The meteorology of North Greenland during the midsummer period

Abstract

AbstractAn elevated ice sheet of the size of Greenland has a strong influence on its own weather. On account of the cooling by radiation of the snow surface and of the lower layers of the air there is a tendency for a system of low‐level outflowing katabatic winds to be set up. The weather is also influenced by the cyclonic systems characteristic of middle latitudes and their associated fronts.Northern Greenland is far from the main track of Atlantic depressions, and as the inland ice is here at its widest, conditions appear suitable for the establishment of the glacial anticyclone which would be expected to be disturbed only rarely by cyclonic systems. In order to study the frequency of these disturbances, and the normal meteorological conditions in the undisturbed periods, an investigation has been made of the weather in the area during the six midsummer weeks of 1953, in particular of the observations made at “Northice”“Northice” i not an accepted place name but in used in this paper for convenience. near the crest of the ridge of the inland ice and at Britannia Sø near the east coast.Owing to the elevation of the ice sheet mean sea‐level synoptic charts cannot be used satisfactorily, and a method of drawing 700 mb charts and using the same techniques as are used in temperate regions for analysis of mean sea‐level charts has been developed. As the weather is predominantly fine all occurrences of appreciable cloudiness, precipitation and abnormal surface wind are significant and in almost all cases were due to cyclonic disturbances and their associated fronts which could be followed on the series of 700 mb charts. A total of 16 depressions or waves caused 19 disturbances (in three cases the effects of the warm and cold fronts were clearly separated) at either one or both of the two stations, but only 5 of these caused precipitation exceeding 1·0 mm at either station.During the anticyclonic period of 11 days when the 700 mb wind was light and variable the weather at Northice was fine with a katabatic surface wind of 280° 13 kt. The diurnal range of temperature at Northice was 6·8°C but only 3·7°C at Britannia Sø. The diurnal variation of relative humidity was small. The upper winds at Northice were mainly S to W at low levels and S to E at 16 km.A comparison of June 1953 with June 1954, and with statistics for other Greenland stations in other years, indicates that the midsummer of 1953 can probably be regarded as representative of a normal midsummer.