Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

UNIVERSITY OF LEEDS

Lead bubble measurement

Sarah Norris and Gerrit de Leeuw 

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

Why study bubbles?

• Bursting bubbles form sea spray aerosol – which can act as cloud condensation nuclei

• When bubbles burst at the ocean’s surface, heat and water mass, plus associated chemicals, bacteria and viruses are transferred from the ocean to the atmosphere.

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

How are bubbles produced?

1) In open ocean mainly produced by wave-breaking (U10 >~ 4ms-1) by entraining air into the surface layer of the ocean.- however over pack ice only open water are the leads

so limited space for breaking waves

2) release of gas below the ocean surface - pack ice melt may release trapped gases in the form

of bubbles - biogenic bubble release

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

Bubble Bursting

Bursting Bubbles produce:• film drops – 100s or

1000s radius < 2m. • jet drops – this ejects a

few (<7) drops ~2-100m in radius.

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

Bubble measurement – TNO mini bubble system

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

Bubble imaging system

The bubble imaging system records 20 Hz images of the bubbles 0.4m below the water surface every 5 minutes for 2 minutes through out each deployment.

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

Photograph of the bubble imaging system and 3 examples of bubble imagery captured by the TNO camera at 20 frames per second.

Images processed to determine bubble sizes, and spectra averaged over user determined periods.

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

15ms-1

13ms-1

13ms-1

10ms-1

12ms-1

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

Open Lead Flux Site

• Located near bubble camera site:– Sonic anemometer

– LiCOR Li-7500 (CO2/H2O)

– CLASP aerosol probe (0.24 < D < 18.5m)– CPC total aerosol

UNIVERSITY OF LEEDS

Institute for Climate & Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

CLASP instrument

Pu

mp

Sensing head

25 cm

• 16 channels - 0.24 to 18.5 m diameter• Flow rate 3 l/min – high sampling statistics allows 10 Hz temporal

resolution• Compact (25 x 8 x 6 cm) – allows collocation with sonic anemometer,

short inlet tube and low flow distortion, & installation in balloon instrument package