# Presentation: 424357

## Shipboard Investigation of Air-sea Interaction and Cloud Processes in the VOCALS Stratocumulus RegionC. W. Fairall(1),  D. Wolfe (1), S. Pezoa (1),S. de Szoeke(1), L. Bariteau (1, 2), Efthymios Serpetzoglou (3), Virendra Ghate (3), and Paquita Zuidema (3) Results from NOAA Stratus Cruises2001-2006

## Slide 2

## Observation SystemsAir-sea Fluxes, Clouds, Precipitation

- Cloud Radar and Microwave Radiometer

**Notes:**
Cloud pictures for stratus 03.

## Measurement Systems for PACS/Stratus Cruises

**Notes:**
Cruise tracks for all 5 cruises.

**Notes:**
Sample PBL/cloud data for 01, 03, and 04.  Color is sonde water vapor mixing ratio.  Red dots are cloud top; black dots are cloud base; blue dots are LCL from 18-m air temperature and humidity.

## Cloud-Aerosol-Drizzle Connection

- Cloud-aerosol Indirect Effect Example from Stratus2005:
- Minimum in PBL aerosol concentration corresponds to broken cloud period and much higher transmission of solar flux to ocean.
- Broken cloud period was during a POC with drizzling mesoscale cloud features.
- Note cloud LWP about the same for solid vs broken clouds.

**Notes:**
Mean diurnal cycles for each year.  Note Dec 04 (diamonds) had  the weakest diurnal cycle of cloud thickness.  

## Deduce Cloud Optical Properties:Observed cloud transmission coefficient

**Notes:**
Cloud transmission coefficient (blue dots, lower panel) is observed solar flux (green dots, upper panel) divided by expected clear sky flux (blue dots, upper panel).

## STRATUS Cloud Optical Properties:LWP and Aerosol RelationshipsFrom the Diurnal Averaging

- Observed Optical thickness vs Observed LWP.  Calif coast Naer=300/cc; Eq Pac Naer=50/cc

- Observed Optical thickness divided by 1-third power of Observed Aerosol Number Concentration versus Observed LWP

## Daily-averaged Stratus observations:SST and Sea-air Temperature difference

**Notes:**
Seasonal cycle of SST is apparent in left panel (double sets of symbols represent ESRL and Ship SST sensor).  Note Oct06 is much warmer because of El Nino.  However, Sea-air temperature difference is only slightly higher in Oct06, indicating the self regulating nature of the system.

**Notes:**
Seasonal variation of cloud properties.

## Diurnal and Daily Average File Formats

- yxz(:,1)=jdd;Julian Day
- yxz(:,2)=rld;Downward IR flux W/m^2
- yxz(:,3)=rlclrd;Clear sky downward IR flux W/m^2
- yxz(:,4)=rsd;Downward solar flux W/m^2
- yxz(:,5)=rsclrd;Clear sky downward solar flux W/m^2
- yxz(:,6)=tsgd;Ship thermosalinograph water temperature (5 m depth)
- yxz(:,7)=tsd; ESRL seasnake water temperature (5 cm depth)
- yxz(:,8)=tad; Air Temperature (18 m) C
- yxz(:,9)=tau opt; Cloud optical thickness
- yxz(:,10)=zbmd; Median cloud base height  m
- yxz(:,11)=topd;  Cloud top height
- yxz(:,12)=wmd; Cloud liquid water path  g/m^2
- yxz(:,13)=cldfd;  Cloud fraction
- yxz(:,14)=aer_mnd1;  Aerosol number, size>.1 micron and size<.2 micron
- yxz(:,15)=aer_mnd2; Aerosol number, size>.3 micron and size<.5 micron
- yxz(:,16)=aer_mnd3; Aerosol number, size>1 micron and size<5 micron
- yxz(:,17)=yrr; Year of the cruise
- yxz(:,18)=raind; Rain rate mm/hr
- yxz(:,19)=uxd; Northerly wind component m/s
- yxz(:,20)=uyd; Easterly wind component m/s
- yxz(:,21)=ud; Wind speed m/s
- yxz(:,22)=hsd; Sensible heat flux W/m^2
- yxz(:,23)=hld; Latent heat flux W/m^2
- yxz(:,24)=taud; Stress N/m^2
- yxz(:,25)=zb1d; 15% cloud base height m
- yxz(:,26)=clodthkd; Cloud thickness m
- yxz(:,27)=ndd;  Number cloud drops deduced from optical thickness
- yxz(:,28)=latd;  Latitude
- yxz(:,29)=lond; Longitude

**Notes:**
Two data files are available that summarize the ship-based surface and cloud observations.  One file is a mean diurnal for each cruise while at the WHOI buoy location; the other is daily mean variables for each cruise.  Variables provided are listed above.