The Radiation Balance of Snow-Free Surfaces at Poste-de-la-Baleine, Québec, May 30 – June 1, 1970

Abstract

On a mesuré le rayonnement solaire global et le bilan du rayonnement pour des surfaces très variées à Poste-de-la-Baleine, au Québec, du 30 mai au 1er juin 1970, pendant des périodes cycloniques et anticycloniques alternantes. À l'exception d'une surface d'eau libre dans le sud-est de la Baie de James et près des îles Belcher, la glace recouvrait la Baie d'Hudson. Les flux provenant de l'ouest et du sud-ouest s'accompagnaient de temps frais, humide et nuageux. On a trouvé une bonne corrélation linéaire entre le bilan du rayonnement et le rayonnement global, pour toutes les surfaces et pour les temps nuageux, depuis le brouillard jusqu'aux cirrus. Les résultats indiquent que, malgré la réduction du rayonnement solaire par les nuages, environ 72% de l'énergie était disponible en surface pour les processus biologiques et physiques. Il faut noter l'importance du flux de chaleur sensible et l'advection de l'air froid provenant de la Baie.Total insolation and net radiation were measured for a wide variety of surfaces at Poste-de-la-Baleine, Québec, from May 30 to June 1, 1970, during alternating cyclonic and anticyclonic situations. With the exception of open water in southeastem James Bay and in the vicinity of the Belcher Islands, the ice cover was complete over Hudson Bayand westerly and southwesterly flow were associated with cool, wet, cloudy weather. For cloudy conditions, including fog and cirrus, and damp surfaces, a close linear relationship was found to exist between net radiation and total insolation for all surfaces. The results indicated that although the insolation was much reduced by cloud cover, about 72% of the energy was available at the surface for physical and biological processes. The importance of the sensible heat flux is noted, and of the cold advection from the Bay

Radiant Energy During Clear Weather in the Growing Season at Poste-de-la-Baleine (Great Whale), Nouveau-Québec

“…This shows clearly in the extrême dates and length of the frost-free period and in the standard déviation of the monthly température (Tables 5 and 6). The influence of wind direction can data 1941-1970. G. M. Hemmerick and G. R. Kendall, 1972 * Season divided arbitrarily at July 15.…”

“…The overall greyness of the scène is matched by the minimal spatial contrast in the amount of daytime radiant energy (net ail wave radiation) available from one kind of surface to another (cf. Wilson and MacFarlane, 1971). Although the daytime ratio of net radiation to incoming solar radiation is high for ail surfaces below the cloud blanket, the total solar energy (diffuse radiation) received at the ground is small, while long-wave atmospheric radiation assumes a greater importance.…”