Manuscrit reçu le 15 février 1980; revisé le 20 août 1980] RÉSUMÉ Le régime journalier du rayonnement solaire global au sol a été reconstitué aux six stations du réseau radiométrique de base canadien situées au Québec à l'aide d'un modèle numérique simulant le transfert de l'énergie solaire à travers l'atmosphère. Les données d'humidité atmosphérique, de trouble atmosphérique et d'albédo au sol ont été interpolées dans le temps et l'espace à partir de la climatologie mensuelle connue de ces champs. La nébulosité a été tirée des séquences horaires des durées d'ensoleillement observées à ces mêmes stations et échelonnées sur une même période de 974 jours. On a estimé les limites de précision du modèle en déterminant l'erreur quadratique moyenne entre la valeur calculée et mesurée pour 1, 2,3,... et 20 jours consécutifs. On a ainsi trouvé que l'erreur quadratique moyenne diminue rapidement pour les regroupements de 1 à 10 jours et se stabilise pour les périodes plus longues. L'amplitude de l'erreur quadratique moyenne varie saisonnièrement et latitudinalement étant en général plus faible en été et au sud. La variabilité des valeurs journalières simulées n'est que légèrement supérieure à celle des données journalières mesurées. Il est démontré finalement que l'utilisation journalière des résultats du modèle est préférable à l'utilisation de la climatologie du régime solaire.ABSTRACT The daily regime of the global solar radiation at the ground has been calculated at the six stations of the Canadian radiation network situated in Quebec with a numerical model simulating the solar energy transfer through the atmosphere. Humidity, background pollution and ground surface albedo data were interpolated in time and space from the known monthly climatology : Cloud data were inferred from hourly sunshine measurements at the stations over the same time period of 974 days. The model's accuracy limits were estimated in determining the root-mean-square error between the calculated and the measured values for 1,2,3, ... and 20 consecutive days. It was found that the root-mean-square error decreased rapidly for groupings of I to 10 days and stabilized for longer periods. The amplitude of the root-mean-square error varies seasonally and latitudinally being in general smaller in summer and in the south. The variability of the daily simulated values is slightly larger than the variability of the daily measured data. Further, it is shown that daily model results are superior to daily climatological statistics of the solar regime.A TMOSPHERE-OCEAN18 (4) 1980, 286-303 0705-5900/80/0000-0286S01.25/0 Simulation de l'énergie solaire au sol / 287 1 Introduction La crise actuelle du pétrole a frappé de plein fouet le monde industrialisé dont l'activité économique est irrémédiablement rattachée aux aléas de la disponibilité de l'or noir. Devant cette conjoncture, les pays industrialisés se doivent d'analyser froidement tant les avantages que les inconvénients, tant les possibilités que les limitations des potentiels énergétiques autres qui pourr...

A method of computing the stratospheric heating rates from available daily data of the Northern Hemisphere is given. It consists of a hybrid approach using both the simple parametric equations in the solar ultraviolet absorption and the radiative transfer equations in the long-wave spectrum (15-micron carbon dioxide and 9.6-micron ozone absorptions). This method has been applied in the stratosphere for the period Jan. 12 to 16, 1959, in order to compute the generation of available potential energy. The results indicate that the method, as well as being suitable for energy budget studies over longer periods of time, is sufficiently accurate to enable one to describe synoptically some of the aspects of the radiative exchange between troposphere and stratosphere. 359 360 MONTHLY WEATHER REVIEW Vol. 97, No. 5 near the Equator and lower concentration in the Arctic a t these levels (Hering et al., 1967).

The energetics of the 500-, loo-, and 25-mb levels are computed on a daily and monthly basis during January 1959. On the average, during the month, zonal wave numbers 1 and 2 were dominant in the eddy kinetic and eddy available potential energy spectra a t 25 and 100 mb; while at 500 mb, the emphasis was shifted to wave numbers 2 and 3. The dominance of the planetary scale over the synoptic scale a t 500 mb was a manifestation of the persistence of a blocking circulation found during the month. The planetary scale tropospheric block had a direct influence on the stratospheric kinetic energy by initiating upward progression of planetary wave energy that in turn was partially absorbed by the stratospheric layers. A 10-to 12-day fluctuation in the blocking circulation was found to be followed by a pulsation of similar frequency in the eddy kinetic energy at 25 mb. Of the three pulses in the block, the second one had the largest amplitude and was followed by a stratospheric warming a t 25 mb. The contour pattern at 25 mb during the warming phase was eccentric in character; whereas the other two eddy kinetic energy pulses, before and later, were characteristically of a bipolar nature. At 25 mb, in situ large-scale baroclinic processes contributed significantly to the occurrence and maintenance of the spectral energy maxima. At the same level, a nonnegligible influence of the large-scale kinetic energy mode was provided by the nonlinear wave energy transfers.

This paper studies the urban heat island in Quebec City and its suburbs on one summer night. The region under study covers an area of 20 km by 20 km which streches from lake Saint-Charles on the north to Levis on the south and from the western suburb of Cap-Rouge to Beauport on the east. The total population of the region is about 400 000.On August 22, 1979 from 22 : 00 to 23 : 30 EDT, 109 measurements of wet-and dry-bulb temperatures were taken at preselected points. On that day, a large high pressure system gave clear skies to central Quebec while Quebec City Airport recorded a maximum temperature of 23 "C. The average wind measured at Duberger meteorological tower between 6 and 121 m above ground was 1.8 m SC' at 22: CO EDT and 0.9 m s-i at 23:30 EDT. Additional data were obtained from three thermographs installed at strategic points and five regular climatological stations, which were used to estimate cooling rates.During the period of measurement, the cooling rate averaged over the eight reference points Was about 0.7 'C h-'. However, the maximum cooling rate, which occured earlier, ranged from 2.2 'C h-i at Duberger to 4.4 'C h-' at Courville-de-Poissy.No relation seems to exist, in our case, between the maximum cooling rate and the heat island spatial structure. Comparison of these results with the ones given by Oke et al. (1972) shows that the eight stations behaved more like rural stations than urban ones.The temperature gradient measured between the center of old Quebec City and the suburbs averaged 6 -C while it was 9 'C for the coldest spot. Clo units were used to characterize the microclimates prevailing on the region for that night; 1 clo would be sufficient for comfort downtown while 1.5 clo is needed in the coldest spot for a slowly walking person. Large open areas like parks or the Lava1 University campus had a definite effect on temperature.The humidity was calculated for each point using standard psychrometric tables; no significant difference could be found over the area expect at points near or above the St. Laurent river where the average dew point was 1.5 "C higher.Each point was classilied into 6 categories according to its predominant land-use as reported by the observers. A multiple regression between temperature on the one hand and altitude and land-use on the other hand was tried; it showed that temperature was significantly correlated with both. Such an equation could be used by town-planners to locate temperature gradients in future urban development over the area; land uses could be planned to enhance or reduce these gradients.This study confirms the idea that urban climate is a mosaic of interacting micro-climates. More measurements, including possibly airborne infra-red thermal imagery, will bc taken during winter in order to assess the winter urban climate of Quebec City.

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