Some remarks on the stratospheric temperature for Fairbanks, Alaska, after the El Chichón Eruption

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Abstract
The first substantial radiative effects of the El Chichón volcanic cloud were observed in Fairbanks in the winter of 1982/83. Winter is the time when stratospheric temperatures can vary widely owing to sudden stratospheric warmings, and interannual variations are large. Mean monthly temperatures of the stratosphere were analysed for the 50‐, 40‐, 30‐, 25‐, 20‐, 15‐, and 10‐mb levels, with the greatest density of the volcanic cloud expected to be around the 20‐mb level. For the four winter months, December 1982 to March 1983, an increase in temperature was observed. This increase was not only observed in Fairbanks, but also for two other stations (McGrath and Anchorage) close by, for which we also analysed the stratospheric temperatures. Further, the interdiurnal variation of temperature (the radiosonde ascents are made at 0200 and 1400 local time) showed marked and significant increases for all three stations. This can be explained by the fact that during daytime the volcanic cloud is warmed by absorption of solar radiation, while at night no substantial temperature effect for this layer was detected.