This thesis exploits two water vapour products from the Microwave Limb Sounder (MLS), an instrument on the Upper Atmosphere Research Satellite, to investigate the spatial distribution and temporal variation of water vapour in the tropical region of the upper troposphere and lower stratosphere. Measurements are centred on 215 hPa in the upper troposphere and at 68 hPa and 100 hPa in the lower stratosphere. MLS provides almost global measurements with good vertical resolution, and offers many advantages over other measurement techniques. Focusing on the tropical region, time-series analysis techniques have been employed to investigate the variability of upper tropospheric water vapour on different timescales. The construction of longitude-time sections has allowed the annual cycle to be investigated in more detail than previously. The amplitude is found to vary greatly with longitude and to be most pronounced over the land-masses of South America and Africa. The oceans are found to have a moderating effect on the annual cycle but secondary maxima occur in regions influenced by the Asian monsoon, and over Indonesia and the central Pacific. An intraseasonal cycle with a period of 30-85 days is evident over the western Pacific at latitudes from 10°N to 20°S. This is associated with eastward moving moist features apparent in longitude-time sections. Through comparison with meteorological fields from the European Centre for Medium Range Weather Fore-casting's re-analysis project, the intraseasonal cycle in water vapour is identified with the convective anomalies associated with the Madden-Julian Oscillation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:643222 |
| Date | January 1999 |
| Creators | Clark, Hannah |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13410 |
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