TRANSPORT SIMULATION OF PASSIVE TRACERS FROM THE NORTHERN HEMISPHERE TO THE SOUTHERN HEMISPHERE

• Main Authors: ヤマザキ コウジ, チバ マサル, Koji YAMAZAKI, Masaru CHIBA
• Format: Report
• Language: English
• Published: Meteorological Research Institute 1992
• Subjects: Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3694; http://id.nii.ac.jp/1291/00003694/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3694&item_no=1&attribute_id=18&file_no=1

In order to study the transport process of anthropogenic gases such as CO_2 and halocarbons, transport simulations are performed for passive tracers emitted from "Japan", "Europe", "North America" and "Amazon" regions. Three-dimensional wind data simulated by the Meteorological Research Institute Global Spectral Model with rhomboidal 24 truncation and 23 levels (MRI-GSPM-R24L23) are used. At each source grid point, one unit of tracer is emitted per day into the lowest model layer throughout the experiment. The starting time is December 1 and the calculation continues until mid-October of the next year. It is found that equatorward transport from the NH source regions takes place mainly around the Siberian High and Mexican High in winter. Large gradients (tracer front) formed near the equator at low levels in all the NH cases. In the SH, tracer density increases with height in the troposphere in all cases. The above features are related to the inter-hemispheric transport. From the NH, tracers spread into the equator through the lower layer, move upward over the equator and are transported through the upper troposphere into the SH. The above results imply that transport is accounted for the observed latitudinal and vertical distribution of CO_2 and halocarbons, in addition to source sink effect. Upward bulges are found in the tropical lower stratosphere and the large vertical gradients in the lower stratosphere of the extratropics, indicating that transport from the troposphere to the stratosphere takes place through the tropical tropopause. In all the NH cases, in particular during the summer of case "Japan", a secondary tracer front is formed at about 40°N.