1. EPIC 2001 SE Pacific Stratocumulus Cruise 9-24 October 2001 Chris Bretherton and Sandra Yuter (U. Wash.) Chris Fairall, Taneil Uttal (NOAA/ETL) Bob Weller (WHOI)

2. Goals Document cloud and boundary layer structure in the SE Pacific Assess the importance of drizzle processes to cloud thickness and extent Compare results with other Sc regimes and with large-scale models Maintain WHOI IMET buoy at 20S 85W

3. NOAA/ETL (surface met., fluxes, mm radar, lidar) Participants

4. UNAM (aerosol concentration and characterization)

5. Participants WHOI (CTDs, IMET buoy)

6. Participants University of Washington (sondes, 5 cm scanning radar, meth blue, cloud photos)

7. EPIC Sc cruise 9-24 Oct. 2001

9. 3 hr rawinsonde launches (Kim Comstock, UW)

10. cld top cld base LCL Cloud top and dBZ (MMCR), base (ceilometer), LCL (surf. met.)

11. [m s -1 ] ECMWF VERTICAL VELOCITY [dBZ] 10 -10 0 Diurnal Cycle

12. Sample of C-band scanning radar and coincident MMCR dBZ 0530 0730

13. Meth Blue Rain Rate Number/second Z=58R 1.1

14. Remotely-sensed cloud microphysics (Rob Wood, UW) …UNAM also found a strong diurnal signal in submicron aerosol conc.

15. MODIS 10/16/2001; 10:00 Local (16:00 UTC) 1 3 10 30 100 300 1000 cm -3 0 50 100 150 200 250 300 g m -2 0 5 10 15 20 25 30 mm Liquid water pathDroplet concentrationEffective radius SHIP 250 km

16. Comparison of 6-day mean 20S 85W profiles with models All models (esp CAM) have too shallow a PBL. CAM2 LWC all in lowest 3 levels (70-630 m). Observed LWC mainly at 800-1300 m. (Peter Caldwell, UW)

17. Conclusions A remarkable dataset was gathered documenting both spatial and diurnal variability of the SE Pacific Sc regime Pronounced diurnal cycle, amplified by subsidence wave from S America. Mesoscale drizzle cells ubiquitous, especially at night; rain mostly evaporates above surface, sensitive to cld drop conc. Boundary layer deeper than current global models; well-mixed in early evening.