ISSN:0094-8276    

DOI:10.1029/GL008i001p00001

年代:1981

数据来源: WILEY

摘要:

SAM II satellite measurements during the July 1979 Poker Flat mission, yielded an aerosol extinction coefficient of 10−4km−1at 1.0 µm wavelength, in the region of the stratospheric aerosol mixing ratio peak (12‐16 km). The stratospheric aerosol optical depth for these data, calculated from the tropopause through 30 km, is approximately 0.001. These results are consistent with the average 1979 summertime values found throughout the

ISSN:0094-8276    

DOI:10.1029/GL008i001p00003

年代:1981

数据来源: WILEY

摘要:

New measurements of mixing ratios of OCS in the lower stratosphere at midlatitude (Northern California) and high‐latitude (Alaska) locations are reported which are in essential agreement with previous results. Weak signals due to stratospheric SO2have been detected, and the estimated mixing ratios ranged from 36 to 51 pptv at altitudes 15.2 to 20.3 km. A very weak signal observed in the analysis is thought to be due to CS2and, if this identification is correct, an upper limit concentration is estimated to be 1 ppt

ISSN:0094-8276    

DOI:10.1029/GL008i001p00005

年代:1981

数据来源: WILEY

摘要:

A method for determining the visible absorption coefficient of stratospheric aerosols is presented. The first eight samples had a median value of 4 × 10−9m−1, with an uncertainty of about ± 5 × 10−9m−1. The resulting estimated single‐scattering albedo was in the ra

ISSN:0094-8276    

DOI:10.1029/GL008i001p00009

年代:1981

数据来源: WILEY

摘要:

A laser nephelometer developed for airborne measurements of polar scattering diagrams of atmospheric aerosols was flown on the NCAR Sabreliner aircraft to obtain data on light‐scattering parameters for stratospheric aerosol particles over Alaska during July 1979. Observed values of the angular variation of scattered‐light intensity were compared with those calculated for different values of the asymmetry parameter g in the Henyey‐Greenstein phase function. Our observations indicate that, for the time and location of the experiments, the Henyey‐Greenstein phase function could be used to calculate polar scattering diagrams to within experimental errors for an asymmetry parameter value of 0.49

ISSN:0094-8276    

DOI:10.1029/GL008i001p00013

年代:1981

数据来源: WILEY

摘要:

Stratospheric aerosols were collected at Poker Flat, Alaska, in July, 1979, to determine particle properties, confirm coincident satellite SAGE measurements, and compare similar results obtained with different airborne samplers. Because of the steep slopes in size‐distribution curves for larger particles, we found properties such as concentration, aerosol mass, and optical extinction are very sensitive to small errors in radii. We calculate that our concentration measurements agree with photoelectric particle counter results when a 16% radius change is introduced. An 8% radius change matches our calculated sulfate mass with filter mass measurements. And a 13% radius change results in agreement between our calculated optical extinction and coincident SAGE satellite results. Recognizing that different instruments can produce 10‐20% differences in measured sizes, we believe the results of these comparative measurements of SAGE and in situ instruments are essentially in agreem

ISSN:0094-8276    

DOI:10.1029/GL008i001p00015

年代:1981

数据来源: WILEY

摘要:

In this paper we describe a sampling and analysis technique that uses the binomial distribution to characterize stratospheric aerosol populations at the 95% level of confidence. Particle samples obtained over Alaska during July 15‐19, 1979, are used; the results show the presence of more small particles at lower altitude than at high altitudes. We also give calculations of the surface area and volume distributions for all aerosol samples collected. Evidence from these data suggests either that Aitken nuclei are injected or diffused across the tropopause and rise into the stratosphere, where they mature into larger particles, or nuclei form in the lower stratosphere and become mature aerosols at high altitude. Samples obtained at another site give the same results, supporting the view that the process of injection or nucleation and maturing of aerosols with altitude may be global and need not occur only in locations exhibiting unique meteorologic feature

ISSN:0094-8276    

DOI:10.1029/GL008i001p00018

年代:1981

数据来源: WILEY

摘要:

A new multi filter sampler (MFS) was used to measure daily profiles of sulfate aerosol in Alaska during the period July 16 through July 19, 1979. During these 4 days, the variability is such that the percent standard deviation of an individual profile from the mean is as high as 23%. The results of these flights are compared with the Project Airstream results from the same time period.

ISSN:0094-8276    

DOI:10.1029/GL008i001p00021

年代:1981

数据来源: WILEY

摘要:

Calculations of the distribution of stratospheric sulfur gases and of stratospheric aerosols are compared with measurements obtained in Alaska during July 1979. Generally, the measurements are reasonably consistent with the model results. COS is the major sulfur‐bearing gas in the stratosphere while CS2plays a lesser role in the formation of sulfate aerosols. Ammonia, which earlier measurements suggested was a major aerosol constituent, is found to be a contaminant, so models without ammonia chemistry may be justified. The model and the measurements suggest that stratospheric sulfuric acid aerosols nucleate just above the tropopause, but they are older and have grown to larger sizes at higher altitude

ISSN:0094-8276    

DOI:10.1029/GL008i001p00023

年代:1981

数据来源: WILEY

摘要:

We have carried out a series of Mie scattering calculations to define the wavelength‐dependent, single scattering properties of aerosols present in the stratosphere during July 1979. Additional radiative transfer computations were conducted to assess the impact of aerosols on Earth’s radiation budget. For these purposes, we employed an extensive set of measurements of aerosol characteristics that were obtained in Alaska from aircraft and satellite platforms. At that time, the optical depth was too small for aerosols to significantly impact Earth’s climate. But the optical depth of the stratospheric aerosol layer has been large enough during some volcanically perturbed periods for the aerosols to have caused a noticeable warming of the stratosphere and cooling of the tropos

ISSN:0094-8276    

DOI:10.1029/GL008i001p00026

年代:1981

数据来源: WILEY