the XR state. 2004 Elsevier Inc. All rights reserved.

CARBO-The Carbon Observatory Instrument Suite: the next generation of Earth observing instruments for global monitoring of carbon gases

The Carbon Observatory Instrument Suite, or CARBO, consists of four carbon observing instruments sharing a common instrument bus, yet targeted for a particular wavelength band each with a unique science observation. They are: a) Instrument 1, wavelength centered at 756 nm for oxygen and solar-induced chlorophyll fluorescence (SIF) observations, b) Instrument 2, centered at 1629 nm, for carbon dioxide (CO2) and methane (CH4) observation, c) Instrument 3, centered at 2062 nm for carbon dioxide and d) Instrument 4, centered at 2328 for carbon monoxide (CO) and methane. From low-Earth orbit, these instruments have a field-of-view of 10 to 15 degrees, and a spatial resolution of 2 km square. These instruments have a spectral resolving power ranging from ten to twenty thousand, and can monitor columnaverage dry air mole fraction of carbon dioxide (XCO2) at 1.5 ppm, and methane (XCH4) at 7 ppb. These new instruments will advance the use of immersion grating technology in spectrometer instruments in order to reduce the size of the instrument, while improving performance. These compact, capable instruments are envisioned to be compatible with small satellites, yet modular to be configured to address the particular science questions at hand. Here we report on the current status of the instrument design and fabrication, focusing primarily on Instruments 1 and 2. We will describe the key science and engineering requirements and the instrument performance error budget. We will discuss the optical design with particular emphasis on the immersion grating, and the advantages this new technology affords compared to previous instruments. We will also discuss the status of the focal plane array and the detector electronics and housing. Finally, we report on a new approach – developed during this instrument design process - which enables simultaneous measurement of both orthogonal polarization states (S and P) over the field-of-view and optical bandpass. We believe this polarization sensing capability will enable science observations which were previously limited by instrumental and observational degeneracies. In particular: improved sensitivity to all species, better sensitivity to surface polarization effects, better constraints on aerosol scattering parameters, and superior discrimination of the vertical distribution of gases and aerosols.

Retrievals of Tropospheric Ozone Profiles from the SynergicObservation of AIRS and OMI: Methodology and Validation

The Tropospheric Emission Spectrometer (TES) on the A-Train Aura satellite was designed to profile tropospheric ozone and its precursors, taking measurements from 2004 to 2018. Starting in 2008, TES global sampling of tropospheric 15 ozone was gradually reduced in latitude with global coverage stopping in 2011. To extend the record of TES, this work presents a multispectral approach that will provide O3 data products with vertical resolution and measurement uncertainty similar to TES by combining the single-footprint thermal infrared (TIR) hyperspectral radiances from the Aqua Atmospheric Infrared Sounder (AIRS) instrument and the ultraviolet (UV) channels from the Aura Ozone Monitoring Instrument (OMI). The joint AIR+OMI O3 retrievals are processed through the MUlti-SpEctra, MUlti-SpEcies, MUlti-SEnsors (MUSES) retrieval 20 algorithm. Comparisons of collocated joint AIRS+OMI and TES to ozonesonde measurements show that both systems have similar errors, with mean and standard deviation of the differences well within the estimated measurement uncertainty. AIRS+OMI and TES have slightly different biases (within 5 parts per billion) versus the sondes. Both AIRS and OMI have wide swath widths (~1,650 km for AIRS; ~2,600 km for OMI) across satellite ground tracks. Consequently, the joint AIRS+OMI measurements have the potential to maintain TES vertical sensitivity while increasing coverage by two orders of 25 magnitude, thus providing an unprecedented new dataset to quantify the evolution of tropospheric ozone. Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2018-138 Manuscript under review for journal Atmos. Meas. Tech. Discussion started: 16 May 2018 c

Multi-year comparisons of ground-based and space-borne Fourier Transform Spectrometers in the high Arctic between 2006 and 2013

This paper presents 8 years (2006–2013) of measurements obtained from Fourier transform spectrometers (FTSs) in the high Arctic at the Polar Environment Atmospheric Research Laboratory (PEARL; 80.05 N, 86.42W). These measurements were taken as part of the Canadian Arctic ACE (Atmospheric Chemistry Experiment) validation campaigns that have been carried out since 2004 during the polar sunrise period (from mid-February to mid-April). Each spring, two ground-based FTSs were used to measure total and partial columns of HF, O3, and trace gases that impact O3 depletion, namely, HCl and HNO3. Additionally, some tropospheric greenhouse gases and pollutant species were measured, namely CH4, N2O, CO, and C2H6. During the same time period, the satellite-based ACE-FTS made measurements near Eureka and provided profiles of the same trace gases. Comparisons have been carried out between the measurements from the Portable Atmospheric Research Interferometric Spectrometer for the InfraRed (PARIS-IR) and the co-located high-resolution Bruker 125HR FTS, as well as with the latest version of the ACE-FTS retrievals (v3.5). The total column comparison between the two colocated ground-based FTSs, PARIS-IR and Bruker 125HR, found very good agreement for most of these species (except HF), with differences well below the estimated uncertainties (≤ 6%) and with high correlations (R ≥ 0.8). Partial columns have been used for the ground-based to space-borne comparison, with coincident measurements selected based on time, distance, and scaled potential vorticity (sPV). The comparisons of the ground-based measurements with ACEFTS show good agreement in the partial columns for most species within 6 % (except for C2H6 and PARIS-IR HF), which is consistent with the total retrieval uncertainty of the ground-based instruments. The correlation coefficients (R) of the partial column comparisons for all eight species range from approximately 0.75 to 0.95. The comparisons show no notable increases of the mean differences over these 8 years, indicating the consistency of these datasets and suggesting that the space-borne ACE-FTS measurements have been stable over this period. In addition, changes in the amounts of these trace gases during springtime between 2006 and 2013 are presented and discussed. Increased O3 (0.9%yr−1), HCl (1.7%yr−1), HF (3.8%yr−1), CH4 (0.5 % yr−1), and C2H6 (2.3%yr−1, 2009–2013) have been found with the PARIS-IR dataset, the longer of the two ground-based records. Published by Copernicus Publications on behalf of the European Geosciences Union. 3274 D. Griffin et al.: Ground-based and space-borne FTS comparisons in the high Arctic (2006–2013)