1. Meteorological and cloud measurements at the Princess Elisabeth Belgian Antarctic Research Station, Dronning Maud Land Irina Gorodetskaya 1, Nicole van Lipzig 1, Michiel van den Broeke 2, Wim Boot 2, Carleen Rejmeer 2, Alexander Mangold 3, Stefan Kneifel 4, Susanne Crewell 4 1 K.U.Leuven, Dept Earth and Environmental Sciences, Belgium; 2 IMAU, Utrecht, Netherlands; 3 Royal Meteorological Institute, Belgium; 4 IGM/Univ Cologne, Germany Abstract To understand the current and future evolution of the Antarctic ice sheet, and its contribution to sea-level changes, a good knowledge of the surface mass balance and each of its components is essential. The goal of our project (HydrAnt) is to study the atmospheric branch of the hydrological cycle in Antarctica using existing and new datasets from in-situ and remote sensing instruments in combination with regional atmospheric modeling. For this we establish a new database that can be used for an in-depth model evaluation of clouds, precipitation and surface radiative budget. The base for our measurements is the new Belgian Antarctic station Princess Elisabeth in Dronning Maud Land, East Antarctica inaugurated during the IPY. In February 2009, we installed an Automatic Weather Station and did two summer seasons of ground- based remote sensing of clouds and precipitation. Utsteinen site is characterized by relatively mild climate with the lowest hourly near-surface air temperature at -38 0 C and the strongest wind speed at 30 m/s (observations during 2009). The site is well protected from the shallow katabatic wind by the mountain massive and the strongest winds are for most cases associated with cyclone passage near the coast. Mid-level clouds are frequently observed at the site. Storms are preceded by lowering cloud base heights to 500-1000m above the surface and a strong increase in cloud base temperatures (by up to 20 0 C). Most of accumulation at the site occurs during episodic strong snowfall during cyclonic events. A combination of measurements from AWS, ceilometer, IR pyrometer and K-band radar will be used for validating RACMO/ANT model representation of meteorology, accumulation, cloud base heights and temperature, cloud radiative forcing, and distinguishing between snow fall and drifting snow. Fig. 4: The Automatic Weather Station installed Feb 2009, 300 m east from Utsteinen Ridge Fig. 1: Mean winter (JJA) near-surface wind vector (RACMO regional model, 1980-1993) over elevation contour lines (in red). van Lipzig et al. 2004. First Results: Kneifel, S., U. Lohnert, A. Battaglia, S. Crewell, D. Siebler: Snow scattering signals in ground-based passive microwave measurements, J. Geophys. Res., 2010, accepted. Pattyn, F., K. Matsuoka, J. Berte (2010) Glacio-meteorological conditions in the vicinity of the Belgian Princess Elisabeth Station, Antarctica. Antarctic Science 22 (1), 79-85, doi:10.1017/S0954102009990344. Van Lipzig N. P. M., 2004: The near surface wind field over the Antarctic continent. Int. J. Climatol., 24, 1973-1982. 1.Automatic weather station: temp, humidity, pressure, wind, up/down broadband SW and LW fluxes, snow height meter, snow temperature profile. 2. Measurements of snow accumulation and snow density in the AWS vicinity 3. Cloud and precipitation instruments: Ceilometer (Vaisala): pulsed diode laser in near-IR (910 nm) measures vertical backscatter profile and cloud base height up to 7.5km low liquid-containing clouds completely attenuate the lidar beam Infrared Radiation pyrometer (Heitronics): Passive radiometer, measures equivalent blackbody brightness temperature in the 8-13 micron atmospheric window spectrum K-band Radar (METEK’s Mirco-Rain Radar): 24GHz FM-CW Doppler radar: reflectivity profile up to 3500m height with 100m range resolution. Hydrometeor detection (falling and drifting snow) based on frequency shift between the received echo and the transmit signal. Fig. 5: Cloud and precipitation remote sensing instruments, installed Jan 2010 on the roof of the PE base Belgian Antarctic station Princess Elisabeth is built on the Utsteinen Ridge in Sor Rondane Mountains, Dronning Maud Land, East Antarctica (71 0 57’S and 23 0 20’, ~1400m asl, 180 km inland). On a large-scale, Utsteinen is located in the high slope region of the Antarctic escarpment, where the katabatic wind forcing is high (Fig. 1) But locally, the site is well protected from katabatic winds by the mountain range (Fig. 2) The site is nearby the high cyclonic density area in the Atlantic Ocean sector x Ceilometer Infrared Radiation Pyrometer K-band Radar Fig. 6 Near-surface air temperature all wind speeds m/s Fig. 7 Near-surface wind speed and direction AWS measurements in 2009: Fig. 8 Snow accumulation at AWS site Utsteinen site is characterized by relatively mild climate with mean annual temperature -19 0 C, the lowest hourly near-surface air temperature -38 0 C and the strongest wind speed 30 m/s. Temperature variability on synoptic time scale (3-7 days) with amplitudes up to 20 0 C Wind above 5 m/s is restricted to the 90-180 0 sector with above average wind speeds mostly easterly The strongest winds are for most cases (80% out of cases with wind speeds > 20 m/s) associated with warm advection and a deep cyclone passage in the 0-30 0 E sector near the coast Several high accumulation events during 2009 (storms with high precipitation? - will see from the radar) = 24 cm we Clouds and precipitation during storm Feb 6-7, 2010: data gap Height, m Fig. 10 Synoptic chart for Feb 7 (ECMWF model,provided by Neumayer station) Fig. 12 Radar reflectivity 1’ sodagram during Feb 7 Acknowledgements: Fig. 2: Utsteinen site satellite image Utsteinen Katabatic winds AWS x S N WE Fig. 11 Cloud base height (blue/green/black crosses) and cloud base temperature (red dots) during Feb 6-7, 2010 Feb 6Feb 7 Contact: Irina.Gorodetskaya@ees.kuleuven.be; tel: +32 16 32 64 53 Ground-based measurements 2009-2010: Site overview: References: Fig. 9 Photo during Feb 7: PE station in 200m On February 6, a wide gale of 961hPa was located at 62S, 13E, moving southwest until it reached 67S, 9E on February 7, then weakening (Fig. 10) Mid level and low clouds observed both days (Fig. 11) Cloud base temperature highly sensitive to cloud base height Feb 7: cloud bases lowered from 2.5-4km in the morning to about 1km in the early afternoon, then at 300-500m; ceilometer reported vertical visibility instead of cloud base throughout the day (precipitation! - see radar below) On February 7, the radar detected snowfall starting from about 7am local time until late evening. The depth of precipitating layer was from the surface up to 1 to 2.5km high indicating continuous presence of midlevel clouds throughout the storm (not detected by ceilometer). The first results show high potential of the set of instruments deployed at the Utsteinen site (AWS, ceilometer, IR pyrometer and K-band radar) for understanding local meteorological conditions and cloud properties, synoptic-scale dependence of accumulation, and distinguishing the snowfall from drifting snow events. The collected data together with other existing and newly emerging data (both ground-based and satellite) will be used to evaluate and improve the regional atmospheric climate model RACMO/ANT2 after which an updated reconstruction of the climate of Antarctica will be done. Conclusions and outlook: We thank Belgian Science Policy for funding the project and IPF for providing the base for our monitoring measurements. Many thanks to people working at the Antarctic base the past two summer seasons: engineers, field guides, cooks... everyone!