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Investigation:

LC-07 (Melack / Novo / Forsberg)

LBA Dataset ID:

LC07_SPECTRORADIOMETRY

Originator(s):

1. NOVO, E.M.L.M.
2. FILHO, W.P.
      3. MELACK, J.M.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

The Amazon basin is the world\'s largest tropical floodplain river system, draining approximately 40% of South America. Water levels in the main rivers vary by, on average, 7 to 13m annually, and these fluctuations are responsible for the movement of water, which exerts a strong influence on the aquatic vegetationn and fauna. About 8000 lakes occur in the central Amazon. Amazon inland waters are optically complex, spanning a wide variability in the concentration of phytoplankton pigments, and suspended and dissolved organic and inorganic matter. Therefore, a challenging problem, in a region as large as the Amazon basin, is to determine routing and changes of the inundating waters based on sparse ground measurements. Remote sensing offers the potential to examine optical properties and exchanges of water in rivers and lakes. The operational application of the technology for water quality management is limited for several reasons. The available technology has not been able to deal with the complexity of inland aquatic systems. Coarse spatial and spectral resolution and low radiometric sensitivity has prevented the widespread use of Landsat Thematic Mapper (TM) Satellite pour l\'Observation de la Terre (SPOT) HRV images. The lack of understanding of how water quality variables affect the remotely sensed reflectance has prevented the development of new algorithms tailored to a wide range of environments. Field spectroradiometry involves the study of the relationship between the spectral characteristics and their chemical and biophysical attributes. We applied this approach to the waters of the central Amazon. Spectra were measured concurrently with water sampling for optically active components. Using these data, we evaluated two spectral band operators for estimating chlorophyll concentrations from reflectance spectra of turbid waters.

Beginning Date:

2000-07-07

Ending Date:

2000-08-02

Metadata Last Updated on:

2013-02-13

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO LC-07 Reflectance Spectra and Water Quality of Amazon Basin Floodplain Lakes:  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1144

Documentation/Other Supporting Documents:

LBA-ECO LC-07 Reflectance Spectra and Water Quality of Amazon Basin Floodplain Lakes:  http://daac.ornl.gov/LBA/guides/LC07_Spectroradiometry.html

Citation Information - Other Details:

Novo E.M.L.M.,W. Pereira Filho and J.M. Melack. 2013. LBA-ECO LC-07 Reflectance Spectra and Water Quality of Amazon Basin Floodplain Lakes. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. http://dx.doi.org/10.3334/ORNLDAAC/1144

Keywords - Theme:

Parameter Topic Term Source Sensor
CHLOROPHYLL BIOSPHERE AQUATIC ECOSYSTEMS LABORATORY SPECTROPHOTOMETER
REFLECTANCE BIOSPHERE AQUATIC ECOSYSTEMS FIELD INVESTIGATION SPECTROMETER
TURBIDITY BIOSPHERE AQUATIC ECOSYSTEMS FIELD INVESTIGATION SECCHI DISKS
WATER TEMPERATURE BIOSPHERE AQUATIC ECOSYSTEMS FIELD INVESTIGATION TEMPERATURE PROBE

Uncontrolled Theme Keyword(s):  BIDIRECTIONAL REFLECTANCE SPECTA, CHLOROPHYLL, DOC, SECCHI DEPTH, TOTAL SUSPENDED SOLIDS

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  AMAZONAS (MANAUS) -2.95830 -3.98110 -60.52640 -63.90140

Related Publication(s):

Novo E.M.L.M., W. Pereira Filho and J.M. Melack. 2004. Assessing the utility of spectral band operators to reduce the influence of total suspended solids on the relationship between chlorophyll concentration and the bidirectional reflectance factor in Amazon waters.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are presented in two ASCII comma separated files:



File #1:Water_chemistry_radiometry_2000

File #2: Radiometry_BRF



File #1:

File name:,Water_chemistry_radiometry_2000.csv

File date:,11-Jun-12

Associated LME:,LC07_Spectroradiometry



Column,Column_heading,Units/format,Explanation

1,Sample_ID,,Sample identification

2,Lake_ID,,Lake identification by name or number

3,Date,YYYMMDD,Sampling date

4,Time,HH:MM,Time of sample collection in local time

5,Latitude,,Sample site geographic coordinates: latitude

6,Longitude,,Sample site geographic coordinates: longitude

7,Secchi depth ,m,Secchi depth reported in meters (m)

8,T_water,degrees C,Temperature of the water in degrees C

9,TSS,mg per L,Concentration of total suspended solids reported in milligrams per liter (mg per L)

10,Chl,mg per m3,Chlorophyll concentration in milligrams per meter cubed

11,DOC,mg per L,Dissolved organic carbon concentration reported in milligrams per liter (mg per L)



,missing data are represented by -9999





Sample data for File #1:

Sample_ID,Lake_ID,Date,Time,Latitude,Longitude,Secchi depth ,T_water,TSS,Chl,DOC

EVE-1,12,20000707,10:30,-3.81806,-62.34778,0.5,27.9,10.40,0.92,4.294

EVE-2,12,20000707,10:55,-3.81861,-62.35222,0.4,28.4,16.18,1.839,4.466

EVE-3,12,20000707,11:12,-3.82,-62.35333,0.38,29.2,25.42,1.379,4.476

EVE-4,12,20000707,11:30,-3.81667,-62.35639,0.5,29.2,25.17,0.92,4.549

EVE-5,12,20000707,11:45,-3.82083,-62.34861,0.5,29.2,19.10,0.92,4.299

EVE-6,12/rio,20000707,13:05,-3.81111,-62.38056,0.3,27.6,25.19,0.92,4.745

EVE-7,12/rio,20000707,13:05,-3.80528,-62.36861,0.3,27.4,26.84,2.299,4.252

EVE-8,10,20000708,11:10,-3.90111,-62.58472,0.28,29,20.43,1.839,3.948

EVE-9,10,20000708,11:25,-3.8975,-62.58333,0.35,29,23.37,1.149,4.467

EVE-10,10,20000708,11:57,-3.88806,-62.57861,0.28,28.6,20.82,0.46,4.738

EVE-11,10,20000708,12:10,-3.89028,-62.58194,0.33,27.4,15.13,1.724,5.637

EVE-12,10,20000708,12:23,-3.89222,-62.59056,0.28,27.4,18.45,1.149,5.215

EVE-13,6,20000710,10:20,-3.98111,-62.76194,1.5,29.6,2.64,7.586,6.059

EVE-14,6,20000710,10:47,-3.97472,-62.76083,1,29.4,8.24,7.356,6.505

EVE-15,6,20000710,11:13,-3.97278,-62.72833,1.35,27.6,13.33,40.428,6.608

EVE-16,6,20000710,11:25,-3.97083,-62.73833,0.9,27.8,9.43,9.655,5.197

EVE-17,6,20000710,11:40,-3.95472,-62.76278,0.9,28.6,12.98,4.138,6.602

EVE-18,6,20000710,11:48,-3.94917,-62.76583,0.7,27.2,14.63,1.379,6.228

EVE-18A,11,20000715,11:48,-3.94917,-62.76583,-9999,-9999,-9999,-9999,7.316

EVE-19,11,20000715,12:10,-3.88028,-63.90139,1.3,27.8,14.45,9.655,6.591

EVE-20,11,20000715,12:25,-3.87556,-63.89528,1.3,27,13.85,5.057,7.758

EVE-21,11,20000715,12:35,-3.87528,-63.88611,1.2,27.4,14.54,4.138,8.75

EVE-22,11,20000715,12:50,-3.88917,-63.875,1.2,27.4,16.84,5.977,5.318

EVE-23,11,20000715,12:58,-3.88556,-63.87639,1.15,27.2,17.17,5.977,3.774

EVE-24,11,20000715,13:08,-3.85472,-63.87639,0.5,27.6,17.40,4.598,3.41

EVE-25,11,20000715,13:20,-3.84583,-63.87806,0.5,27.4,17.87,0.92,-9999

EVE-26,5,20000717,11:40,-3.88111,-63.49972,1.8,27.8,12.21,5.977,6.64

EVE-27,5,20000717,11:55,-3.88528,-63.49111,2,27,8.84,4.138,4.879





File #2:

File name:,Radiometry_BRF.csv

File date:,8-June_2012

Associated LME file:,LC07_Spectroradiometry



1,Lake_ID,Lake identification by name or number

2,Date,YYYYMMDD,Sampling date

3,Time,HH:MM, Sampling time in local time

4,Latitude,decimal degrees, Latitude of sampling location in decimal degrees

5,Longitude,decimal degrees,Longitude of sampling location in decimal degrees

6,Sample_ID,, Sample identification

7 through 178,wavelength in nanometers,,Bidirectional reflectance factor for individual wavelengths identified in the column header



Sample data for File #2:

Lake_ID,Date,Time,Latitude,Longitude,Sample_ID,399.5,402.1,404.7,407.3,409.9,412.5,415.1,417.7,420.3,422.8,425.4,428,430.6,433.2,435.8,438.6,441.4,444.2,447,449.8,452.6,455.3,458.1,460.9,463.7,466.5,469.3,472.1,474.9,477.7,480.5,483.3,486.1,488.9,491.6,494.4,497.2,500,502.8,505.6,508.4,511.2,514,516.8,519.6,522.4,525.2,527.9,530.7,533.5,536.3,539.1,541.9,544.7,547.5,550.4,553.3,556.1,559,561.9,564.8,567.6,570.5,573.4,576.2,579.1,582,585,587.9,590.9,593.8,596.7,599.7,602.6,605.5,608.5,611.4,614.4,617.3,620.2,623.2,626.1,629,632,634.9,637.9,640.8,643.7,646.7,649.6,652.5,655.5,658.4,661.4,664.3,667.2,670.2,673.1,676,679,681.9,684.9,687.8,690.7,693.7,696.6,699.6,702.5,705.5,708.5,711.5,714.4,717.4,720.4,723.4,726.3,729.3,732.3,735.3,738.2,741.2,744.2,747.1,750.1,753.1,756.1,759,762,765,768,771.1,774.1,777.1,780.1,783.2,786.2,789.2,792.2,795.3,798.3,801.3,804.3,807.4,810.4,813.6,816.8,820.1,823.3,826.5,829.7,832.9,836.1,839.3,842.5,845.7,848.8,852,855.2,858.4,861.5,864.7,867.9,871.1,874.2,877.4,880.6,883.7,886.9,890.1,893.3,896.4,899.6

12,20010707,10:30,-3.81806,-62.34778,am01,0.023397,0.023117,0.023211,0.023837, 0.02387,0.023666,0.023605,0.023858,0.024138,0.024185,0.024726,0.024949,0.025216,0.025435,0.025966,0.026051,0.026678,0.026956,0.027168,0.027488,0.02822,0.028653,0.028945,0.029455,0.029808,0.030194,0.030688,0.03094,0.031461,0.031678,0.032003,0.032597,0.03316,0.033697,0.034103,0.034739,0.035267,0.036012,0.036665,0.03728,0.038032,0.038748,0.039474,0.040337,0.040988,0.041865,0.042623,0.043423,0.044524,0.045463,0.046423,0.047263,0.048298,0.049269,0.050292,0.051354,0.052524,0.053434,0.054285,0.055405,0.05672,0.057773,0.058791,0.05917,0.060133,0.06137,0.06205,0.062892,0.063151,0.063427,0.063715,0.063294,0.063217,0.062981,0.062904,0.062829,0.062741,0.063112,0.063383,0.063734,0.063922,0.064434,0.064741,0.064804,0.065187,0.065578,0.065817,0.065973,0.066587,0.066522,0.066634,0.066267,0.065816,0.065375,0.064803,0.06432,0.06443,0.064385,0.064295,0.064215,0.064088,0.063758,0.063244,0.062572,0.061638,0.060363,0.058648,0.056587,0.054645,0.052436,0.049406,0.046732,0.043274,0.039692,0.035714,0.031609,0.027966,0.024885,0.022537,0.020725,0.019595,0.019168,0.018644,0.018459,0.018342,0.018382,0.018606,0.018734,0.018565,0.018707,0.018695,0.018647,0.018944,0.019217,0.019414,0.019857,0.020223,0.020789,0.021166,0.021463,0.021314,0.021769,0.021627,0.021161,0.020972,0.019948,0.018809,0.017739,0.016545,0.015313,0.014097,0.013053,0.012285,0.012126,0.012053,0.011698,0.01148,0.011175,0.010695,0.010565,0.010463,0.010471,0.01006,0.01004,0.009658,0.009319,0.009434,0.009271,0.008865,0.009035,0.008718,0.008874

12,20010707,10:55,-3.81861,-62.35222,am02,0.019931,0.019389,0.019987,0.019864, 0.019807,0.019954,0.020172,0.020218,0.020307,0.020154,0.020487,0.020506,0.020902,0.021249,0.021329,0.02161,0.021904,0.022199,0.022183,0.022512,0.022986,0.023363,0.023585,0.024023,0.024296,0.024595,0.024824,0.02521,0.025468,0.025565,0.025933,0.026335,0.026862,0.027217,0.027686,0.028044,0.028643,0.029093,0.029614,0.030179,0.030822,0.03129,0.031981,0.032453,0.03312,0.033821,0.034426,0.035281,0.036086,0.036837,0.037753,0.038504,0.03923,0.04009,0.040874,0.041761,0.042652,0.043518,0.044299,0.045118,0.046243,0.047202,0.048034,0.048326,0.0492,0.050248,0.050841,0.051365,0.051707,0.051895,0.051924,0.051634,0.051533,0.051341,0.051239,0.051233,0.051178,0.05136,0.051678,0.05184,0.052093,0.052656,0.052864,0.053064,0.053377,0.053741,0.053786,0.053913,0.054415,0.054471,0.054385,0.054014,0.053827,0.05323,0.052783,0.052673,0.052617,0.052431,0.052531,0.052141,0.05221,0.052013,0.051617,0.05075,0.049897,0.048766,0.047336,0.045509,0.043716,0.041576,0.039461,0.036912,0.033898,0.030829,0.027597,0.024631,0.021574,0.019142,0.017085,0.015889,0.014945,0.01462,0.014143,0.014249,0.014266,0.014338,0.014252,0.014155,0.014346,0.014233,0.014117,0.01426,0.014572,0.014782,0.014846,0.015091,0.01527,0.015698,0.015983,0.016207,0.01643,0.01678,0.016455,0.01624,0.015857,0.015223,0.014629,0.013685,0.012652,0.011601,0.011013,0.010105,0.009828,0.009297,0.009241,0.008875,0.00902,0.008692,0.008638,0.008533,0.008451,0.008055,0.008048,0.008032,0.007646,0.007293,0.007383,0.007164,0.007092,0.007133,0.007179,0.00721

12,20010707,11:12,-3.82,-62.35333,am03,0.020797,0.02088,0.020632,0.020999,0.020823,0.020882,0.02103,0.021431,0.021456,0.021986,0.0219,0.022215,0.022561,0.022859,0.023184,0.023683,0.02387,0.024577,0.024676,0.024882,0.025489,0.026008,0.026372,0.026739,0.027154,0.027594,0.027952,0.028266,0.028652,0.0289,0.029428,0.029834,0.030382,0.03092,0.031353,0.031844,0.032581,0.033174,0.033668,0.03444,0.035148,0.035838,0.03655,0.03722,0.03806,0.038757,0.039526,0.040528,0.041293,0.042228,0.043172,0.044161,0.044967,0.045897,0.046901,0.047968,0.048985,0.049945,0.050835,0.051796,0.053107,0.054128,0.055082,0.055556,0.056423,0.057597,0.058447,0.05905,0.059473,0.059926,0.059992,0.059546,0.059462,0.059447,0.059363,0.059456,0.059529,0.05963,0.060071,0.060144,0.06051,0.061201,0.061481,0.061517,0.06188,0.062263,0.062279,0.062426,0.063007,0.063148,0.063204,0.062766,0.0625,0.062016,0.061667,0.061408,0.061477,0.061396,0.061286,0.061196,0.06105,0.060962,0.060125,0.059689,0.058703,0.057389,0.055969,0.053892,0.051913,0.049953,0.047161,0.044362,0.041111,0.037765,0.034091,0.029967,0.026368,0.023737,0.021447,0.019689,0.018931,0.018194,0.017679,0.017487,0.017663,0.017647,0.017815,0.017485,0.0173,0.017487,0.017551,0.017916,0.018215,0.018108,0.018652,0.019063,0.019397,0.019516,0.020302,0.020149,0.020426,0.020862,0.020686,0.020177,0.019949,0.019423,0.018286,0.016726,0.015572,0.014385,0.013216,0.012632,0.011876,0.011722,0.011249,0.011295,0.01107,0.010762,0.010695,0.010565,0.01006,0.010068,0.01006,0.009639,0.009256,0.009319,0.009024,0.00885,0.008865,0.008559,0.008718,0.008319

12,20010707,11:30,-3.81667,-62.35639,am04,0.019931,0.020134,0.019987,0.020431,0.020315,0.020418,0.020601,0.020623,0.02069,0.021253,0.021194,0.021531,0.021898,0.022215,0.022566,0.022795,0.023308,0.023784,0.023928,0.024171,0.025034,0.025347,0.025729,0.026112,0.026541,0.026795,0.02717,0.027502,0.027903,0.028159,0.028508,0.029098,0.029641,0.029994,0.030436,0.03112,0.031686,0.032287,0.032787,0.033552,0.034066,0.034928,0.035453,0.036304,0.037145,0.037843,0.038434,0.039443,0.040395,0.04115,0.042088,0.043066,0.044041,0.044773,0.045771,0.04684,0.047681,0.04866,0.049564,0.050532,0.051842,0.052852,0.053783,0.054033,0.054861,0.056207,0.057046,0.057634,0.058042,0.058278,0.058337,0.058089,0.058001,0.057992,0.057696,0.057769,0.057816,0.058107,0.058304,0.058573,0.05869,0.059353,0.059851,0.059873,0.059991,0.060606,0.060628,0.060771,0.061337,0.061461,0.061489,0.061015,0.060714,0.060207,0.059838,0.059555,0.059329,0.059495,0.059371,0.059276,0.059116,0.059004,0.058423,0.05767,0.056648,0.055605,0.054183,0.052395,0.050395,0.048092,0.045557,0.042668,0.039668,0.036224,0.032468,0.028736,0.02517,0.022588,0.020356,0.018653,0.017934,0.017219,0.017036,0.016839,0.016644,0.016544,0.016627,0.016653,0.016878,0.016267,0.016787,0.017185,0.017122,0.017369,0.017891,0.018268,0.018572,0.018668,0.019006,0.019711,0.019538,0.019955,0.019746,0.019685,0.018926,0.018373,0.017241,0.016219,0.015085,0.013921,0.012775,0.012211,0.011466,0.011318,0.010848,0.010488,0.01066,0.010348,0.010284,0.010158,0.009658,0.009666,0.009658,0.009237,0.008853,0.008914,0.008614,0.008428,0.008422,0.008084,0.008205,0.008319

12,20010707,11:45,-3.82083,-62.34861,am07,0.032929,0.032811,0.033527,0.033485,0.03352,0.033411,0.033476,0.033967,0.0341,0.034078,0.034617,0.03486,0.035169,0.035415,0.035858,0.036412,0.036787,0.037262,0.037388,0.037915,0.038462,0.039013,0.039237,0.039691,0.04022,0.040592,0.040852,0.041444,0.04176,0.041867,0.042487,0.043094,0.043535,0.044066,0.044554,0.045232,0.045829,0.046479,0.047241,0.047932,0.048666,0.0493,0.050073,0.050788,0.051601,0.052468,0.053188,0.054279,0.055296,0.056244,0.057262,0.058029,0.05903,0.059948,0.061028,0.062077,0.063327,0.064267,0.064996,0.066234,0.067558,0.068526,0.069733,0.070015,0.070871,0.072294,0.073058,0.073812,0.074392,0.074753,0.075093,0.074745,0.074901,0.075036,0.074984,0.075058,0.075161,0.075517,0.075751,0.076077,0.076433,0.076905,0.077084,0.077483,0.077704,0.078125,0.078084,0.078506,0.078998,0.079055,0.079373,0.07902,0.078827,0.078553,0.078129,0.078084,0.078389,0.07824,0.078249,0.078485,0.078453,0.0783,0.077708,0.07699,0.076313,0.07523,0.074129,0.072156,0.070431,0.06857,0.065768,0.062987,0.059863,0.055877,0.051542,0.046798,0.042749,0.038668,0.035623,0.033851,0.032215,0.031514,0.030858,0.030764,0.030571,0.030882,0.030879,0.030808,0.030802,0.0305,0.030904,0.031079,0.031694,0.031781,0.032356,0.032963,0.03343,0.033517,0.034125,0.034604,0.03508,0.034921,0.035261,0.034449,0.03376,0.032546,0.030825,0.02889,0.026764,0.024594,0.022907,0.021474,0.020475,0.019806,0.018883,0.018556,0.01804,0.017384,0.016865,0.01666,0.016097,0.015707,0.015292,0.014859,0.014487,0.014182,0.013536,0.013485,0.013298,0.012839,0.012821,0.012757

Data Application and Derivation:

These data could be used to determine if a predictive relationship between reflectance factors and chlorophyll concentrations exists for waters with high concentrations of total suspended solids.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Water chemistry:

Accuracy for chlorophyll-a lab analysis was 0.1 mg/m3. Accuracy for determination of total suspended solids and inorganic suspended solids was 0.005 mg/L. Organic suspended solids concentration was calculated as the difference between total suspended solids and inorganic suspended solids. Field and lab manipulations may change DIC concentration of water samples slightly.



Specifications of parameters measured with a routinely calibrated Horiba U-10 water quality meter:



pH: Glass electrode, resolution: 0.01 pH units, repeatability: 0.05 pH units, temperature compensation: 0-50 degrees C.



Conductivity: Alternating four-electrode, resolution: for the range of 0 to 1 uS per cm 0.01 uS per cm, for the range of 1 to 10 uS per cm 0.1 uS per cm and for the range of 10 to 100 uS per cm 1.0 uS per cm, repeatability: plus or minus 1 percent of full scale, temperature compensation: 0-50 degrees C.



Turbidity: Scattering/transmitting light, resolution: 1 NTU, repeatability: plus or minus 3 percent of full scale, temperature compensation: N/A.



Temperature: Thermister, resolution: 0.1 degree C, repeatability: plus or minus 0.3 degrees C, temperature compensation: N/A



Radiometric and wavelength calibration are described at url: snr.unl.edu/agmet/instrument-se590-main.asp.



In addition to the nominal accuracy constraints of Spectron SE-590 and

the calibration of the barium sulphate (BaSO4) plate, variable field

conditions affect water reflectance measurements in ways that are

difficult to determine. Despite the procedures described in the methods

section, which were adopted to minimize interferences, unknown

inaccuracies of water reflectance measurements derive mainly from the

following changes of conditions at the time of sampling: roughness of

water surface, cloud cover movements, and geometry of acquisition

(hand-held operation of the sensor from a boat vessel subject to

movements from wave action). In general, these sources of inaccuracies

produce an additive reflectance effect in the 400 to 900 nm wavelength

range of interest. Rudorff et al. (2007) compared spectral reflectance

of Amazon water bodies measured in the field using a Spectron SE-590 and

an orbital EO-1 Hyperion image.

Process Description:

Data Acquisition Materials and Methods:

Study sites:



Our study was conducted in the central Amazon basin in the low lying varzea of

the Solimoes River (varzea is the local name for floodplain formed by the overflow of white water rivers) and igapo (igapo is the local name for floodplain formed by the overflow of black water rivers) of the Negro River. White water is characteristic of the Solimoes main stem and some of the floodplain lakes connected to the river. They are rich in dissolved and suspended materials drained from the Andes. The black water is the dominant water in the Negro River and it is characterized by a low concentration of suspended and dissolved components, except for a high concentration of dissolved organic carbon.



During July 2000 the Amazon floodplain aquatic systems were sampled to build

a spectral library composed of 60 complete sets (in situ reflectance, water samples for chemical analyses, and in situ water measurements) and 90 incomplete sets (in situ reflectance and in situ water measurements). The main axis of the lake was determined and divided into equidistant segments. The sampling stations were set in places free from bottom effects. At every sampling station, the bidirectional reflectance factor (BRF) was measured from a boat using a portable spectrometer (Spectron SE-590). The sensor collected data in the 400 to 900 nm range at spectral intervals of 3 nm and with a 15 degree field-of-view (FOV) lens attached. A polarized lens was attached to the sensor to correct for sky reflection from the water surface. A barium sulphate (BaSO4) plate of known reflectance was used as reference. The water leaving radiance (Lw) was measured keeping the sun-sensor azimuth at 90 degrees and aiming at the water surface at a 45 degrees zenith angle to reduce sky radiance and the surface reflectance (Steffen et al. 1993). The radiance of the reference panel to a laboratory reflectance standard (Lr) was measured at the same geometry. Each of the sampled spectra was the average of four readings. Water samples were collected at three depths with a Van Dorn bottle and combined before being used for determination of dissolved and suspended components. The following variables were determined from water samples: total suspended solids (mg per L) according to Wetzel and Likens (1991), chlorophyll concentration (mg per m3) according to Nush (1980) and dissolved organic carbon (mg per L) according to APHA (1998). The following in situ measurements were obtained with a Horiba U-10 Water Quality Checker: conductivity, pH and depth. Each sampling station was classified by visual assessment of water colour into three broad classes: white, clear or black. Secchi depth was measured with a white 20 cm Secchi disk.

References:

APHA, 1998, Standard Methods for the Examination of Water and Wastewater, 20 edn

(Washington, DC: American Public Health Association).



Nush, E.A., 1980, Comparison of different methods for chlorophyll and phaeopigment determination. Archiv fur Hydrobiologie, 14, 14-39.



Rudorff, C.M., Novo, E.M.L.M., Galvao, L.S., and Pereira Filho, W. 2007. Analise derivativa de dados hiperespectrais medidos em nivel de campo e orbital para caracterizar a composicao de aguas opticamente complexas na Amazonia.

Acta Amazonica, 37(2), 269 � 280. doi:10.1590/S0044-59672007000200014



Steffen, C., Costa, M.P.F., and Gama, F.F., 1993, Spectral reflectance of Tucuru reservoir waters in the Brazilian Amazon. Proceedings of SPIE, 1937, 103-111.



Wetzel, R.G., and Likens, G.E., 1991, Limnological Analyses (New York: Springer-

Verlag).

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