Temperature dynamics in crevasse-drainage systems of Antarctic glaciers

During the 33rd Bulgarian Antarctic Expedition, field studies were conducted to examine the internal microclimate of crevasse-drainage systems of the three glaciers: Balkan Ice Field, Johnsons and Contell Glaciers. The research is focusing on the relationship between fluctuations of surface meteorology parameters, internal air glacier temperatures in the crevasses and possible connection with solar activity. The total duration of the study exceeds 60 days, making it the longest temperature monitoring of glacier crevasses in Antarctica. Measurements of air temperature, humidity, and atmospheric pressure were carried out using autonomous sensors, while ultrasonic anemometers recorded airflow direction and speed inside the crevasses. Sensors were placed at depths of up to 25 m in central zones and 10 m near the glacier edges. The study identified a distinct temperature gradient at 3-meter intervals and mapped the depth of zones with persistently negative temperatures. Increased solar activity was associated with lower internal glacier temperatures and stronger air circulation. A negative correlation was found between solar activity and both temperature and downward airflow within crevasses. A glacial cave under the Balkan Ice Field allowed access to subglacial waters and sediment sampling. For the period of one year, the ablation zone of the Balkan Ice Field had expanded, and the constant negative temperature zone had deepened by 6–7 m since the previous expedition. Contell Glacier showed greater thermal stability and resistance to change compared to the larger ice fields. The extended daylight in January (approximately 20 hours) facilitated reliable correlation with solar activity patterns.