Fuell, Kevin K.

Jedlovec, Gary J.

Stano, Geoffrey

White, Kristopher D.

NASA Technical Reports Server

VIIRS Impact to Operational Nowcasts/Forecasts via User Assessments by NASA SPoRT
Assessment Results 
Forecasters from the High Latitude as well as Southern Region Coastal and
Inland groups submitted feedback on 80 specific events evaluating the
impact to aviation nowcasts/forecasts as well as to differentiating fog from
other cloud features (see graphs below). The interpretation of the RGB
imagery was a learning process for many users; however, a notable
percentage indicated large to very large impact from the products. In
addition to the provided training, an RGB library of case examples is desired
to more quickly increase the user’s understanding. While future
geostationary instruments will have similar RGB capabilities, users at high
latitude will continue to benefit from VIIRS-like instruments.
Forecaster feedback:Medford, OR (MFR) 14 Dec 2013
“Valley low cloud and fog simply jumps off the screen in all of 
these products tonight.  […] Was able to discern that low 
cloud/fog was more widespread in the valleys than with any 
other products.”
or
Forecaster feedback from Morristown, TN (MRX), 20 Sep 2013,
“[…] the Nighttime Microphysics product […] did an outstanding job of 
clearly showing areas of fog vs. clouds […]. It was far superior to the 
11-3.9 μm product in this regard. The DNB Radiance RGB showed fog 
clearly as well […].”
VIIRS Nighttime Microphysics RGB, 0736 UTC 20 September 2014 VIIRS Day-Night Band Radiance RGB, 0736 UTC 20 September 2014
High clouds (thick)
Fog in valleys
Mid clouds (thin)
Low clouds in 
elevated valleys
Low/mid 
clouds (thick)
High clouds (thin)
Fog in valleys
Low clouds in 
elevated valleysHigh clouds (thin)
Low/mid 
clouds (thick)
SPoRT blog post from Huntsville, AL (HUN), 22 Sep 2013,
“The Nighttime Microphysics RGB helped again to delineate small 
areas of locally dense fog. […] Due to the resolution of the imagery 
and the efficiency it provides for fog detection, it could be helpful for 
limiting the extent of areas under advisory, and allowing for more 
descriptive impacts in advisory products.”
VIIRS Nighttime Microphysics RGB, 0658 UTC 22 September 2014 VIIRS Day-Night Band Radiance RGB, 6587 UTC 22 September 2014
High clouds (thick)
Low clouds in 
southern 
Appalachians
Fog in valleys
High clouds (thin)
High clouds (thick)
Thin cirrus mostly 
translucent in the 
Day-Night Band RGB
Fog in valleys
Low clouds in 
southern 
Appalachians
SPoRT blog post, Applications Integration Meteorologist, 19 Dec 2013
“In this situation, forecasters would have a much better idea of the 
extent of the low cloud deck. […] cloud bases were around 1-2 kft in 
that area of southern Texas, which could have significant impacts on 
sensible weather and forecasts, especially for aviation.”
High clouds (thick)
Large area of low stratus is 
visible beneath thin cirrus in 
the Day-Night Band RGB
High clouds (blue colors)
Large area of low stratus is 
obscured in the 11-3.9 μm 
imagery
Low clouds (yellow colors)
Front Range Collaboration: Outflow Boundaries, Jul 2013
A day-night band RGB using VIIRS IR (left) shows low (warmer) 
features as yellow and high (cooler) features as blue. The 
NtMicro RGB combines several VIIRS channels to discriminate 
cloud height, thickness, and fog. Low clouds resulting from 
outflow of storms are more efficiently analyzed.
SPoRT Blog from 
Alaska, 31 Jan 2014,
Copper River Basin to 
the Northeast of 
Anchorage.  Fog is 
more easily identified 
in NtMicro RGB 
compared to 
traditional 11-3.9μm 
difference.  
Variations in fog and 
stratus thickness are 
also more evident
Nighttime Microphysics RGB Day Night Band
11-3.9μm Difference: “Fog” 11μm Longwave Infrared
Mix of fog and 
stratus in valleys
Fog and thick 
stratus appear 
similar here
Note change 
in color
Snow/ice cover more 
reflective in  DNB
Fog is “warmer” in IR and 
mixes w/ other features
Very Small
14%
Small
12%
Some
38%
Large
31%
Very Large
5%
Impact of NtMicro RGB to Aviation 
Forecast Issues (e.g. TAFs product)
Very Small
14%
Small
12%
Some
33%
Large
26%
Very Large
15%
Impact of NtMicro RGB 
to Differentiate Fog from Low Cloud
Very Small
39%
Small
17%
Some
33%
Large
8%
Very Large
3%
Impact of DNB RGB to Aviation 
Forecast Issues (e.g. TAFs product)
Overview
NASA/SPoRT is using VIIRS data to create single and multi-channel imagery (i.e.
RGB) products to address needs of NWS forecasters related to the analysis of
fog and cloud features that pose hazards to the aviation community. The
Nighttime Microphysics (NtMicro) RGB and Day-Night Band (DNB) RGB
products have been transitioned to CONUS and Alaska users and product
assessments have been conducted. The following are annotated examples of
the impact of VIIRS imagery as provided via user feedback submitted as part of
an assessment. Detailed reports with these examples have been created.
kevin.fuell@nasa.govKevin Fuell (UAH), Kris White (NOAA/NWS), Geoffrey Stano (ENSCO), Gary Jedlovec (NASA/SPoRT)
High Latitude
(Winter 2013/14)
VIIRS Assessments 
Kevin Fuell
VIIRS Day-Night Band Radiance RGB (left), and VIIRS 11-3.9 μm (right), valid 0749 UTC 19 Dec 2013 
MFR
CYS
BOU
MFL
RAH
MOB
https://ntrs.nasa.gov/search.jsp?R=20150000310 2019-08-31T14:24:05+00:00Z


VIIRS Impact to Operational Nowcasts/Forecasts via User Assessments by NASA SPoRT

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