Spectrally resolved observations of atmospheric emitted radiance in the H2O rotation band

This paper presents the project Earth Cooling by Water Vapor Radiation, an observational programme, which aims at developing a database of spectrally resolved far infrared observations, in atmospheric dry conditions, in order to validate radiative transfer models and test the quality of water vapor continuum and line parameters. The project provides the very first set of far-infrared spectral downwelling radiance measurements, in dry atmospheric conditions, which are complemented with Raman Lidar-derived temperature and water vapor profiles

Detection of a tropospheric ozone anomaly using a newly developed ozone retrieval algorithm for an up-looking infrared interferometer

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): D06304, doi:10.1029/2008JD010270.On 2 June 2003, the Baltimore Bomem Atmospheric Emitted Radiance Interferometer (BBAERI) recorded an infrared spectral time series indicating the presence of a tropospheric ozone anomaly. The measurements were collected during an Atmospheric Infrared Sounder (AIRS) validation campaign called the 2003 AIRS BBAERI Ocean Validation Experiment (ABOVE03) conducted at the United States Coast Guard Chesapeake Light station located 14 miles due east of Virginia Beach, Virginia (36.91°N, 75.71°W). Ozone retrievals were performed with the Kurt Lightner Ozone BBAERI Retrieval (KLOBBER) algorithm, which retrieves tropospheric column ozone, surface to 300 mbar, from zenith-viewing atmospheric thermal emission spectra. KLOBBER is modeled after the AIRS retrieval algorithm consisting of a synthetic statistical regression followed by a physical retrieval. The physical retrieval is implemented using the k-Compressed Atmospheric Radiative Transfer Algorithm (kCARTA) to compute spectra. The time series of retrieved integrated ozone column on 2 June 2003 displays spikes of about 10 Dobson units, well above the error of the KLOBBER algorithm. Using instrumentation at Chesapeake Light, satellite imaging, trace gas retrievals from satellites, and Potential Vorticity (PV) computations, it was determined that these sudden increases in column ozone likely were caused by a combination of midtropospheric biomass burning products from forest fires in Siberia, Russia, and stratospheric intrusion by a tropopause fold occurring over central Canada and the midwestern United States.NASA for its support through grant NAG5- 1156-7 for AIRS Validation and grant NNG04GN42G for development of AIRS trace gas products, and through a subcontract with JPL on the AIRS Project prime contract NAS7-03001 for continuing optimization and validation of AIRS trace gas products.

An assessment of the tropical humidity‐temperature covariance using AIRS

We investigate the horizontal and vertical structure of the covariance between water vapor and temperature in the tropical troposphere, using satellite measurements from the Atmospheric InfraRed Sounder (AIRS). Our analysis reveals large spatial gradients in the local covariance between water vapor and temperature. Positive correlations dominate the tropical lower and upper troposphere, while regions of negative correlation are common in the tropical middle troposphere. While regressions of the tropical mean water vapor and temperature profiles reveal slopes of the same order of magnitude of the Clausius‐Clapeyron regime, the regression of local values can be up to an order of magnitude larger than the Clausius‐Clapeyron prediction. Results from the NOAA GFDL global circulation model are also shown for comparison

WATER VAPOR CONTINUUM IN THE 1300−2200cm−11300-2200 cm^{-1} REGION

Author Institution: University of Maryland, Baltimore County, Baltimore, MD 21228; Molecular Physics Division, Gaithersburg, MD 20899Water vapor transmission spectra in the $1300-2200 cm^{-1}$ region were recorded using a BOMEM fourier transform spectrometer at resolutions of 0.01, 0.04, and $2.00 cm^{-1}$. Self-, nitrogen-, and oxygen-broadened spectra were collected over a range of pressures and temperatures at path lengths of 12, 44, and 84 meters using a White-type cell. The near-line local absorption was calculated using the recently measured line parameters of Toth in order to determine the continuum from these data. Simulations of the difficult retrieval of the water continuum from these spectra within the band help guide our analysis and highlight the sensitivity of our retrieved continuum to uncertainties in the spectra and in the line parameters. Comparisons to existing continuum data and models will be presented

Characterization of Water Vapor and Carbon Dioxide Spectral Line Parameters in the Two micron Region

1. R. M. Sova, M. E. Thomas, D. Tobin, D. Byrum and L. L. Strow, ""Characterization of Candidate DLAL Lidar Water Vapor and Carbon Dioxide Absorption Lines in the Two Micron Region,'' SPIE Proccedings - Optical Instrumentation for Regional and Global Atmospheric Studies 2365, Nov., 1994.Author Institution: Applied Physics Laboratory, Laurel, Maryland 20723.; University of Maryland Baltimore County, Baltimore Marviand 21228.DIAL lidar for water vapor and temperature remote sensing in the eye safe atmospheric window regions has been receiving much interest. Such systems rely on accurate spectral line characterization. Typically the HITRAN data base on atmospheric spectral lines is used. However, the database is incomplete and not sufficiently accurate. A series of transmittance measurements are made on water vapor and carbon dioxide to verify and improve the HITRAN data base in $2\mu m$ spectral $region^{1}$. A 3 meter base path White cell attached to a BOMEM DA3.02 is used for the transmittance measurements. The White cell is set to a path length of 216 meters for all experiments. Measurements on pure $H_{2}O$ at various pressures, $N_{2}$ broadened $H_{2}O$ and $N_{2^{-}}O_{2}$ broadened $H_{2}O$ are collected at room temperature. Also, measurements on pure $CO_{2}$ at various pressures and $N_{2}$ broadened $CO_{2}$ are collected at room temperature. Data analysis is performed on lines that are accessible by lasers. The measured spectrum is converted to the absorption coefficient and is fitted to a synthetic spectrum to determine the spectral line parameters. This includes the pressure shift, halfwidth and line strength. Water vapor exhibits a strong pressure shift effect. Oxygen broadening is observed to be significantly less than that due to nitrogen. Some lines show good agreement (within a few percent) with the HITRAN database, other lines disagree by more than $\pm 10$. Thus care must be exercised in applying the HITRAN data based to DLAL lidar applications. The pressure shift, self-halfwidth and oxygen-broadened halfwidth are not available on the HITRAN database

Improved agreement of AIRS tropospheric carbon monoxide products with other EOS sensors using optimal estimation retrievals

We present in this paper an alternative retrieval algorithm for the Atmospheric Infrared Sounder (AIRS) tropospheric Carbon Monoxide (CO) products using the Optimal Estimation (OE) technique, which is different from the AIRS operational algorithm. The primary objective for this study was to compare AIRS CO, as well as the other retrieval properties such as the Averaging Kernels (AKs), the Degrees of Freedom for Signal (DOFS), and the error covariance matrix, against the Tropospheric Emission Spectrometer (TES) and the Measurement of Pollution in the Troposphere (MOPITT) CO, which were also derived using the OE technique. We also demonstrate that AIRS OE CO results are much more realistic than AIRS V5 operational CO, especially in the lower troposphere and in the Southern Hemisphere (SH). These products are validated with in situ profiles obtained by the Differential Absorption Carbon Monoxide Measurements (DACOM), which took place as part of NASA's Intercontinental Chemical Transport Experiment (INTEX-B) field mission that was conducted over the northern Pacific in Spring 2006. To demonstrate the differences existing in the current operational products we first show a detailed direct comparison between AIRS V5 and TES operational V3 CO for the global datasets from December 2005 to July 2008. We then present global CO comparisons between AIRS OE, TES V3, and MOPITT V4 at selected pressure levels as well as for the total column amounts. We conclude that the tropospheric CO retrievals from AIRS OE and TES V3 agree to within 5–10 ppbv or 5% on average globally and throughout the free troposphere. The agreements in total column CO amounts between AIRS OE and MOPITT V4 have improved significantly compared to AIRS V5 with global relative RMS differences now being 12.7%

Experimental Investigation of the Self-- and N

We present here an experimental study of the self- and N 2 -broadened H 2 O continuum in microwindows within the 2 fundamental centered at ¸1600 cm \Gamma1 . The continuum is derived from transmission spectra recorded at room temperature with a BOMEM Fourier Transform Spectrometer at a resolution of ¸0.040 cm \Gamma1 . Although we find general agreement with previous studies, our results suggest that there is significant near-wing super-Lorentzian behavior which produces highly wavenumber dependent structure in the continuum as it is presently defined. Key words: Infrared absorption, water vapor, continuum, spectral lineshape, Fourier transform spectrometer. c fl Optical Society of America, 1995. 1. Introduction Deviations of H 2 O spectral lineshapes from Lorentz have been studied extensively for the atmospheric windows at 4 and 10 ¯m and several thorough reviews exist 1;2 . Non-Lorentz H 2 O lineshapes can also have a significant impact within the strong pure rotational and ..