pacs stratus 2003

Preliminary Results from Stratus 03 Cruise on R/V Revelle

Fairall, Zuidema, Hare, Kollias, TomlinsonWCRP/CLIVAR/VAMOS Panel Meeting 7

Guayaquil, EcuadorMarch 2004

PACS STRATUS 2003• left Manta Ecuador, went to 85W line, traveled south to 20S• stayed at WHOI buoy from Nov. 15 – 21 (12 UTC)• traveled east along 20S to Arica Chile• data taken Nov. 13 – Nov. 24

Differences from the (October) EPIC 2001 cruise:• fewer & thinner clouds & less drizzle,particularly at the buoy (now at stratus deck edge)• diurnal cycle in large-scale subsidence in

inversion/cloud-top height weaker?• SSTs ~ 1K warmer; cloudbase higher

Aerosol measurements taken (new) but no C-band radar

Observation Systems

Climate Reference Buoy Cloud Radar and Microwave Radiometer

Above-BL moisture appears to subside into the BL, separated by ~ 4 days, coinciding with a rising

cloud top and drizzle at surface (JD 324).

Pink indicates radar-derived cloud top

BL winds from SE, above-BL-winds more variable (synoptics?)

Both virtual potential temperature and LCL show influence of drizzle

85W, 20S: Inversion less developed in Nov. 2003 than Oct. 2001Boundary layer warmer ~ 1.5K, higher moisture content, less RH

PACS03

EPIC01

RH TT

v e

q

Clouds at buoy thin compared to the rest of the cruise (and to EPIC 2001)

Chris Fairall’s simple aerosol counter compares well to Don Collins’ aerosol measurements (r>0.1 micron)

Aerosol indirect effectWithin well-mixed non-precipitating clouds, expect

lnr/lnN = 0.3 sometimes it’s there, sometimes not

What is the relationship between drizzle, aerosol, and liquid water path ?

As well as surface fluxes….

Comparison of Cloud Diurnal Cycle:Epic2001 vs Stratus2003