Rocketsonde Temperature Variability at High-Latitude Canadian Stations

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  • 1 Atmospheric Environment Service, Toronto, Canada
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Abstract

Rocketsonde temperature measurements made with the Arcasonde-1A payload at Fort Churchill and Primrose Lake, Canada, have been corrected for the effects of aerodynamic heating, time lag, radio frequency heating, longwave radiation and, in particular, solar radiation. In spite of some inherent difficulties in adequately correcting for these factors, particularly at higher altitudes, reasonably good sets of corrected data were obtained and then analyzed for periodicities in the temperature wave. A series of measurements made at Fort Churchill in September 1966 spanning 72 hours at 4 h intervals, was used to investigate diurnal temperature variations. Diurnal temperature ranges were found to be 1.7 K, 3.0 K,, 3.3 K,, 6.3 K, 5.3 K, 9.3 K, 7.3 K and 8.6 K at 25, 30, 35, 40, 45, 50, 55 and 60 km respectively. The times of maximum temperature were found to be, with respect to local noon, 2 h before at 25 km, noon at 30 km, 2 h after at 35 km, 2 h after at 40 km, 3 h after at 45 km, 2–4 h after at 50–60 km. There was evidence of semi-diurnal variations at 25, 30, 35, 45 and 60 km.

Four years of data at Fort Churchill and two years at Primrose Lake were used to investigate annual and shorter-period variations. The maximum in the annual cycle occurred in June in the 25–55 km region at both stations and up to 63 km at Fort Churchill. The annual temperature ranges were of similar magnitudes at both stations, increasing from 10 K at 25 km to about 35 K at 45 km and decreasing thereafter to about 25 K at 55 km and about 20 K at 60 km (at Fort Churchill). There was some evidence of semi-annual variations at 25 km over the two stations with a subsidiary maximum in January in addition to the main one in June. The range of the semi-annual variation was about 5 K at that altitude.

Abstract

Rocketsonde temperature measurements made with the Arcasonde-1A payload at Fort Churchill and Primrose Lake, Canada, have been corrected for the effects of aerodynamic heating, time lag, radio frequency heating, longwave radiation and, in particular, solar radiation. In spite of some inherent difficulties in adequately correcting for these factors, particularly at higher altitudes, reasonably good sets of corrected data were obtained and then analyzed for periodicities in the temperature wave. A series of measurements made at Fort Churchill in September 1966 spanning 72 hours at 4 h intervals, was used to investigate diurnal temperature variations. Diurnal temperature ranges were found to be 1.7 K, 3.0 K,, 3.3 K,, 6.3 K, 5.3 K, 9.3 K, 7.3 K and 8.6 K at 25, 30, 35, 40, 45, 50, 55 and 60 km respectively. The times of maximum temperature were found to be, with respect to local noon, 2 h before at 25 km, noon at 30 km, 2 h after at 35 km, 2 h after at 40 km, 3 h after at 45 km, 2–4 h after at 50–60 km. There was evidence of semi-diurnal variations at 25, 30, 35, 45 and 60 km.

Four years of data at Fort Churchill and two years at Primrose Lake were used to investigate annual and shorter-period variations. The maximum in the annual cycle occurred in June in the 25–55 km region at both stations and up to 63 km at Fort Churchill. The annual temperature ranges were of similar magnitudes at both stations, increasing from 10 K at 25 km to about 35 K at 45 km and decreasing thereafter to about 25 K at 55 km and about 20 K at 60 km (at Fort Churchill). There was some evidence of semi-annual variations at 25 km over the two stations with a subsidiary maximum in January in addition to the main one in June. The range of the semi-annual variation was about 5 K at that altitude.

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