Bromine partitioning in the tropical tropopause layer: implications for stratospheric injection

• Autores: Fernandez, Rafael Pedro; Salawitch, R. J.; Kinnison, D. E.; Lamarque, J. F.; Saiz-lopez, Alfonso
• Año de publicación: 2014
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Bromine Chemistry; Very-Short Lived species; Tropical Rings of Atomic Halogens; Tropospheric and Stratosphreic Ozone; Halocarbons
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Very short-lived (VSL) bromocarbons are produced at a prodigious rate by ocean biology and these source compounds (SGVSL), together with their inorganic degradation products (PGVSL), are lofted by vigorous convection to the tropical tropopause layer (TTL). Using a state-of-the-art photochemical mechanism within a global model, we calculate annual average stratospheric injection of total bromine due to VSL sources to be 5 pptv (parts per trillion by volume), with ~ 3 pptv entering the stratosphere as PGVSL and ~ 2 pptv as SGVSL. The geographic distribution and partitioning of VSL bromine within the TTL, and its consequent stratospheric injection, is highly dependent on the oceanic flux, the strength of convection and the occurrence of heterogeneous recycling reactions. Our calculations indicate atomic Br should be the dominant inorganic species in large regions of the TTL during daytime, due to the low ozone and cold conditions of this region. We propose the existence of a "tropical ring of atomic bromine" located approximately between 15 and 19 km and between 30° N and 30° S. Daytime Br / BrO ratios of up to ~ 4 are predicted within this inhomogeneous ring in regions of highly convective transport, such as the tropical Western Pacific. Therefore, we suggest that experimental programs designed to quantify the bromine budget of the TTL and the stratospheric injection of VSL biogenic bromocarbons should include a strategy for the measurement of atomic Br during daytime as well as HOBr and BrCl during nighttime.
Fil: Fernandez, Rafael Pedro. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina
Fil: Salawitch, R. J.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados Unidos
Fil: Kinnison, D. E.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados Unidos
Fil: Lamarque, J. F.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados Unidos
Fil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; España