共查询到20条相似文献，搜索用时 578 毫秒
1.
Krueger AJ 《Science (New York, N.Y.)》1969,166(3908):998-1000
Rocket-borne radiometer determinations of ozone distributions by absorption of ultraviolet sunlight show anomalous eflects near 3000 angstroms. The instrument uses four 40-angstrom filters in the spectral region between 2650 and 3300 angstroms. At altitudes below 40 kilometers, signals from filters centered near 3000 angstroms appear reduced at least 25 percent below calculated values. However, at higher altitudes an unpredicted sharp increase in signals is observed. These effects are inconsistent with ozone absorption and cannot be ascribed to instrument characteristics. A previously unobserved absorption band of an atmospheric constituent, possibly the metastable excited states of molecular oxygen O(2)((1)Delta(g)) or O(2)((1)Sigma(g)+) can account for the anomalous effects. 相似文献
2.
An infrared heterodyne radiometer with a spectral resolution of 0.04 reciprocal centimeters has been used to remotely detect samples of ozone, sulfur dioxide, ammonia, and ethylene at room temperature, and samples of nitric oxide at 390K. Each gas was observed in a background of nitrogen or oxygen at atmospheric pressure. Sensitivities to some of these gases are adequate for detection of ambient concentrations as low as a few parts per billion. 相似文献
3.
Luther FM 《Science (New York, N.Y.)》1976,192(4234):49-51
The changes in the solar absorption by nitrogen dioxide and ozone induced by the injection of NO(x) (oxides of nitrogen) in the stratosphere are complementary, even though the nitrogen dioxide absorption is only a small fraction of the ozone absorption for an unperturbed stratosphere. The factors causing this effect are described, and an analysis is made of the perturbed solar radiation budget. 相似文献
4.
During the winter of 1979, the solar ultraviolet irradiance varied with a period of 13.5 days and an amplitude of 1 percent. The zonal mean ozone values in the tropics varied with the solar irradiance, with an amplitude of 0.25 to 0.60 percent. This observation agrees with earlier calculations, although the response may be overestimated. These results imply changes in ozone at an altitude of 48 kilometers of up to 12 percent over an 11-year solar cycle. Interpretation of ozone changes in the upper stratosphere will require measurements of solar ultraviolet radiation at wavelengths near 200 nanometers. 相似文献
5.
Kliore AJ Lindal GF Patel IR Sweetnam DN Hotz HB McDonough TR 《Science (New York, N.Y.)》1980,207(4429):446-449
Radio occultation measurements at S band (2.293 gigahertz) of the ionosphere and upper neutral atmosphere of Saturn were obtained during the flyby of the Pioneer 11 Saturn spacecraft on 5 September 1979. Preliminary analysis of the occultation exit data taken at a latitude of 9.5 degrees S and a solar zenith angle of 90.6 degrees revealed the presence of a rather thin ionosphere, having a main peak electron density of about 9.4 x 10/(3) per cubic centimeter at an altitude of about 2800 above the level of a neutral number density of 10(19) per cubic centimeter and a lower peak of about 7 x 10(3) per cubic centimeter at 2200 kilometers. Data in the neutral atmosphere were obtained to a pressure level of about 120 millibars. The temperature structure derived from these data is consistent with the results of the Pioneer 11 Saturn infrared radiometer experiment (for a helium fraction of 15 percent) and with models derived from Earth-based observations for a helium fraction by number of about 4 to 10 percent. The helium fraction will be further defined by mutual iteration with the infrared radiometer team. 相似文献
6.
7.
An infrared radiometer system has been developed that can alert a pilot of an aircraft 2 to 9 minutes in advance of an encounter with clear air turbulence. The time between the warning and the clear air turbulence event varies with the flight altitude of the aircraft. In turbulence-free areas, the incidence of false alarms is found to be less than one in 3.4 hours of flight time compared to less than one per 10 hours of flight time in areas with turbulence. 相似文献
8.
Three simultaneous observations of atomic chlorine (Cl) and the chlorine monoxide radical (ClO) are reported which encompass the altitude interval between 25 and 45 kilometers. Together, Cl and ClO form a gas-phase catalytic cycle potentially capable of depleting stratospheric ozone. Observed Cl and C1O densities, although variable, imply that chlorine compounds constitute an important part of the stratospheric ozone budget. The results are compared with recent models of stratospheric photochemistry which have been used as a basis for predicting ozone depletion resulting from fluorocarbon release. 相似文献
9.
Tomasko MG Doose LR Palmer J Holmes A Wolfe W Castillo ND Smith PH 《Science (New York, N.Y.)》1979,203(4382):795-797
The solar flux radiometer aboard the Pioneer Venus large probe operated successfully during its descent through the atmosphere of Venus. Upward, downward, and net fluxes from 0.4 to 1.0 micrometers were obtained at more than 390 levels between 185 millibars (at an altitude of approximately 61 kilometers) and the surface. Fluxes from 0.4 to 1.8 micrometers were also obtained between 185 millibars and about the level at which the pressure was 2 atmospheres. Data from 80 to 185 millibars should be available after additional decoding by the Deep Space Network. Upward and downward intensities in a narrower band from 0.59 to 0.66 micrometers were also obtained throughout the descent in order to constrain cloud properties. The measurements indicate three cloud regions above the 1.3-atmosphere level (at an altitude of approximately 49 kilometers) and a clear atmosphere beneath that level. At the 67 degrees solar zenith of the probe entry site, some 15 watts per square meter are absorbed at the surface by a dark ground, which implies that about 2 percent of the solar energy incident on the planet is absorbed at the ground. 相似文献
10.
Measured trends in stratospheric ozone 总被引：1，自引：0，他引：1
Stolarski R Bojkov R Bishop L Zerefos C Staehelin J Zawodny J 《Science (New York, N.Y.)》1992,256(5055):342-349
Recent findings, based on both ground-based and satellite measurements, have established that there has been an apparent downward trend in the total column amount of ozone over mid-latitude areas of the Northern Hemisphere in all seasons. Measurements of the altitude profile of the change in the ozone concentration have established that decreases are taking place in the lower stratosphere in the region of highest ozone concentration. Analysis of updated ozone records, through March of 1991, including 29 stations in the former Soviet Union, and analysis of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer and Stratospheric Aerosol and Gas Experiment instruments confirm many of the findings originally derived from the Dobson record concerning northern midlatitude changes in ozone. The data from many instruments now provide a fairly consistent picture of the change that has occurred in stratospheric ozone levels. 相似文献
11.
Proffitt MH Aikin K Margitan JJ Loewenstein M Podolske JR Weaver A Chan KR Fast H Elkins JW 《Science (New York, N.Y.)》1993,261(5125):1150-1154
Measurements made in the outer ring of the northern polar vortex from October 1991 through March 1992 reveal an altitude-dependent change in ozone, with a decrease at the bottom of the vortex and a substantial increase at the highest altitudes accessible to measurement. The increase is the result of ozone-rich air entering the vortex, and the decrease reflects ozone loss accumulated after the descent of the air through high concentrations of reactive chlorine. The depleted air that is released out of the bottom of the vortex is sufficient to significantly reduce column ozone at mid-latitudes. 相似文献
12.
K Hebestreit J Stutz D Rosen V Matveiv M Peleg M Luria U Platt 《Science (New York, N.Y.)》1999,283(5398):55-57
Episodes of elevated bromine oxide (BrO) concentration are known to occur at high latitudes in the Arctic boundary layer and to lead to catalytic destruction of ozone at those latitudes; these events have not been observed at lower latitudes. With the use of differential optical absorption spectroscopy (DOAS), locally high BrO concentrations were observed at mid-latitudes at the Dead Sea, Israel, during spring 1997. Mixing ratios peaked daily at around 80 parts per trillion around noon and were correlated with low boundary-layer ozone mixing ratios. 相似文献
13.
Fahey DW Gao RS Carslaw KS Kettleborough J Popp PJ Northway MJ Holecek JC Ciciora SC McLaughlin RJ Thompson TL Winkler RH Baumgardner DG Gandrud B Wennberg PO Dhaniyala S McKinney K Peter T Salawitch RJ Bui TP Elkins JW Webster CR Atlas EL Jost H Wilson JC Herman RL Kleinböhl A von König M 《Science (New York, N.Y.)》2001,291(5506):1026-1031
Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These in situ observations were made over a large altitude range (16 to 21 kilometers) and horizontal extent (1800 kilometers) on several airborne sampling flights during a period of several weeks. With diameters of 10 to 20 micrometers, these sedimenting particles have significant potential to denitrify the lower stratosphere. A microphysical model of nitric acid trihydrate particles is able to simulate the growth and sedimentation of these large sizes in the lower stratosphere, but the nucleation process is not yet known. Accurate modeling of the formation of these large particles is essential for understanding Arctic denitrification and predicting future Arctic ozone abundances. 相似文献
14.
Pettengill GH Ford PG Johnson WT Raney RK Soderblom LA 《Science (New York, N.Y.)》1991,252(5003):260-265
The Magellan Venus orbiter carries only one scientific instrument: a 12.6-centimeter wavelength radar system shared among three data-taking modes. The synthetic-aperture mode images radar echoes from the Venus surface at a resolution of between 120 and 300 meters, depending on spacecraft altitude. In the altimetric mode, relative height measurement accuracies may approach 5 meters, depending on the terrain's roughness, although orbital uncertainties place a floor of about 50 meters on the absolute uncertainty. In areas of extremely rough topography, accuracy is limited by the inherent line-of-sight radar resolution of about 88 meters. The maximum elevation observed to date, corresponding to a planetary radius of 6062 kilometers, lies within Maxwell Mons. When used as a thermal emission radiometer, the system can determine surface emissivities to an absolute accuracy of about 0.02. Mosaicked and archival digital data products will be released in compact disk (CDROM) format. 相似文献
15.
Newman PA 《Science (New York, N.Y.)》1994,264(5158):543-546
The Antarctic ozone hole results from catalytic destruction of ozone by chlorine radicals. The hole develops in August, reaches its full depth in early October, and is gone by early December of each year. Extremely low total ozone measurements were made at the Antarctic Dumont d'Urville station in 1958. These measurements were derived from spectrographic plates of the blue sky, the moon, and two stars. These Dumont plate data are inconsistent with 1958 Dobson spectrophotometer ozone measurements, inconsistent with present-day Antarctic observations, and inconsistent with meteorological and theoretical information. There is no credible evidence for an ozone hole in 1958. 相似文献
16.
Chase SC Hatzenbeler H Kieffer HH Miner E Münch G Neugebauer G 《Science (New York, N.Y.)》1972,175(4019):308-309
The brightness temperatures at 10 and 20 micrometers measured by the Mariner 9 infrared radiometer differ substantially from those predicted by the radiometer results of Mariners 6 and 7. The results indicate a significant latitude-dependent contribution of the atmospheric dust to the observed thermal emission. 相似文献
17.
A Michelson interferometer spectrometer carried aboard the Nimbus 3 satellite, launched 14 April 1969, measured the spectrum between 400 and 2000 wave numbers with a resolution of 5 wave numbers. High-quality spectra have been obtained on a global scale, and preliminary results indicate that the absorption bands of carbon dioxide, water vapor, and ozone can be used to obtain vertical distributions of temperature, water vapor, and ozone. 相似文献
18.
Brune WH Toohey DW Anderson JG Starr WL Vedder JF Danielsen EF 《Science (New York, N.Y.)》1988,242(4878):558-562
In order to test photochemical theories linking chlorofluorocarbon derivatives to ozone(O(3)) depletion at high latitudes in the springtime, several related atmospheric species, including O(3), chlorine monoxide(ClO), and bromine monoxide (BrO) were measured in the lower stratosphere with instruments mounted on the NASA ER-2 aircraft on 13 February 1988. The flight path from Moffett Field, California (37 degrees N, 121 degrees W), to Great Slave Lake, Canada (61 degrees N, 115 degrees W), extended to the center of the polar jet associated with but outside of the Arctic vortex, in which the abundance of O(3) was twice its mid-latitude value, whereas BrO levels were 5 parts per trillion by volume (pptv) between 18 and 21 kilometers, and 2.4 pptv below that altitude. The ClO mixing ratio was as much as 65 pptv at 60 degrees N latitude at an altitude of 20 kilometers, and was enhanced over mid-latitude values by a factor of 3 to 5 at altitudes above 18 kilometers and by as much as a factor of 40 at altitudes below 17 kilometers. Levels of ClO and O(3) were highly correlated on all measured distance scales, and both showed an abrupt change in character at 54 degrees N latitude. The enhancement of ClO abundance north of 54 degrees N was most likely caused by low nitrogen dioxide levels in the flight path. 相似文献
19.
Evidence is presented which suggests that trends in the ozone concentration and stratospheric temperature, reported between the early 1960's and 1976, are to a large extent due to solar ultraviolet flux variability associated with the 11-year solar cycle. Radiative-convective-photochemical simulations of ozone and temperature variations have been made with a solar ultraviolet flux variability model. Results for temperatures and ozone concentrations, when compared with published data, show good agreement. 相似文献
20.
The hydroperoxyl radical (HO(2)) plays a key role in stratospheric chemistry through the HOx catalytic cycle of ozone destruction. Earlier measurements of stratospheric HO(2) have given mixed results; some measured mixing ratios greatly exceed theoretical predictions. Measurements of HO(2) have now been made with a balloon-borne farinfrared spectrometer. The measured daytime profile is in excellent agreement with theory up to 40 kilometers; above this level the measurements exceed theory by 30 percent, perhaps because of underprediction of ozone at these altitudes. The nighttime HO(2) profile is strongly depressed with respect to the daytime profile, in general agreement with theory. 相似文献