OCN 5401

Chapter 3

Heat Transfer

Instructor: Dr. George A. Maul

gmaul@fit.edu / X 7453

Heat Flux(W·m-2 = J·s-1·m-2)

• Qs – radiation from the sun

• Qb – back radiation from Earth

• Qe – evaporative heat loss or gain

• Qh – sensible heat loss or gain

• Qv – advective heat loss or gain

Qt = Qs – Qb – Qe – Qh – Qv

James Prescott Joule, FRS

Radiation Paths

reflected

refractedabsorbedscattered

transmitted

V1

V2

Index of Refraction (η2/η1) = V1/V2

ηwater-air = 1.333 (at 20°C)

irradiance

Willebrord Snell

 

Solar Spectrum

d

e

hvdM

kT

hv

o

1

2)(

0

5

2

Max Planck

Stefan-Boltzmann Law

CSUN: What is the solar constant?

SUNSUNEarth

SUNSUN C

r

rT

2

24

4

4

where

If TSUN = 5775K, CSUN = ?

  

 

Distributed solar irradiance at top of atmosphere (MJ/m2/day)

Solar irradiance

The solar constant isn’t constant!

SOHO

UV images of 11 year solar cycle

Note the sunspots

Albedo

Distribution of Water and Land

Solar Heating

Inflow = Outflow CSUN(1-A)πr2 = 4πr2σT4

If A=0.3 and CSUN=1367 W·m-2, what is T=?

Earth’s mean temperature balance requires an extra term

414 EARTHSUN

GHE TAC

Q

QGHE: What is the greenhouse effect?

TEarth: What is Earth’s temperature?

A: Is Earth’s albedo fixed?

How would Earth’s temperature change if the albedo changed from 30% to 29%?

4%)30(30.01

4 AEARTHSUN

GHE TC

Q

4%)29(29.01

4 AEARTHSUN

GHE TC

Q minus

)(30.029.04

4%)29(

4%)30( AEARTHAEARTH

SUN TTC

If TEARTH(A=30%) = 288K, TEARTH(A=29%) = ?

Relative Humidity (RH) and Saturation Vapor Pressure (es)

 

Example: RH = ?Tair = 30°; Tdew point = 10°es = 39 mb; eair = 12 mb

Evaporation from the Sea Surface

Qe = ρwaterE·LEvaporation (E) is in meters per second, and

latent heat of evaporation (L) is L= 2495 x 103 J·kg-1

Evaporation minus precipitation in millimeters per day

Seasonal Thermoclineand Mixed-Layer Depth

Earth Remote Sensing

Passive Microwave Remote Sensing

SSM/I – Special Sensor Microwave Imagermicrowave brightness temperatures at

19.35, 22.2, 37.0, and 85.5 GHz

Sea Ice Variability

Sea level from satellite altimetry

(active microwave sensing)

𝐷( 𝐽 ∙𝑘𝑔−1)≡∫𝛼 ∙𝑑𝑝

Infrared Satellite Imagery

Exitance vs. Wavelength

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Wavelength (micrometers)

Lo

g E

xita

nce

Solar Irradiance at 1 AU

Earth Exitance at 288K

Infrared Image

Upper few millimeters of the sea surface

Sea Surface Temperature (SST)Skin Temperature and Bulk Temperature

OCN 5401

Questions?

Chapter 3