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Sea salt aerosols: Their generation and role in the climate system

Sea salt aerosols: Their generation and role in the climate system. Ph. D. Dissertation Proposal Magdalena D. Anguelova. College of Marine Studies University of Delaware. November 12, 1999. Outline. What?. Problem statement. Why?. Implications. Implementation. How?.

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Sea salt aerosols: Their generation and role in the climate system

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  1. Sea salt aerosols: Their generation and role in the climate system Ph. D. Dissertation Proposal Magdalena D. Anguelova College of Marine Studies University of Delaware November 12, 1999

  2. Outline What? • Problem statement Why? • Implications • Implementation How?

  3. Problem statement • Modify the currently available sea-salt generation function. • Evaluate the effect of sea-salt aerosols on the climate system.

  4. The Role of the Aerosols • Scatter sunlight; • Facilitate cloud droplet formation; • In climate: • In atmospheric chemistry: • Provide site for chemical reactions.

  5. Aerosols in Climate Models “...However, it generates too much big sea-salt particles at high wind speeds compared to observations and is therefore neglected in the simulation.” • Improves model predictions; • Canadian Climate Model (Gong, Barrie, Blanchet, 1997) • Use the first sea-salt generation function (Monahan et al., 1986)

  6. Sea Spray Formation • Direct; • Indirect. Andreas et al., 1995

  7. Sea Spray Sizes r, m 0.1 1 10 100 500 • Film drops: 0.5 to 5 m • Jet drops: 3 to 50 m • Spume drops: 20 to > 500 m Andreas, 1998

  8. Sizes Relevant to Aerosol Forcing r, m 0.1 1 10 100 500 • Long residence time. • Gravitational settling. Aerosol forcing Heat exchange

  9. Modeling Sea Spray dF/dr = dF0 /dr + dF1 /dr Monahan et al., 1986 r, m 0.8 0.1 1 10 100 500

  10. Modeling the Indirect Mechanism -B2 d F0 /d r = 1.373 U103.41 r -3(1 + 0.057r1.05) 101.19e B = (0.38 - log r) / 0.65 Monahan et al., 1986 Whitecap coverage W d F0 /d r = f (U10 , r)

  11. Modeling the Direct Mechanism d F1 /d r = C1 (U10) r -110 m r 37.5 m d F1 /d r = C2 (U10) r -2.837.5 m r 100 m Andreas, 1998 Coefficients Ci d F1 /d r = f (U10 , r)

  12. The Goal f (U10 , T, Ts , S, f , d , C, r) W (U10 , T, Ts , S, f , d , C) Ci(U10 , T, Ts , S, f , d , C) Method d F/d r = f (U10, r) d F0 /d r d F1 /d r ?

  13. The Concept Observed Calculated e - es W = ef - es A B Ts eTs= = es(1-W )Ts + W ef Ts TB

  14. Data Compute W The Procedure • Preparation • Brightness temperature; • Wind mask; • Cloud mask; • Rain mask; • Available Ts; • Calculate e; • Calculate es; • Calculate ef ; • Calculate W. e • Sea surface temperature; es es • Salinity;

  15. Data Brightness Temperature SSM/I 19 GHz March 27, 1998 Grid: 0.5o 0.5o Ascending pass TB (h), K

  16. Data Sea Surface Temperature AVHRR Ts , oC

  17. Wind Mask Preparation U10 > 10 m s-1 U10 , m s-1

  18. Cloud Mask Preparation L < 5 mg cm-2 L , mg cm-2

  19. Rain Mask 165 K 175 K 165 K 130 K Preparation TB (37v) - TB (37h) > 50 and TB (19h) < T1 TB (h), K

  20. All Masks on TB Preparation e TB (h), K

  21. All Masks on SST Preparation es Ts , oC

  22. Available TB Preparation TB (h), K

  23. Emissivity of Sea Water Results e (h) 0.29 to 0.45

  24. Specular Emissivity e Results es (h) 0.26 to 0.28

  25. Emissivity of Foam e es Results ef (h) 0.91 to 0.94

  26. Whitecap Coverage Results W (h)

  27. Comparison e - es ef - es W = Conventional Method W = 3.8410-6 U10 Proposed Method 4% - 30% W (h) 1% - 19%

  28. Questions "Deeds speak louder than words" The Boasting Traveller, Aesop

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