Atmospheric Ionisation In Regions of Low Cloud Formation At Various Time Scales.
Abstract
The recently reported correlation between Galactic Cosmic Rays (GCR) and low cloud properties raises the possibility of a new mechanism linking solar variability to cli- mate. However, GCR are negatively correlated with Total Solar Irradiance (TSI), and with the current lack of experimental evidence to confirm or otherwise the role of ion- isation in cloud processes, it is yet to be determined whether GCR or TSI provide a plausible explanation of the GCR-low cloud correlation. GCR flux arriving at earth is subject to Forbush decreases ( hours to a few days), and at longer time scales ( 1000's years) variability in the geomagnetic field, which are not present in TSI. If these features can be identified in low cloud properties and/or climate proxies, it would distinguish GCR from TSI as a possible mechanism to explain the GCR-low cloud correlation. Cosmic ray observations from different geomagnetic latitudes are used to estimate the response in atmospheric ionisation to forbush decreases and a varying geomagnetic field. Satellite observations of low cloud variability during for- bush decreases are investigated. Climatic influences from a varying geomagnetic field have previously been explored by comparing climate proxies with cosmogenic nu- clides. Here it will be shown that while a change in the geomagnetic field will have a strong effect on the production of cosmogenic nuclides, it has a significantly reduced effect on atmospheric ionisation in regions of low cloud formation.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.5951M