1 Lecture 17 Ocean Remote Sensing 9 December 2008

2 Final Exam Friday – December 19 1:30-3:30 2/3 from lectures 12-17, 1/3 from previous lectures (focusing on topic areas covered in the first 2 exams)

3 Office Hours Not available this afternoon – Office hours on Thurs, Dec 11 Can meet Thurs/Fri, Dec 11/12 by appointment Not available Mon-Thurs, Dec 15-19

4 Ocean Chlorophyll/Production SAR Ocean Observations

5 Lecture Topics 1.Geographic perspectives on importance of oceanic processes 2.SAR Ocean Observations 3.Global SST data products 4.Sea surface topography 5.Monitoring El Nino with satellite data 6.Monitoring ocean productivity

6 Geographic perspectives on importance of oceanic processes Influences of oceans on continental climates Large-scale oceanic circulation

7

8

9

10

11 Geographic perspectives on importance of oceanic processes Influences of oceans on continental climates Large-scale oceanic circulation

12

13 1.Ocean current drivers 2.Ocean current modifiers –Continents –Coriolis effect

14

15

16 Thermocline

17 Currents are also influenced by the rotation of the earth This rotation causes a natural deflection of currents Clockwise in the Northern Hemisphere Counter clockwise in the Southern Hemisphere This is called the coriolis effect

18 Lecture Topics 1.Geographic perspectives on importance of oceanic processes 2.SAR Ocean Applications 3.Global SST data products 4.Sea surface topography 5.Monitoring El Nino with satellite data 6.Monitoring ocean productivity

19 Microwave backscatter from water surfaces results from Bragg Scattering from small surface waves – Many processes alter the Bragg wavelength, and thus cause changes in EM energy detected by SARs

20 SAR Ocean Applications Detection of oil slicks Monitoring surface gravity waves Monitoring internal waves Detection of bottom features

21 Airborne SAR Imagery of Oil Spills Oil on water surface dampens formation of short wavelength Bragg Waves

22 Seasat SAR (L-band) image of an oil spill U.S. Coast Guard deploys airborne SAR systems for detection of oil spills in coastal waters

23 Tilt and hydrodynamic modulation by gravity waves

24 Airborne SAR imagery of gravity waves

25 Monochromatic light Monochromatic light is diffracted as it passes through a narrow slit Degree of diffraction ~ 1 / slot width

26 SAR Image of gravity waves digital

27 SAR Image of gravity waves In a fourier transform, the distance between the peaks of energy is proportional to the wavelength of the imaged gravity waves, and a line connecting the peaks represents the direction of the waves

28

29 Seasat SAR image of gravity waves

30 Internal Wave Formation

31 Internal Wave Formation

32 Surface Hydrodynamic Modulation by Internal Waves

33 Internal Waves

34 Airborne SAR Images of Internal Waves

35 ERS C-VV SAR image collected off of west African Coast

36 ERS C-VV SAR image collected off of Galopagos Islands showing internal waves

37 Seasat SAR Image of Natucket Shoals

38

39 Hydrodynamic Modulation by Bottom Feature/Current Interactions

40

41

42 Hydrodynamic Modulation Current slows downCurrent speeds up

43 Current Direction

44 Lecture Topics 1.Geographic perspectives on importance of oceanic processes 2.SAR Ocean Applications 3.Global SST data products 4.Sea surface topography 5.Monitoring El Nino with satellite data 6.Monitoring ocean productivity

45 Figure 4 in Njoku and Brown, Sea Surface Temperature, pages

46

47 Global Sea Surface Temperature Products Data are compiled over a weekly or monthly period Algorithms to remove cloud-contaminated pixels are applied to data Average SST for the remaining pixels are calculated Data are resampled to a coarse resolution (e.g, 36 km) Data are interpolated to fill in missing pixels al_climo_mon.html

48

49 AVHRR Sea Surface Temperature Map

50 MODIS Sea Surface Temperature Map

51 SST Map SST Anomaly Map

52

53 Lecture Topics 1.Geographic perspectives on importance of oceanic processes 2.SAR Ocean Applications 3.Estimating Sea Surface Temperature (SST) with AVHRR 4.Global SST data products 5.Sea surface topography 6.Monitoring El Nino with satellite data 7.Monitoring ocean productivity

54 Altimeters Altimeters measure round-trip travel time of microwave radar pulse to determine distance to sea surface! From this (and additional info) we can determine the dynamic sea surface topography

55 Spaceborne Scatterometer Resolution = 50 km Obtains measurements looking upwind, cross- wind, and downwind Empirical Algorithms used to estimate wind speed and direction

56

57 Lecture Topics 1.Geographic perspectives on importance of oceanic processes 2.SAR Ocean Applications 3.Global SST data products 4.Sea surface topography 5.Monitoring El Nino with satellite data 6.Monitoring ocean productivity

58 Thermocline

59 Thermocline

60 Movies of SST and Elevation Anomalies

61 Lecture Topics 1.Geographic perspectives on importance of oceanic processes 2.SAR Ocean Applications 3.Estimating Sea Surface Temperature (SST) with AVHRR 4.Global SST data products 5.Sea surface topography 6.Monitoring El Nino with satellite data 7.Monitoring ocean productivity

62 SeaWiFs Launched km swath 1.1 x 1.1 km pixel

63 Example SeaWifs Chlorophyll Algorithms Chl = 10 (a + bR) Algorithm 1 - R = log (R443/R550) Algorithm 2 – R = log [(R520 + R565)/R490]

64

65

66

67 Data obtained from ORBIMAGE at: browse.pl?dy=11627&tp=MO&lev=2&hp=

68 Monthly Composite

69

70