Archive for the ‘MODIS’ Category
As New Mexico enters a third consecutive year of extreme drought conditions, the wildfire season has been active once again. The Tres Lagunas Fire started on May 30, 2013 and on the afternoon of the following day a second fire, the Thompson Ridge Fire, was started. Both fires were ignited by downed power lines during strong wind events.
Satellite products received from SPoRT are very useful for graphical products that we share with partners and the general public. In the early days of the event, it’s important that the public has a heightened awareness of the locations of the fires, associated smoke impacts, and the general character of the fire. Two graphicasts that were recently posted on our home page and Facebook page are included in this post. Note that the bottom right corner is left blank for the graphicast time stamp information. Another graphicast using the VIIRS Day-Night Radiance product was previously shared on a separate blog entry.
In the first, we used the MODIS true color imagery to show the smoke plume associated with the Tres Lagunas Fire. Areas along Interstate 25 were impacted by the smoke.
By the following day, a second fire was ignited and both remained active over the weekend. The high resolution images included in SPoRT’s hybrid 3.9 μm “hot spot” loop not only provide an accurate location of the wildfire, but can illustrate differences in the character of the fire. In the example below, a continuous hot spot is associated with the Thompson Ridge Fire. However, the Tres Lagunas Fire had spread more rapidly, and had burned more acres at this time, and the hot spot imagery depicts a burn with an active perimeter. The 3.9μm image was combined with an awips topo map on awips to provide topographical references. Both of these graphicasts were also posted to Facebook, where they received higher than normal shares.
The Tres Lagunas fire erupted during the mid afternoon hours of May 30, 2013. The fire grew quickly to 450+ acres and remained active into the overnight hours. Critical fire weather conditions will redevelop today thus more growth is expected.
I’ve been working the midnight shift at the office for the last few nights and have found the MODIS and VIIRS RGB imagery particularly useful. I have viewed the imagery each night and even referenced it specifically in my Area Forecast Discussion early on the morning of the 16th.
A swath of dry air wrapping around the base of the closed low could be seen moving into the region, from Louisiana into Mississippi early on the morning of May 16th. While this was apparent in standard 4 km GOES water vapor imagery, the MODIS Airmass RGB certainly showed more detail. This type of imagery also has the ability to delineate airmass of differing characteristics. Notice the warm, moist airmass across much of the Southeast, ahead of and along the cloud shield. The Nighttime Microphysics RGB image valid at the same time below provided more detail of low level clouds upstream and in the local area, which was important for the forecast.
Since it was apparent that some clearing was indeed possible, if not likely for parts of the area during the morning and into the afternoon, I decided to increase my forecast temperatures. With this type of imagery, it is far easier to delineate between cloud types, and makes the forecast process more efficient. I also noticed that much of the cloud cover at the time to our west, particularly over the Arklamiss area, was mostly cirrus clouds.
This morning, the aviation forecaster and I used the imagery to distinguish between cloud types once again.
While an area of deep convection can be seen in northern Alabama (red colors in north central AL), at the time we were actually more concerned about the low clouds and fog impacting our TAF sites. The image above showed that the low stratus were present across much of northern Alabama and prevalent enough to keep IFR conditions in for the MSL TAF. Additionally, a narrow line of clouds stretching from NE Oklahoma to north central Mississippi could be seen in the imagery. This turned out to be a weak, albeit developing baroclinic boundary upon which deep convection resulted in Mississippi. The RGB imagery above essentially make the forecast process much more efficient and were utilized in several aspects of forecasting this morning. We are eager to get this type of imagery in AWIPS II at some point in the near future.
The MODIS dust and nighttime microphysics products proved very useful during a potent cold frontal passage across eastern NM during the early morning of April 23, 2013. Widespread extreme to exceptional drought conditions have lead to many days this month reporting blowing dust. While most blowing dust cases have occurred during the day, this case is more interesting since the dust occurred at night while low clouds were developing behind the front. The four panel image below illustrates how all the MODIS imagery used together provides better insight into areas of dust versus low clouds. The top left image is the MODIS dust product, the upper right image is the MODIS nighttime microphysics, the lower left is the MODIS 11-3.9micron, and the lower right is the MODIS-GOES hybrid 11micron. The front is clearly visible in the dust product and supported well by the surface observations. Dust at night appears in dark magenta, low clouds light blue in the microphysics product, and yellow in the 11-3.9micron. Visibilities were reported down to 3 to 5 miles around Clovis and Portales and 1.5 miles at Roswell as the front barreled through. Click image to enlarge.
NWS ABQ continues to research the MODIS RGB airmass imagery and its potential to improve prediction of significant fire weather, wind, and dust events across New Mexico. The MODIS satellite captured a stunning example of a dynamic dry slot within the base of a strong mid latitude cyclogenesis over the central Rockies. Blowing dust in association with the strong jet core sliding directly over eastern NM produced very hazardous conditions for much of the afternoon. The lead meteorologist from Cannon Air Force Base reported visibilities down to around 100 yards at times with the sky completely obscured for roughly 5 hours. This was the worst dust storm for the region that he could remember going back to 2006. He also mentioned the region is about as close to the Dust Bowl as he can imagine with essentially no top soil left after multiple strong wind events already this season and persistent severe to extreme drought.
An interesting picture has been making the rounds though social media showing the temperature departure from average for the first 18 days of March 2012 compared to this March, courtesy of Climate Central via the NWS Twin Cities, MN (Fig. 1; original article posted at: http://www.climatecentral.org/news/from-heat-wave-to-snowstorms-March-weather-goes-to-extremes-15763). March 2013 is almost a mirror image of the temperature anomaly map from last March, although not to the same magnitude of departure.
The effect of these radically disparate temperatures are now being seen in the SPoRT real-time MODIS vegetation product, which is generated once daily at 0.01-degree resolution (~1 km) over the Continental U.S. Figure 2 shows a comparison between the 22 March 2012 SPoRT-MODIS green vegetation fraction (GVF) composite and the MODIS GVF composite generated a year later. Brown regions indicate the lowest fractional coverage of healthy green vegetation, while dark green colors show areas of dense, healthy vegetation. The most noticeable differences in GVF can be seen over the Great Lakes, southern Canada and the southern Plains. A difference field in Fig. 3 shows more clearly the magnitude of the one-year GVF change. Portions of Canada, the Great Lakes region, northeastern U.S., and the Southern Plains are seeing lower GVF by about 20-50% compared to last year at this time. These GVF comparison images are available daily on SPoRT’s web page at http://weather.msfc.nasa.gov/sport/case_studies/sportGvf.html, and could be further accentuated given the prospect of continued below-average temperatures through 1 April in the eastern U.S.
Because GVF can vary so widely in certain regions from year to year, it is important to use actual vegetation data rather than a multi-year climatological representation in numerical weather prediction (NWP) applications. Such large GVF differences during the transition seasons can lead to errors in how the NWP model partitions incoming solar energy into heat and moisture fluxes at the surface. SPoRT has made its real-time MODIS GVF product available to the modeling community using the Weather Research and Forecasting model and Environmental Modeling System. Currently, two of SPoRT’s collaborating partners in the National Weather Service (Houston, TX and Mobile, AL forecast offices) are assessing the utility of using real-time MODIS vegetation data in place of the default climatology GVF (in addition to other SPoRT datasets) within the framework of the Environmental Modeling System.
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.
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.
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!
The MODIS-VIIRS Snow-Cloud RGB product has been fun to watch over the past week as the two main snow fields from our blizzard of February 24-25 disappeared. Check out these two neat animated gifs from Quay and Torrance counties for the period February 27th – March 2nd. Click the images to animate. The previous post from February 27th showed these two areas on the MODIS true color images. It took roughly a week for the snow fields to melt but they are finally gone after above normal temperatures impacted the region. Only very minor differences are still occurring with temperature and humidity forecasts as soil moisture dries out across this area.
The heaviest snowfall from the blizzard of February 24-25, 2013 can still be seen on satellite imagery across portions of east central NM. The 1km True Color imagery shows a very well defined area where the heaviest snowfall occurred and the 500-meter Visible imagery from this same area details some interesting terrain features. The satellite images were posted as a Graphicast today and shared via Facebook. The snow pack is still having a significant influence on humidity and temperature forecasts in this area and forecasters continue using the imagery to provide greater accuracy. The snow cover imagery validated the 12 hour snowfall forecast during the heart of blizzard conditions with exceptional accuracy. Snowfall amounts were slightly less than forecast however the areal coverage was pinpointed very well.