VIIRS Dust product captures Mount Pavlof’s Plume

Author: Emily Berndt

Mount Pavlof, one of Alaska’s most active volcanoes, has been erupting since last week. The plume has caused some disruption of flights and ash fallout in nearby communities. The Alaska Volcano Observatory has been closely monitoring it’s activity (http://www.avo.alaska.edu/activity/Pavlof.php). The steam, ash, and gas plume is continually created as hot lava contacts snow and ice. The steam, ash, and gas plume has occasionally reached up to 20,000 ft and has been carried downwind as much as 100 km to the northeast, east, and southeast  before dissipating. This graphic from the Alaska Volcano Observatory shows the location of Mount Pavlof within the Aleutian Island Chain.

The plume can be seen in the VIIRS RGB Dust product. Let’s first look at the VIIRS true color product. Inside the red circle, you can see a faint brown plume, but it’s not easy to see (click on the images).

VIIRS True Color Image 2135 UTC 18 May 2013

Now take a look at the VIIRS RGB Dust product. On the three images below there is a pink/red streak (inside the purple circle) emanating from the location of Mount Pavlof.

This is an excellent example of the utility of multichannel RGB products to obtain a clearer view of the location and extent of volcanic plumes.

VIIRS RGB Dust Imagery 2135 UTC 18 May 2013

VIIRS RGB Dust Imagery 1138 UTC 18 May 2013

VIIRS RGB Dust Imagery 2332 UTC 17 May 2013

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Initial Qualitative Evaluation of Retrieved CrIMSS Profiles

Level 2 retrieved temperature and moisture profiles in clear and partly cloudy conditions can be obtained from the new Cross-track Infrared Microwave Sounding Suite (CrIMSS), which uses infrared measurements from the Cross-track Infrared Sounder (CrIS) and microwave measurements from the Advanced Technology Microwave Sounder (ATMS).  These observations are available from the Suomi-NPP as operational legacy observations to those coming on the JPSS.

SPoRT has begun processing the 42-level temperature and 22-level moisture CrIMSS Environmental Data Record (EDR) data and qualitatively comparing these soundings to other hyperspectral sounders (AIRS and IASI), in situ observations (RAOBs), and regional models (North American Mesoscale (NAM) and Rapid Refresh (RAP)).  All of these comparisons are available on SPoRT’s hyperspectral sounding comparison page (http://weather.msfc.nasa.gov/sport/hyperspectral_comparisons/).

As an example of these comparisons, the three images below were taken from that webpage for soundings at Vandenberg Air Force Base (VBG) in California all valid around 2100 UTC on 31 March 2013.  Note that the CrIMSS and AIRS soundings both match very closely to the RAP temperature sounding with near-perfect agreement of tropopause height in the AIRS sounding and similar tropopause placement in the CrIMSS sounding.  Both the AIRS and CrIMSS soundings highlight a low-level moist conditions and mid-level dry conditions.  Satellite soundings in this form can be used by forecasters to gain additional confidence in their model guidance or obtain additional information in regions where there are not other upper air observations (such as over Northern Mexico and the Gulf of Mexico).

Temperature and dew point soundings at VBG at 2100 UTC on 31 March 2013.

Temperature and dew point soundings from CrIMSS at VBG at 2100 UTC on 31 March 2013.

Temperature and dew point soundings from AIRS at VBG at 2100 UTC on 31 March 2013. Thicker line indicates highest quality data.

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Full Moonlight Observations with the VIIRS Day-Night Band Imagery

I wanted to point out a couple of Day-Night Band (DMB) observations from the VIIRS instrument aboard the Suomi NPP satellite since we are at full moon.  Yesterday, smoke from firest could easily be seen in GOES 4-km visible imagery.  However, the loss of visible at nighttime with conventional geostationary imagery makes it nearly impossible to detect smoke plumes at night.  The DNB imagery, while just a snapshot from a polar orbiter, at least allows for a check of how phenomena have evolved since the loss of standard daytime visible imagery.  Notice the plumes of smoke in the loop of GOES imagery below.

Image 1. GOES visible imagery and METAR observations loop 2231-0045 UTC March 26-27 2013.

A few of the smoke plumes really stand out: one in SW Arkansas at site KDEQ, one west of McComb, MS and another between Jackson and Hattiesburg, MS.  Notice that the smoke plume from the fire in far SE OK was reducing visibility at KDEQ in SW Arkansas.  At times, visibility was reduced to 1 3/4 SM, which is within IFR conditions.  If this was a Terminal Aerodrome Forecast (TAF) site, this would cause potentially large aviation impacts and a forecaster would want to know about the evolution of the fire and smoke after sunset.  Granted, while only serving as a snapshot, the DNB imagery (images 2 and 3 below) show that the fires and smoke in the region had essentially dissipated by the satellite pass at approximately 0751 UTC Mar March 27.

Image 2. VIIRS DNB Reflectance image valid 0752 UTC 27 March 2013.

Image 3. VIIRS DNB Radiance RGB product valid 0752 UTC 27 March 2013.

Now, the question might remain, did the smoke actually disappear/dissipate or are the smoke plumes simply not showing up in the imagery?  It seems more likely that the smoke/fires had dissipated.  Early morning daytime visible imagery just after sunrise (not shown) indicated that the fires indeed had burned out.

Now, for another type of phenomenon…snow.

During the day, clouds may linger over recent snowfall and it can be difficult for forecasters to discern the true extent of the snow.  Sure, observations allow forecasters a sense of the extent of snow cover, but may not allow for a sufficient assessment of its true extent.  Notice in the short loop below, the clouds moving across recent snow in sections of the Midwest.

Image 4. GOES visible image loop valid 2315 – 0015 UTC March 26-27 2013.

In the imagery above, a trained eye can differentiate snow on the ground in portions of eastern Missouri and western Illinois from cloud cover.  However, forecasters and others would want to know the extent of snow cover on the ground over the area.  The VIIRS DNB Radiance RGB combined with the VIIRS Nighttime Microphysics RGB later that night after clouds had cleared somewhat helped to answer that question.

Imager 5. VIIRS DNB Radiance RGB valid 0752 UTC 27 March 2013.

Image 6. VIIRS Nighttime Microphysics image valid 0752 UTC 27 March 2013.

In the DNB RGB image above (image 5), the snow field is relatively easy to see extending from eastern Missouri into western Ohio.  Some clouds still obscure the view and SPoRT’s Nighttime Microphysics RGB product (image 6 above) makes it very easy to distinguish clouds from areas of snow.  The low/mid clouds in the area appear as yellows/oranges, while higher, colder clouds appear as deeper magenta/reds.  Toggling the two images (as shown in image 7 below) makes the ease of detecting snow vs. clouds apparent.

Image 7. Toggle of Nighttime Microphysics RGB with DNB radiance RGB, both images valid 0752 UTC March 27 2013.

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Recent Fires and Smoke Across Alabama…

Warm, dry and windy conditions last week led to the development of numerous wildfires across the region, while some fires were controlled burns prescribed by the National Park Service and the Alabama Forestry Commission.  Some of these fires produced sufficient amounts of smoke to be observed by geostationary and polar-orbiting satellites.  On Friday, mostly clear sky conditions allowed a view of some of the larger fires and their smoke from the VIIRS instrument aboard the Suomi NPP satellite.  The SPoRT True Color RGB product from the VIIRS instrument provided a quick and relatively easy view of the smoke plumes that developed across the area on Friday afternoon.

SPoRT True Color RGB from the VIIRS instrument valid 1802 UTC 15 Mar 2013

In particular, note the presence of smoke plumes (white/gray streaks) from fires in the Bankhead Nat’l Forest (northern Alabama) and from firest between Birmingham and Montgomery.  Another smoke plume, although a little more difficult to see, was located southwest of Middleton Field (KGZH) in Evergreen, AL and adjacent to the far NW corner of the Florida peninsula.  Southwesterly winds pushed smoke from this fire for a several mile stretch along the I-65 corridor northeast of the Mobile area.  Persistent SW winds during the afternoon eventually pushed this smoke plume into the Evergreen, AL area affecting Middleton Field (noted on the Google Earth image) with reduced visibility to 5sm (marginal visual flight rule range) by 2143 UTC.

SPoRT True Color RGB from the VIIRS instrument valid 1802 UTC 15 Mar 2013

 

SPoRT True Color RGB from the VIIRS instrument valid 1945 UTC 15 Mar 2013

The smoke plume is a little more difficult to see in the last VIIRS image (valid 1945 UTC) as this area was on the far SE corner of the image swath, however, the smoke plume is still visible and has moved closer to Middleton Field.  Within two hours, visibility at the airport dropped to 5sm.  Given the appearance of the smoke plumes, the one affecting I-65 between Birmingham and Montgomery likely produced much lower visibilities for a stretch of several miles.  This type of imagery can be very useful for nowcasting and for forecasting visibility reductions at aiports in terminal aerodrome forecasts.  One lingering issue is how to estimate the visibility based on the appearance of the smoke in the satellite imagery.  Perhaps future algorithms will be able to address this important issue.

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Early February Blizzard Part 2

Author: Emily Berndt

The February 8-9, 2013, Northeast Blizzard did indeed produce near hurricane force wind gusts. In the original blog post on February 8th, featuring this storm, I noted the presence of stratospheric air on the RGB Air Mass Imagery and high concentrations of ozone present as seen by AIRS. The presence of these signatures was a good indicator that a stratospheric intrusion was present and could lead to high surface wind gusts. The graphic below from the NWS Eastern Region Headquarters shows a summary of the highest wind gusts during the event. Note that winds greater than 74 mph are equivalent to a category 1 Hurricane. Parts of Virginia,  Massachusetts, Rhode Island, Connecticut, and Maine were impacted by hurricane force wind gusts.

Summary of Wind Gusts during the February 8-9, 2013 Northeast Blizzard     (Courtesy of NWS ERH)

Further investigation of ozone with the Ozone Mapping and Profiler Suite (OMPS) part of the new Suomi National Polar-orbiting Partnership (NPP) Mission provides a snapshot of global daily ozone concentration.  Click on the image below to see the animation of Daily Ozone from February 6th-9th. The animation below  shows ozone concentrations greater than 300 Dobson Units stretching south over the Northeast states. The OMPS Daily ozone product is valuable in showing the daily progression of higher concentrations of ozone associated with stratospheric intrusions.  How does this region of higher ozone values compare to RGB Air Mass Imagery?

The MODIS RGB Air Mass Imagery helps confirm the presence of warm, dry, stratospheric air drawn into the storm. The darker orange colors represent the presence of stratospheric air.  Comparing the position of the ozone-rich stratospheric air in the animation (click on the image) with the location of the warm, dry stratospheric air on the MODIS RGB Air Mass Imagery confirms there was higher momentum stratospheric air available to be drawn into the storm and transported to the surface to create hurricane force wind gusts. Of course further investigation of cross sections is necessary to further establish the link between the stratosphere and the high winds that were created during this event.

Suomi NPP OMPS Daily Ozone in Dobson Units February 6-11th 2013

Terra MODIS RGB Air Mass Imagery from February 9, 2013 0304 UTC.

So what can we say about this next storm posed to impact the Northeast today through Friday. The National Weather Service is anticipating gusts up to 45-55 mph as the storm intensifies off the coast. A current surface analysis shows there are wind gusts upward of 45 knots (52 mph) along the coastline. An Aqua MODIS RGB Air Mass image from 0709 UTC this morning shows a broad area of orange covering the southeastern US. This warm, dry stratospheric air is being drawn into the storm. The most current OMPS Daily ozone image again shows higher values of ozone concentrated over the same area as the warm, dry stratospheric air.  Over the next few days, I’ll be watching  the progression of OMPS ozone and stratospheric air on the RGB Air Mass Imagery!

Surface Observations March 6th, 2013 1643 UTC                      (courtesy of http://weather.rap.ucar.edu/)

AQUA MODIS RGB Air Mass Imagery March 6th 2013 0709 UTC

Suomi NPP OMPS Daily Ozone in Dobson Units March 4-6th 2013

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Early February Northeast Blizzard

The Northeast is bearing down for a blizzard as two storm systems are expected to merge off the East Coast early Saturday morning. Currently, one low pressure center is near Lake Erie and the other one is off the Virginia coast (see surface map below). Once the two systems phase off the East Coast, the new system is expected to rapidly deepen to 970 mb. Blizzard conditions will result as 1-2 feet of snow falls and winds gust to as high as 70 mph.

HPC 1500 UTC Surface Analysis Feb. 8, 2013

From a satellite perspective, how can some of the new GOES-R imagery and AIRS profiles help identify significant features associated with this unique synoptic set up? Below is an RGB Air Mass image from 0634 UTC this morning. The image gives a clear view of the coastal storm. Notice the green colors to the south of the main cloud shield, indicated by a blue arrow. The green colors represent warm, moist tropical air that is being drawn into the storm.  This air mass will provide abundant moisture to produce the robust snow fall amounts expected. A VIIRS/CRiS RGB Air Mass image from 0733 UTC this morning gives a broader view of the Eastern United States and shows the structure of both storms. The storm situated over the Great Lakes will usher cold air into the Northeast. There are also green colors to the north and northwest of the Great Lakes storm however they indicate cold, moist air.

NASA SPoRT Aqua MODIS RGB Air Mass Image  0634 UTC Feb. 8, 2013.
Yellow arrow points to ozone rich stratospheric air and Blue arrow points to warm, moist tropical air.

NASA SPoRT VIIRS/CRiS RGB Air Mass Image     0733 UTC Feb. 8, 2013.
Yellow arrow points to ozone rich stratospheric air

Stratospheric intrusions are commonly associated with rapidly developing cyclones and may be responsible for transporting higher momentum air to the surface to produce damaging winds at the surface. If we piece together information from the RGB Air Mass imagery, AIRS total column ozone, and a 300 mb map, can we find an explanation to why this system will be associated with strong wind gusts?  The 1200 UTC 300 mb observations, pictured below, show a 125 kt jet streak north of Maine. The red/orange colors in the MODIS RGB Air Mass imagery indicate the presence of a jet streak and high potential vorticity air.  The AIRS total column ozone, pictured below, indicates higher values of ozone in the same vicinity. The presence of high potential vorticity air and larger amounts of ozone signify higher momentum stratospheric air intruding into the troposphere. Some of this stratospheric air is being drawn into the Great Lakes storm, shown by the yellow arrows on the VIIRS/CRiS RGB Air Mass image. Unfortunately  there was not an AIRS pass to the east of the storm system to further confirm ozone-rich stratospheric air. As the system continues to progress, more AIRS data and RGB Air Mass data will be investigated to watch how stratospheric air is drawn into the storm and how it relates to the production of surface wind gusts.

300 mb Heights (dm) and Isotachs (kts) 1200 UTC Feb. 8, 2013. Image from NCAR RAL Real Time Weather Data website

AIRS Total Column Ozone 0630-0636 UTC            Feb. 8, 2013

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VIIRS DNB Imagery Captures Typhoon Bopha Moments Before First Landfall

Typhoon Bopha made initial landfall in the Southeastern Philippines during the local overnight hours on 4 December 2012.  Due to its landfall occurring at night, traditional visibile satellite imagery would not have been available.  However, NASA/NOAA/DoD’s Visible Infrared Imaging Radiometer Suite (VIIRS) features a Day Night Band (DNB), which detects cloud features using reflected moonlight and enables forecasters the ability to see the storm even when no sunlight is present.  The VIIRS DNB captured the size and intensity of the storm moments before this its initial landfall along the eastern coast of the Island of Mindanao, which resulted in wind and landslide damage to that region.  Brought into SPoRT’s Tiled Mapping Service (TMS) and making a slight adjustment to the transparency of the VIIRS image, one can see both details of the storm’s eye and its proximity to land features.

VIIRS DNB Imagery at 1710 UTC on 3 December shows proximity of Typhoon Bopha to The Philippines prior to landfall.

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VIIRS Day-Night Band Comparisons of Northeastern City Lights

As clouds are starting to dissipate with the slow demise of Sandy, we are getting some beneficial peeks through the clouds with the VIIRS Day-Night Band (DNB).  As we demonstrated with Isaac in the New Orleans area, the DNB is great for inferring quite a bit about power outages and even cloud cover through interactions of emitted light versus reflected moonlight.  We have assembled two examples of the DNB imagery over the northeastern United States.  The first image is from the morning of October 26.  Although some low clouds were present across several states, they were not thick enough to completely mask the cities below, resulting in a vibrant display of light (though diffuse) throughout the major cities extending from Washington D.C./Baltimore through Boston.

This morning, November 1, we obtained some additional city light views (and some cloud cover remnants from Post-Tropical Cyclone Sandy) across the area.  As you toggle between the first two slides, your eyes will pick up some loss of city lights along the coastal areas of New Jersey, Long Island, and portions of southern Maine.  News reports confirm power outages in many of these areas.  Unfortunately, some of the lingering cloud cover makes it a bit difficult to make strong claims about power outages in more areas, as some of the missing city lights may be cloud-obscured.  However, these coastal areas appear to be cloud free given that the city lights that *are* present are appearing as fine, small points of bright light that are not being diffused or scattered by clouds at higher altitude.  We can highlight areas where we feel pretty confident that the changes are due to power loss, not cloud cover, but it can be tricky given that even thin clouds can obscure the lights below – similar to viewing cities from above in an airplane.  There may be other areas where city lights are out but not fully viewable in the difference image – for example, portions of eastern Massachusetts would likely have had similar impacts, but this morning’s cloud cover makes it difficult to determine.  In these images, the clouds that are present are visible from reflected moonlight given that we are still at or near to the full moon phase.

As skies continue to clear, there may also be other means of watching the recovery by looking for city lights that reappear.  This is just another great example of VIIRS applications in response to disasters.  SPoRT provides this type of imagery via our website and to NWS partnering offices and National Centers that we collaborate with through NOAA’s Joint Polar Satellite System (JPSS) Proving Ground.  The final imagery here are derived from data obtained from the Cooperative Institute for Meteorological Satellite Studies (CIMSS) at the University of Wisconsin Madison and are processed using a lunar reflectance algorithm provided to us by colleagues at the Cooperative Institute for Research in the Atmosphere (CIRA) at Colorado State University in Ft. Collins, Colorado.

Day night band reflectance imagery prior to the approach of Sandy, observed on October 26. City lights show up as bright white areas since they emit far more light than would be reflected by moonlight alone.

Day night band reflectance imagery a few days after the landfall of Sandy, seen here on the morning of November 1. Many city light areas are missing, though some are also obscured by cloud cover remnants from the storm.

 

Annotated image helping to identify some areas where power outages may be occurring, inferred from loss of bright city lights in the VIIRS day-night band. Note that other areas such as eastern Massachusetts may also have some outages, but remaining clouds obstruct our view.

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SPoRT Blended SSTs, VIIRS Day-Night-Band RGBs and Observations of Sandy

Former Hurricane Sandy has now moved ashore, with impacts ranging from flooding in parts of the mid-Atlantic and Northeast Regions, to heavy snow and blizzard conditions in the central and southern Appalachians, while wind and other damage to infrastructure has caused power outages to an estimated 7.5 million people.  Partially fueling this storm was very warm water in association with the Gulf Stream just off the eastern U.S. shore, with water temperatures estimated at some 0.5 C to 1.5 C (~1-3 F) above normal for this time of year, as shown in the images below from the Climate Prediction Center / NCEP.

I decided to plot the storm’s track across the SPoRT blended SST product to see how this storm tracked across the region of highest SSTs.  Since the SPoRT SST product updates every 12 hours with the most recent available data, I created a loop of the SSTs, updating with the 06Z and 18Z product times (click on the image twice to get to the looping page…it may take a minute to load).  The SSTs update as the storm track points are plotted on the map.  The storm track points are available from the National Hurricane Center (NHC) at the GIS Data and Products page (http://www.nhc.noaa.gov/gis/), and it should be understood that these are considered preliminary.

Figure 2. Loop of SPoRT 2 km blended (MODIS, NESDIS and REMSS) SST product from Oct 27 0600Z through Oct 29 1800Z. Hurricane Sandy tracks, made available from the NHC GIS and products database are overlain in 6-hourly increments.  You may need to click the image twice to get to the looping page.

Figure 3. SST Temperatures

Notice that the storm tracked through a region with SSTs generally above 25C (refer to figure 3 for the sea surface temperature legend for these images), until after it crossed the Gulf Stream heading NW, sometime between 1200Z and 1800Z on the 29th.  However, the warmest water in association with the Gulf Stream was aligned to the west of the storm during most of its track.  At night, when horizontal temperature gradients were probably larger along/near the Gulf Stream, bands of convection appear to have been favored on the southwestern/western portion of the storm, as captured in these VIIRS Day-night-band (DNB) images below.  Of course, other dynamical factors (e.g. low-level streamline convergence, wind shear) also likely played a role in determining the locations of deep convection.  As early as the morning of Oct 27th, forecast discussions from the NHC began to note that the strongest and broadest area of hurricane-force winds were located in the storm’s west to southwest flank, in difference to most tropical cyclones in the Northern Hemisphere, where the strongest winds are generally located in the NE or SE quadrants.

Figure 4. VIIRS 0.73 km Day-night-band RGB imagery valid 27 Oct 0642Z, overlain with NHC preliminary track for Hurricane Sandy.

Figure 5. VIIRS 0.73 km Day-night-band RGB imagery valid 28 Oct 0625Z, overlain with NHC preliminary track for Hurricane Sandy.

Figure 6. VIIRS 0.73 km Day-night-band RGB imagery valid 29 Oct 0606Z, overlain with NHC preliminary track for Hurricane Sandy.

Notice that the brightest white clouds and adjacent areas of greater cloud texture (contrasting shadows and light) in these images are indicative of areas of deep convection, which lay mostly to the west/southwest of the center of Hurricane Sandy during its track.  To better collocate areas of deep convection with the SSTs, I applied transparency to the VIIRS DNB in the next series of images and conbined the DNB imagery with the SPoRT blended SSTs.  It can be seen that development for deep convection favored the warm waters of the Gulf Stream, as might be expected.  Perhaps this led to the unusually large storm size and concentration of strongest and broadest hurricane force winds within the SW quadrant of the storm.

Figure 7. VIIRS 0.73 km Day-night-band RGB imagery valid 27 Oct 0642Z (partially transparent), with SPoRT SST blended product and NHC preliminary track for Hurricane Sandy.

Figure 8. VIIRS 0.73 km Day-night-band RGB imagery valid 28 Oct 0625Z (partially transparent), with SPoRT SST blended product and NHC preliminary track for Hurricane Sandy.

Figure 9. VIIRS 0.73 km Day-night-band RGB imagery valid 29 Oct 0606Z (partially transparent), with SPoRT SST blended product and NHC preliminary track for Hurricane Sandy.

Finally, a loop of the best available VIIRS DNB imagery during the track of Hurricane Sandy through the region can be seen below.  The last couple of images are after the former hurricane had moved ashore.  The last two images in the loop are valid at 0550Z and 0728Z on Oct 30th.

Figure 10. Loop of best available VIIRS 0.73 km DNB RGB images during the track of Hurricane Sandy. The last two images are valid after the storm had come ashore.

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Comparison of Air Mass RGBs for Extratropical Cyclone Sandy

The early morning overpasses of the NASA Aqua Satellite and NASA/NOAA Suomi-NPP Satellite both captured the progress of extratropical cyclone (nee Hurricane) Sandy as it moved across Pennsylvania.  SPoRT blends data from the Suomi-NPP Cross-track Infrared Sounder (CrIS) with data from the Visible Infrared Imager Radiometer Suite (VIIRS) to produce the Air Mass RGB product because of water vapor and ozone channels missing from VIIRS.  SPoRT also produces the same imagery from the Moderate-resolution Imaging Spectroradiometer (MODIS), which contains all of necessary channels for product development.  These data are made available to the NWS/NCEP in their NAWIPS decision support system and are available in KML format for display in Google Earth.

Below are two images taken less than 30 minutes apart from the two satellites.  On top is the CrIS/VIIRS Air Mass RGB image taken at 0728 UTC on October 30.  The bottom image is the MODIS Air Mass RGB image taken at 0751 UTC on October 30.  While the CrIS/VIIRS image is at slightly lower resolution due to effects from the larger CrIS footprint, the imagery is quite useful in identifying all of the atmospheric features.  Both images captured the location and structure of the storm system’s cloudy areas.  Also, both images captured the green-shaded moist air over the midwest and Great Lakes and the dry air that was being wrapped into the Northeastern side of the storm.

The blended CrIS/VIIRS RGB image is a great example of the type of exciting product that we can expect from the Joint Polar Satellite System (JPSS) in the future in support of operational weather forecasting.

Air Mass RGB Image from NASA/NOAA CrIS and VIIRS instruments depicting Extratropical Cyclone Sandy at 0728 UTC on 30 October 2012. Note that the features in this image are very consistent with the features in the MODIS RGB image below.

Air Mass RGB Image from NASA’s MODIS (Aqua) instrument depicting Extratropical Cyclone Sandy at 0751 UTC on 30 October 2012.

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