Naohiko Hirasawa

Abrupt changes in meteorological conditions observed at an inland Antarctic Station in association with wintertime blocking

Time evolution of a prominent wintertime blocking event over East Antarctica and the associated drastic changes in weather conditions observed at an inland station are documented. A strong blocking ridge was formed at the leading edge of a quasi-stationary Rossby wavetrain where a wave activity flux emanating from the subtropics was convergent. The ridge pumped up heat and moisture from lower latitudes into inland Antarctica with a strong poleward flow along its upstream flank. The station was situated under this flow just for two days, during which the normal condition with cold and clear weather was markedly disturbed. The flow climbing up the continental slope led to cloud formation above the inland station. Enhanced downward longwave radiation from the clouds and enhanced vertical mixing associated with the record-setting wind speeds resulted in a sudden, drastic increase in surface air temperature and the breakdown of the developed surface inversion layer.

Influence of large-scale atmospheric circulation on marine air intrusion toward the East Antarctic coast

Marine air intrusions into Antarctica play a key role in high-precipitation events. Here we use shipboard observations of water vapor isotopologues between Australia and Syowa on the East Antarctic coast to elucidate the mechanism by which large-scale circulation influences marine air intrusions. The temporal isotopic variations at Syowa reflect the meridional movement of a marine air front. They are also associated with atmospheric circulation anomalies that enhance the southward movement of cyclones over the Southern Ocean. The relationship between large-scale circulation and the movement of the front is explained by northerly winds which, in association with cyclones, move toward the Antarctic coast and push marine air with isotopically enriched moisture into the inland covered by glacial air with depleted isotopic values. Future changes in large-scale circulation may have a significant impact on the frequency and intensity of marine air intrusion into Antarctica.

Development and Operational Experiences of UAVs for Scientific Research in Antarctica

Several models of UAVs have been developed for scientific missions such as aerial geomagnetic survey, meteorological observation, and ground observation instead of manned airplanes especially in Antarctica. The UAV fleet is divided into three groups, i.e., a small UAV for low altitude, relatively large UAVs for mid-altitude, and a small glider UAV for high altitude. Several results, operational experiences of the UAVs, lessons learned including the operations in Antarctica, and several problems to be solved are reported in this chapter.