Snowdrift climate of Greenland and Antarctica

1. Snowdrift climate of Greenland and Antarctica Jan Lenaerts Michiel van den Broeke Institute for Marine and Atmospheric Research, Utrecht University, Netherlands

2. Goals SMB = PR - RU - SUs - SUds- ERds surface mass balance Snowdrift sublimation Snowdrift erosion introduction Regional climate model (RACMO2) + Snowdrift routine AGU FALL MEETING 2011

3. Methodology methods AGU FALL MEETING 2011

4. Spatial variability Results i AGU FALL MEETING 2011

5. Interannual variability GREENLAND results ii AGU FALL MEETING 2011

6. Seasonal variability ANTARCTICA results iii Summer: SUsand Melt // Winter: only SUds Annual cycle in SUds related to wind speed and surface snow conditions AGU FALL MEETING 2011

7. Wind climate evaluation i 115 quality-controlled AWS stations AGU FALL MEETING 2011

8. Wind climate (II) • Horizontal resolution is crucial • Extreme wind speeds are underestimated Entire ice sheet Without “rough” areas evaluation ii AGU FALL MEETING 2011

9. Wind climate (III) evaluation iii AGU FALL MEETING 2011

10. Snowdrift frequency Neumayer station, DML, East Antarctica In-situ stations evaluation iv AGU FALL MEETING 2011 Remote sensing (laser altimetry)

11. Snowdrift frequency (II) evaluation v Palm et al., 2011 Laser altimetry + DEM -> depth of snowdrift layer Only strong events (> 20 m) and non-cloudy conditions AGU FALL MEETING 2011

12. Ablation areas evaluation vi Snowdrift (partly) explains presence and location of ablation areas AGU FALL MEETING 2011

13. Conclusions conclusions First attempt of describing snowdrift climate on large ice sheets Model evaluation focuses on wind speed climate and snowdrift frequency (in-situ and from space) Snowdrift sublimation is a significant contributor to the ice sheet SMB, mainly on Antarctica and in winter Snowdrift erosion is locally important Snowdrift increases near-surface humidity and impacts top snow layer characteristics AGU FALL MEETING 2011