Post on 29-Dec-2015
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