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Kahn, BH, Irion FW, Dang VT, Manning EM, Nasiri SL, Naud CM, Blaisdell JM, Schreier MM, Yue Q, Bowman KW, Fetzer EJ, Hulley GC, Liou KN, Lubin D, Ou SC, Susskind J, Takano Y, Tian B, Worden JR.  2014.  The Atmospheric Infrared Sounder version 6 cloud products. Atmospheric Chemistry and Physics. 14:399-426.   10.5194/acp-14-399-2014   AbstractWebsite

The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter (D-e), and ice cloud optical thickness (tau) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of tau are found in the storm tracks and near convection in the tropics, while D-e is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of tau is significantly larger than for the total cloud fraction, ice cloud frequency, and D-e, and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

Kerr, J, Seckmeyer G, Bais AF, Bernhard G, Blumthaler M, Diaz SB, Krotkov NA, Lubin D, Mckenzie RL, Sabziparvar AA, Verdebout J.  2002.  Surface Ultraviolet Radiation: Past and Future. Scientific assessment of ozone depletion, 2002. Executive summary. ( Organization W, Ed.).:5.1-5.46., [Washington, D.C.]; [Nairobi, Kenya]; [Geneva, Switzerland]; [Brussels, Belgium]: National Oceanic and Atmospheric Administration : National Aeronautics and Space Administration ; United Nations Environment Programme ; World Meteorological Organization ; European Commission Abstract
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Kirkman, D, Tytler D, Suzuki N, Melis C, Hollywood S, James K, So G, Lubin D, Jena T, Norman ML, Paschos P.  2005.  The HI opacity of the intergalactic medium at redshifts 1.6 < z < 3.2. Monthly Notices of the Royal Astronomical Society. 360:1373-1380.   10.1111/j.1365-2966.2005.09126.x   AbstractWebsite

We use high-quality echelle spectra of 24 quasi-stellar objects to provide a calibrated measurement of the total amount of Ly alpha forest absorption (DA) over the redshift range 2.2 < z < 3.2. Our measurement of DA excludes absorption from metal lines or the Ly alpha lines of Lyman-limit systems and damped Ly alpha systems. We use artificial spectra with realistic flux calibration errors to show that we are able to place continuum levels that are accurate to better than 1 per cent. When we combine our results with our previous results between 1.6 < z < 2.2, we find that the redshift evolution of DA is well described over f1.6 < z < 3.2 as A (1 +z)(gamma), where A = 0.0062 and gamma = 2.75. We detect no significant deviations from a smooth power-law evolution over the redshift range studied. We find less H i absorption than expected at z = 3, implying that the ultraviolet background is similar to 40 per cent higher than expected. Our data appears to be consistent with an H i ionization rate of Gamma similar to 1.4 x 10(-12) s(-1).

Kirkman, D, Tytler D, O'Meara JM, Burles S, Lubin D, Suzuki N, Carswell RF, Turner MS, Wampler EJ.  2001.  New Hubble Space Telescope spectra of QSO PG 1718+4807: No evidence for strong deuterium absorption. Astrophysical Journal. 559:23-28.   10.1086/322357   AbstractWebsite

The Z(abs) similar to 0.701 absorption system toward QSO PG 1718 + 4807 is the only example of a QSO absorption system which might have a deuterium/hydrogen ratio approximately 10 times the value found toward other QSOs. We have obtained new Space Telescope Imaging Spectrograph spectra from the Hubble Space Telescope of the Ly alpha and Lyman limit regions of the system. These spectra give the redshift and velocity dispersion of the neutral hydrogen, which produces most of the observed absorption. The Ly alpha line is too narrow to account for all of the observed absorption. It was previously known that extra absorption is needed on the blue side of the main H I near the expected position of deuterium. We do not find evidence in the current data that the extra absorption is entirely deuterium and find that it is more likely that some of the extra absorption is contaminating H. Until new data can be found that can independently constrain the line parameters of the potential contaminating H, it will not be possible to measure D/H in this system. Some uncertainty persists because we have a low signal-to-noise ratio and the extra absorption-be it deuterium or hydrogen-is heavily blended with the Ly alpha absorption from the main hydrogen absorption.

Kirkman, D, Tytler D, Burles S, Lubin D, O'Meara JM.  2000.  QSO 0130-4021: A third QSO showing a low deuterium-to-hydrogen abundance ratio. Astrophysical Journal. 529:655-660.   10.1086/308317   AbstractWebsite

We have discovered a third quasar absorption system which is consistent with a low deuterium-to-hydrogen abundance ratio, D/H = 3.4 x 10(-5). The z(abs) similar to 2.8 partial Lyman limit system toward Q0130-4021 provides the strongest evidence to date against large D/H ratios because the H I absorption, which consists of a single high column density component with unsaturated high-order Lyman series lines, is readily modeled-a task which is more complex in other D/H systems. We have obtained 22 hr of spectra from the High-Resolution Echelle Spectrograph on the W. RI. Keek Telescope, which allow a detailed description of the hydrogen. We see excess absorption on the blue wing of the H I Ly alpha line, near the expected position of deuterium. However, we find that deuterium cannot explain all of the excess absorption, and hence there must be contamination by additional absorption, probably H I. This extra H I can account for most or all of the absorption at the D position, and hence D/H = 0 is allowed. We find an upper limit of D/H less than or equal to 6.7 x 10(-5) in this system, consistent with the value of D/H similar or equal to 3.4 x 10(-5) deduced toward QSO 1009 + 2956 and QSO 1937 - 1009 by Buries and Tytler. This absorption system shows only weak metal-line absorption, and we estimate [Si/H] less than or equal to -2.6, indicating that the D/H ratio of the system is likely primordial. All four of the known high-redshift absorption-line systems simple enough to provide useful limits on D are consistent with D/H = 3.4 +/- 0.25 x 10(-5). Conversely, this QSO provides the third case which is inconsistent with much larger values.