We study two intense Forbush decreases that occurred during two adjacent SOLTIP (Solar connection of Transient Interplanetary Processes) intervals; namely SOLTIP 1 (22–27 March 1991) and SOLTIP 2 (1–17 June 1991); galactic cosmic ray intensity at the depth of the second Forbush decrease was the lowest ever recorded since continuous monitoring by Climax neutron monitor began in 1951 (58% below the solar minimum value of 1954), indicating extreme conditions in the heliosphere that prevented galactic cosmic rays from reaching the Earth. These decreases were seen propagating in outer heliosphere by the deep space missions Voyagers 1, 2 and Pioneer 10, 11, with suitable time delays. We analyze hourly, pressure corrected, neutron monitor data from the global sites in both hemispheres, and muon telescopes located underground; they respond to 10–300 GV range of the galactic cosmic ray spectrum. This circumstance provides us an ideal opportunity to study the rigidity dependence of the amplitudes of the two Forbush decreases. In both cases the amplitude is found to be a power law in rigidity, with negative exponents. 相似文献
Halocarbons, such as CFC-11, CFC-12 and HCFC-22, are important trace gases in the atmosphere through their role as greenhouse gases and their influence on stratospheric ozone chemistry. This paper focuses on an initial study using integration of spectral radiance measurements from a spaceborne limb sounding Fourier Transform Spectrometer (FTS) to retrieve these compounds in the upper troposphere and lower stratosphere (UTLS). The instrument employed in this study is the Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS-E) which obtains spectral data in the altitude range of 6–68 km at an unapodized spectral resolution of 0.025 cm−1. We have used optimal estimation techniques to retrieve vertical information for these compounds using a radiometric approach.
It is shown that significant retrieval information is obtained at up to five measured levels in the UTLS for CFC-11, up to six for CFC-12 and up to two levels for HCFC-22. An initial error analysis indicates significant sensitivity of our retrievals to variability in operationally retrieved pressure and temperature data. For each halocarbon, gain, offset and spectroscopic uncertainties generally each contribute less than 10% to the total error. Finally, tracer correlations are used to compare the datasets to equivalent relationships derived here from version 2 ATMOS data with very good agreements for CFC-12 but with more variability in the CFC-11 comparisons. 相似文献