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Project Description for Meteor-3/TOMS (Total Ozone Mapping Spectrometer)
No full textThis document provides Goddard Space Flight Center's (GSFC) Project Description for the Meteor-3/TOMS mission_ The Meteor-3/TOMS mission is a joint USA/USSR scientific program in which a US Total Ozone Mapping Spectrometer (TOMS) instrument will fly on a USSR Meteor-3 spacecraft. The National Aeronautics and Space Administration (NASA) has initiated the Meteor-3/TOMS Project to provide a continuation of the decade-long global coverage obtained with the Nimbus-7 TOMS instrument. The scientific goal is to gather global total ozone data of an environmental importance to both countries as well as to all peoples of the earth
Detection of biomass burning smoke from TOMS measurements
No full textA 14.5 year gridded data set of tropospheric absorbing aerosol index was derived from the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) reflectivity difference between 340 and 380 nm channels. Based upon radiative transfer calculations, the reflectivity anomaly between these two UV wavelength channels is very sensitive to smoke and soot aerosols from biomass burning and forest fires, volcanic ash clouds as well as desert mineral dust. We demonstrate the ability of the TOMS instrument to detect and track smoke and soot aerosols generated by biomass burning in South America. TOMS data can clearly distinguish between absorbing particles (smoke and dust) and non-absorbing aerosols (clouds and haze). For South American fires, comparisons of TOMS data are consistent with the limited amount of ground-based observations (Porto Nacional, Brazil) and show generally good agreement with other satellite imagery. TOMS data shows large-scale transport of smoke particulates generated by the burning fires in the South America, which subsequentially advects smoke aerosols as far as the Atlantic Ocean east of Uruguay.The authors would like to acknowledge the efforts of the TOMS Ozone Processing Team (OPT) for the new Version 7 data. We thank D. P. McNamara (Applied Research Corporation) for providing us with output from the Goddard trajectory model developed by M. Schoeberl, L. Lait, and P. Newman. The NOAA-NASA GOES Pathfinder program is also acknowledged for the GOES-7 visible imagery.https://onlinelibrary.wiley.com/doi/abs/10.1029/96GL0045
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Fields and Toms: The Hover Collection of Karuk Baskets
No full textThe Hover Collection of Karuk Baskets.Virginia M. Fields, text; James D. Toms, photographs. Clarke Memorial Museum, 240 E Street, Eureka, California 95501, 1985. $21.00 (paper)
Irreducible numerical semigroups having Toms decomposition
No full textIn this article we prove that if S is an irreducible numerical semigroup and S is generated by an interval or S has multiplicity 3 or 4, then it enjoys Toms decomposition. We also prove that if a numerical semigroup can be expressed as an expansion of a numerical semigroup generated by an interval, then it is irreducible and has Toms decomposition
Comparing OMI-TOMS and OMI-DOAS total ozone column data
No full textThe Ozone Monitoring Instrument (OMI) project team uses two total ozone retrieval algorithms in order to maintain the long-term record established with Total Ozone Mapping Spectrometer (TOMS) data as well as to improve the ozone column estimate using the hyperspectral capability of OMI. The purpose of this study is to assess where the algorithms produce comparable results and where the differences are significant. Starting with the same set of Earth reflectance data, the total ozone data used in this study have been derived using OMI-TOMS and OMI-Differential Optical Absorption Spectroscopy (DOAS) algorithms. OMI-TOMS is based on the TOMS version 8 algorithm that has been used to process TOMS data taken since November 1978. The OMI-DOAS retrieval algorithm was developed specifically for OMI. It takes advantage of the hyperspectral feature of the OMI instrument to reduce errors due to aerosols, clouds, surface, and sulfur dioxide from volcanic eruptions. The OMI-DOAS algorithm also has improved correction for cloud height. The mean differences in the ozone column derived from the two algorithms vary from 0 to 9 DU (0-3%), and their correlation coefficients vary between 0.89 and 0.99 with latitude and season. The largest differences occur in the polar regions and over clouds. Some of the differences are due to stray light, dark current, and other instrumental errors that have been corrected in the new version of the OMI radiance/irradiance data set (collection 3). Other differences are algorithmic. OMI-DOAS algorithmic errors identified through this analysis are also being corrected in collection 3 reprocessing. However, for consistency with the long-term TOMS record, OMI-TOMS collection 3 data will still be based on the TOMS V8 algorithm. Preliminary analysis shows much better agreement in the two total ozone data sets after reprocessing. Reprocessed collection 3 data from both algorithms will be available before the end of 2007. Continuing the TOMS total ozone column data record that dates back to November 1978 is the primary OMI mission goal that is achievable with either OMI total ozone column data product. Copyright 2008 by the American Geophysical Union. U7 - Export Date: 2 August 2010 U7 - Source: Scopus U7 - Art. No.: D16S2
NIMBUS-7/TOMS detection of mineral dust over the north Africa and the eastern north Atlantic Ocean
No full textIt has recently been found that the ultraviolet measurements obtained with the Nimbus 7 total ozone mapping spectrometer (TOMS) instrument can be used to retrieve information on the distribution of aerosols over oceanic and continental surfaces. Here we examine the use of the derived TOMS aerosol index (AI) for the detection of absorbing aerosol in terms of mineral dust aerosol over the North Atlantic Ocean and North Africa. Specifically, we compare the TOMS AI with the time series of daily aerosol measurements made in the boundary layer at Sal Island (Cape Verde), Barbados, and Miami and in the free troposphere on Tenerife (Canary Islands); these sites are frequently impacted by African dust events. At Tenerife, over the time period 1988–1992, TOMS detected 80% of the African dust events that yielded daily average dust concentrations greater than 20 μg m⁻³; at Barbados and Miami, TOMS detected 65% and 44% respectively of the events over the period 1979–1992. If we exclude events during which some of the TOMS data are missing and also short (1-day) dust events, TOMS detected 99% of the events at Tenerife, 97% at Barbados, and 81% at Miami. TOMS was also successful in detecting the “low altitude” African dust events recorded at Sal during the winter season. Over Africa we compare the TOMS AI data with ground-based measurements of aerosol optical thickness (AOT) obtained during field experiments in Senegal and Niger; these yield a nearly linear relationship between the TOMS AI and the AOT. Discrepancies between ground-based measurements (in terms of dust concentrations or AOT) and TOMS AI can be attributed to a number of factors: variations in the physical properties of the aerosol; the sensitivity of the TOMS response to the altitude of the aerosol layer; or the coarse spatial resolution of the TOMS pixel. Nonetheless, our results clearly show that the TOMS AI provides a remarkably accurate picture of mineral dust distributions in the atmosphere over both continental and oceanic regions.We thank Didier Tanr6 for providing the AOT measurements from field experiments in Senegal and Niger, Richard Arimoto for providing the aerosol data from Tenerife, and Miguel Izaguirre for programing support. This work was supported by NASA contract NAG54020 and by NSF grants ATM9414846 and ATM9414808 in support of the AEROCE program.https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/1998JD20008
Le tombe 33, 91, 99 e 202 della Necropoli di Selciatello Sopra e l'eredità nuragica a Tarquinia
No full textNimbus-7 TOMS Version 7 Calibration
No full textThis report describes an improved instrument characterization used for the Version 7 processing of the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) data record. An improved internal calibration technique referred to as spectral discrimination is used to provide long-term calibration precision of +/- 1%/decade in total column ozone amount. A revised wavelength scale results in a day one calibration that agrees with other satellite and ground-based measurements of total ozone, while a wavelength independent adjustment of the initial radiometric calibration constants provides good agreement with surface reflectivity measured by other satellite-borne ultraviolet measurements. The impact of other aspects of the Nimbus-7 TOMS instrument performance are also discussed. The Version 7 data should be used in all future studies involving the Nimbus-7 TOMS measurements of ozone. The data are available through the NASA Goddard Space Flight Center's Distributive Active Archive Center (DAAC)
A geostationary imaging spectrometer TOMS instrument
No full textOne design for a geostationary Total Ozone Mapping Spectrometer (TOMS) with many desirable features is an imaging spectrometer. A preliminary study makes use of a 0.25 m Czerny-Turner spectrometer with which the Earth is imaged on a charge-coupled device (CCD) in dispersed light. The wavelength is determined by a movable grating which can be set arbitrarily by ground control. The signal integration time depends on wavelength but this system allows arbitrary timing by command. Special circumstances such as a requirement to track a low-lying sulfur dioxide cloud or a need to discriminate high level ozone from total ozone at midlatitudes could be obtained by adding a particular wavelength to the normally pre-programmed time sequence. The incident solar irradiance is measured by deploying a diffuser plate in the field of view. Individual detector elements correspond to scene elements in which the several wavelengths are serially sampled and the Earth radiance is compared to the incident sunlight. Thus the problem of uncorrelated drift of multiple detectors is removed
Sea-Land Total Ozone Differences from TOMS: GHOST Effect
No full textMean global TOMS (Total Ozone Mapping Spectrometer) ozone data, averaged in time, reveals persistent year-to-year differences in total ozone between continents and oceans. This feature has been named GHOST (global hidden ozone structures from TOMS). During Northern Hemisphere summer it can be seen within the latitudinal belt between 40°S and 50°N. The most pronounced land-sea difference in total ozone with values of up to 18 Dobson units is observed between latitudes 35°N and 40°N. The gradients associated with the coastlines are stronger in summer, when transient planetary wave activity decreases, but is still observable in the winter period. The Iberian Peninsula has been selected as a case study to examine the effect of each possible contribution quantitatively. It has been found that the truncation of the lower tropospheric column due to the topography explains 26% of the land-sea differences, while permanent differences in tropopause height distribution can account for a further 8%. After these “corrections” other structures remain. Additional contributions due to the TOMS total ozone retrieval algorithm artifact (absorbing aerosol distribution) are also explored. After considering the optical depths and absorbance of aerosols above the Iberian Peninsula, the remaining 66% is compatible with the presence of UV-absorbing aerosols whose effects may not be correctly accounted for in the TOMS retrieval algorithm
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