UNIVERSITY OF LEEDS

Institute for Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

VACC - Volatility Aerosol Composition and Concentration

UNIVERSITY OF LEEDS

Institute for Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

VACC – Science Summary

• Is CN mixed into cloud from above and/or below?– Out of cloud deep profiles – Porpoise through area to look for variation in CN– Characterise CN concentration and composion below

and above cloud

• If isolated cloud available characterise CN concentration and composition of inflow and outflow

– orbits at different levels or straight and level legs perpendicular to wind. (depends on the extent of the cloud)

UNIVERSITY OF LEEDS

Institute for Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

VACC – flight leg requirements• CPC – N (R > 5 nm)

• 10 Hz data• flow controlled at 3 l/min all levels• No special flight requirements

• SMPS – dN/dR (5 nm < R < ~200 nm)• Scan every 2.5 minutes• Sample flow controlled at 1 l/min all levels• Sheath flow controlled at 10 l/min all levels• Flight requirements:

• Constant altitude for duration of scan• Preferably straight but can deal with wide angle turn/orbit

• OPC – Volatility – constant temperature – dN/dR (50 nm < R < 1 µm)• 1 Hz data• Sample flow controlled at 0.12 l/min at all levels• No special flight requirements

• OPC – Volatility – scanning temperature - dN/dR (50 nm < R < 1 µm)• Scan every 8 minutes• Sample flow controlled at 0.12 l/min at all levels• Flight requirements:

• Constant altitude for duration of scan• Preferably straight but can deal with wide angle turn/orbit

• Summary• Flight speed as slow as possible• Altitude profiles of CPC and OPC-volatility-set temperature obtainable• For SMPS or OPC-volatility – scanning temperature: require straight and level or level in slow turn flight legs.• Minimum operational pressure 500 mb ~6000m• Cannot operate in cloud

UNIVERSITY OF LEEDS

Institute for Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

B047 – 09:22 (UTC)

UNIVERSITY OF LEEDS

Institute for Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

No particles R > 0.55μm

75°C100°C

130°C160°C

200°C

230°C

260°C300°C

Sample can be considered dry.

Ammonium Hydrogen Sulphate

Ammonium SulphateSodium Hydrogen Carbonate

Ammonium Nitrate

MSA / Sulphuric acid

UNIVERSITY OF LEEDS

Institute for Atmospheric ScienceSCHOOL OF EARTH AND ENVIRONMENT

External/Internal Mixing.

T

a

T

b

R1 R2

N2

N1

R1 R2

N2

N1

R1

N

R1

N1

N N = N1 + N2

T a

T b

T T c

T d

T T e

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

N

R1 R2

2N