Monterey Area Ship Track (MAST) Experiment

Virendra P. Ghate

MPO 531

Outline

• Motivation

• Objectives of MAST

• Instrumentation

• Procedure

• Observations/Results

• Conclusions

Motivation

MODIS 27 Jan 2006

Why study them?

• Twomey Effect:

" cloud reflectivity is enhanced due to increased concentrations of cloud droplets associated with the increased condensation nuclei associated with polluted air "

Twomey 1977

Why study them?

• Albrecht Effect

" Increase in the CCN leads to smaller effective cloud drop radius leading to inhibition of drizzle and further increase in cloud cover "

Albrecht 1989

MAST Objectives

• Aerosol-Cloud Interactions and cloud microphysics.

• Boundary Layer perturbations by ship.

• Cloud Dynamics.

• Background Environmental conditions.

Durkee et al. 2000

Cloud Microphysics Objectives

• Aerosols from ship’s stack are responsible for ship track formation.

• Aerosols from ship’s water wake are responsible for ship track formation.

• Aerosol injection in precipitating clouds tends to inhibit precipitation.

• Etc.

Durkee et al. 2000

Platforms

Aircrafts• UW’s C131 • UK Met. Office C130 • NRL Airship

Ships• R/V Glorita• Steam turbine ships• Gas turbine ships• Diesel engine ships• Nuclear powered

ships

Satellite Observations

Aerosol Instruments

1. 2 Grab bags fitted with Teflon filter

2. Desert Research Institute’s CCN counter

3. Counter-flow Virtual Impacter

4. Passive Cavity Aerosol Spectrometer Probe

5. TSI 3010 Condensation Nuclei (CN) counter

6. Radially Classified Aerosol Detector (RCAD)

7. Active Scattering Aerosol Spectrometer Probe (ASASP-X)

Taxi to MAST research area

Locate ship using radar

Get plume location

Ship speed, wind velocity

Sample BL at different heights with plume perpendicular

transects

Try locating plume cloud entrance location

Decrease in Re

Re(ship track) - Re(ambient) (µm)

Increase in CCN concentration

% increase in drop concentration

Cloud Microphysical Response

Cloud Microphysical Response

“All Aerosols are not activated as CCN”

CCN Activation

Several Distances away from Hanjin Barcelona

Chemical Signature

• Increase of 3-4 µg m-3 in sulphate concentration above the ambient values.

• NYK Sunrise plume contained higher silicon component.

• Links strong evidence to plume formation from stack emissions.

Diesel Vs Steam/Gas turbine

Diesel Engine powered Steam/Gas Turbine

powered

Marine Fuel oil Navy Distillate Fuel

Higher NCCN/Ntotal

ratio

Lower NCCN/Ntotal

ratio

Particle range

0.01 – 0.1 µm

Particle range

<0.03 µm

Background Cloud Conditions

Wake Particles

• Very few particles >0.2 µm

• Particles not lofted to cloud fast enough

Conclusions

• Particles from ship stack responsible for ship track formation.

• Diesel powered ships produce stronger and more ship tracks.

• Ship tracks are more prolific in less polluted ambient air.

• Deeper BL depth (>800 m) inhibits ship track formation.

• No ships produced recognizable signature in water wake in size distribution or chemically