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

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

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

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

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

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

7. Sea Spray Sizes r,  m 5001001010.1 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 n Long residence time. n n Gravitational settling. Heat exchangeAerosol forcing r,  m 5001001010.1

9. Modeling Sea Spray dF/dr = dF 0 /dr + dF 1 /dr Monahan et al., 1986 r,  m 5001001010.1 0.8

10. Modeling the Indirect Mechanism d F 0 /d r = 1.373 U 10 3.41 r -3 (1 + 0.057r 1.05 ) 10 1.19e -B2-B2 B = (0.38 - log r) / 0.65 Monahan et al., 1986 d F 0 /d r = f (U 10, r) Whitecap coverage W

11. Modeling the Direct Mechanism d F 1 /d r = C 1 (U 10 ) r -1 10  m  r  37.5  m d F 1 /d r = C 2 (U 10 ) r -2.8 37.5  m  r  100  m Andreas, 1998 d F 1 /d r = f (U 10, r) Coefficients C i

12. The Goal d F 0 /d r d F /d r = f (U 10, r) f (U 10,  T, T s, S, f, d, C, r) ? W (U 10,  T, T s, S, f, d, C) d F 1 /d r C i (U 10,  T, T s, S, f, d, C) Method

13. TsTs The Concept e - e s e f - e s W = eT s =CalculatedObserved TBTB = e s (1-W )T s + W e f T s B A

14. The Procedure n Data n Compute W n n Preparation n n Brightness temperature; n n Wind mask; n n Cloud mask; n n Rain mask; n n Available T s ; n n Calculate e; n n Calculate e s ; n n Calculate e f ; n n Calculate W. e eses eses n n Salinity; n n Sea surface temperature;

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

16. Sea Surface Temperature T s, o C AVHRR Data

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

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

19. Rain Mask T B (h), K T B (37v) - T B (37h) > 50 and T B (19h) < T 1 130 K 165 K 175 K Preparation

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

21. All Masks on SST T s, o C eses Preparation

22. Available T B T B (h), K Preparation

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

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

25. Emissivity of Foam e f (h) 0.91 to 0.94 e eses Results

26. Whitecap Coverage W (h) Results

27. Comparison W (h) e - e s e f - e s W = W = 3.84  10 -6 U 10 Conventional MethodProposed Method 4% - 30% 1% - 19%

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