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James M. Russell - One of the best experts on this subject based on the ideXlab platform.
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A COMPARISON OF OBSERVED (I-•LOE) AND MODELED (CCM2) METHANE AND STRATOSPHERIC WATER VAPOR
2016Co-Authors: Philip W. Mote, James M. Russell, James R. Holton, Byron A. BovilleAbstract:Abstract. Recent measurements (21 September- 15 October 1992) of methane and water vapor by the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) are compared with model results for the same season from a troposphere-middle atmosphere version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2). Several im-portant features of the two constituent fields are well repro-duced by the CCM2, despite the use of simplified methane photochemistry in the CCM2 and some notable differences between the model's zonal mean circulation and climatology. Observed features imulated by the model include the follow-ing: 1) subsidence over a deep layer in the Southern Hemi-sphere polar vortex; 2) widespread dehydration i the polar vortex; 3) existence of a region of low water vapor mixing ratios extending from the Antarctic into the Northern Hemi-sphere tropics, which suggests that Antarctic dehydration contributes tomidlatitude and tropical dryness in the strato-sphere
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Atmospheric Chemistry and Physics
2014Co-Authors: -u. J. Grooß, James M. RussellAbstract:Abstract. The Halogen Occultation Experiment (HALOE
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accuracy of atmospheric trends inferred from the Halogen Occultation Experiment data
Journal of Applied Remote Sensing, 2009Co-Authors: Larry L. Gordley, Ellis E. Remsberg, Martin Mchugh, James M. Russell, Earl Thompson, Brian MagillAbstract:The Halogen Occultation Experiment (HALOE) operated in orbit for over 14 years, providing high quality measurements from the upper troposphere into the lower thermosphere. Since the quality of this data set depended on the long-term stability of the instrument, a series of analysis tests were designed to routinely monitor instrument performance. These tests evaluated possible changes in the gas cells, electronic gains, optical performance, and signal temperature dependencies. The gas cell stability was determined from an analysis of the Doppler shift signature in retrieved mixing ratios. Electronic gain stability was determined by instrument scans of the solar disk, each with different balance settings. Optical and tracking performance was also determined from solar scan data. The only statistically significant changes detected were: 1. a small methane gas cell change, causing less than 0.5% per decade change in retrieved methane, and 2. a small optical alignment change in the HF channel that only affects HF results below 25 kilometers. These detailed analyses indicate that the HALOE instrument remained stable throughout the mission, adding confidence to the long-term atmospheric trends deduced from HALOE products.
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calculation of chemical ozone loss in the arctic winter 1996 1997 using ozone tracer correlations comparison of improved limb atmospheric spectrometer ilas and Halogen Occultation Experiment haloe results
Journal of Geophysical Research, 2003Co-Authors: Simone Tilmes, James M. Russell, Rolf Muller, J U Groos, D S Mckenna, Yasuhiro SasanoAbstract:[1] The ozone-tracer correlation method is used to deduce the stratospheric ozone loss in the Arctic winter 1996–1997. Improvements of the technique are applied, such as a new calculation of the vortex edge [Nash et al., 1996] and an improved early vortex reference function. Winter 1996–1997 is characterized by a late formation and an unusually long lifetime of the polar vortex. Remnants of vortex air were found until May. Chemical ozone losses deduced from two satellite data sets, namely Improved Limb Atmospheric Spectrometer (ILAS) and Halogen Occultation Experiment (HALOE), are discussed. The ILAS observations allow a detailed analysis of the temporal evolution of the ozone-tracer correlation inside the polar vortex and, in particular, of the development of the early vortex. For November and December 1996, it is shown that horizontal mixing still influences the ozone-tracer relation. Significant PSC related chemical ozone loss occurred beginning at mid-February, and the averaged column ozone loss is increasing toward the middle of May. From April onwards, ozone profiles in the vortex became more uniform. The decrease of ozone in the vortex remnants in April and May occurred due to chemistry. HALOE observations are available for March to May 1997. In the period 4–16 March 1997, the calculated ozone loss deduced from HALOE and ILAS is in good agreement. The average of the result from the two instruments is 15 ± 7 Dobson units (DU) inside the vortex core, in the altitude range of 450–550 K. At the end of March, a discrepancy between HALOE and ILAS ozone loss arises due to a significant difference (0.6 ppmv) between the two data sets in the relatively low ozone minimum measured at 475 K. Nonetheless, both data sets consistently show an inhomogeneity in ozone loss inside the vortex core at the end of March. The vortex is separated in two parts, one with a large ozone loss (HALOE 40–45 DU, ILAS 30–35 DU) and one with a moderate ozone loss (HALOE 15–30 DU, ILAS 5–25 DU) for 450–550 K. The ozone loss from HALOE in 380–550 K at that time was calculated to be 90–110 DU for the large ozone loss and 20–80 DU for the moderate ozone loss. The vortex average of column ozone loss from HALOE inside the vortex core at the end of March is 61 ± 20 DU, which is an increase of about 20% compared to the earlier study by Muller et al. [1997b] brought about by the improvement of the technique.
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discovery of a water vapor layer in the arctic summer mesosphere implications for polar mesospheric clouds
Geophysical Research Letters, 2001Co-Authors: Michael E Summers, Larry L. Gordley, James M. Russell, David E Siskind, Robert R Conway, C R Englert, M H Stevens, Marty MchughAbstract:We report the discovery of a layer of enhanced water vapor in the Arctic summer mesosphere that was made utilizing two new techniques for remotely determining water vapor abundances. The first utilizes Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) OH measurements as a proxy for water vapor. The second is a re analysis of Halogen Occultation Experiment (HALOE) water vapor data with a technique to simultaneously determine polar mesospheric cloud (PMC) ice particle extinction along with the water vapor abundance. These results reveal a narrow layer of enhanced water vapor centered between 82-84 km altitude and coincident with PMCs, that exhibits water vapor mixing ratios of 10-15 ppmv. This indicates that a higher degree of supersaturation is present in the PMC region, and that PMCs are thus more efficient at sequestering total water (both ice particles and vapor) within the layer, than previously believed.
Larry L. Gordley - One of the best experts on this subject based on the ideXlab platform.
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Retrieval Algorithms for the Halogen Occultation Experiment
2009Co-Authors: Robert E Thompson, Larry L. GordleyAbstract:The Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) provided high quality measurements of key middle atmosphere constituents, aerosol characteristics, and temperature for 14 years (1991-2005). This report is an outline of the Level 2 retrieval algorithms, and it also describes the great care that was taken in characterizing the instrument prior to launch and throughout its mission life. It represents an historical record of the techniques used to analyze the data and of the steps that must be considered for the development of a similar Experiment for future satellite missions.
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accuracy of atmospheric trends inferred from the Halogen Occultation Experiment data
Journal of Applied Remote Sensing, 2009Co-Authors: Larry L. Gordley, Ellis E. Remsberg, Martin Mchugh, James M. Russell, Earl Thompson, Brian MagillAbstract:The Halogen Occultation Experiment (HALOE) operated in orbit for over 14 years, providing high quality measurements from the upper troposphere into the lower thermosphere. Since the quality of this data set depended on the long-term stability of the instrument, a series of analysis tests were designed to routinely monitor instrument performance. These tests evaluated possible changes in the gas cells, electronic gains, optical performance, and signal temperature dependencies. The gas cell stability was determined from an analysis of the Doppler shift signature in retrieved mixing ratios. Electronic gain stability was determined by instrument scans of the solar disk, each with different balance settings. Optical and tracking performance was also determined from solar scan data. The only statistically significant changes detected were: 1. a small methane gas cell change, causing less than 0.5% per decade change in retrieved methane, and 2. a small optical alignment change in the HF channel that only affects HF results below 25 kilometers. These detailed analyses indicate that the HALOE instrument remained stable throughout the mission, adding confidence to the long-term atmospheric trends deduced from HALOE products.
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an assessment of the quality of Halogen Occultation Experiment temperature profiles in the mesosphere based on comparisons with rayleigh backscatter lidar and inflatable falling sphere measurements
Journal of Geophysical Research, 2002Co-Authors: Ellis E. Remsberg, Lance E Deaver, G S Lingenfelser, Praful P Bhatt, R E Thompson, Martin Mchugh, J. Wells, Larry L. Gordley, J. M. Russell, Philippe KeckhutAbstract:[1] Bias errors for retrieved temperature profiles T(p) from the Halogen Occultation Experiment (HALOE) are evaluated by pairing with nearby soundings from ground-based Rayleigh lidar and from inflatable falling spheres. Findings for the mesosphere must be based on large sets of pairings because an individual HALOE T(p) measurement is somewhat noisy and may not view the same atmospheric structure. Simulated estimates of total bias errors for the HALOE profiles are of the order of 2% (or 5 K). The average biases with the lidar profiles at 44°N, 6°E are within 3 K from 33 to 66 km and 4 K to 74 km, at least when zonal easterlies (and reduced wave activity) prevail. Tidal effects can account for most of that difference. Comparisons with shipboard lidar soundings that begin near 100 km indicate no significant bias even in the 77 to 85 km range. Similar comparisons with falling sphere profiles at Cape Canaveral and Wallops Island indicate no significant bias from 40 to 66 km and 71 to 85 km. HALOE profiles are warmer than sphere values from 67 to 70 km, but this is also the altitude region where the sphere profile has greater uncertainties. For those months when the lidar soundings indicate inversion layers the sets of profiles paired with lidar indicate that the HALOE T(p) is somewhat colder in the upper mesosphere, in part owing to the effects of limb path averaging of horizontal structure by HALOE and its inability to completely resolve the inversion layer maximum. On the basis of the combined sets of findings it is concluded that most of the error in a single HALOE T(p) is random, except where there is a sharp inversion. Daily zonal averages of the HALOE profiles are accurate and useful for defining the seasonal and longer-term variations of T(p) in the mesosphere.
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discovery of a water vapor layer in the arctic summer mesosphere implications for polar mesospheric clouds
Geophysical Research Letters, 2001Co-Authors: Michael E Summers, Larry L. Gordley, James M. Russell, David E Siskind, Robert R Conway, C R Englert, M H Stevens, Marty MchughAbstract:We report the discovery of a layer of enhanced water vapor in the Arctic summer mesosphere that was made utilizing two new techniques for remotely determining water vapor abundances. The first utilizes Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) OH measurements as a proxy for water vapor. The second is a re analysis of Halogen Occultation Experiment (HALOE) water vapor data with a technique to simultaneously determine polar mesospheric cloud (PMC) ice particle extinction along with the water vapor abundance. These results reveal a narrow layer of enhanced water vapor centered between 82-84 km altitude and coincident with PMCs, that exhibits water vapor mixing ratios of 10-15 ppmv. This indicates that a higher degree of supersaturation is present in the PMC region, and that PMCs are thus more efficient at sequestering total water (both ice particles and vapor) within the layer, than previously believed.
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first confirmation that water ice is the primary component of polar mesospheric clouds
Geophysical Research Letters, 2001Co-Authors: Mark E Hervig, Martin Mchugh, Larry L. Gordley, James M. Russell, Robert E Thompson, Michael E SummersAbstract:Polar mesospheric clouds (PMCs) have been measured in the infrared for the first time by the Halogen Occultation Experiment (HALOE). PMC extinctions retrieved from measurements at eight wavelengths show remarkable agreement with model spectra based on ice particle extinction. The infrared spectrum of ice has a unique signature, and the HALOE-model agreement thus provides the first physical confirmation that water ice is the primary component of PMCs. PMC particle effective radii were estimated from the HALOE extinctions based on a first order fit of model extinctions.
Ellis E. Remsberg - One of the best experts on this subject based on the ideXlab platform.
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trends and solar cycle effects in temperature versus altitude from the Halogen Occultation Experiment for the mesosphere and upper stratosphere
Journal of Geophysical Research, 2009Co-Authors: Ellis E. RemsbergAbstract:[1] Fourteen-year time series of mesospheric and upper stratospheric temperature versus altitude or T(z) from the Halogen Occultation Experiment (HALOE) are analyzed and reported. The data have been binned according to 10°-wide latitude zones from 40°S to 40°N and at 10 altitudes from 43 to 80 km: a total of 90 separate time series. Multiple linear regression analysis techniques have been applied to those time series. This study focuses on resolving their 11-year solar cycle (SC) (or SC-like) responses and their linear trend terms. Findings for T(z) from HALOE are compared with published results from ground-based Rayleigh lidar and from rocketsonde measurements. SC-like responses from HALOE compare well with those from the lidar station data. The cooling trends from HALOE also agree reasonably well with those from the lidar data at low latitudes for the concurrent decade. Cooling trends of the lower mesosphere from HALOE are not as large as those from rocketsondes and from the lidar station time series of the previous two decades, presumably because the changes in the upper stratospheric ozone are near zero during the HALOE time period and do not contribute to its trends.
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trends and solar cycle effects in temperature versus altitude from the Halogen Occultation Experiment for the mesosphere and upper stratosphere
Journal of Geophysical Research, 2009Co-Authors: Ellis E. RemsbergAbstract:Fourteen-year time series of mesospheric and upper stratospheric temperatures from the Halogen Occultation Experiment (HALOE) are analyzed and reported. The data have been binned according to ten-degree wide latitude zones from 40S to 40N and at 10 altitudes from 43 to 80 km-a total of 90 separate time series. Multiple linear regression (MLR) analysis techniques have been applied to those time series. This study focuses on resolving their 11-yr solar cycle (or SC-like) responses and their linear trend terms. Findings for T(z) from HALOE are compared directly with published results from ground-based Rayleigh lidar and rocketsonde measurements. SC-like responses from HALOE compare well with those from lidar station data at low latitudes. The cooling trends from HALOE also agree reasonably well with those from the lidar data for the concurrent decade. Cooling trends of the lower mesosphere from HALOE are not as large as those from rocketsondes and from lidar station time series of the previous two decades, presumably because the changes in the upper stratospheric ozone were near zero during the HALOE time period and did not affect those trends.
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accuracy of atmospheric trends inferred from the Halogen Occultation Experiment data
Journal of Applied Remote Sensing, 2009Co-Authors: Larry L. Gordley, Ellis E. Remsberg, Martin Mchugh, James M. Russell, Earl Thompson, Brian MagillAbstract:The Halogen Occultation Experiment (HALOE) operated in orbit for over 14 years, providing high quality measurements from the upper troposphere into the lower thermosphere. Since the quality of this data set depended on the long-term stability of the instrument, a series of analysis tests were designed to routinely monitor instrument performance. These tests evaluated possible changes in the gas cells, electronic gains, optical performance, and signal temperature dependencies. The gas cell stability was determined from an analysis of the Doppler shift signature in retrieved mixing ratios. Electronic gain stability was determined by instrument scans of the solar disk, each with different balance settings. Optical and tracking performance was also determined from solar scan data. The only statistically significant changes detected were: 1. a small methane gas cell change, causing less than 0.5% per decade change in retrieved methane, and 2. a small optical alignment change in the HF channel that only affects HF results below 25 kilometers. These detailed analyses indicate that the HALOE instrument remained stable throughout the mission, adding confidence to the long-term atmospheric trends deduced from HALOE products.
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a reanalysis for the seasonal and longer period cycles and the trends in middle atmosphere temperature from the Halogen Occultation Experiment
Journal of Geophysical Research, 2007Co-Authors: Ellis E. RemsbergAbstract:[1] Remsberg and Deaver (2005) reported on multiple linear regression (MLR) analyses of time series of middle-atmosphere temperature versus pressure (or T(p)) profiles from the Halogen Occultation Experiment (HALOE) for its seasonal and longer-period cycles. Their results are extended herein to just over 14 years and updated to properly account for the effects of autocorrelation in their time series of zonally averaged data. The updated seasonal and annual average terms are provided, and they can be used to generate near-global, temperature distributions from 2 to 0.007 hPa that are representative of the period 1991–2005. Quasi-biennial oscillation (QBO-like; 853-day) and subbiennial (640-day) terms are also resolved and provided, and they exhibit good consistency across the range of latitudes and pressure altitudes. Further, somewhat exploratory analyses of the residuals from each of the 208 time series yield significant 11-year solar cycle (or SC-like) and linear trend terms at a number of latitudes and levels. Where significant, those terms are included in the final MLR models. The amplitudes of the SC-like terms for the mesosphere agree reasonably with calculations of the direct solar radiative effects for T(p). Those SC-like amplitudes increase by about a factor of 2 from the lower to the upper mesosphere and are larger at the middle than at the low latitudes. The diagnosed T(p) cooling trends from HALOE for the low latitudes are in the range of −0.5 to −1.0 K/decade, which is in good agreement with the findings from models of the radiative effects on pressure surfaces due to known increases in atmospheric CO2. The diagnosed HALOE trends are somewhat larger than those predicted with models for middle latitudes of the upper mesosphere. Cooling trends also are found to be increasing from about −0.5 to −1.0 K/decade from 1 to 2 hPa of the upper stratosphere, also in reasonable agreement with modeled results.
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solar Occultation satellite data and derived meteorological products sampling issues and comparisons with aura mls
2007Co-Authors: G L Manney, Ellis E. Remsberg, P F Bernath, J M Zawodny, W H Daffer, K W Hoppel, K A Walker, B Knosp, Chris D Boone, M L SanteeAbstract:Derived Meteorological Products (DMPs, including potential temperature (theta), potential vorticity, equivalent latitude (EqL), horizontal winds and tropopause locations) have been produced for the locations and times of measurements by several solar Occultation (SO) instruments and the Aura Microwave Limb Sounder (MLS). DMPs are calculated from several meteorological analyses for the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer, Stratospheric Aerosol and Gas Experiment II and III, Halogen Occultation Experiment, and Polar Ozone and Aerosol Measurement II and III SO instruments and MLS. Time-series comparisons of MLS version 1.5 and SO data using DMPs show good qualitative agreement in time evolution of O3, N2O, H20, CO, HNO3, HCl and temperature; quantitative agreement is good in most cases. EqL-coordinate comparisons of MLS version 2.2 and SO data show good quantitative agreement throughout the stratosphere for most of these species, with significant biases for a few species in localized regions. Comparisons in EqL coordinates of MLS and SO data, and of SO data with geographically coincident MLS data provide insight into where and how sampling effects are important in interpretation of the sparse SO data, thus assisting in fully utilizing the SO data in scientific studies and comparisons with other sparse datasets. The DMPs are valuable for scientific studies and to facilitate validation of non-coincident measurements.
Mark E Hervig - One of the best experts on this subject based on the ideXlab platform.
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satellite observations of ozone in the upper mesosphere
Journal of Geophysical Research, 2013Co-Authors: Anne K Smith, B Funke, M Lopezpuertas, Mark E Hervig, V L Harvey, Martin G Mlynczak, M Garciacomas, Martin Kaufmann, E Kyrola, I C McdadeAbstract:[1] Ozone profiles in the upper mesosphere (70–100 km) retrieved from nine instruments are compared. Ozone from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument is used as the basis of comparison. Other measurements are from the Halogen Occultation Experiment, the High Resolution Doppler Imager, the Michelson Interferometer for Passive Atmospheric Sounding, the Global Ozone Monitoring by Occultation of Stars, the Atmospheric Chemistry Experiment—Fourier Transform Spectrometer, the Solar Occultation For Ice Experiment, the Optical Spectrograph and InfraRed Imaging System, and the Superconducting Submillimeter-Wave Limb-Emission Sounder. Comparisons of each data set with SABER using coincident profiles indicate agreement in the basic vertical profile of ozone but also some systematic differences in daytime ozone. Ozone from the SABER 9.6 μm channel is higher than the other measurements over the altitude range 60–80 km by 20–50%. Nighttime comparisons indicate better relative agreement (<10% difference). Taking all the data, not limited to coincidences, shows the global and seasonal distributions of ozone in the upper mesosphere from each instrument. The average maximum in ozone mixing ratio is around 90–92 km during daytime and 95 km at night. There is a maximum in ozone density at night (∼90 km) and during some hours of the day. The latitude structure of ozone has appreciable variations with season, particularly in the tropical upper mesosphere. The basic latitude-altitude structure of ozone depends on local time, even when the analysis is restricted to day-only observations.
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Halogen Occultation Experiment and stratospheric aerosol and gas Experiment ii observations of tropopause cirrus and aerosol during the 1990s
Journal of Geophysical Research, 2003Co-Authors: S T Massie, William J Randel, D Baumgardner, Mark E HervigAbstract:[1] Averages of Halogen Occultation Experiment (HALOE) aerosol extinction at 121 hPa for 1993–1999 and Stratospheric Aerosol and Gas Experiment (SAGE II) aerosol extinction between 100 and 140 hPa for 1987–1999 are analyzed in the tropics (20°S–20°N). Multiple wavelength techniques for HALOE and SAGE II data are used to distinguish cirrus from aerosol observations following the eruption of Mount Pinatubo in 1991. SAGE II and HALOE cirrus extinction values are 34 and 28% less, respectively, in 1993 than in 1995–1999, while aerosol extinction decreases over the same time period. SAGE II and HALOE decreases in the frequency of occurrence of cirrus in 1993 are qualitatively similar to the SAGE II decreases in the frequency of occurrence of cirrus, discussed by Wang et al. [1995], after the eruption of El Chichon. Tropopause temperature anomalies in 1993 most likely do not account for the decrease in cirrus observed in 1993 by both the HALOE and SAGE II Experiments.
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first confirmation that water ice is the primary component of polar mesospheric clouds
Geophysical Research Letters, 2001Co-Authors: Mark E Hervig, Martin Mchugh, Larry L. Gordley, James M. Russell, Robert E Thompson, Michael E SummersAbstract:Polar mesospheric clouds (PMCs) have been measured in the infrared for the first time by the Halogen Occultation Experiment (HALOE). PMC extinctions retrieved from measurements at eight wavelengths show remarkable agreement with model spectra based on ice particle extinction. The infrared spectrum of ice has a unique signature, and the HALOE-model agreement thus provides the first physical confirmation that water ice is the primary component of PMCs. PMC particle effective radii were estimated from the HALOE extinctions based on a first order fit of model extinctions.
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an investigation of aerosol measurements from the Halogen Occultation Experiment validation size distributions composition and relation to other chemical species
1998Co-Authors: Terry Deshler, Mark E HervigAbstract:The efforts envisioned within the original proposal (accepted February 1994) and the extension of this proposal (accepted February 1997) included measurement validations, the retrieval of aerosol size distributions and distribution moments, aerosol correction studies, and investigations of polar stratospheric clouds. A majority of the results from this grant have been published. The principal results from this grant are discussed.
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validation of aerosol measurements from the Halogen Occultation Experiment
Journal of Geophysical Research, 1996Co-Authors: Mark E Hervig, Larry L. Gordley, James M. Russell, Roland S Drayson, Jane Park, Terry DeshlerAbstract:Measurements from the Halogen Occultation Experiment (HALOE) are used to infer profiles of aerosol extinction at five infrared wavelengths. This paper provides a validation of the aerosol measurements based on uncertainty analysis, internal validations, comparisons with theory, and comparisons with independent measurements. Monte Carlo calculations using accepted values of random and systematic errors determine typical measurement uncertainties of less than 15% for pressures from 100 to 10 mbar. Comparisons of coincident HALOE sunrise and sunset observations indicate systematic differences (sunrise > sunset) for pressures less than 10 mbar. Random sunrise-sunset differences, taken as an upper limit of the measurement precision, are generally from 10 to ∼30% for pressures from 100 to 10 mbar. Measured extinction ratios are compared with ratios determined from theory. These comparisons show that the measurements are consistent with theory at pressures from 100 to 10 mbar, depending on channels, latitude, and season. HALOE extinctions are compared with extinctions calculated from balloon-borne particle counter measurements. The results show random differences from 30 to 50% for pressures from 100 to 10 mbar and systematic differences (HALOE > particle counters) for pressures less than 40 mbar. The results indicate that the HALOE 2.80 μm aerosol measurements are much less reliable than the other four measurements.
Lance E Deaver - One of the best experts on this subject based on the ideXlab platform.
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an assessment of the quality of Halogen Occultation Experiment temperature profiles in the mesosphere based on comparisons with rayleigh backscatter lidar and inflatable falling sphere measurements
Journal of Geophysical Research, 2002Co-Authors: Ellis E. Remsberg, Lance E Deaver, G S Lingenfelser, Praful P Bhatt, R E Thompson, Martin Mchugh, J. Wells, Larry L. Gordley, J. M. Russell, Philippe KeckhutAbstract:[1] Bias errors for retrieved temperature profiles T(p) from the Halogen Occultation Experiment (HALOE) are evaluated by pairing with nearby soundings from ground-based Rayleigh lidar and from inflatable falling spheres. Findings for the mesosphere must be based on large sets of pairings because an individual HALOE T(p) measurement is somewhat noisy and may not view the same atmospheric structure. Simulated estimates of total bias errors for the HALOE profiles are of the order of 2% (or 5 K). The average biases with the lidar profiles at 44°N, 6°E are within 3 K from 33 to 66 km and 4 K to 74 km, at least when zonal easterlies (and reduced wave activity) prevail. Tidal effects can account for most of that difference. Comparisons with shipboard lidar soundings that begin near 100 km indicate no significant bias even in the 77 to 85 km range. Similar comparisons with falling sphere profiles at Cape Canaveral and Wallops Island indicate no significant bias from 40 to 66 km and 71 to 85 km. HALOE profiles are warmer than sphere values from 67 to 70 km, but this is also the altitude region where the sphere profile has greater uncertainties. For those months when the lidar soundings indicate inversion layers the sets of profiles paired with lidar indicate that the HALOE T(p) is somewhat colder in the upper mesosphere, in part owing to the effects of limb path averaging of horizontal structure by HALOE and its inability to completely resolve the inversion layer maximum. On the basis of the combined sets of findings it is concluded that most of the error in a single HALOE T(p) is random, except where there is a sharp inversion. Daily zonal averages of the HALOE profiles are accurate and useful for defining the seasonal and longer-term variations of T(p) in the mesosphere.
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ozone changes in the lower stratosphere from the Halogen Occultation Experiment for 1991 through 1999
Journal of Geophysical Research, 2001Co-Authors: Ellis E. Remsberg, Praful P Bhatt, Lance E DeaverAbstract:The Upper Atmospheric Research Satellite (UARS) Halogen Occultation Experiment (HALOE) Version 19 ozone profile data set was analyzed for both periodic and nonseasonal polynomial changes in lower stratospheric ozone for 1991-1999. The profile data were screened for cloud contamination at the lowest levels and were then integrated within six half-Umkehr (each ∼2.5 km thick) layers from 32 to 253 hPa. The column values were then binned and averaged into 10°-wide latitude regions but separated into sunrise and sunset measurements, yielding an effective time series of zonal-averaged ozone that spans 8 years. The results extend to near tropopause levels, 253 hPa in the extratropics and 127 hPa in the tropics. Multiple linear regression techniques were applied to the data of each latitude zone and half-Umkehr layer. We developed models that included annual, semiannual, and interannual periodic terms plus polynomial terms at 50°N, 30°N, equator, 30°S, and 50°S. The amplitudes of the three periodic terms vary with latitude and pressure altitude and do not maintain their same order of importance in all cases, emphasizing the changes and hemispheric asymmetry of the transport mechanisms in the lower stratosphere. We find no clear evidence for long-term change at most latitudes and layers. Steady declines in ozone of 0.5% yr -1 were found in the 32-45 hPa layer at 50°S, most likely due to transport of ozone-depleted air from higher latitudes. Our lowest tropical layer (90-127 hPa) shows an ozone decline in the early 1990s but an increase in the last half of the decade. Steady increases of ozone of 3-4% yr -1 were found at 50°N from 127 to 253 hPa and at 30°N from 179 to 253 hPa, probably in response to a changing net circulation for the Northern Hemisphere lower stratosphere. However, there is no highly significant trend at 50°N for the column ozone over the deeper layer from 8 to 253 hPa. For Northern Hemisphere middle latitudes it is concluded that the previously reported declines of zonal-average ozone in the lower stratosphere for the 1980s and early 1990s have not continued over the decade of the 1990s.
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Halogen Occultation Experiment confirmation of stratospheric chlorine decreases in accordance with the Montreal protocol
Journal of Geophysical Research: Atmospheres, 2000Co-Authors: James G. Anderson, James M. Russell, Stanley C. Solomon, Lance E DeaverAbstract:Near-global time series of Halogen Occultation Experiment (HALOE) derived total Cl, F, and the Cl/F ratio were evaluated and compared with data from two ground-based CFC measurement programs and United Nations Environment Programme (UNEP) best-case scenarios for CFC emissions. The HALOE Cl profiles confirm that the chlorine burden near the stratopause is decreasing and this decrease is driven by tropospheric decreases of methyl chloroform. The HALOE F profiles show that the fluorine burden near the stratopause is primarily influenced by CFC-12. The Cl/F ratio, which is insensitive to transport effects at 55 km, shows that the atmosphere near the stratopause is becoming more fluorinated since the inception of the HALOE mission and less chlorinated since the start of 1997. The temporal changes in the derived Cl, F, and Cl/F ratio at 55 km are in accord with UNEP projections and in situ observations. These combined results demonstrate that the Montreal Protocol and subsequent strengthening amendments are currently having the desired effect of reducing stratospheric chlorine.
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analysis of near global trends and variability in Halogen Occultation Experiment hf and hcl data in the middle atmosphere
Journal of Geophysical Research, 1999Co-Authors: Geoffrey D Considine, Ellis E. Remsberg, Lance E Deaver, James M. RussellAbstract:We present an analysis of trends and variability in daily-averaged near-global Halogen Occultation Experiment (HALOE) retrievals of HF and HCl at 55 km. The goal of decomposing HALOE measurements into a series of components is to determine the temporal scales associated with variability and to estimate the trends in HF and HCl. To determine the significance of each component in the statistical model, partial correlations are calculated between the data and each model element using the rank-order correlation coefficient. We also account for the effects of serial correlation in our data (i.e., the lack of independence between consecutive points) in the determination of statistical significance. The results provide evidence of highly statistically significant slowdowns in the rates of accumulation of HF and HCl at 55 km. HF shows evidence of interannual and annual variability at 55 km that is not evident in HCl due to the short chemical lifetime of HCl.
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validation of hydrogen fluoride measurements made by the Halogen Occultation Experiment from the uars platform
Journal of Geophysical Research, 1996Co-Authors: James M. Russell, Lance E Deaver, Larry L. Gordley, M R Gunson, Wesley A Traub, Jae H Park, A F Tuck, Mingzhao Luo, Geoffrey C Toon, David G JohnsonAbstract:The Halogen Occultation Experiment (HALOE) on UARS uses the method of solar Occultation limb sounding to measure the composition and structure of the stratosphere and mesosphere. One of the HALOE channels is spectrally centered at 3.4 μm to measure the vertical profile and global distribution of hydrogen chloride. The mean difference between HALOE and 14 balloon correlative underflight measurements ranges from 8% to 19% throughout most of the stratosphere. This difference is within the limits of error bar overlap for the two data sets. The mean differences between HALOE and HCl data from ATMOS flights on the space shuttle is of the order of 15 to 20% for the 1992 flight and 10% for the 1993 flight. Generally, HALOE results tend to be low in these comparisons. Also, comparisons with two-dimensional model calculations and HALOE data are in good qualitative agreement regarding vertical profile shapes and features in a pressure versus latitude cross section. HCl values increase from ∼0.3 parts per billion by volume (ppbv) to 1 ppbv in the lower stratosphere to 2.6 ppbv to 3.3 ppbv just above the stratopause which is the upper limit of HALOE single-profile measurements. There is a dependence of HCl results on the angle between the orbit plane and the Earth-Sun vector with HCl varying by ±9% in the upper stratosphere. This variation appears to be altitude dependent and it is not discernible in the data below about 10 mbar.
