摘要:

There is a spatial and a temporal correspondence between changes in Pacific sea surface temperature and changes in atmospheric carbon dioxide, after seasonal trends have been removed.

ISSN:0094-8276    

DOI:10.1029/GL004i001p00001

年代:1977

数据来源: WILEY

摘要:

High resolution infrared absorptivities of chlorine nitrate (ClONO2) are required in order to quantitatively evaluate, by examination of infrared spectra obtained recently from balloon‐borne spectrometers, the possible occurrence of this compound in the stratosphere. In the present study, infrared absorptivities for four absorption bands of gaseous ClONO2have been measured at 0.0625 cm−1spectral resolution with a Fourier transform infrared (FT‐IR) system. Spectra were obtained at two pressures (0.05 and 1.05 torr) of pure ClONO2and with 125 torr of N2added to a 0.50 torr sample. Absorptivities for a range of spectral resolutions (0.0625, 0.125, 0.25 and 0.50 cm−1) have been calculated from t

ISSN:0094-8276    

DOI:10.1029/GL004i001p00003

年代:1977

数据来源: WILEY

摘要:

The flash photolysis‐resonance fluorescence technique has been utilized to measure the rate constants for the reactions of chlorine nitrate (ClONO2) with two stratospheric radicals, O(³P) and OH. Both rate constants were measured at a pressure of 20 Torr and a temperature of 245 K. The reactions with their corresponding rate constant in units of cm−3molecule−1s−1are: O(³P) + ClONO2→ Products, k1= (2.0 ± 0.2) × 10−13; OH + ClONO2→ Products, k2= (3.7 ± 0.2) × 10−13.The above results, coupled with the photolysis rate of ClONO2, indicate that these chemical degradation pathways contribute less than 10% to the removal of ClON

ISSN:0094-8276    

DOI:10.1029/GL004i001p00007

年代:1977

数据来源: WILEY

摘要:

An experiment was performed using the powerful radar at Arecibo (18°N 67°E, 51° dip) to look for stratospheric and mesospheric echoes in the UHF frequency band. Strong echoes were returned from the stratospheric region, whereas no distinct returns were obtained from mesospheric heights. These results, when compared to those reported for the VHF radar at Jicamarca, support wavenumber dependences of the scattering mechanisms, such that scattering due to neutral air turbulence should be more effective at UHF frequencies than at VHF in the stratosphere, while the reverse should be true in the mesosphere. The results suggest the feasibility of utilizing the present UHF incoherent scatter radar for remote sensing of winds in the stratosphe

ISSN:0094-8276    

DOI:10.1029/GL004i001p00010

年代:1977

数据来源: WILEY

摘要:

Measurements have been made of the HF and VHF radiation at 3, 30, 139, and 295 MHz produced during lightning return strokes, in correlation with wideband electric field measurements covering from about 300 Hz to 2 MHz. Intense pulses of RF are observed during the first return stroke in a discharge to ground, but with a 10‐30 µsec time delay between the beginning of the stroke and the occurrence of significant RF radiation. The delay occurs at all frequencies and is short enough to suggest that the main channel and/or branches are the main initial sources of RF during the first stroke. During a subsequent return stroke, the RF starts an average of 265 µsec prior to the onset of the stroke. At 139 and 295 MHz, the subsequent stroke RF lasts only about 115 µsec; however, at 3 MHz, the radiation frequently persists up to and during the st

ISSN:0094-8276    

DOI:10.1029/GL004i001p00013

年代:1977

数据来源: WILEY

摘要:

A numerical kinetic aerosol model is utilized to study conditions under which secondary sulfuric acid aerosol can be formed in an urban atmosphere. This model incorporates the mechanisms of photochemical reactions, heteromolecular nucleation, heteromolecular condensation and thermal coagulation. Various atmospheric conditions are used to study the effects of production rate of sulfuric acid gaseous molecules, relative humidity, temperature, initial particle size distribution and kinetic coefficient for nucleation and condensation growth on the formation of new secondary sulfuric acid aerosol. Our model calculations show that the rate‐limiting factor for the formation of these secondary aerosols is the amount of the sulfuric acid gaseous molecules available in the atmospher

ISSN:0094-8276    

DOI:10.1029/GL004i001p00017

年代:1977

数据来源: WILEY

摘要:

Total ozone data are statistically analyzed to estimate the trend detection capability which would provide early warning of ozone depletion. Based on a worldwide sample of nine stations, an abnormal global ozone change of 0.26% per year persisting over 6 years would be judged statistically significant, if it were to occur and could not be explained by historical patterns. A resulting 1.56% early warning can limit maximum reversible depletion to 2.3%, if the cause were due to chlorofluoromethanes FC‐11 and FC‐12. The analysis shows no evidence of an abnormal global trend persisting in the 1970's. The potential exists for detecting even smaller changes by using data from all the current land‐based stations and satel

ISSN:0094-8276    

DOI:10.1029/GL004i001p00021

年代:1977

数据来源: WILEY

摘要:

Variation in the eddy diffusion coefficient near the turbopause affects not only the composition but also the wind and temperature fields of the thermosphere. Composition and wind fields are strongly coupled such that for long term (annual) variations the eddy diffusion effects are entirely different in one and three dimensional models. Horizontal winds, driven by the oxygen bulge which in turn is induced by eddy diffusion, act as a feedback to significantly reduce the composition variations in general and the ratio between He and O amplitudes in particular. The resulting He amplitude from three dimensional calculations is by about a factor of ten lower than the O amplitude above 150 km, in striking contrast to composition data. Due to temperature variations, isopycnic levels develop at 250 km (He) and 450 km (O), such that at higher altitudes both species vary in phase with the eddy diffusion coefficient. The eddy diffusion mechanism must thus be excluded as a principle candidate for describing the spherical asymmetries in the annual variation of the thermosphere. The temperature increase associated with adiabatie heating from the wind component can be substantial; turbulent energy is thereby effectively transported from the mesosphere up into the thermosphere.

ISSN:0094-8276    

DOI:10.1029/GL004i001p00025

年代:1977

数据来源: WILEY

摘要:

A newly developed mass spectrometer which employs a sputter ion pump was flown on a balloon in May, 1975, and obtained mass spectra for neutral constituents in the stratosphere. The measured mass spectra show an abnormally high concentration at the mass number of 64, to be about 30 ppm. This particular component has a similar altitude profile to that of the aerosols, and could be assigned to sulfur dioxide. Such a high concentration of SO2that was measured in this flight may be partly associated with the eruption of Mt. Fuego.

ISSN:0094-8276    

DOI:10.1029/GL004i001p00029

年代:1977

数据来源: WILEY

摘要:

We present an empirical model of global exospheric temperatures and densities of neutral constituents, based on data from 228 geomagnetically quiet days during the operation of the Esro 4 gas analyzer (mean Ap= 7). By means of an expansion in spherical harmonics the model infers exospheric temperatures from both the measured N2and Ar densities. O and He densities are presented as extrapolated density distributions at 120 km altitude. The Esro 4 model complements the similar Ogo 6 mass spectrometer model with observations at considerably lower altitudes (240‐320 km) and lower levels of solar activity Inferred exospheric temperatures are typically 5‐9% below Ogo 6 model values for F10.7=

ISSN:0094-8276    

DOI:10.1029/GL004i001p00033

年代:1977

数据来源: WILEY