M. E. Hervig

Publications (4)0 Total impact

• Source

  Available from: James M. Russell III

  Article: Retrieval of temperature and pressure using broadband solar occultation: SOFIE approach and results

  B. T. Marshall, L. E. Deaver, R. E. Thompson, L. L. Gordley, M. J. McHugh, M. E. Hervig, J. M. Russell III
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  ABSTRACT: Measurement of atmospheric temperature as a function of pressure, T(P), is key to understanding many atmospheric processes and a prerequisite for retrieving gas mixing ratios and other parameters from solar occultation measurements. This paper gives a brief overview of the solar occultation measurement technique followed by a detailed discussion of the mechanisms that make the measurement sensitive to temperature. Methods for retrieving T(P) using both broadband transmittance and refraction are discussed. Investigations using measurements of broadband transmittance in two CO2 absorption bands (the 4.3 and 2.7 μm bands) and refractive bending are then presented. These investigations include sensitivity studies, simulated retrieval studies, and examples from SOFIE.
  Atmospheric Measurement Techniques Discussions. 01/2010;
• Article: Polar Stratospheric Clouds Due to Vapor Enhancement: HALOE Observations of the Antarctic Vortex in 1993

  M. E. Hervig, K. S. Carslaw, T. Peter, T. Deshler, L. L. Gordley, G. Redaelli, U. Biermann, Russell, J. M, III
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  ABSTRACT: Aerosol measurements from the Halogen Occultation Experiment (HALOE) during the Antarctic spring of 1993 are compared with calculations of the volume of different types of polar stratospheric clouds (PSCs) at equilibrium. tHe observed volumes increased by a factor of APPROX. 30 coincident with water vapor enhancements of approx. 3 ppmv, suggesting that the enhancement of water vapor was important in determining PSC growth. The enhanced water vapor was coincident with increased methane mixing ratios, and trajectory analysis suggests that the vapor enhancements were consistent with transport from lower latitudes. The nitric acid distribution was not measured and is treated either as constant or as positively correlated with the observed water. Comparing the observed volumes with model calculations assuming constant nitric acid suggests that the PSCs were composed of liquid ternary H2SO4-H2O-HNO3 aerosols (LTA) rather than solid nitric acid trihydrate (NAT). However, if the water vapor intrusions were accompanied by enhanced nitric acid, the observations closely match predictions for solid NAT, and those for LTA. These comparisons highlight the importance of the vapor distributions for modeling PSC growth and suggest that vapor resupply is important for late spring PSC growth. This work also highlights some inherent limitations of large field of view limb-viewing instruments for the observation of PSCs.
  01/1998;
• Article: Validation of Temperature Measurements from the Halogen Occultation Experiment

  M. E. Hervig, Russell, J. M, III, L. L. Gordley, S. R. Drayson, K. Stone, R. E. Thompson, M. E. Gelman, I. S. McDermid, A. Hauchecorne, P. Keckhut, T. J. Mcgee, U. N. Singh, M. R. Gross
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  ABSTRACT: The Halogen Occultation Experiment (HALOE) onboard UARS measures profiles of limb path solar attenuation in eight infrared bands. These measurements are used to infer profiles of temperature, gas mixing ratios of seven species, and aerosol extinction at five wavelengths. The objective of this paper is to validate profiles of temperature retrieved from atmospheric transmission measurements in the 2.80 micron CO2 band. Temperatures are retrieved for levels above where aerosol affects the signals (35 km) to altitudes where the signal-to-noise decreases to unity (approx. 85 km). At altitudes from 45 to 35 km the profile undergoes a gradual transition from retrieved to National Meteorological Center (NMC) temperatures and below 35 km the profile is strictly from the NMC. This validation covers the uncertainty analysis, internal validations, and comparisons with independent measurements. Monte Carlo calculations using all known random and systematic errors determine typical measurement uncertainties of 5 K for altitudes below 80 km. Comparisons of coincident HALOE sunrise and sunset measurements are an indicator of the upper limit of measurement uncertainty. The sunrise-sunset comparisons have random and systematic differences which are less than 10 K for altitudes below 80 km. Comparisons of HALOE to lidar and rocket measurements typically have random differences of approx. 5 K for altitudes below 65 km. The mean differences for the correlative comparisons indicate that HALOE temperatures have a cold bias (2 to 5 K) in the upper stratosphere and stratopause.
  05/1996;
• Article: Validation of Aerosol Measurements from the Halogen Occultation Experiment

  M. E. Hervig, Russell, James M, III, Larry L. Gordley, J. H. Park, S. Roland Drayson, Terry Deshler
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  ABSTRACT: 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 approximately 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 micrometers aerosol measurements are much less reliable than the other four measurements.
  05/1996;
• Article: The First Year of AIM SOFIE Water Vapor in the Polar Mesosphere: Comparisons With HALOE and Model Expectations

  M. E. Summers, L. L. Gordley, M. E. Hervig, C. E. Randall, P. Rong, J. M. Russell, D. E. Siskind, M. H. Stevens
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  ABSTRACT: Observations of mesospheric water vapor along with PMC properties by the SOFIE experiment on the AIM spacecraft have provided a means to quantify in detail the water/ice budget in the formation and evolution of PMCs. We will give an overview of the SOFIE water vapor measurements from the first year of the AIM mission, which encompasses one northern and one southern PMC season. These initial results from SOFIE confirm an enhancement of water vapor within the PMC layer that develops simultaneously with the PMC layer as in HALOE data, but there are several apparent differences between SOFIE water measurements and that expected based upon a 12 year climatological average of HALOE measurements. Differences of the layer s peak value and thickness, as seen in HALOE and SOFIE, persist throughout the PMC season. In monthly averages where the HALOE peak values typically exceeds 10 ppmv and occasionally reaches 13 ppmv during July and August, the SOFIE water rarely exceeds 8 ppmv. However, some of these differences are likely due to different SOFIE and HALOE observational sampling, signal to noise, and vertical resolution. Also, the SOFIE water measurement is insensitive to ice spectra. We will discuss these differences and current SOFIE water vapor validation efforts.
• Article: Relationships between PMC and PMSE from SOFIE and radar observations in both hemispheres (Invited)

  M. E. Hervig, L. L. Gordley, M. Rapp, S. Kirkwood, J. M. Russell, S. M. Bailey
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  ABSTRACT: Observations from the Solar Occultation For Ice Experiment (SOFIE) reveal that ice particles near the polar summer mesopause generally exist in a continuous layer extending from roughly 80 km to above the mesopause. Ice particles at the lower altitude range have been observed visually as noctilucent clouds (NLC) and remotely as polar mesospheric clouds (PMC). Radars detect polar mesospheric summer echoes (PMSE), which typically extend from just below PMC altitudes to the mesopause and above. PMSE are attributed to changes in the radio refractive index due to the presence of ice particles which acquire a charge in the ambient D-region. Based on simultaneous lidar NLC and radar PMSE observations, it has long been suspected that both phenomena are different manifestations of the same mesospheric ice clouds. Due to the high sensitivity of SOFIE and its ability to detect even tiny ice particles, this hypothesis can now be rigorously tested. We explore relationships between PMC and PMSE using radar observations in the northern and southern polar regions, in conjunction with SOFIE ice measurements.
• Article: DUst Sounder and Temperature Imager Experiment (DUSTIE)

  M. J. McHugh, C. S. Fish, M. J. Taylor, L. L. Gordley, M. E. Hervig, M. E. Summers, D. E. Siskind
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  ABSTRACT: The Dust Sounder and Temperature Imager Experiment (DUSTIE) is a proposed CubeSat mission to determine the global distribution of cosmic smoke in the atmosphere. The Earth is under continual bombardment by comets and meteoroids. Over the last 5 billion years they have brought water and the basics of life to our planet. Today they are vaporized during atmospheric entry and deposited as microscopic smoke particles in the upper atmosphere. These cosmic particles are known to be important in a host of atmospheric processes, including nucleation of ice particles, ion chemistry in the thermosphere and heterogeneous chemistry in the mesosphere. Despite this, our current understanding is based on scant observations and theory. The successful deployment of DUSTIE will offer a major advance in this important emerging area of research. DUSTIE will use a digital camera to image the Sun at 0.420 µm during spacecraft sunrise and sunset. This will provide measurements to characterize the smoke distribution over the altitude range of ~40 to 90 km. A high-inclination orbit will provide near-global coverage monthly. Simultaneous refraction measurements will yield atmospheric density profiles up to 75 km. Measured smoke extinctions will be used to derive smoke particle volume and surface area densities. DUSTIE will utilize a 3U form factor CubeSat and rely heavily upon commercial-off-the-shelf (COTS) components and proven technologies.
• Article: PMC Morphology and its Dependence on Water Vapor and Temperature: Highlights From the AIM Mission

  C. E. Randall, S. M. Bailey, C. Bardeen, S. Benze, L. Gordley, M. Hervig, B. Karlsson, D. R. Marsh, A. Merkel, M. Mills, D. Siskind, M. Stevens
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  ABSTRACT: The Aeronomy of Ice in the Mesosphere (AIM) mission has provided nearly two years of unprecedented data on polar mesospheric clouds (PMCs). This talk will provide an overview of AIM contributions to improving our understanding of PMC morphology and the dependence of PMCs on water vapor and temperature. Highlights from recent and ongoing investigations using measurements from the AIM Cloud Imaging and Particle Size (CIPS) experiment and Solar Occultation For Ice Experiment (SOFIE) will be described. We will show that AIM measurements of PMCs, water vapor, and temperature compare well with correlative data, and we will present determinations of SOFIE and CIPS particle sizes. Correlations between SOFIE measurements of water vapor, temperature, and PMCs, as well as between CIPS measurements of PMCs over the polar region and ancillary (global) measurements of water vapor and temperature, suggest mechanistic connections between the forcing variables and PMCs. These connections are explored further with two different models, the Navy Operational Global Atmospheric Prediction System (NOGAPS) and the National Center for Atmospheric Research Whole Atmosphere Community Climate Model (WACCM).