Thermodynamics of Atmospheres and Oceans
Surface Energy Balance
What is the temperature of a raindrop as it falls through the air:
a) dew point temperature
b) wet bulb temperature
c) physical temperature of the air
d) equivalent temperature
Rainfall typically (cools, warms) the ocean surface. cools
The heat flux from precipitation will (increase, decrease, remain the same) if the rainfall
rate increases increase
For the same precipitation rate, snow will cool the surface (more than, less than, the
same) as rain. more than
1. Match the sign of the bulk Richardson number to state of static stability of the atmosphere:
_____c________ RiB = 0
a. stable
_____a________ RiB > 0
b. unstable
_____b________ RiB < 0
c. neutral
2. Match the value of the bulk Richardson number to the approximate value of the heat
transfer coefficient, CDH for z/zo=550.(see Fig. 9.3)
b
RiB = 0
a. 5.0 x 10-3
c
RiB = 0.5
b. 1.33 x 10-3
a
RiB = -0.5
c. 1.0 x 10-4
3. The surface latent heat flux will (increase, decrease, remain the same) if wind speed is
increased
increase
4. The surface sensible heat flux will (increase, decrease, remain the same) if the surface
roughness length increases increase
5. The surface latent heat flux will (increase, decrease, remain the same) if the ocean
salinity increases.
decrease
6. The surface latent heat flux will (increase, decrease, remain the same) if the sea
surface temperature increases.
increase
7. A crude estimate of the surface moisture flux, Ė, over a large homogeneous body of
water is given by,
Ė = ρaCq ux (q0 – qa)
where ρa is density, Cq=1.3x10-3 (dimensionless), and ux is wind speed. Subscripts a and 0 represent
values at 10 m above the surface and the surface value, respectively. Calculate Ė under
the following conditions: ux=5 ms-1 pa= 1000mb, qa = 20g/kg and T0 = 30ºC (assume that
q0 corresponds to saturation) and compare for the following situations:
a) “a fresh water” lake
b) the ocean with s=35 psu
c) the ocean with s-35 psu, where the skin SST correction is ignored (assume bulk SST is
0.3ºC warmer than T0, the skin SST)
For Part a)
Calculate virtual temp using Tv = (1+(.608)*q)T=306.7K
Calculate density of air using virtual temperature ρa
=P/RdTv=100000(N/m2)/287(J/Kkg)/306.7K=1.136kg/m3
Calculate q0 = ε(es/p-(1- ε)es) = .622*(42.430mb)/(1000mb-(1-.622)42.430mb)=.0268
Now, we can calculate Ė = (1.136kg/m3)(1.3x10-3)(5m/s)(.0268-.02)=5.02x10-5kg/m2s
b) Ė = 4.65x10-5kg/m2s
8. The net surface heat flux is highest (most heat into the ocean) for
a) tropical western Pacific
b) east Greenland Sea during winter
c) Gulf Stream during winter
d) Gulf Stream during summer
e) subtropics during summer
9. The net surface heat flux is lowest (least heat into the ocean) for
a) tropical western Pacific
b) east Greenland Sea during winter
c) Gulf Stream during winter
d) Gulf Stream during summer
e) subtropics during summer
10. What causes the net surface radiation flux in the Gulf Stream and East Greenland Sea
to be negative in winter?
You have lower incoming SW radiation due to the sun position yet latent heat loss
from the warm waters combined with cold air masses gives you high evaporation
11. Why is the latent heat flux loss in the Gulf Stream during winter so large?
The warm water that is transported northward has a high evaporation rate
12. If the surface latent heat flux is measured, how can you determine the surface
evaporation flux from this measurement?
FQLH
0
E0  
Llv
13. Which of the following processes increase ocean salinity?
a) precipitation
b) evaporation
c) river runoff
d) melting of sea ice
e) freezing of sea ice
The fresh water balance (precipitation minus evaporation) is greater than zero, less than
zero, or equal to zero, in the following oceanic regions (see Fig. 9.5):
14. Tropics 10N to 10S
15. Subtropics 20-35N, 20-35S
___>0_________
___<0_________
16. Subpolar 50N-70N, 50S-70S ___>0_________
17. Units for heat flux FQ0 are __W/m2______
18. Units for salinity flux FS0 are __kg psu / m2s____
19. Units for heat flux FB0 are __kg/ms3_______
20. The equation for ocean surface buoyancy flux (no runoff or sea ice) can be written as
g
SH
FB0 = c
F rad
Q0 + F Q0 – L lv E +  l c plPr Twa – T 0 – g E –  l P r s 0
p0
Evaporation modifies buoyancy in two ways, via the latent heat flux and also via the
salinity. Compare the thermal vs salinity effects of evaporation on the ocean surface
buoyancy flux (e.g. determine their ratio). Which will dominate under which
circumstances?
Taking the ratio between the cooling term and the salinity term from the equation
 Llv
you get
 c p 0 s0
Salinity dominates in the polar regions, while latent heat dominates in the lower
latitudes
21. Which of the following will promote instability (sinking) at the ocean surface?
a) net radiative heat loss
b) evaporation
c) precipitation
d) sea ice growth
22. Which will have a greater stabilizing effect on stabilizing the ocean surface, rainfall
or snowfall??
rainfall
3. The skin temperature is typically about 0.3oC (warmer, cooler) than the bulk sea surface
temperature
cooler
State how each of the following processes will influence the sea surface temperature (SST) and
depth of the tropical ocean mixed layer (hm) (increase, decrease, remain same). Briefly explain.
1. Increasing the cloud cover during the daytime
SST___decrease_____ hm____increase______
Most heating of SS occurs from visible spectrum, once removed cooling creates instability
2. Large rainfall
SST___increase______ hm ___decrease______
Freshening allows for warmer SST increasing stability
3. increased wind speed
SST___decrease_____ hm___increase______
More turbulent mixing driven by the increase in wind brings cooler waters to the surface
4. increased evaporation rate
SST___decrease_____ hm___increase______
Typically driven by turbulent wind, so again mixes the layer, increases salinity keeping the
surface cool and causing instability bringing cooler water to the surface
5. increased entrainment of deep ocean water
SST___decrease_____ hm__increase______
Caused by increased winds and mixing bringing cooler water to surface
State how each of the following processes will influence the mixed layer salinity (s) and ocean
mixed layer depth (hm) under sea ice (increase, decrease, remain same). Briefly explain.
6. melting of sea ice
s__decrease______ hm___decrease_____
Melting freshens the water in the ocean and allows more warming creating a stable situation
7. freezing of sea ice
s__increase______ hm___increase______
Freezing removes fresh water from the ocean and causes instability producing more mixing