1. Sea Surface Temperature
OC Remote Sensing of the Atmosphere and Ocean - Summer 2001
Sea Surface Temperature

2. From Schwartzchild’s Equation:
AVHRR Channels

3. None of these are in perfect windows
None of these are in perfect windows so there will always be some contribution from the path term due primarily to absorption/emission by water vapor
Ch4 Ch5
Transmittance

4. Does the addition of atmospheric water vapor increase or decrease TB?
Let’s look at a simple case - addition of a homgeneous layer
Ts, es=1
Ta, td=0.9 1
Becomes,
or,

5. How does the amount of water vapor affect the spectral variation of TB
How does the amount of water vapor affect the spectral variation of TB? [referring to AVHRR Channel (4) and Channel (5)]
Ts, es=1
Ta, td (4) =0.95, td (5) = d(4)=-ln(0.95)=0.051 , d(5)= (for nadir view)
If we double the amount of water vapor, what changes? vs
d doubles so… d(4)=0.102, d(5)= and, td (4) =0.90, td (5) =0.81
Since Ts and Ta don’t change with wavelength, now…

6. MCSST - Multichannel Sea Surface Temperature
This technique assumes that the true surface temperature can be derived from a linear composite of the AVHRR Ch 4 and 5 brightness temperatures (accounting for water vapor variations)
Ts = A + B T4 + C T5
A, B, and C can then be determined empirically:
Measure TS (ship, buoy, etc.) in many places coincident with measurements of T4 and T5 (AVHRR)
Statistically determine A, B, and C that produce a best fit of
Ts(x) = A + B T4(x) + C T5(x)
Or at night we can also use Ch 3 (3.7mm wavelength)
(why?)
Ts(x) = D + E T3(x) + F T4(x) + G T5(x)

9. Pacific SST Anomaly

10. This is a false colour image, produced using brightness temperatures from one of ATSR-2's thermal infra-red detectors (11.0 micron).
The image was obtained from ATSR-2's nadir view, during a day-time pass of the Gulf of California.
The hottest areas (shown in gray) are mostly land. The cooler sea-surface temperatures are shown using purple (coolest) to red (warmest).
The range of temperatures shown in the is approximately 280 Kelvin to 300 Kelvin.
The ATSR channels are at wavelengths of 1.6um (visible,)
and three thermal bands at 3.7um, 11um, and 12um.

11. MODIS
11um band; brightness temperature May 2, 2001 The red pixels in this image show the warmer areas (approaching 25°C), greens are intermediate values (12-13°C), and blues are relatively
low values (less than 10°C). Notice the considerable detail in the swirls and gyres of the current patterns in the Gulf Stream.