BOREAS TE-10 Leaf Optical Properties for SSA Species

Summary

The BOREAS TE-10 team collected several data sets in support of its
efforts to characterize and interpret information on the reflectance,
transmittance, gas exchange, oxygen evolution, and biochemical
properties of boreal vegetation. This data set describes the spectral
optical properties (reflectance and transmittance) of boreal forest
conifers and broadleaf tree leaves as measured with a Spectron
Engineering SE590 spectroradiometer at the SSA OBS, OJP, YJP, OA,
OA-AUX, YA-AUX, and YA sites. The data were collected during the growing
seasons of 1994 and 1996 and are stored in tabular ASCII files.

Table of Contents

1\. Data Set/Model Overview

2\. Investigator(s)

3\. Theory of Measurements

4\. Equipment

5\. Data Acquisition Methods

6\. Observations

7\. Data Description

8\. Data Organization

9\. Data Manipulations

10\. Errors

11\. Notes

12\. Application of the Data Set/Model

13\. Future Modifications and Plans

14\. Software

15\. Data Access

16\. Output Products and Availability

17\. References

18\. Glossary of Terms

19\. List of Acronyms

20\. Document Information

1\. Data Set Overview

1.1 Data Set Identification

BOREAS TE-10 1994 and 1996 Leaf Optical Properties for SSA Species

1.2 Data Set Introduction

This data set describes the spectral optical properties (reflectance and
transmittance) of included leaves and needles from boreal forest tree
species as measured with a Spectron Engineering SE590 spectroradiometer
at the BOReal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area
(SSA) Old Black Spruce (OBS), Old Jack Pine (OJP), Young Jack Pine
(YJP), Old Aspen (OA), Old Aspen Auxiliary (OA-AUX), Young Aspen
Auxiliary (YA-AUX), and Young Aspen (YA) sites.

1.3 Objective/Purpose

The purposes of this work were to:

1\) Obtain a canopy profile of needle spectral optical properties.

2\) Examine interspecific and interseasonal differences in these
parameters.

3\) Correlate physiological processes at the leaf/needle level with
optical measurements amenable to remote sensing.

4\) Examine the relationships between the physiological parameters,
especially photosynthesis and conductance rates, and the optical
parameters (fraction of Absorbed Photosynthetically Active Radiation
(fAPAR) and spectral vegetation indices (SVI)).

5\) Parameterize the canopy-level radiative transfer and physiological
models utilized in landscape analyses by other investigators.

1.4 Summary of Parameters and Variables

Hemispherical reflectance (R) and transmittance (T) factors were
measured for needles of various growth years and individual leaves
illuminated at near-normal incidence measured using an external light
source and LI-COR LI-1800-12 integrating sphere attached to a Spectron
Engineering SE590 spectroradiometer.

1.5 Discussion

Hemispherical reflectance and transmittance factors of individual
needles (ages: current year, previous year, 2 years ago, and up to 5
years ago growth) and broadleaf tree leaves (current year) were measured
using a LI-COR LI-1800-12 Integrating Sphere attached to a Spectron
Engineering SE590 spectroradiometer, and the image analysis system. The
SSA sites studied were OBS, OJP, YJP, OA, OA-AUX, YA-AUX, and YA.

1.6 Related Data Sets

BOREAS TE-10 Gas Exchange Data

BOREAS TE-12 Leaf Optical Data for SSA Species

2\. Investigator(s)

2.1 Investigator(s) Name and Title

Dr. Elizabeth Middleton

Project Scientist

Dr. Joseph Sullivan

Assistant Professor

2.2 Title of Investigation

CO~2~ and Water Fluxes in the Boreal Forest Overstory: Relationship to
fAPAR and Vegetation Indices for Needles/Leaves

2.3 Contact Information

[Contact 1]{.underline}:

Stephen S. Chan

Biospheric Sciences Branch

NASA GSFC

Greenbelt, MD

\(301\) 286-2386

sailun@ltpmail.gsfc.nasa.gov

[Contact 2]{.underline}:

Dr. Elizabeth Middleton

Biospheric Sciences Branch

NASA GSFC

Greenbelt, MD

\(301\) 286-8344

\(301\) 286-0239 (fax)

betsym@ltpmail.gsfc.nasa.gov

[Contact 3]{.underline}:

Andrea Papagno

Raytheon STX Corporation

NASA GSFC

Greenbelt, MD

\(301\) 286-3134

\(301\) 286-0239 (fax)

apapagno@pop900.gsfc.nasa.gov

[Contact 4]{.underline}:

Shelaine Curd

Raytheon STX Corporation

NASA GSFC

Greenbelt, MD

\(301\) 286-2447

\(301\) 286-0239 (fax)

shelaine.curd@gsfc.nasa.gov

3\. Theory of Measurements

Leaves, needles, and bark are canopy elements that are important in
scattering radiation in boreal forest vegetation (Norman and Jarvis,
1974). Needle and bark properties can vary considerably depending on age
and height in the canopy; elements deep in the canopy may be covered
with algae and fungi, and shade-induced effects on shoot development may
exist (Norman and Jarvis, 1974; Smith and Carter, 1988). In the
near-infrared portion of the electromagnetic spectrum, little radiation
is absorbed; thus, scattering by canopy elements will be significant. In
contrast, leaves and needles absorb a large portion of PAR (Daughtry et
al., 1989; Williams, 1991). Conifer needles absorb more PAR than
deciduous leaves; twigs, especially the current year\'s growth, also
absorb PAR (Williams, 1991). Thus, the scattering component of PAR may
be small except in sparse canopies with high underlying surface albedo.

4\. Equipment

4.1 Sensor/Instrument Description

The Spectron Engineering SE590 is a portable battery-operated
spectroradiometer consisting of a CE500 data analyzer/logger controller,
CE390 spectral detector head, and an external battery charger/power
supply. The CE500 is a self-contained microprocessor-based controller
that processes the signal from the detector head, amplifying and
digitizing it with 12-bit resolution. For each spectral scan, the
controller actuates the CE390 shutter, measures and stores the dark
current, calculates optimum integration time, acquires the spectrum, and
automatically subtracts the noise for all 256 spectral elements. Each
scan was recorded individually. The entire 12-bit binary spectrum is
stored in a double-precision register until it is transmitted through
the RS-232C port. The spectral detector head uses a diffraction grating
as the dispersive element; the spectrum is imaged onto a 256-element
photodiode array. Each element integrates simultaneously, acquiring the
spectrum in a fraction of a second. The interconnect cable from the
spectral head to the controller couples the spectral signals to the
controller and the timing and control signals to the detector head. A
shutter in the detector head, operated by the controller, closes the
light path for dark current measurements. For further information,
consult the SE590 operating manual. The serial numbers for the SE590s
used in 1994 and 1996 are 2071 and 1051, respectively.

The LI-COR LI-1800-12 integrating sphere is an instrument for collecting
radiation that has been reflected from or transmitted through a sample
material. An external light source illuminates a spot on the sample. A
standard light source (11.4-mm diameter) and a modified light source
that restricts the illumination spot size (3.5-mm x 11-mm) were used.
The lamp used in the external light source is a 6-Volt 10-Watt
glass-halogen. For a further description, see the LI-COR Integrating
Sphere Instruction Manual. Serial Number 2071 was used in 1994, and 1051
was used in 1996..

An image analysis system was used to measure the gaps between sample
elements (e.g., needles) when a sample did not fill the entire
integrating sphere sample port or a single sample element was too narrow
to be completely encompassed by the modified light source.

The image analysis system included a black-and-white (B/W)
charge-coupled device (CCD) video camera, a monochrome frame-grabber
board, an IBM PC-compatible laptop unit with docking station, a light
table, and a video monitor display with full 640 x 480 pixel^2^ spatial
resolution and 256 gray levels. This system was used to determine gap
fraction per sample, defined as the ratio of needle gap area to that of
the total illuminated area within the aperture (round or slitted) of a
precision reference template placed on a light table as viewed from
above by the camera. The template, a small metal disk, was viewed alone
and the area measured. then the template was viewed with the sample on
top of it and the area left uncovered by the needles was measured. so
the ratio of the gap area to total area makes the gap fraction. Software
for image capture was \"Computer Eyes/RT\" (Digital Vision, Inc.,
Dedham, MA) and for processing was \"Mocha\" (SPSS, Inc., Chicago, IL).
Appropriate calibration procedures were used: a) for the area of a
standard template, each sample; b) for the stray light/dark current
scans per measurement set; and c) for the wavelength stability of the
radiometer and its spectral radiance coefficients.

A monochrome frame-grabber board (UM-08128-B) was used to input the
signal from the camera into an IBM-compatible laptop computer with a
docking station. SPSS Inc.'s software Mocha ver. 2.0 was used to measure
the areas of the incident light source beams and gaps. The display
monitor was an IBM VGA with 640- by 480-pixel resolution.

4.1.1 Collection Environment

The vertical profile of the canopy was divided into three layers: top,
middle, and bottom. Measurements were taken at the SSA OBS (Picea
mariana), OJP (Pinus banksiana and Apocynum androsaemifolium), YJP
(Pinus banksiana), YA (Populus tremuloides and Corylus cornuta Marsh),
OA (Populus tremuloides and Corylus cornuta Marsh), OA-AUX (Populus
tremuloides and Corylus cornuta Marsh), and YA-AUX (Populus tremuloides
and Corylus cornuta Marsh and Picea glauca). At the OBS, OA, OA-AUX, and
OJP sites, sample collection was made from canopy access towers
constructed onsite by BOREAS staff. At the YJP, YA, and YA-AUX sites,
collection was accomplished from the ground. Collection of hazelnut
understory was also accomplished from the ground. In 1994, data were
obtained during three discrete measurement periods (1 to 2 days each
period) designated by BOREAS as Intensive Field Campaigns (IFCs) (IFC-1,
-2, -3). In 1994, these IFCs were selected to measure parameters at bud
breaks and leaf expansion (24-May to 12-Jun), during midsummer or peak
growing season (26-Jul to 08-Aug) and at the onset of dormancy or
senescence in autumn (30-Aug to 15-Sep). In 1996, collection dates did
not necessarily coincide with any official IFCs. In 1994, the samples
were measured individually. The period of measurement in 1996 was during
July. On collection/observation day 14-Jul-1996, the 1992 and 1993
samples were combined and the 1994 and 1995 samples were combined.
Branch tips measured were excised from the trees and sealed in plastic
bags with moist towels. After collection, samples were refrigerated
until the measurements were conducted in the room-temperature field
laboratory.

4.1.2 Source/Platform

During these measurements, the spectroradiometer and the integrating
sphere were mounted on a tripod in the laboratory.

4.1.3 Source/Platform Mission Objectives

Not applicable.

4.1.4 Key Variables

Adaxial and abaxial spectral reflectance and transmittance. For both
broadleaves and conifer needles, the designation of foliar surfaces as
either adaxial (dorsal or upper) or abaxial (ventral or underside) is
made on an anatomical basis (Esau, 1977). For broadleaves (both dicots
and monocots), the adaxial (dorsal) surface is the one adjacent to the
palisade mesophyll layer, and the abaxial (ventral) surface is adjacent
to the spongy mesophyll layer. For conifers, the adaxial surface is the
flat (or less curved) facet whose surface lies closest to the xylem at
the needle core, while the abaxial surface is the typically more curved
and opposite facet whose surface lies closest to the phloem at the
needle core.

4.1.5 Principles of Operation

The SE590 spectral detector head uses a diffraction grating as the
dispersive element; the spectrum is imaged onto a 256-element photodiode
array. Each element integrates simultaneously, acquiring the spectrum in
a fraction of a second.

The LI-COR LI-1800-12 integrating sphere is an external integrating
sphere, which means that the sample is external to the sphere; when the
sample is in place, a small part of the sample actually makes up part of
the sphere wall. For further information, see the LI-COR 1800-12
Integrating Sphere Instruction Manual.

The CCD camera transmits a signal to the frame-grabber board, which
translates the intensity of each pixel to a gray scale from 0 (black) to
255 (white) levels. The Mocha software program was set up to count the
number of pixels in a defined area of interest for a range of gray
scales that represent the \"white\" gaps between the sample elements.
The white threshold was determined by adjusting the threshold so that a
standard size (area) reference template actually registered the correct
area.

4.1.6 Sensor/Instrument Measurement Geometry

All instrumentation took place under laboratory conditions. The SE590
was mounted on top of the LI-COR LI-1800-12 integrating sphere. A tripod
was attached to the support connecting the SE590 and integrating sphere.
A modified external light source with a slitted beam (3.5 mm x 11 mm)
was used to illuminate narrow samples and associated reference. A
standard external light source with a circular beam (11.4-mm diameter
spot size) was used to illuminate all other samples and associated
reference. The light source was kept in a horizontal position according
to integrating sphere manual requirements.

4.1.7 Manufacturer of Sensor/Instrument

Spectron Engineering SE590 Spectroradiometer:

Spectron Engineering, Inc.

25 Yuma Court

Denver, CO 80223

\(303\) 733-1060

LI-COR LI-1800-12 Integrating Sphere:

LI-COR, Inc.

Box 4425

Lincoln, NE 68504

\(402\) 467-3567

B/W CCD WVBL200 Video Camera

Panasonic

MOCHA Software (ver. 2.0):

SPSS, Inc.

233 S. Wacker Drive

11th Floor

Chicago, IL 60606-6307

1 (800) 543-2185

1 (800) 841-0064 (fax)

4.2 Calibration

Appropriate calibration procedures were used: a) for the area of a
standard template, each sample; b) for the stray light/dark current
scans per measurement set; and c) for the wavelength stability of the
radiometer and its spectral radiance coefficients.

4.2.1 Specifications

Each SE590 has a unique wavelength associated with each of its 252
bands. A cubic spline interpolation was applied to the 252 bands to
standardize the wavelengths to every 5 nm from 400 to 1000 nm, so that
wavelength-to-wavelength comparisons can be made among SE590s.

4.2.1.1 Tolerance

None given.

4.2.2 Frequency of Calibration

The SE590s were calibrated against Hg and Ar vapor lamps before and
after each IFC or collection session.

4.2.3 Other Calibration Information

For 1994:

Wavelengths, in nanometers, and their corresponding channels (ch), used
for data reduction.

Wavelength Characterization (nm) for BOREAS Terrestrial Ecology (TE)-10
SE590 on 31-May-1994 by NASA GSFC (SE590 serial number 2071):

channel wavelength ch. wavelength ch. wavelength ch. wavelength

\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-- \-\-- \-\-\-\-\-\-\-\-\-- \-\--
\-\-\-\-\-\-\-\-\-- \-\-- \-\-\-\-\-\-\-\-\--

1 359.6461 64 534.7401 127 721.4871 190 919.8871

2 362.3343 65 537.6133 128 724.5453 191 923.1302

3 365.0255 66 540.4895 129 727.6064 192 926.3763

4 367.7196 67 543.3686 130 730.6705 193 929.6253

5 370.4167 68 546.2506 131 733.7374 194 932.8773

6 373.1167 69 549.1355 132 736.8074 195 936.1322

7 375.8196 70 552.0235 133 739.8803 196 939.39

8 378.5255 71 554.9143 134 742.9561 197 942.6508

9 381.2343 72 557.8081 135 746.0348 198 945.9145

10 383.9461 73 560.7048 136 749.1165 199 949.1812

11 386.6607 74 563.6044 137 752.2011 200 952.4508

12 389.3783 75 566.507 138 755.2886 201 955.7233

13 392.0989 76 569.4125 139 758.3791 202 958.9987

14 394.8224 77 572.321 140 761.4726 203 962.2771

15 397.5488 78 575.2324 141 764.5689 204 965.5584

16 400.2782 79 578.1467 142 767.6682 205 968.8427

17 403.0105 80 581.064 143 770.7704 206 972.1299

18 405.7457 81 583.9841 144 773.8756 207 975.42

19 408.4838 82 586.9073 145 776.9837 208 978.7131

20 411.225 83 589.8334 146 780.0947 209 982.0091

21 413.969 84 592.7624 147 783.2087 210 985.3081

22 416.716 85 595.6943 148 786.3256 211 988.6099

23 419.4659 86 598.6292 149 789.4455 212 991.9147

24 422.2187 87 601.567 150 792.5683 213 995.2225

25 424.9745 88 604.5077 151 795.694 214 998.5332

26 427.7332 89 607.4514 152 798.8226 215 1001.846

27 430.4949 90 610.3981 153 801.9542 216 1005.163

28 433.2595 91 613.3476 154 805.0887 217 1008.482

29 436.027 92 616.3001 155 808.2262 218 1011.805

30 438.7975 93 619.2555 156 811.3666 219 1015.13

31 441.5708 94 622.2139 157 814.5099 220 1018.459

32 444.3472 95 625.1752 158 817.6562 221 1021.79

33 447.1265 96 628.1394 159 820.8054 222 1025.124

34 449.9087 97 631.1066 160 823.9576 223 1028.461

35 452.6938 98 634.0767 161 827.1126 224 1031.801

36 455.4819 99 637.0498 162 830.2706 225 1035.144

37 458.2729 100 640.0258 163 833.4316 226 1038.49

38 461.0668 101 643.0047 164 836.5955 227 1041.839

39 463.8637 102 645.9865 165 839.7623 228 1045.191

40 466.6636 103 648.9713 166 842.9321 229 1048.545

41 469.4663 104 651.959 167 846.1048 230 1051.903

42 472.272 105 654.9497 168 849.2804 231 1055.264

43 475.0806 106 657.9433 169 852.4589 232 1058.627

44 477.8922 107 660.9398 170 855.6405 233 1061.994

45 480.7067 108 663.9393 171 858.8249 234 1065.363

46 483.5241 109 666.9417 172 862.0123 235 1068.735

47 486.3445 110 669.9471 173 865.2026 236 1072.111

48 489.1678 111 672.9553 174 868.3958 237 1075.489

49 491.9941 112 675.9665 175 871.592 238 1078.87

50 494.8233 113 678.9807 176 874.7911 239 1082.254

51 497.6554 114 681.9978 177 877.9932 240 1085.641

52 500.4904 115 685.0178 178 881.1982 241 1089.031

53 503.3284 116 688.0408 179 884.4061 242 1092.424

54 506.1693 117 691.0667 180 887.617 243 1095.82

55 509.0132 118 694.0955 181 890.8307 244 1099.219

56 511.86 119 697.1272 182 894.0475 245 1102.62

57 514.7097 120 700.162 183 897.2672 246 1106.025

58 517.5624 121 703.1996 184 900.4898 247 1109.432

59 520.418 122 706.2402 185 903.7153 248 1112.843

60 523.2766 123 709.2837 186 906.9438 249 1116.256

61 526.138 124 712.3301 187 910.1752 250 1119.673

62 529.0024 125 715.3795 188 913.4095 251 1123.092

63 531.8698 126 718.4318 189 916.6468 252 1126.514

For 1996:

Wavelengths, in nanometers, and their corresponding channels, used for
data reduction.

Wavelength Characterization (nm) for BOREAS TE-10 SE590 on 19-May-1996
by NASA GSFC (SE590 serial number 1051):

ch. wavelength ch. wavelength ch. wavelength ch. wavelength

\-\-- \-\-\-\-\-\-\-\-\-- \-\-- \-\-\-\-\-\-\-\-\-- \-\--
\-\-\-\-\-\-\-\-\-- \-\-- \-\-\-\-\-\-\-\-\--

1 360.1405 64 535.3193 127 722.5816 190 921.0249

2 362.9569 65 537.9889 128 725.6702 191 923.5632

3 366.4362 66 541.1645 129 727.8751 192 926.5912

4 369.2162 67 543.9707 130 730.7025 193 931.4050

5 370.6827 68 546.2993 131 734.3596 194 934.4142

6 373.5435 69 549.7904 132 737.8586 195 936.2727

7 376.1163 70 552.4260 133 740.2515 196 939.8535

8 378.7204 71 555.3782 134 743.3154 197 942.9930

9 382.4035 72 558.2172 135 747.1053 198 947.1103

10 385.6378 73 561.9365 136 750.4144 199 949.8366

11 387.9678 74 564.9579 137 752.2017 200 952.7264

12 389.4546 75 567.6845 138 755.3228 201 956.8641

13 392.1760 76 569.5253 139 759.0406 202 959.8645

14 395.1965 77 573.2707 140 763.4584 203 963.1107

15 397.7772 78 575.2397 141 764.6765 204 967.0283

16 400.4819 79 579.1161 142 768.4408 205 969.6374

17 403.0910 80 581.6889 143 771.3158 206 973.4302

18 406.1777 81 585.3271 144 774.3496 207 976.1201

19 409.4557 82 587.1065 145 777.1546 208 978.8361

20 411.9212 83 590.0847 146 781.1493 209 983.2477

21 414.6198 84 594.0846 147 784.5945 210 985.5351

22 417.5016 85 596.4154 148 786.4127 211 990.1134

23 420.2417 86 598.7330 149 789.8508 212 993.0454

24 423.4704 87 601.8935 150 792.8632 213 995.8198

25 426.7591 88 604.8884 151 795.7158 214 999.0036

26 429.4513 89 608.6492 152 800.2796 215 1002.6315

27 430.5617 90 610.9973 153 802.2711 216 1005.7451

28 433.8799 91 613.6475 154 805.7332 217 1009.4871

29 436.2423 92 617.6015 155 809.1172 218 1013.0036

30 439.8257 93 619.5585 156 811.5326 219 1015.9353

31 442.8191 94 622.6438 157 815.6465 220 1019.1051

32 445.1902 95 625.6931 158 817.9621 221 1021.9994

33 447.2221 96 629.0358 159 821.7254 222 1025.8942

34 450.4475 97 631.4492 160 824.7415 223 1028.6137

35 453.6972 98 634.8992 161 828.5148 224 1032.6801

36 455.8462 99 637.0956 162 830.6718 225 1035.4542

37 458.9906 100 640.1055 163 834.1582 226 1038.6841

38 462.2092 101 643.4478 164 837.6238 227 1042.0068

39 465.0868 102 646.6421 165 840.2246 228 1045.3784

40 467.5963 103 649.7776 166 842.9457 229 1049.1268

41 469.4833 104 651.9899 167 847.2484 230 1051.9782

42 472.7325 105 655.1663 168 849.3214 231 1055.3909

43 475.9141 106 659.8316 169 852.6053 232 1059.2382

44 479.0778 107 661.3675 170 856.0376 233 1063.5007

45 480.9206 108 664.0426 171 859.6738 234 1066.2681

46 483.5598 109 667.6396 172 863.4929 235 1068.9670

47 487.3832 110 670.2188 173 865.7373 236 1073.9716

48 489.9419 111 673.0377 174 868.4055 237 1075.6882

49 492.1505 112 677.4711 175 872.3803 238 1079.6127

50 495.6179 113 679.6326 176 875.2328 239 1083.1027

51 497.7992 114 682.0668 177 879.0570 240 1086.6284

52 500.9829 115 686.0143 178 881.4289 241 1089.3537

53 504.4008 116 688.6492 179 885.2314 242 1092.7966

54 506.7443 117 691.6828 180 888.7613 243 1096.3125

55 509.7821 118 694.6542 181 892.0937 244 1099.3362

56 512.6732 119 698.4924 182 895.2754 245 1104.0854

57 514.8358 120 700.9617 183 897.2797 246 1106.1711

58 518.5168 121 703.7869 184 901.5139 247 1109.6832

59 520.9057 122 706.4359 185 903.9839 248 1113.4952

60 524.6469 123 709.6463 186 907.1931 249 1117.2942

61 526.8958 124 712.4398 187 910.2802 250 1120.0276

62 529.1754 125 716.6992 188 913.4571 251 1123.8413

63 532.3863 126 719.1289 189 916.9567 252 1127.0125

5\. Data Acquisition Methods

Measurements were made on aspen and hazelnut leaves obtained from the
upper and lower canopy layers of the tree overstories. At the sites,
branches were accessed from canopy access towers erected by BOREAS
Staff. Stray light was measured at the beginning of each day and/or with
each light source used. The color of the leaves was coded using the
Munsell color chips (Munsell, 1977) prior to optical measurements. The
method of sample measurement is described below:

The sample element filled the integrating sphere sample port. Procedures
for optical property measurements are described by Daughtry et al.
(1989). Individual leaves or stems were cut from the plant. The needles
remained attached to the stem during the measurement. Each leaf or
needles measured was inserted into the integrating sphere sample port
with the adaxial (top) surface facing the inside of the sphere. Three
measurements followed: 1) light reflected from the reference for the
adaxial surface, 2) light reflected from the adaxial surface, and 3)
light transmitted through the abaxial (bottom) surface. The sample was
removed from the sample port and reinserted so that the abaxial surface
faced the inside of the sphere; the sample was arranged so that the same
portion of the sample was measured. Three additional measurements
followed: 1) light transmitted through the adaxial surface, 2) light
reflected from the abaxial surface, and 3) light reflected from the
reference for the abaxial surface. All samples were illuminated with the
standard external light source. Because of the difficulty in measuring
needle samples, some transmittance values in the visible spectrum were
calculated to be negative and were not indicative of true values. The
methodology used for correcting the transmittance values is given in
Section 9.1.1. For further information and indepth explanation regarding
transmittance correction technique, please refer to Middleton et al.
(IGARSS 1996).

6\. Observations

6.1 Data Notes

None given.

6.2 Field Notes

None given.

7\. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

Samples were taken from the top, middle and bottom of the canopy as
indicated in the CANOPY_LOCATION parameter in the data sets. The OJP,
OA, and OBS samples were obtained with the aid of canopy access towers
located at the OJP, OA, OA-AUX, and OBS sites. The SSA measurement sites
and associated North American Datum of 1983 (NAD83) coordinates are:

OBS canopy access tower located at the flux tower site, site id G8I4T,
Lat/Long: 53.98717 N, 105.11779 W, Universal Transverse Mercator (UTM)
Zone 13, N:5,982,100.5 E;492,276.5.

OA canopy access tower located 100 m up the path to the flux tower site,
site id C3B7T, Lat/Long: 53.62889 N, 106.19779 W, UTM Zone 13,
N:5,942,899.9 E:420,790.5.

OA-AUX was the canopy access tower located by the trailhead/parking area
for the path leading to the flux tower at site id C3B7T, Lat/Long:
53.62889 N, 106.19779 W, UTM Zone 13, N:5,942,899.9 E:420,790.5. This
SSA-OA-AUX site was farther up the path than SSA-OA from the flux tower
site.

OJP canopy access tower flux tower site, site id G2L3T, Lat/Long:
53.91634 N, 104.69203 W, UTM Zone 13, N:5,974,257.5 E:520,227.7.

YA canopy access tower, site id D0H4T, Lat/Long: 53.65601 N, 105.32314
W, UTM Zone 13, N:5,945,298.9, E:478,644.1.

YJP near flux tower site, site id F8L6T, Lat/Long: 53.87581 N, 104.64529
W, UTM Zone 13, N:5,969,762.5 E:523,320.2.

YA-AUX site id D6H4A, Lat/Long: 53.708 N, 105.315 W, UTM Zone 13, N:
5,951,112.1 E: 479,177.5 near the Snow Castle Lodge.

Please note that at YA-AUX black spruce, jack pine, aspen, balsam fir,
balsam poplar, tamarack, hazelnut, and several other shrub and
herbaceous species were also present.

7.1.2 Spatial Coverage Map

Not available.

7.1.3 Spatial Resolution

The measurements were obtained from single leaves and needles collected
from sample trees near the coordinates given in Section 7.1.1.

7.1.4 Projection

Not applicable.

7.1.5 Grid Description

Not applicable.

7.2 Temporal Characteristics

Preparation for measurement took 5 minutes per broadleaf sample and 10
minutes per conifer sample. The measurements for each sample took under
5 minutes. Samples were stored for 2 to 3 hours in the refrigerator.

7.2.1 Temporal Coverage

In 1994, data were collected from 24-May to 15-Sep. In 1996, data were
collected from 11 to 16-Jul.

7.2.2 Temporal Coverage Map

Samples were collected from 8:00 a.m. to 3:00 p.m. on the following days
in 1994:

Site IFC-1 IFC-2 IFC-3

\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\--

SSA-OBS 02-Jun-1994 29-Jul-1994 15-Sep-1994

SSA-OJP 01-Jun-1994 23-Jul-1994 08-Sep-1994

SSA-YJP 28-May-1994 23-Jul-1994 09-Sep-1994

SSA-YA-AUX N/A 31-Jul-1994 12-Sep-1994

SSA-OA 24-May-1994 20-Jul-1994 14-Sep-1994

29-May-1994

09-Jun-1994

SSA-YA 25-May-1994 29-Jul-1994 01-Sep-1994

03-Jun-1994 11-Sep-1994

SSA-OA-AUX N/A 20-Jul-1994 01-Sep-1994

For 1996:

Samples were collected from 8:00 a.m. to 3:00 p.m. on the following days
in 1996:

Site Dates

\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\--

SSA-OBS 15-Jul-1996

SSA-OJP 12-Jul-1996

SSA-YJP 13-Jul-1996 and 16 Jul-1996

SSA-YA-AUX 11-Jul-1996

7.2.3 Temporal Resolution

None given.

7.3 Data Characteristics

Data characteristics are defined in the companion data definition file
(te10lopt.def).

7.4 Sample Data Record

Sample data format shown in the companion data definition file
(te10lopt.def).

8\. Data Organization

8.1 Data Granularity

All of the TE-10 Leaf Optical Properties for SSA Species are contained
in one dataset.

8.2 Data Format(s)

The data files contain a series of numerical and character fields of
varying length separated by commas. The character fields are enclosed in
single quotation marks. There are no spaces between the fields. Sample
data records are shown in the companion data definition file
(te10lopt.def).

9\. Data Manipulations

9.1 Formulae

In the formulas below, for leaf samples, the leaf would cover the whole
area of the aperture resulting in a zero gap fraction and negating that
term in the equation.

For 1994, these formulae were used for both conifers and broadleafs:

(Fr-Fn) Rr

reflectance = \-\-\-\-\-\-- \* \-\-- \[1\]

(Fwr-Fn) G3

Ft Rr

transmittance = \-\-\-\-\-\-- \* \-\-- \[2\]

(Fwt-Fn) G3

where

Fr = flux measured in reflectance mode

Ft = flux measured in transmittance mode

Fn = flux measured in reflectance mode with no sample

Fwr, Fwt = flux measured in reference mode for side of leaf illuminated
during reflectance and transmittance measurements, respectively

Rr = reflectance of BaSO~4~ reference surface

G3 = function of sphere reflectance and geometry and

sample reflectance

For 1996, these formulae were used for both conifers and broadleafs:

REFLECTANCE

(RT-STR) 1

Adaxial: RC(top)=\[\-\-\-\-\-\-\-\--\]\*\-\-\-\-\--\*100 \[3\]

(RFT-STR) (1-GF)

(RB-STR) 1

Abaxial: RC(bottom)=\[\-\-\-\-\-\-\--\]\*\-\-\-\-\--\*100 \[4\]

(RFB-STR) (1-GF)

TRANSMITTANCE

TT w\*GF 1 \[5\]

Adaxial: TC(top)=\[\-\-\-\-\-\-\-\-- - \-\-\-\-\-\--\]\*\-\-\-\-\--\*100
(Old Formula)

(RFB-STR) (X-STR) (1-GF)

TT w\*GF 2 \[6\]

TC(top)={\-\-\-\-\-\-\-\-- - \[\-\-\-\-\-\--\] }\*100 (Revised Formula)

(RFB-STR) (X-STR)

TT w\*GF 2 1 \[7\]

TC(top)={\-\-\-\-\-\-\-\-- - \[\-\-\-\-\-\--\] }\*\-\-\-\-\--\*100
(Revised Formula-2)

(RFB-STR) (X-STR) (1-GF)

TB w\*GF 1 \[8\]

Abaxial: TC(bottom)=\[\-\-\-\-\-\-\-\-- -
\-\-\-\-\-\--\]\*\-\-\-\-\--\*100 (Old Formula)

(RFT-STR) (X-STR) (1-GF)

TB w\*GF 2 \[9\]

TC(bottom)={\-\-\-\-\-\-\-\-- - \[\-\-\-\-\-\--\] }\*100 (Revised
Formula)

(RFT-STR) (X-STR)

TB w\*GF 2 1 \[10\]

TC(bottom)={\-\-\-\-\-\-\-\-- - \[\-\-\-\-\-\--\]
}\*\-\-\-\-\--\*100(Revised Formula-2)

(RFT-STR) (X-STR) (1-GF)

Parameters:

GF gap fraction

RC corrected reflectance

RFB observed reference standard bottom (adaxial)

RFT observed reference standard top (abaxial)

RB observed reflectance bottom (side of needle surface)

RT observed reflectance top (side of needle surface)

STR observed stray light in reflectance mode

TC corrected transmittance

TB observed transmittance bottom (side of needle surface)

TT observed transmittance top (side of needle surface)

w observed sphere wall reflectance

9.1.1 Derivation Techniques and Algorithms

The corrected transmittance is a function of three parameters: the
original calculated transmittance, gap fraction, and slope.

CALIBRATION DATA SET

In order to obtain values for the slope parameter, calibration data sets
of conifer needles were taken in 1994 and 1996 at the sites in the SSA,
located in the general vicinities of Candle Lake and Nipowan,
Saskatchewan, Canada. Optical properties of the needles were then
measured with varying gap fractions. Calibration data sets were compiled
using gap fractions varying from approximately 0%-45%. The spectral
regions associated with the greatest absorption (e.g., chlorophyll) were
found to be most affected: negative transmittances were calculated in
the visible for virtually all gap fractions, for these needles.

GAP FRACTION

Unlike broadleaves, conifer needles are unable to occupy the entire
aperture of the measuring device. Therefore, a certain percentage of
energy is allowed to pass beyond the sample to the measuring device,
without being disturbed by the physical properties of the needle. This
percentage is the gap fraction parameter, which is the percentage of
aperture uncovered by needles. Gap fraction was calculated for all the
conifer needle samples. Preliminary analysis suggested that the effect
of the gap fraction on leaf optical properties was a function of energy
wavelength. In other words, gap fraction affected properties at higher
percentages in the visible spectrum than in the near-infrared spectrum,
implying the need for another parameter.

SLOPE for 1994

In order to obtain values for the slope parameter, a calibration data
set of conifer needles was taken at sites in the SSA. Optical properties
of the needles were then measured with varying gap fractions and similar
techniques as used for the three IFCs. The spectral regions associated
with the greatest absorption (e.g., chlorophyll) were found to be most
affected: negative transmittance were calculated in the visible for
virtually all gap fractions, for these needles. The measured
transmittance is linearly related to gap fraction, and the regression
coefficients of these relationships was used as the slope parameter.

SLOPE for 1996

Slope is calculated by using the transmittance data from the calibration
data sets. The measured transmittance is linearly related to gap
fraction, and the regression coefficients of these relationships was
used as the slope parameter. It was deemed unnecessary to use any
correction below a 17% gap fraction.

CORRECTED TRANSMITTANCE

The corrected transmittance values were then calculated as the product
of gap fraction and slope, subtracted from the original calculated
transmittance.

(Corrected T) = (Measured T) - (Gap Fraction \* Slope) \[11\]

9.2 Data Processing Sequence

9.2.1 Processing Steps

None given.

9.2.2 Processing Changes

None given.

9.3 Calculations

None given.

9.3.1 Special Corrections/Adjustments

Because different procedures were used in 1996 by the instrument
operator, a correction was applied to the 1996 black spruce data to make
them consistent with all the other data collected in 1994 and 1996.
During all but the 1996 black spruce collection sessions, the
integrating sphere was empty during referencing procedures. In 1996, an
empty sample holder was in place on the integrating sphere at all times,
including when the initial reference measurements were made.

Having the empty sample holder in place during the initial referencing
procedures in the 1996 black spruce sessions resulted in a reduction of
black spruce reflectance values. This affected the black spruce data due
to the very small needle size which necessitated the use of the sample
holder with the slitted aperture. To normalize the 1996 black spruce
data with the other data collected in 1994 and 1996, an offset value was
calculated by using a ratio of stray light from the wall (STRW) to the
stray light from the sample (STRS), which was then applied to the data.
The offset value for black spruce was calculated by:

\[12\]

(STRW/STRS ratio of 1996 jack pine data)/(STRW/STRS ratio of 1996 black
spruce data) = offset for the 1996 black spruce data.

9.3.2 Calculated Variables

None given.

9.4 Graphs and Plots

None given.

10\. Errors

10.1 Sources of Error

During the 1996 summer collection session, a slightly different data
acquisition methodology was used which resulted in a reduction of black
spruce reflectance values. An empty sample holder was in place within
the integrating sphere at all times, including during the initial
reference-taking steps. Previously, the sample holder was absent while
referencing. This affected only the black spruce data because of the
very small needle size, which necessitated the use of the sample holder
with the slitted aperture. To normalize the 1996 summer session black
spruce data with the other data from 1994 and 1996, an offset value was
calculated by using a ratio of the STRW/STRS from the 1996 black spruce
data and the STRW/STRS from the 1996 jack pine data, which was then
applied to the data. The offset was calculated using:

(STRW/STRS ratio of 1996 jack pine data)/(STRW/STRS ratio of 1996 black
spruce data) = offset for the 1996 black spruce data.

10.2 Quality Assessment

10.2.1 Data Validation by Source

Comparisons were made with other BOREAS results and with published
results.

10.2.2 Confidence Level/Accuracy Judgment

In 1994, the methods used during IFC-1 produced some minor distortions
in the data that were not totally eliminated by postcollection
processing, resulting in an 80% confidence level in IFC-1 data.
Revisions in techniques and streamlining of sample collection and
measurement methods were implemented as needed. These occurred mainly
during IFC-1, which acted as TE-10\'s learning phase. Therefore,
confidence in IFC-2 and IFC-3 data is much stronger, with a degree of
reliability greater than 90%.

10.2.3 Measurement Error for Parameters

None given.

10.2.4 Additional Quality Assessments

Calculated results were plotted, and the plots were compared with those
from published papers.

10.2.5 Data Verification by Data Center

Data were examined for general consistency and clarity.

11\. Notes

None given.

11.1 Limitations of the Data

None given.

11.2 Known Problems with the Data

Because of the difficulty in measuring needle samples, some
transmittance values in the visible spectrum measured negative and were
not indicative of true values.

11.3 Usage Guidance

None given.

11.4 Other Relevant Information

In 1996, the small size and quantity of black spruce needles present on
the trees sampled, because of low production, necessitated combining two
age classes of needles in several instances to achieve a large enough
sample size.

Acknowledgment of other research staff who assisted in this study:

Scott K. Mitchell, UMD Undergraduate Student

Robert J. Rusin, UMD Undergraduate Student

David A. Shirey, UMD Graduate Student

12\. Application of the Data Set

This data set will be of interest to investigators undertaking data
comparisons and integrations, and parameterization or validation of
canopy models requiring leaf-level optical information at these and
similar sites.

13\. Future Modifications and Plans

None given.

14\. Software

14.1 Software Description

Computer Eyes /RT (Digital Vision, Inc., Dedham, MA)

Custom software developed by M.A. Mesarch of UNL

Excel 5.0 for Windows (Microsoft)

Mocha (SPSS, Inc., Chicago, IL)

Systat 6.0 (SPSS, Inc., Chicago, IL)

14.2 Software Access

None given.

15\. Data Access

15.1 Contact for Data Center/Data Access Information

These BOREAS data are available from the Earth Observing System Data and
Information System (EOS-DIS) Oak Ridge National Laboratory (ORNL)
Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is:

ORNL DAAC User Services

Oak Ridge National Laboratory

\(865\) 241-3952

ornldaac@ornl.gov

ornl@eos.nasa.gov

15.2 Procedures for Obtaining Data

BOREAS data may be obtained through the ORNL DAAC World Wide Web site at
http://www-eosdis.ornl.gov/ or users may place requests for data by
telephone, electronic mail, or fax.

15.3 Output Products and Availability

Requested data can be provided electronically on the ORNL DAAC\'s
anonymous FTP site or on various media including, CD-ROMs, 8-MM tapes,
or diskettes.

The complete set of BOREAS data CD-ROMs, entitled \"Collected Data of
the Boreal Ecosystem-Atmosphere Study\", edited by Newcomer, J., et al.,
NASA, 1999, are also available.

16\. Output Products and Availability

16.1 Tape Products

None

16.2 Film Products

None.

16.3 Other Products

Tabular American Standard Code for Information Interchange (ASCII)
files.

17\. References

17.1 Platform/Sensor/Instrument/Data Processing Documentation

LI-COR LI-1800-12 Integrating Sphere Instruction Manual. 1983. Pub. No.
8305-0034. LI-COR, Inc., Lincoln, NE.

Spectron Engineering, Inc., Operating Manual: SE590 field portable
data-logging

spectroradiometer, Serial Number Spectron Engineering, Denver, CO 80223.

17.2 Journal Articles and Study Reports

Daughtry, C.S.T., L.L. Biehl, and K.J. Ranson. 1989. A new technique to
measure the spectral properties of conifer needles. Remote Sensing
Environment 27:81-91.

Esau, K. 1977. Anatomy of Seed Plants, 2nd ed. John Wiley & Sons, New
York, 550 pp.

Mesarch, M.A. et al. 1998. A Revised Measurement Methodology for Conifer
Needles Spectral Properties: Evaluating the Influence of Gaps Between
Elements. Remote Sensing Review. (submitted 1998).

Middleton, E.M. et al. 1996. A Revised Measurement Methodology for
Spectral Optical Properties of Conifer Needles. As presented for
Proceedings, 1996 International Geoscience and Remote Sensing Symposium
(IGARSS \'96).

Middleton, E.M., S.S. Chan, R.J. Rusin and S.K. Mitchell. 1997. Optical
Properties of Black Spruce and Jack Pine needles at BOREAS sites in
Saskatchewan, Canada. Canadian Journal of Remote Sensing. vol. 23, no.
2, pp. 108-119.

Munsell Color (Firm). 1977. Munsell Color Charts for Plants Tissues. 2nd
ed. Munsell Color (Firm), Baltimore, MD, 6 pp. 17 color charts.

Norman, J.M. and P.G. Jarvis. 1974. Photosynthesis in Stika Spruce
\[Picea Sitchenis (Bong.) Carr.\] III. Measurements of canopy structure
and interception of radiation. J. Appl. Ecol. 11:375-398.

Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study:
Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94).

Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den
Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D.
Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere
study (BOREAS): an overview and early results from the 1994 field year.
Bulletin of the American Meteorological Society. 76(9):1549-1577.

Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal
Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC
94).

Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study:
Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96).

Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal
Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC
96).

Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry,
M. Ryan, K.J. Ranson, P.M. Crill, D.P. Lettenmaier, H. Margolis, J.
Cihlar, J. Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T. Gower, D.
Halliwell, D. Williams, B. Goodison, D.E. Wickland, and F.E. Guertin.
1997. BOREAS in 1997: Experiment Overview, Scientific Results and Future
Directions. Journal of Geophysical Research 102 (D24): 28,731-28,770.

Smith, W.K. and G.A. Carter. 1988. Shoot structural effects on needle
temperatures and photosynthesis in conifers. Amer. J. of Bot.
75:496-500.

Wickland, D. 1995. The boreal ecosystem-atmosphere study (BOREAS): an
overview and early results from the 1994 field year. Bulletin of the
American Meteorological Society. 76(9):1549-1577.

Williams, D.L. 1991. A comparison of spectral reflectance properties at
the needle branch and canopy level for selected conifer species. Remote
Sensing Environment 35:79-93.

17.3 Archive/DBMS Usage Documentation

None.

18\. Glossary of Terms

Abaxial: The ventral or underside of leaf or needle.

Adaxial: The dorsal or upper of leaf or needle.

Channel (ch): One band on the SE590, each having a unique wavelength.

Gap fraction: The percentage of aperture not covered by needles.

Reflectance (R): Light shines on the specified surface, bounces off this

surface, and then bounces around in the integrating sphere;

the spectroradiometer then measures the integrated light that

is bouncing around in the sphere.

STRS: Stray light from the sample.

STRW: Stray light from the wall.

Transmittance (T): Light shines on the specified surface, goes through
the needle, and then passes into the integrating sphere; the
spectroradiometer then measures the integrated light that is bouncing
around in the sphere.

19\. List of Acronyms

ASCII - American Standard Code for Information Interchange

BOREAS - BOReal Ecosystem-Atmosphere Study

BORIS - BOREAS Information System

B/W - Black and White

CCD - Charge-Coupled Device

DAAC - Distributed Active Archive Center

EOS - Earth Observing System

EOSDIS - EOS Data and Information System

fAPAR - fraction of Absorbed Photosynthetically Active Radiation

GF - Gap Fraction

GMT - Greenwich Mean Time

GSFC - Goddard Space Flight Center

IFC - Intensive Field Campaign

IGARSS - International Geoscience And Remote Sensing Symposium

NAD83 - North American Datum of 1983

NASA - National Aeronautics and Space Administration

NDVI - Normalized Difference Vegetation Index

NSA - Northern Study Area

OA - Old Aspen

OA-AUX - Old Aspen Auxiliary

OBS - Old Black Spruce

OJP - Old Jack Pine

ORNL - Oak Ridge National Laboratory

PANP - Prince Albert National Park

PAR - Photosynthetically Active Radiation

SSA - Southern Study Area

STDEV - Standard Deviation

SVI - Spectral Vegetation Index

TE - Terrestrial Ecology

URL - Uniform Resource Locator

UTM - Universal Transverse Mercator

WS - White Spruce

YA - Young Aspen

YA-AUX - Young Aspen Auxiliary

YJP - Young Jack Pine

20\. Document Information

20.1 Document Revision Date

Written: 26-Jun-1997

Last updated: 28-Sep-1998

20.2 Document Review Date(s)

BORIS Review: 15-Jul-1998

Science Review: 06-Aug-1998

20.3 Document ID

20.4 Citation

S.S. Chan and E M. Middleton

Biospheric Sciences Branch, Code 923

NASA GSFC

20.5 Document Curator

20.6 Document URL

[Keywords]{.underline}

Optical Properties

Spectra

Reflectance

Transmittance