Beyond the two cases of water

Transcription

1 44 th Intl. Liège Colloquium on Ocean Dynamics 11 May 2012 Beyond the two cases of water Water constituent retrieval algorithms and their validity ranges Odermatt, D. 1,2, Gitelson, A. 3, Brando, V.E. 4, & Schaepman, M. 1 (2012). Review of constituent retrieval in optically deep and complex waters from satellite imagery. Remote Sensing of Environment, 118/0, Remote Sensing Laboratories, University of Zurich, Switzerland. 2 eawag acuatic research, Kastanienbaum, Switzerland. 3 School of Natural Resources, University of Nebraska, Lincoln, United States. 4 CSIRO Land and Water, Environmental Earth Observation Programme, Canberra, Australia. 1

2 Outline Introduction Water classifications and recent criticism Methods Review approach Results Sensor and constituent specific validations Conclusions Synthesis and suggestions 2

3 Introduction Forel-Ule scale (1889) Arnone et al. (2004) photo by Janet Vail 3

4 Introduction Jerlov water types coastal ocean open ocean Dietrich et al. (1975) based on Jerlov (1951) 4

5 Introduction triangular scheme J Jerlov types 1B-9 C +P +Y b CHL-a 440 nm Prieur & Sathyendranath (1981) based on Morel & Prieur (1977) a w +a y 5

6 Introduction case 1/case 2 Case 1: Optical properties are determined primarily by phytoplankton and related CDOM and detritus. Case 2: Everything else. Sathyendranath (2000) definitions by Morel (1988) 6

7 Introduction criticism of case 1/2 Mobley, C. D., Stramski, D., Bissett, W. P., & Boss, E. (2004). Optical modeling of ocean waters: Is the Case 1 Case 2 classification still useful? Oceanography, 17(2),

8 Introduction criticism of case 1/2 Strengths - guided the development of early bio-optical models - conduced to the success of the first ocean color remote sensing missions - provided a global perspective on open oceans Weaknesses - is a rough simplification that served a past stage of knowledge - has only limited value for current challenges in bio-optical modeling - may bring bring ambiguity, confusion, misuse, or an excuse for poor performance of algorithms (Mobley et al., 2004) 8

9 Review approach scope We reviewed Matchup validation studies for constituent retrieval from satellite imagery of optically deep and complex waters with explicit concentration ranges and R 2 that were published in ISI listed journals between Jan 2006 and May These criteria apply to a total of 52 papers. 9

10 Review approach goals To quantify the use of recent algorithms and sensors To clarify algorithm applicability ranges within case 2 To remedy the ambiguous use of attributes like turbid and clear, and suggest CHL-a ranges that join contradictory definitions of trophic levels* and algorithm validity ranges * Chapra & Dobson (1981), Wetzel (1983), Bukata (1995), Carlson & Simpson (1996), Nürnberg (1996) 10

11 11

12 5 SeaWiFS 2 MODIS 1 GLI 8 MERIS 2 MODIS 1 HICO 2 TM/ETM+ 1 MERIS 12

13 13

14 5 empirical 5 semi-analytical 14

15 Results band ratios for CDOM 15

16 Results spectral inversion algorithms 13 Validation studies Algorithm CHL [mg/m 3 ] TSM [g/m 3 ] CDOM [m -1 ] max min max min max min Binding et al. (2011) NN algal_ Cui et al. (2010) NN algal_ Minghelli-Roman et al. (2011) NN algal_ Binding et al. (2011) NN C2R Giardino et al. (2010) NN C2R Matthews et al. (2010) NN C2R Odermatt et al. (2010) NN C2R Schroeder et al. (2007b) NN FUB Shuchman et al. (2006) Coupled NN Giardino et al. (2007) MIM Odermatt et al. (2008) MIP Santini et al. (2010) 2 step invers V. D. Woerd & Pasterkamp (2008) Hydropt

17 Results CHL-a validity range scheme 17

18 Results CHL-a validity range scheme OC3 and OC4 are validated for CHL-a in oligotrophic waters of low CDOM and TSM 18

19 Results CHL-a validity range scheme Red edge band ratios are validated for CHL-a in eutrophic waters, for a wide range of CDOM and low to intermediate TSM 19

20 Results TSM validity range scheme 20

21 Results CDOM validity range scheme 21

22 Conclusions The number and retrieval ranges of band ratio validation studies allow a good estimate of general strengths and weaknesses MERIS 708 nm band has been a unique advantage MERIS neural networks are the only spectral inversion algorithms with sufficient validation from several independent studies Validity range schemes display suitable algorithms for all types of waters, provided that valid IOPs are used 22

23 Outroduction This work: Odermatt, D., Gitelson, A., Brando, V.E., & Schaepman, M. (2012). Review of constituent retrieval in optically deep and complex waters from satellite imagery. Remote Sensing of Environment, 118/0, See also: Matthews, M. W. (2011). A current review of empirical procedures of remote sensing in inland and near-coastal transitional waters. International Journal of Remote Sensing, 32(21),

24 Annex partition by SeaWiFS case 1 case 2 N-spring N-summer N-autumn N-winter Lee & Hu (2006) 24

25 Annex trophic levels Authors Oligotrophic Mesotrophic Eutrophic Hypereutr. Chapra & Dobson (1981) >5.6 n.a. Wetzel (1983) n.a. N-spring N-summer Bukata et al. (1995) >18 Carlson & Simpson (1996) >56 Nürnberg (1996) >25 Odermatt et al. (2012) >10? N-autumn N-winter 25