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Diviner PDS Level 3 Data Products
Benjamin T. Greenhagen JHU Applied Physics Laboratory
Joshua L. Bandfield Space Science InsFtute
LRO Data User’s Workshop, The Woodlands, TX 3/15/15
• What are the Diviner Level 3 Data Products? – Standard ChrisFansen Feature Value (STD_CF)
• CumulaFve Map – Normalized to Equatorial Noon CF Value (NEN_CF)
• CumulaFve Map – Rock Abundance (RA)
• CumulaFve Map, Individual Map Cycles – Soil Temperature (ST)
• CumulaFve Map, Individual Map Cycles – Normalized Soil Temperature (STN)
• CumulaFve Map – Root Means Square (RMS)
• Individual Map Cycles
• These data products are available at 128 ppd – NEN_CF is available at 32 ppd
Plagioclase (7.86 µm)
Pyroxene (8.25 µm)
Olivine (8.67 µm)
16
11
12
14 15 17
CF vs. ComposiFon • CF shics to shorter wavelengths
with increasing silicate polymerizaFon
• CF posiFon is most sensiFve to plagioclase/olivine abundance
• Pyroxene composiFons are not unique
Low/Mid LaFtude CF DistribuFon Highland Mean = 8.15 μm
Mare Mean = 8.30 μm
Wavelength (μm)
Histogram Bin Frac=on
Q
Plagioclase Feldspar Pyroxene Olivine
A F
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 9.0
Greenhagen et al., 2010; Science
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
6 7 8 9 10 11
Effective Em
issivity (0
.1 offs
ets)
Wavelength (μm)
8-‐μm Channel ComposiFonal Data
• CF of lunar soils in lunar environment is nearly parabolic
• Simultaneously solve three quadraFc equaFons
• In brightness temperature space • TbMax = C – B2 / (4*A)
• Use Tbmax to calculate effecFve emissivity (unit emissivity at CF)
• In emissivity space • CFVal = -‐B / (2*A)
• CF value is defined as the modeled approximaFon of the CF
Emission in a Simulated Lunar Environment
67711
61501
14259
15301
10084
62241
Spectra digiFzed from Salisbury et al., 1973
Standard CF Value Maps (STD_CF)
8.55
8.40
8.25
8.10
7.95
7.80
CF PosiFon
Map Cycle 11 Map Cycle 12 Map Cycle 13
+
+ 43 others
+
Solar Incidence (i) WeighFng
0
0.2
0.4
0.6
0.8
1
0 10 20 30 40 50 60 70
Weight
Solar incidence (degrees)
2
1718cos +⎟
⎠
⎞⎜⎝
⎛
=i
wt
Tb < 250 & i > 70 are not used
Equatorial DayFme Coverage
Green Crater 133 E / 3.5 N
400
360
320
280
240
200
Ch 7 Brig
htne
ss Tem
perature (K
)
Science Mission + Extended Mission
60 E 120 E 0 E 60 W 120 W
Standard CF Value Maps (STD_CF)
180 W 180 E
30 N
60 N
30 S
60 S
8.55
8.40
8.25
8.10
7.95
7.80
CF Value
0 N
Map Cycle 11 Map Cycle 12 Map Cycle 13
+
+ 43 others
+
Solar Incidence (i) WeighFng
60 E 120 E 0 E 60 W 120 W
Standard CF Value Maps (STD_CF)
180 W 180 E
30 N
60 N
30 S
60 S
0 N
Map Cycle 11 Map Cycle 12 Map Cycle 13
+
+ 43 others
+
Solar Incidence (i) WeighFng
* Previous STD_CF map for comparison *
8.55
8.40
8.25
8.10
7.95
7.80
CF Value
60 E 120 E 0 E 60 W 120 W
CorrecFng Standard CF Value Maps
180 W 180 E
30 N
60 N
30 S
60 S
0 N
Standard CF Values
Map Cycle 12
Map Cycle 13
15:00
17:00
13:00
15:00
VariaFons with both laFtude and local Fme
CF shics to shorter wavelengths with increasing solar incidence
8.55
8.40
8.25
8.10
7.95
7.80
CF Value
60 E 120 E 0 E 60 W 120 W
Corrected CF Value Maps (NEN_CF)
180 W 180 E
30 N
60 N
30 S
60 S
0 N
Corrected CF Values
• March 2011 release includes corrected CF values from Greenhagen et al. 2010, (Science) – Corrects laFtude and local Fme but NOT topography
• Development conFnues on an empirical correcFon incorporaFng topography and illuminaFon and emission geometry
8.55
8.40
8.25
8.10
7.95
7.80
CF Value
60 E 120 E 0 E 60 W 120 W
Corrected CF Value Maps (NEN_CF)
180 W 180 E
30 N
60 N
30 S
60 S
0 N
30 N
60 N
30 S
60 S
0 N
Standard CF Values
Corrected CF Values
8.55
8.40
8.25
8.10
7.95
7.80
CF Value
Caveats for using Diviner CF Maps • The quality of a CF value is dependent on the solar incidence angle / viewing geometry – Topographic effects can be large – Generally OK for incidence angles less than 30 degrees – Plan to include a measure of confidence / uncertainty in future release
• Abnormal pixels are given fixed CF values – Caused by out of band composiFons and/or poor data quality – SIS will be updated to include details – CF values outside 7 to 9.5 are not included – InvesFgaFng ways to report “good” abnormal pixels
• Effects of space weathering are not corrected – Generally ~0.1 µm for immature to mature – Plan to include space weathering correcFon in future release
Lunar Thermophysics • Nighyme temperatures are very sensiFve to the physical nature of the surface – Rocks will stay ~100K warmer than the regolith throughout the night
– Layering, slopes, etc. also affect surface temperatures
100
150
200
250
300
350
400
24 18 12 6 Hours Past Noon
Rock
Unlayered Regolith
Layered Regolith
Surface Tem
perature (K)
Equatorial Nighyme Coverage
140
130
120
110
100
90
Ch 7 Brig
htne
ss Tem
perature (K
)
Science Mission + Extended Mission
Green Crater 133 E / 3.5 N
0 N
30 N
60 N
30 S
60 S 0 E 60 E 120 E 180 E 60 W 120 W 180 W
Rock Abundance (RA)
15
5%
2.5%
0%
Areal Rock Ab
undance
Acer Bandfield et al., 2011
• Model Uses Diviner chs 6-‐8 centered near 18, 35, and 75 mm • Model temperature of rocks with laFtude/local Fme and
opFmize modeled radiance by varying Soil Temperature (ST) and areal Rock Abundance (RA)
• IniFal results provide realisFc numbers and data are well-‐behaved
– Younger craters show higher Rock Abundances (e.g. Tycho)
0 N
30 N
60 N
30 S
60 S 0 E 60 E 120 E 180 E 60 W 120 W 180 W
5%
2.5%
0%
Areal Rock Ab
undance
Bullialdus Crater Tycho Crater
CopernicusCrater Aristarchus Crater
Rock Abundance (RA)
Acer Bandfield et al., 2011
Rima Bode Landing Site
• Large spaFal variability in rock abundance
• Comparisons with LROC NAC images show excellent qualitaFve agreement
LROC – M102193170LC
LS Center Point
More Rocky
Less Rocky
Average Rock Abundance – 10%
More Rocky!
Average Rock Abundance – 1.3%
Less Rocky!
0 N
30 N
60 N
30 S
60 S 0 E 60 E 120 E 180 E 60 W 120 W 180 W
120
95
70
Nighy
me Soil Tempe
rature • Nighyme temperature of the modeled soil component
– Soil Temperature (ST) – Soil Temperature Normalized (STN) to remove laFtude variaFons
(above) • Rocky areas have elevated temperatures • Cold anomalies at higher laFtudes driven by topography • Some Equatorial “cold spots”
– Colder than average features associated with some small craters
Nighyme Soil Temperature
Acer Bandfield et al., 2011
New 128 ppd RA Products • 46 separate rock abundance, regolith temperature, and RMS fiyng error maps – These maps parallel the nighyme Level 2 GDR products and are constructed from Diviner Ch. 6-‐8
• Local Fmes are restricted to 19:30 to 05:30 • Includes topographic data from LROC DTM to determine local Fme and laFtude – Used to adjust apparent local Fme and laFtude – Rock abundance model now references the apparent local Fme and laFtude to reduce topography effects.
• LaFtude range extended to +/-‐80 degrees – Data on steep slopes at higher laFtudes masked
Old rock abundance – topography influences values at high latitudes
New rock abundance – pole facing slopes have >80° minimum solar incidence
Old rock abundance – Tycho Antipode
New rock abundance – Tycho Antipode
Improved Calibration and Rock Abundance
• Correlated noise is present in all Diviner detectors/channels
• This produces a
“stuttering” effect present in rock abundance and regolith tmeperature maps
Rock abundance 128 ppd - “stuttering” is present at the ~0.5% level
Data Quality Improvement
• New rock abundance maps will be produced from improved Diviner Level 2 data products
Rock Abundance 0-2% Original (left) and corrected (right)
Regolith Temperature 88-100 K Original (left) and corrected (right)
• Diviner Level 3 Data Products – Standard ChrisFansen Feature Value (STD_CF)
• CumulaFve Map – 128 ppd / 60S-‐60N
– Normalized to Equatorial Noon CF Value (NEN_CF) • CumulaFve Map – 32 ppd / 60S-‐60N
– Rock Abundance (RA) • CumulaFve Map, Individual Map Cycles – 128 ppd / 80S-‐80N
– Soil Temperature (ST) • CumulaFve Map, Individual Map Cycles – 128 ppd / 80S-‐80N
– Normalized Soil Temperature (STN) • CumulaFve Map – 128 ppd / 70S-‐70N
– Root Means Square (RMS) • Individual Map Cycles – 128 ppd / 70S-‐70N
Summary
