Sea salt aerosols Their generation and role in

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 n What? Problem statement n Why? Implications n Implementation How?

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

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

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

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

Sea Spray Sizes n Film drops: 0. 5 to 5 m n Jet drops: 3 to 50 m n Spume drops: 20 to > 500 m 0. 1 Andreas, 1998 1 10 100 500 r, m

Sizes Relevant to Aerosol Forcing n Long residence time. n Gravitational settling. Aerosol forcing 0. 1 1 10 Heat exchange 100 500 r, m

Modeling Sea Spray d. F/dr = d. F 0 /dr + d. F 1 /dr Monahan et al. , 1986 0. 1 0. 8 1 10 100 500 r, m

Modeling the Indirect Mechanism d F 0 /d r = 1. 373 U 103. 41 r -3(1 + 0. 057 r 1. 05) 10 B = (0. 38 - log r) / 0. 65 2 B 1. 19 e Monahan et al. , 1986 d F 0 /d r = f (U 10 , r) Whitecap coverage W

Modeling the Direct Mechanism d F 1 /d r = C 1 (U 10) r -1 10 d F 1 /d r = C 2 (U 10) r -2. 8 37. 5 m r 100 m r 37. 5 m m Andreas, 1998 d F 1 /d r = f (U 10 , r) Coefficients Ci

The Goal d F /d r = f (U 10 , r) f (U 10 , T, Ts , S, f , d , C, r) d F 0 /d r W (U 10 , T, Ts , S, f , d , C) Method d F 1 /d r ? Ci (U 10 , T, Ts , S, f , d , C)

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

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

a t a Brightness Temperature D March 27, 1998 TB (h), K Grid: 0. 5 o Ascending pass SSM/I 19 GHz

a t a Sea Surface Temperature D AVHRR Ts , o. C

n o i t a r Prepa Wind Mask U 10 > 10 m s-1 U 10 , m s-1

n o i t a r Prepa Cloud Mask L < 5 mg cm-2 L , mg cm-2

n o i t a r Rain Mask Prepa TB (37 v) - TB (37 h) > 50 and TB (19 h) < T 1 165 K 175 K 165 K 130 K TB (h), K

n o i t a r Prepa All Masks on TB e TB (h), K

n o i t a r All Masks on SST Prepa es Ts , o. C

n o i t a r Prepa TB (h), K Available TB

s t l Emissivity of Sea Water u s Re e (h) 0. 29 to 0. 45

s t l u s Re es (h) 0. 26 to 0. 28 Specular Emissivity e

s t l u s Re ef (h) 0. 91 to 0. 94 Emissivity of Foam es e

s t l u s Re W (h) Whitecap Coverage

Comparison Proposed Method e - es W= e -e f s W (h) Conventional Method W = 3. 84 10 -6 U 10 1% - 19% 4% - 30%

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