VIIRS Global DNB Product Status
Chris Elvidge
Earth Observation Group
NOAA National Geophysical Data Center
Kim Baugh, Feng-Chi Hsu, Mikhail Zhizhin
CIRES, University of Colorado
October 22, 2012
1
Enabling software developed at NGDC
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Reprojection toolkit
DNB terrain correction
Stray light filter
M10 combustion source detection system
M15 cloud detection relative to NCEP surface
temperature grids
• Modification of DMSP nighttime lights
compositing software
2
Stray Light Filter
Raw
Subtracted component
Filtered
The First VIIRS Global Cloud-Free Composite
April 18-26, 2012 - Low moon nights
Output is a 15 arc second grid (86401 x 33601)
The First VIIRS Global Cloud-Free Composite
April 18-26, 2012
Washington, DC
VIIRS
DMSP-OLS
The First VIIRS Global Cloud-Free Composite
April 18-26, 2012
Denver, Colorado
VIIRS
DMSP-OLS
The First VIIRS Global Cloud-Free Composite
April 18-26, 2012
Delhi, India
VIIRS
DMSP-OLS
Issues
Northward Extent 65 Degrees
Residual Stray Light
1.
2.
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4.
5.
Difficulty setting noise threshold due to residual stray light
Current hardware lacks memory to geolocate aggregates north of 65 degrees
Slight westward bias in DNB geolocation relative to M10 gas flare detections
Low numbers of cloud-free coverages in numerous locations
Fuzzy lights can be found in some areas
Geolocation Bias
Basra Gas Flares, Iraq
Red = M10 composite
Cyan = DNB composite
The DNB geolocation is
shifted slightly to the
west.
9
Plan to Address Issues
1. Stray Light: Make separate composites for stray light and
non-stray light data. Stray light is present for data
observed with ground solar zenith angles in the range of 90
to 118 degrees. Develop separate noise thresholds, remove
background noise, recombine.
2. Extending North: Move processing to computer with more
memory. This is happening this week!
3. Geolocation Bias: Measure the bias between DNB and
M10 combustion source detections in the global cloud-free
composites. Introduce bias correction as a variable in the
reprojection toolkit. Reprocess!
4. Expanding the number of cloud-free coverages: Add data
from additional months.
5. Fuzzy lights: Develop fuzzy light detector. Screen out fuzzy
lights in the compositing process.
Composite with no stray light contaminated data
Composite with stray light contaminated data
Composite with stray light filtered data
Effect of Stray Light Filtering
Use of April cloud-free composite as a reference for
the detection of power outages on November 1, 2012