Showing papers by "Steven T. Massie published in 2001"
TL;DR: In this paper, the interannual variability of the tropical tropopause region between 14 and 18 km is examined using ob-servations of convection, winds, and tropopsause temperatures from reanalyses and water vapor from satellites.
Abstract: The interannual variability of the tropical tropopause region between 14 and 18 km is examined using ob- servations of convection, winds, and tropopause temperatures from reanalyses and water vapor from satellites. This variability is compared to a simulation using the Community Climate Model version 3 (CCM3) general circulation model forced by observed sea surface temperatures. A coherent picture of the effect of the El Nino- Southern Oscillation (ENSO) on the tropopause region is presented in the NCEP-NCAR reanalyses and CCM3. ENSO modifies convection in the Tropics, and the temperature and circulation of the tropical tropopause region, in agreement with idealized models of tropical heating. CCM3 reproduces most details of these changes, but not the zonal mean temperature variations present in the analysis fields, which are not related to ENSO. ENSO also forces significant changes in observed and simulated water vapor fields. In the upper troposphere water vapor is at maximum near convection, while in the tropopause region water vapor is at minimum in the regions of convection and surrounding it. Convection, cirrus clouds, temperatures, and transport are all linked to describe the water vapor distribution and highlight the role of transport in the tropopause region.
82 citations
TL;DR: In this article, relative extinction coefficients as a function of wavelength were determined for stratospheric aerosols from the Mount Pinatubo eruptions in June of 1991, using the Halogen Occultation Experiment (HALOE) data at latitudes 20°-55° in the northern hemisphere from November 1991 to February 1992.
Abstract: Relative extinction coefficients as a function of wavelength are determined for stratospheric aerosols from the Mount Pinatubo eruptions in June of 1991, using the Halogen Occultation Experiment (HALOE) data at latitudes 20°–55° in the northern hemisphere from November 1991 to February 1992. Extinction coefficients at each of the eight ELALOE channels are obtained from the ratio of two transmittance profiles of consecutive occultation measurements separated by 25° longitude, one loaded with aerosols larger than the other during the early stage of aerosol dispersion after the eruptions. These coefficients are compared to theoretical Mie calculation values. Composition and a single mode particle size distribution are derived as a function of altitude. The retrievals indicate that the weight percentage of H2SO4 for 45 occultation cases is larger than the equilibrium value by about 5 wt %, while the size distribution parameters are within the range of those measured in situ at Laramie, Wyoming.
8 citations
21 Feb 2001
TL;DR: Extinction coefficients for stratospheric aerosols at 8 HALOE (HALogen Occultation Experiment) wavelengths are determined by comparing transmittances data for two adjacent solar occultation measurements, where one limb path is loaded with aerosols but the other path is free of aerosols as discussed by the authors.
Abstract: Extinction coefficients for stratospheric aerosols at 8 HALOE (HALogen Occultation Experiment) wavelengths are determined by comparing transmittances data for two adjacent solar occultation measurements, where one limb path is loaded with aerosols but the other path is free of aerosols. These extinction coefficients are used to infer the aerosol properties such as composition and size distribution parameters. Mie theory has been used to calculate the extinction coefficients, and a nonlinear least square method is applied to determine the aerosol properties. Sixteen cases are selected for the retrieval in southern hemisphere at latitudes from 21 to 48 deg S for the period of 29 Mar - 31 May 1992. Retrieved size width ranges from 1.1 to 1.5 and radius ranges from 0.25 to 0.45 micrometers. These size parameters are within the ranges of in situ measurements at Laramie, Wyoming. Retrieved weight percent of H2SO4 is larger than the equilibrium value by about 5 to approximately 10 weight percent, similar to the results for northern hemisphere at latitudes 20 to 55 deg N for the period from Nov 1991 to Feb. 1992.