TEMPERATURA GRUNTU W CALYPSOBYEN (ZACHODNI SPITSBERGEN) W SEZONIE LETNIM 1994 ROKU

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1 Anna BI LIK Department of Meteorology and Climatology Institute of Earth Sciences Maria Curie-Skłodowska University Akademicka Lublin, POLAND Wyprawy Geograficzne па Spitsbergen IV Zjazd Geomorfologów Polskich UMCS, Lublin 3-6 czerwca 1998 y^t GROUND TEMPERATURE IN CALYPSOBYEN (WESTERN SPITSBERGEN) IN THE SUMMER OF 1994 TEMPERATURA GRUNTU W CALYPSOBYEN (ZACHODNI SPITSBERGEN) W SEZONIE LETNIM 1994 ROKU The paper uses the data obtained during IX Geographical Expedition of Maria Curie-Sklodowska University to Spitsbergen in Measurements, among others, of ground temperature1 (continuation of the studies began in 1986) were made in two localities in Calypsobyen (Fig. 1): Locality 1 - base station localized on the flat marine terrace poorly covered with vegetation (mosses, lichen, saxifrage); Locality 2 - sandy beach at the bottom of the cliff without vegatation. Day and night ground measurements in Calypsobyen were made from 9 July to 20 August 1994 by means of soil elbowed thermometers (depth 5-50 cm) and extension soil thermometers (depth cm). In locality 1 the ground temperature was measured at depths: 5, 10, 50, 100, 150 cm and in locality 2 at depths: 50, 100, 150 and 200 cm. The ground temperature course was analyzed on the basis of the data from four observational times: 00, 06, 12, 18 GMT. From them the mean values of ground temperature at each depth were calculated (Tab. 1). As follows from the data, a decrease of ground temperature with the depth was observed in both localities. The average ground temperature in locality 1 at the depth of 5 cm was higher by 6 C than at the depth of 150 cm. The highest values of ground temperature, exceeding 8 C, were observed in the layer of up to 10 cm. Above the depth of 150 cm the lowest ground temperature did not reach a positive value. During the whole measurement period the lowest value ( C) was recorded at the depth of 200 cm in locality 2. At every level there were distinct differences between the highest and lowest values of ground temperature but these differences decreased with the depth. 1 General weather condition are presented in the paper "Weather course in Calypsobyen (West Spitsbergen) in July and August

2 Tab. 1. Occurrence of the ground temperatures in Calypsobyen ( ) Station Depth (cm) 1 Temperature ( C) mean highest lowest differences The ground temperature course in locality 1 (Fig. 2) at the depths of 5 and 10 cm in the whole measurement period reflects the weather conditions, particularly the air temperature (Fig. 3). The influence of weather conditions on ground temperature diminishes with the increase in depth. Moreover, a shift of changes in time with depth can be observed. It is interesting to trace the ground temperature course and its distribution from 7 to 14 August. At that time very cool masses of air appeared causing a sudden decrease of air temperature (from 5.1 C - 7 August to 0.2 C - 11 August). This cool caused a sudden drop of ground temperature in the whole profile. At the same time it caused an equalization of ground temperature in the layer of up to 100 cm. After a period of significant cool the ground temperature increased but did not reach such values as at the end of July. The ground temperature course at the depth of 150 cm shows a slow increase trend in the whole measurement period. The above -mentioned four day cool did not disturb the temperature distribution at this depth. In locality 2 (Fig. 4) the ground temperature is characterized by a similar course to that in locality 1. However, the significant cool did not cause as large a drop in the ground temperature at the depth of 50 cm as in locality 1. A comparison of the ground temperature course in both localities is interesting (Fig. 5). During the whole measurement period at all depths (50, 100 and 150 cm), the ground temperature in locality 2 was always higher than in locality 1. Until 25 July, at the depth of 50 cm, the mean day and night temperature differences in both localities did not exceed 1 C. These differences increased evidently during the significant increase or decrease of air temperature. It follows from the comparison that the sandy ground (locality 2) gets warm faster and loses heat more slowly than the dry tundra (locality 1) with the Arctic brown soil. At the depth of 100 cm the temperature differences in both localities were smaller than at the depth of 50 cm. A large drop in air temperature during 18

3 9-13 August caused an equalization of ground temperature in localities 1 and 2. From 10 August to the end of the period studied the differences in ground temperature in these localities did not exceed 0.5 C. At the depth of 150 cm the differences in ground temperature between locality 1 and locality 2 were only from -0.4 C to - 0. Г С. Thus small changes of ground temperature were observed at this depth in both localities. Quick changes of weather conditions (increase or decrease in air temperature) did not affect the ground temperature course at the depth of 150 cm independently of the bedrock. The analysis of the distribution thermoisopleths of (Fig. 6) shows that the ground layer close to the surface is subject to significant influence of air temperature changes, much greater than the layer situated more deeply. Quite a regular distribution of thermoisopleths is observed in the layer close to the surface (up to 50 cm) till 8 August and in the lower layers till 9 and 10 August. Then a distinct disorder in the thermoisopleth course is observed which is indicated by a vertical arrangement of the isopleths caused by the above-mentioned few days of cool. This disorder was clearly seen in the layer up to 130 cm. In the averaged day and night ground temperature course in locality 1 (Fig. 7) at a depth of 5 and 10 cm the ground temperature increase was observed from 06 to 18 hours GMT and a ground temperature decrease from 18 to 06 GMT. The changes of ground temperature were observed from 06 to 18 GMT (increase) and from 10 to 06 GMT (decrease). The earlier papers on the expeditions to Spitsbergen (Repelewska-Pękalowa et al. 1987, Gluza, Repelewska-Pękalowa 1988, Gluza 1990) reported that the day and night ground temperature in the same locality differed from that in Then the lowest mean values of ground temperature during the day and night were recorded at 00 GMT but not at 06 GMT as in Also the highest mean values of ground temperature were at a different time, mainly at 12 GMT. The ground temperature course as observed in 1994, i.e. with the ground lowest temperature at 06 GMT and highest at 18 GMT, is characteristic of the locality with wet soil or movable water in the covers (Repelewska-Pękalowa et al. 1987, 1988, Gluza 1990). It should be emphasized that the 1994 summer on Spitsbergen was very wet due to frequent and intense precipitation mm (Bilik 1994). Therefore the tundra area was soaked with water during the whole measurement period and covered with a thin snow layer for a few days. Tundra lost heat during evaporation and as a result the period of ground heating was longer (by 6 hours). Therefore the highest values of ground temperature are shifted from 12 GMT to 18 GMT. However, the ground temperature changes were not observed deeper than 50 cm.

4 REFERENCES BILIK A., 1994: Weather course in Calypsobyen (West Spitsbergen) in July and August Wyprawy Geograficzne na Spitsbergen, UMCS Lublin, GLUZA A. F., 1990: Distribution of the ground temperatures in July, August and September 1988 on Calypsostranda (Southern Bellsund - Western Spitsbergen). Wyprawy Geograficzne na Spitsbergen, UMCS Lublin, GLUZA A. F., REPELEWSKA-PĘKALOWA J., 1988: Temperatura gruntu na równinie Calypsostrandy (rejon Bellsundu, Zachodni Spitsbergen). Wyprawy Geograficzne na Spitsbergen, UMCS Lublin, REPELEWSKA-PĘKALOWA J., GLUZA A. F.: 1988: Dynamika czynnej warstwy zmarzliny w rejonie południowego obrzeżenia Bellsundu (Zachodni Spitsbergen), Wyprawy Geograficzne na Spitsbergen. UMCS Lublin, REPELEWSKA-PĘKALOWA J., GLUZA A. F., DĄBROWSKI K., 1987: Termika tundry i dynamika czynnej warstwy zmarzliny na przedpolu lodowców Scotta i Renarda (rejon Bellsundu, Zachodni Spitsbergen). XIV Sympozjum Polarne, Lublin, REPELEWSKA-PĘKALOWA J., GLUZA A. F., PĘKALA K., 1988: Wpływ lokalnych czynników na miąższość i termikę czynnej warstwy zmarzliny na Calypsostrandzie (rejon Bellsundu, Zachodni Spitsbergen). XV Sympozjum Polarne, Wrocław, STRESZCZENIE Pomiary temperatury gruntu w Calypsobyen prowadzono od 9 lipca do 20 sierpnia 1994 roku na dwóch stanowiskach (rye. 1) na głębokościach od 5 do 200 cm. Do analizy przebiegu temperatury gruntu wykorzystano dane z czterech terminów obserwacyjnych: 00, 06, 12, 18 GMT. Na ich podstawie obliczono średnie wartości temperatury na poszczególnych głębokościach (tab. 1). W ciągu całego okresu pomiarowego widoczny był spadek temperatury gruntu wraz z głębokością. Na każdym poziomie występowały wyraźne różnice między najwyższymi a najniższymi wartościami temperatury gruntu. Różnice te zmniejszały się wraz z głębokością. Przebieg temperatury gruntu (ryc. 2 i 4) nawiązuje d o przebiegu warunków pogodowych. Wpływ ten wyraźnie maleje w miarę wzrostu głębokości. Ponadto zaznacza się przesunięcie zmian w czasie wraz z głębokością. Z porównania przebiegów temperatury gruntu (ryc. 5) wynika, że w ciągu całego okresu pomiarowego, na wszystkich głębokościach (50, 100,150 cm) temperatura gruntu na stanowisku nr 1 (tundra z glebą brunatną arktyczną) jest zawsze niższa niż na stanowisku nr 2 (grunt piaszczysty). Analiza rozkładu termoizoplet (ryc. 6) wykazuje, że warstwa gruntu leżąca blisko powierzchni podlega silnym wpływom zmian temperatury powietrza, wyraźnie większym niż warstwa leżąca głębiej. W uśrednionym przebiegu dobowym temperatury gruntu na stanowisku nr 1 (ryc. 7), na głębokości 5 i 10 cm, najniższą temperaturę gruntu obserwowano o godz. 6 GMT a najwyższą o godz. 18 GMT. Taki przebieg temperatury gruntu w ciągu doby jest charakterystyczny dla stanowiska z gruntem podmokłym lub wodą ruchomą w pokrywach. 20

5 SVALBARD / [7~ U 5 Ж Fig. 1. Localization (A) and geomorphological scheme of study area (B) (after Repelewska-Pękalowa & Gluza, 1988): 1 -marine terraces, 2-patterned grounds zone, 3 - glacis, 4 - beach, 5 - storm ridge, 6 - dead cliff, 7 - erosive forms, 8 - measurement points Rye. 1. Położenie (A) i szkic geomorfologiczny badanego obszaru (В) (wg Repelewskiej-Pękalowej i Gluzy,1988): 1- terasy morskie, 2 - strefa gruntów strukturalnych, 3 - glacis, 4 - plaża, 5 - wał burzowy, 6 - martwy kliff, 7 - formy erozyjne, 8 - stanowiska pomiarowe 21

6 Fig. 2. Course of ground temperature in Calypsobyen ( ) in locality 1 Ryc. 2. Przebieg temperatury gruntu w Calypsobyen ( ) na stanowisku 1 Fig. 3. Course of mean day and night air temperature at the height of 200 cm in Calypsobyen in locality 1 Ryc. 3. Przebieg średniej dobowej temperatury powietrza na wysokości 200 cm w Calypsobyen na stanowisku 1 Fig. 4 Course of ground temperature in Calypsobyen in locality 2 Ryc. 4. Przebieg temperatury gruntu w Calypsobyen na stanowisku 2 22

7 ' l ! i i i I i i i i ' I i i i i i i i i i i i i i i i S Fig. 5 Comparison of ground temperature courses in localities 1 and 2 Rye. 5. Porównanie przebiegów temperatury gruntu w Calypsobyen na stanowisku 1 i 2 cm depth depth cm Fig. 6 Distribution of thermoisopleths in Calypsobyen in locality 1 Rye. 6. Rozkład termoizoplet w Calypsobyen na stanowisku 1 Fig. 7 Averaged day and night ground temperature course in locality 1 Rye. 7. Uśredniony przebieg dobowy temperatury gruntu w Calypsobyen na stanowisku 1