Preliminary Results from Stratus 03 Cruise
on R/V Revelle
Fairall, Zuidema, Hare, Kollias, Tomlinson
WCRP/CLIVAR/VAMOS Panel Meeting 7
Guayaquil, Ecuador
March 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
•
Aerosol measurements taken (new) but no C-band radar
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
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. 2001
Boundary layer warmer ~ 1.5K, higher moisture content, less RH
RH
q
T
q
q
v
PACS03
EPIC01
qe
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 effect
Within well-mixed non-precipitating clouds, expect
-dlnr/dlnN = 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