OCN 5401 Chapter 3 Heat Transfer Instructor: Dr. George A. Maul / X 7453

Heat Flux (W·m -2 = J·s -1 ·m -2 ) Q s – radiation from the sun Q b – back radiation from Earth Q e – evaporative heat loss or gain Q h – sensible heat loss or gain Q v – advective heat loss or gain Q t = Q s – Q b – Q e – Q h – Q v James Prescott Joule, FRS

Radiation Paths reflected refracted absorbed scattered transmitted V1V1 V2V2 Index of Refraction (η 2 /η 1 ) = V 1 /V 2 η water-air = (at 20°C) irradiance Willebrord Snell

Solar Spectrum Max Planck

C SUN : What is the solar constant? where If T SUN = 5775K, C SUN = ? Distributed solar irradiance at top of atmosphere (MJ/m 2 /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 C SUN (1-A)πr 2 = 4πr 2 σT 4 If A=0.3 and C SUN =1367 W·m -2, what is T=?

Earth’s mean temperature balance requires an extra term Q GHE : What is the greenhouse effect? T Earth : 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%? minus If T EARTH(A=30%) = 288K, T EARTH(A=29%) = ?

Relative Humidity (RH) and Saturation Vapor Pressure (e s ) Example: RH = ? T air = 30°; T dew point = 10° e s = 39 mb; e air = 12 mb

Evaporation from the Sea Surface Q e = ρ water E·L Evaporation (E) is in meters per second, and latent heat of evaporation (L) is L= 2495 x 10 3 J·kg -1 Evaporation minus precipitation in millimeters per day

Seasonal Thermocline and Mixed-Layer Depth

Earth Remote Sensing

Passive Microwave Remote Sensing SSM/I – Special Sensor Microwave Imager microwave brightness temperatures at 19.35, 22.2, 37.0, and 85.5 GHz

Sea Ice Variability

Sea level from satellite altimetry (active microwave sensing)

Infrared Satellite Imagery Infrared Image

Upper few millimeters of the sea surface

Sea Surface Temperature (SST) Skin Temperature and Bulk Temperature

OCN 5401 Questions? Chapter 3