Jay Herman

Followers

Following

Public Views

Uploads

Papers by Jay Herman

Version 2 total ozone mapping spectrometer ultraviolet algorithm: problems and enhancements

Optical Engineering, 2002

... The sign and magnitude of the monthly/yearly sampling bias depends on local cloud diurnalstat... more

Global and Seasonal Aerosol Optical Depths Derived From Ultraviolet Observations by Satellites (TOMS)

ABSTRACT

NO2 column amounts from ground‐based Pandora and MFDOAS spectrometers using the direct‐sun DOAS technique: Intercomparisons and application to OMI validation

Journal of Geophysical Research: Atmospheres, 2009

Vertical column amounts of nitrogen dioxide, C(NO2), are derived from ground‐based direct solar i... more Vertical column amounts of nitrogen dioxide, C(NO2), are derived from ground‐based direct solar irradiance measurements using two new and independently developed spectrometer systems, Pandora (Goddard Space Flight Center) and MFDOAS (Washington State University). We discuss the advantages of C(NO2) retrievals based on Direct Sun ‐ Differential Optical Absorption Spectroscopy (DS‐DOAS). The C(NO2) data are presented from field campaigns using Pandora at Aristotle University (AUTH), Thessaloniki, Greece; a second field campaign involving both new instruments at Goddard Space Flight Center (GSFC), Greenbelt, Maryland; a Pandora time series from December 2006 to October 2008 at GSFC; and a MFDOAS time series for spring 2008 at Pacific Northwest National Laboratory (PNNL), Richland, Washington. Pandora and MFDOAS were compared at GFSC and found to closely agree, with both instruments having a clear‐sky precision of 0.01 DU (1 DU = 2.67 × 1016 molecules/cm2) and a nominal accuracy of 0.1 ...

Download

A new self‐calibration method applied to TOMS and SBUV backscattered ultraviolet data to determine long‐term global ozone change

Journal of Geophysical Research: Atmospheres, 1991

The currently archived (1989) total ozone mapping spectrometer (TOMS) and solar backscattered ult... more The currently archived (1989) total ozone mapping spectrometer (TOMS) and solar backscattered ultraviolet (SBUV) total ozone data (version 5) show a global average decrease of about 9.0% from November 1978 to November 1988. This large decrease disagrees with an approximate 3.5% decrease estimated from the ground‐based Dobson network. The primary source of disagreement was found to arise from an overestimate of reflectivity change and its incorrect wavelengths dependence for the diffuser plate used when measuring solar irradiance. Both of these factors have led to an overestimate of the rate of atmospheric ozone depletion by SBUV and TOMS. For total ozone measured by TOMS, a means has been found to use the measured radiance‐irradiance ratio from several wavelengths pairs to construct an internally self consistent calibration. The method uses the wavelength dependence of the sensitivity to calibration errors and the requirement that albedo ratios for each wavelength pair yield the sam...

Analysis of the eight-year trend in ozone depletion from empirical models of solar backscattered ultraviolet instrument degradation

Journal of Geophysical Research, 1990

Arguments are presented showing that the basic empirical model of the solar backscatter UV (SBUV)... more Arguments are presented showing that the basic empirical model of the solar backscatter UV (SBUV) instrument degradation used by Cebula et al. (1988) in their analysis of the SBUV data is likely to lead to an incorrect estimate of the ozone trend. A correction factor is given as a function of time and altitude that brings the SBUV data into approximate agreement with the SAGE, SME, and Dobson network ozone trends. It is suggested that the currently archived SBUV ozone data should be used with caution for periods of analysis exceeding 1 yr, since it is likely that the yearly decreases contained in the archived data are too large.

Optical effects of polar stratospheric clouds on the retrieval of TOMS total ozone

Journal of Geophysical Research: Atmospheres, 1992

Small areas of sharply reduced ozone density appear frequently in the maps produced from polar re... more Small areas of sharply reduced ozone density appear frequently in the maps produced from polar region total ozone mapping spectrometer (TOMS) data. These mini‐holes are of the order of 1000 km in extent with a lifetime of a few days. On the basis of measurements from ground‐based instruments, balloon‐borne ozonesondes, and simultaneous measurements of aerosol and ozone concentrations during aircraft flights in the Arctic and Antarctic regions, the appearance of polar stratospheric clouds (PSCs) are frequently associated with false reductions in ozone derived from the TOMS albedo data. By combining radiative transfer calculations with the observed PSC and ozone data, it is shown that PSCs located near or above the ozone density maximum (with optical thickness greater than 0.1) can explain most of the differences between TOMS ozone data and ground or in situ ozone measurements. Several examples of real and false TOMS mini‐hole phenomenon are investigated using data from the 1989 Airbo...

Low ozone amounts during 1992–1993 from Nimbus 7 and Meteor 3 total ozone mapping spectrometers

Journal of Geophysical Research: Atmospheres, 1994

The global distribution of ozone during the October 31, 1978, to May 6, 1993, observing lifetime ... more The global distribution of ozone during the October 31, 1978, to May 6, 1993, observing lifetime of the Nimbus 7 total ozone mapping spectrometer (TOMS) is described, with emphasis on the low ozone amounts observed during 1992 and 1993. Ozone amount time series are extended beyond May 6, 1993, to the end of July 1993 using preliminary Meteor 3 TOMS data. Time series for zonally averaged ozone amounts show that there has not been a significant shift in the seasonal patterns of ozone maxima and minima caused by the Mount Pinatubo eruption or by the onset of very low ozone values during 1992 and 1993. There has been a relatively slow, nearly linear decrease in the amount of ozone over the entire globe from 1979 to the end of 1991, with rates ranging from no change at the equator to a 4–6% decrease per decade at midlatitudes and a 10–12% decrease per decade at higher latitudes. After the eruption of Mount Pinatubo during June 1991, the ozone amount decreased in the equatorial latitudes ...

Global spatially and temporally resolved measurements of ozone, absorbing aerosol plumes, and cloud reflectivity from the 10-channel EPIC spectroradiometer as part of the DSCOVR Lagrange-1 mission

ABSTRACT Taking advantage of the unique earth-observing position afforded by the Lagrange-1 orbit... more ABSTRACT Taking advantage of the unique earth-observing position afforded by the Lagrange-1 orbit at 1.5 million km from the earth, the diurnal variation and global distribution of cloud cover, and aerosol plumes, and ozone will be derived. The results will be obtained from using 4 UV channels (317.5, 325, 340, and 388 nm) out of 10 total channels (UV and Visible). The temporal cadence for global mapping will be at least once per 90 minutes. Previously, the diurnal variation of cloud cover, which has been laboriously obtained from 30 years of combined multiple polar orbiting satellite data, will easily be obtained in one year using the EPIC instrument. Clouds and aerosol plumes will be resolved with EPIC&#39;s spatial resolution of 10 to 20 km from near sunrise to near sunset. Similarly, the evolution of aerosol dust and smoke plumes will be seen including the differences between morning, mid-day, and evening amounts.

The Effect of Energetically Produced 02 + on the Ion Temperatures

In the Martian ionosphere the dominant solar ionization products are O/sup +/ and COâ/sup +/. The... more In the Martian ionosphere the dominant solar ionization products are O/sup +/ and COâ/sup +/. These ions are rapidly converted to Oâ/sup +/ by ion neutral reactions resulting in Oâ/sup +/ as the dominant ion. As Oâ/sup +/ has a lower ionization potential, each reaction results in approximately 1.2 eV of energy to be shared by the reaction products. The

Interferometric Characterization of the Earth's Atmosphere from Lagrange Point 2

Download

Models of the Venus Ionosphere

Planetary Atmospheres, 1971

The effective magnetic dip angle may be composed in part of: (1) an actual geometrical tilt deriv... more The effective magnetic dip angle may be composed in part of: (1) an actual geometrical tilt derived from the sum of the intrinsic and induced fields; (2) bulk motion of the high j3 Venus ionosphere that produces significant distortion in the magnetic field; (3) the possible presence of turbulence that can change the effective thermal conductivity K=QK^.

Download

The dayside ionosphere of Venus

Planetary and Space Science, 1971

JUNE 1870 c co 0 11^9t d d^' ^---GODDARD SPACE nIGHT CENTER -1 GREENBELT, MARYLAND rN'70-315'73 R... more

Download

Topside Ionosphere of Venus and its Interaction with the Solar Wind

Nature, 1970

Download

Helium in the topside Venus ionosphere

Journal of Geophysical Research, 1973

Download

The effect of energetically produced O2+on the ion temperatures of the Martian thermosphere

Journal of Geophysical Research, 1979

African desert dust in the Caribbean atmosphere: Microbiology and public health

Aerobiologia, 2001

Air samples collected on St. John in the U.S.Virgin Islands were screened for the presenceof viab... more Air samples collected on St. John in the U.S.Virgin Islands were screened for the presenceof viable bacteria and fungi to determine ifthe number of cultivatable microbes in theatmosphere differed between ``clear atmosphericconditions'' and ``African dust-events.'' Resultsindicate that during ``African dust-events,'' thenumbers of cultivatable airborne microorganismscan be 2 to 3 times that found during ``clearatmospheric conditions.'' Direct microbialcounts of air samples