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  • March « 2009 « CIMSS Satellite Blog
    reported to be as high as 50 000 60 000 feet above ground level A number of Volcanic Ash Advisories were issued and Alaska Airlines canceled 35 flights in and out of Anchorage International Airport as a precaution since airborne volcanic ash is known to be a significant hazard to aviation The beginning phase of the later stronger eruption that began around 12 30 UTC can be seen on MODIS imagery below Note the cluster of very hot pixels on the 3 7 µm Channel 20 shortwave IR image red color enhancement temperatures as high as 57º C which was a signature of the heat of the eruption at the summit of the volcano in contrast very cold IR brightness temperatures seen on the 11 0 µm Channel 31 IR image as cold as 57º C orange to red color enhancement highlighted the portion of the volcanic eruption cloud that had reached very high altitudes in a very short time MODIS 3 7 µm and 11 0 µm IR images A sequence of 1 km resolution NOAA 15 NOAA 17 and NOAA 18 10 8 µm IR images below shows a few of the initial volcanic plume features circled in cyan at 4 different times 06 52 UTC just after the initial eruption 11 46 UTC with an elongated plume which had drifted off to the northeast of Redoubt 13 27 UTC with a more dense plume feature that appeared to be spreading out in a NW SE direction and 14 30 UTC showing another dense plume that had spread out even further in the N S direction NOAA 15 NOAA 17 NOAA 18 10 8 µm IR images The volcanic plume could also be seen on imagery from the WSR 88D radar located near Kenai Alaska below Surface ash falls of 1 8 to 1 4 inch were reported at Skwentna northwest of Anchorage and ash was reported on all airport surfaces at Talkeetna north of Anchorage in fact ash was reported on the ground as far north as Healy Kenai Alaska radar composite reflectivity A 500 meter resolution MODIS true color Red Green Blue RGB composite image below shows a signature of ash fall on top of the pristine white snow cover of the Alaska Range as denoted by the lighter brown tint A higher resolution version is available from the Alaska Volcano Observatory MODIS true color RGB composite image 24 MARCH UPDATE courtesy of Mike Pavolonis NOAA NESDIS ASPB Shown below are some AVHRR ash retrievals ash concentration ash height and ash effective particle radius from the 23 24 March eruptions All of these AVHRR products will be produced operationally by NOAA NESDIS starting sometime next Spring 2010 Ash shows up as red in the accompanying false color images upper left panels Notice that the retrieved ash particle sizes are fairly large mean effective radius of 7 10 micron This may be one of the reasons that the 11 12 micron brightness temperature difference BTD signal was

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2009/03 (2012-11-14)
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  • February « 2009 « CIMSS Satellite Blog
    greater in the area of the warm signature feature seen on satellite imagery however their ice analysis did indicate that anywhere from 2 10 to 6 10 of the total ice coverage consisted of relatively young ice having a thickness of only 10 30 cm Canadian Ice Service regional ice analysis 16 February 2009 So what would be the source such a warm signal on the IR satellite image was there some sort of warm current of water beneath ice that would cause a significant amount of thermal energy to bleed through the relatively thin ice and be detected as warmer temperatures on the IR imagery Was the ice thickness less than normal due to abnormally warm temperatures during the previous summer months which increased the water temperatures enough to then slow the rate of ice formation during the winter In addition it should be noted that the North Water Polynya is a seasonally recurring area of ice free or limited ice water that forms in Baffin Bay which connects to the far southern portion of the Nares Strait but would that polynya extend as far north into the Nares Strait as the Robeson Channel If you have any ideas hypotheses or conspiracy theories that would help to explain this curious satellite feature we d love to hear them send us an email 03 MARCH UPDATE I received an email from Trudy Wohlleben of the Canadian Ice Service with a fantastic explanation of why we re seeing such a warm ice signature on the satellite imagery This year and the last two years have been quite unusual The ice in Nares Strait usually consolidates around the beginning of February and normally you would not see an elongated warm signature extending right up the strait as you are seeing this winter The ice then usually breaks up in the last week of July The normal 1971 2000 winter situation is shown on this map http ice ec gc ca IA NWCA MCSI ar ctmed0301 gif where black is 10 10 consolidated ice coverage and where red is mobile 9 10 10 ice coverage Nares Strait did not consolidate in 2007 allowing for a continuous flow of thick multi year ice from the Arctic Ocean down to Baffin Bay It did consolidate in 2008 but further north than normal with the ice bridge starting at the north end of Kane Basin instead of in Smith Sound This year 2009 it hasn t consolidated yet again So far unlike 2007 an ice bridge HAS formed preventing a flow of Arctic multi year sea ice into the Strait But unlike 2008 it has formed at the far north end of Robeson Channel Because of the location of the ice bridge at the north end of Robeson Channel instead of in the normal position in Smith Sound and because of the prevailing northerly winds through the Strait a polynya has formed extending the length of Nares Strait The winds continuously push newly formed ice southwards

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2009/02 (2012-11-14)
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  • January « 2009 « CIMSS Satellite Blog
    later in the day but other smaller shorter wave features were seen to the north over far northeastern Iowa and southern central Wisconsin AWIPS images of the 1 km resolution MODIS visible 3 7 µm shortwave IR 6 7 µm water vapor and 11 0 µm IR window channels below revealed the following points 1 a strong component of solar reflection on the shortwave IR image brightness temperature values were as warm as 25º to 35º C darker gray color enhancement suggested that the cloud billows were composed of supercooled water droplets 2 the upward downward gravity wave motions were also evident on the water vapor imagery and 3 the IR window brightness temperature values were generally in the 20º to 29º C range cyan to dark blue color enhancement MODIS visible shortwave IR water vapor IR window images The MODIS Cloud Phase and Cloud Top Temperature products below supported the idea of predominantly supercooled water droplet clouds blue color enhancement with minimum Cloud Top Temperature values of 22º C along the Wisconsin Illinois border region MODIS visible cloud phase cloud top temperature images A MODIS visible image with an overlay of CIMSS Mesoscale Winds and pilot reports of turbulence below showed that the winds in the middle to upper troposphere were fairly strong from the southwest several wind speeds of 160 200 knots were indicated between the pressure levels of 250 and 337 hPa and there were a handful of pilot reports of light to moderate turbulence with one report at an altitude of 37 000 feet over extreme northern Illinois near the gravity wave feature CIMSS GOES mesoscale winds The rawinsonde data from Davenport Iowa below a few hours after the gravity wave features were seen on the satellite imagery showed a pronounced temperature inversion between the 450 500 hPa pressure levels the air temperatures in that layer were in the 21 to 26º C range in agreement with the MODIS IR brightness temperature and Cloud Top Temperature values associated with the main gravity wave feature According to the GOES 12 sounder Cloud Top Height product the tops of these cloud features were within the 12 000 15 000 feet range which seemed a bit on the low side judging from the rawinsonde data Davenport Iowa rawinsonde data Posted in Aviation GOES sounder GOES 13 MODIS Satellite winds Comments Off Freeze in Florida January 22nd 2009 MODIS 11 0 µm IR GOES 12 10 7 µm IR GOES 12 sounder Skin Temperature Much of the central and southern Florida peninsula experienced temperatures at or below freezing on the morning of 22 January 2009 Surface air temperatures were as cold as 15º F at Archbold in the Tampa NWS County Warning Area CWA 16º F at Plymouth in the Melbourne CWA and 23º F at Palmdale in the Miami CWA A comparison of AWIPS images of the 1 km resolution MODIS 11 0 µm IR window channel the 4 km resolution GOES 12 10 7 µm IR window channel

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2009/01 (2012-11-14)
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  • December « 2008 « CIMSS Satellite Blog
    15 UTC 47 mph at Sheboygan in eastern Wisconsin at 18 24 UTC and 65 mph at Charlevoix in northern Lower Michigan at 00 25 UTC Blue River Wisconsin wind profiler data The core of the mid tropospheric dry air had moved over southern Lower Michigan by late afternoon and the GOES 13 Sounder and Imager water vapor channel weighting functions calculated using the 00 00 UTC rawinsonde data from Detroit below indicated that the layer of radiation being detected by the Sounder 7 4 µm channel was peaking at a very low altitude red plot with a significant component of that radiation likely coming from the surface Detroit Michigan GOES 13 water vapor channel weighting functions It is interesting to note that an animation of the GOES 13 Sounder 7 4 µm water vapor channel imagery with the map overlay removed below displayed a clear signature of the outline of portions of Lake Superior and Lake Michigan after the driest air had moved over the region the strong thermal signature of the cold land warmer water surface boundary was able to reach the satellite since there was very little middle and upper tropospheric water vapor present to attenuate the signal GOES 13 Sounder 7 4 µm water vapor images with map overlay removed Posted in GOES sounder GOES 13 MODIS Comments Off Thunderstorm causes a power blackout in Oahu Hawaii December 27th 2008 GOES 11 10 7 µm InfraRed IR images A strong thunderstorm which produced heavy rain and frequent lightning was apparently a factor in triggering a power blackout that affected the Hawaiian island of Oahu for at least 12 hours beginning on the evening of 26 December 2008 in fact this was the first time all of Oahu had lost power since October 2006 when a 6 7 magnitude earthquake shook the Hawaiian Islands and knocked out power on Oahu and parts of other islands for up to two days GOES 11 10 7 µm IR images above showed the rapid development and the subsequent rapid dissipation of this thunderstorm over Oahu the island located at the center of the images which formed around 04 00 UTC on 27 December 6 PM local time on 26 December The IR cloud top brightness temperatures quickly cooled to a minimum value of 45º C violet color enhancement at 04 30 UTC but then cloud top temperatures increased to values warmer than 40º C as the storm moved northwestward away from the island of Oahu by 06 00 UTC An upper level low had been located to the east of the Hawaiian Islands for several days and GOES 11 6 7 µm water vapor images below showed that this low moved slowly westward during the 25 27 December period Also note the roll up of smaller cyclonic vorticies along the northern edge of the moisture field of the upper low CIMSS water vapor winds products indicated that these vorticies were forming in an environment of low wind shear that existed

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2008/12 (2012-11-14)
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  • November « 2008 « CIMSS Satellite Blog
    Ice cloud was present pink color enhancement MODIS visible IR window Cloud Top Temperature and Cloud Phase Vertical cross sections of RUC13 model fields below courtesy of Dan Miller Science and Operations Officer at the Duluth MN National Weather Service forecast office did a fairly realistic job of depicting a deep pocket of upward vertical velocity Omega purple contours within the 800 300 hPa layer that was providing the forcing for the standing wave cloud band and as moist layers Relative Humidity greater than 50 green shading passed through the deep pocket of Omega a standing wave cloud band formed that could then seen on satellite imagery The higher altitude moist layer arriving at the later time periods seems to correspond to the layer that produced the cirrus plume and this higher layer was at temperatures colder than 30º C in agreement with the temperatures seen on the MODIS IR image and Cloud Top Temperature product Vertical cross sections of RUC13 model fields A closer view using 250 meter resolution MODIS true color and false color imagery from the SSEC MODIS Today site below actually depicted two separate standing wave cloud bands with the high altitude cirrus streaming off the upper portion of the bands showing up quite nicely One could also see that many of the smaller lakes across northeastern Minnesota were either completely frozen or were in the process of becoming ice covered MODIS true color and false color images Posted in GOES 12 GOES 13 MODIS Comments Off Freezing drizzle in Colorado November 20th 2008 MODIS Fog Stratus product topography A cold and moist upslope northeasterly flow had pushed up against the Front Range of the Rocky Mountains in Colorado during the pre dawn hours on 20 November 2008 a comparison of AWIPS images of the MODIS Fog Stratus product and the topography above showed that the western edge of the stratus deck was backed up against the highest terrain that runs north south across central Colorado AWIPS images of the MODIS Fog Stratus product Cloud Top Temperature CTT product and Cloud Phase product below indicated that CTT values were generally in the 8 to 15º C range with the Cloud Phase product indicating that the cloud was composed of supercooled water droplets Without the presence of ice crystals in the clouds the resulting precipitation type across parts of eastern Colorado was freezing drizzle at locations whose surface air temperature had dropped below freezing as was seen at Denver Centennial Airport KAPA and Elbert Mountain KMNH at 10 00 UTC 4 AM local time Winter Weather Advisories were issued for a number of counties due to the freezing drizzle causing roadway icing MODIS Fog Stratus product Cloud Top Temperature product and Cloud Phase product This extensive stratus cloud deck could be further characterized by examining the GOES 12 Fog Stratus product in conjunction with the Low Cloud Base product and the sounder derived Cloud Top Height product below the cloud bases were all below 1000 feet green

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2008/11 (2012-11-14)
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  • October « 2008 « CIMSS Satellite Blog
    cold air drainage into the valleys was lost the effective resolution of the 4 km GOES IR pixels increase in size to about about 20 km over northern Alaska due to the large satellite viewing angle The coldest IR brightness temperatures seen on GOES data in that region at 12 30 UTC was 39º C 38º F compared to 45º C 49º F indicated by the AVHRR data at 12 38 UTC GOES 11 10 7 µm IR images According to the USA Today tabulation of daily national temperature extremes this is the earliest 40º F temperature reported in the US during the 1995 2008 period the earliest 40º date was 05 November in 1999 with the latest 40º date being 31 December in 2002 While this was also the earliest recorded 40º temperature for Chandalar Lake it did not threaten the monthly October record low temperature for the state of Alaska which was 48º F or 44º C at Clear Water set in 1975 Posted in AVHRR GOES 11 Winter weather Comments Off Snow cover over the northeastern US and southeastern Canada October 23rd 2008 MODIS Visible Snow ice Land Surface Temperature and NDVI AWIPS images of the MODIS visible channel 2 1 µm near IR snow ice channel Land Surface Temperature LST product and Normalized Difference Vegetation Index NDVI product above showed an area of snow cover over parts of upstate New York Vermont New Hampshire and Maine in the northeastern US as well as Quebec and New Brunswick in southeastern Canada on 23 October 2008 Snowfall amounts over that region were generally in the 2 6 inch range NOHRSC with as much as 7 inches reported at Killington in Vermont This snow cover was also very evident on true color imagery from the SSEC MODIS Today site Some items to point out on the AWIPS MODIS imagery above the snow cover appears as brighter shades of white on the visible image as do the cirrus cloud features over the far northwestern corner of the image and the stratocumulus clouds found over the eastern and southeastern portions of the image the snow cover appears darker on the 2 1 µm near IR snow ice channel since snow or ice is a strong absorber of radiation at that wavelength the LST values were about 10º F colder over the snow cover upper 20s to low 30s F darker blue colors compared to adjacent bare ground areas NDVI values over the snow cover were also significantly lower 0 1 to 0 2 compared to the adjacent areas that still had green vegetation in place Even though the MODIS LST values over the snow cover were about 10º F lower the actual instrument shelter air temperatures reported across the region were only a few degrees F colder over the areas with snow on the ground below in part due to the relatively high October sun angle MODIS LST product with METAR reports As an aside an examination of the patch of

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2008/10 (2012-11-14)
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  • September « 2008 « CIMSS Satellite Blog
    temperatures were warmer than 0º C along the frontal cloud band north of Hawaii suggesting rather shallow cloud features AWIPS image of GOES 11 10 7 µm IR channel and MADIS winds A closer view using GOES 11 visible imagery below revealed that a series of mesoscale vorticies had developed along the frontal boundary Another interesting feature was the persistent volcanic plume downwind of the big island of Hawaii streaming toward the southwest due to ongoing activity at the Kilauea volcano since Spring 2008 see the April 2008 CIMSS satellite blog entry Also note the long thin line of cumulus clouds below the volcanic plume a result of lee side convergence GOES 11 visible images A comparison of GOES 11 and GOES 13 visible images below shows that the volcanic plume was even more apparent with the larger viewing angle and more favorable forward scattering geometry from the GOES 13 satellite positioned at 105º W longitude vs 135º W longitude for GOES 11 GOES 11 and GOES 13 visible images Posted in GOES 11 GOES 13 Satellite winds Volcanic activity Comments Off Subtropical Storm Laura September 29th 2008 GOES 12 IR image QuikSCAT WindSat wind vectors An image of the GOES 12 10 7 µm IR channel with an overlay of QuikSCAT WindSat wind vectors from the CIMSS Tropical Cyclones site above revealed that wind speeds were near 50 knots within a curved band of deep convection located just to the east of the center of Subtropical Storm Laura on 29 September 2008 Animations of the GOES 12 10 7 µm IR channel and visible channel images below showed the curved band of deep convection developing further and wrapping around the northern and then the western quadrants of the storm during the hours that followed small scale swirls were also seen on the visible imagery rotating around the low level center of Laura GOES 12 10 7 µm IR images GOES 12 visible images Laura was eventually classified as a Tropical Storm on the following day 30 September Posted in GOES 12 Tropical cyclones Comments Off Older Entries Webmaster Follow us on Search for Pages About this site CIMSS Satellite Proving Ground Contact us Mobile users POES AVHRR in AWIPS SatePedia Suomi NPP JPSS Proving Ground VISIT SHyMet Training Topics September 2008 M T W T F S S Aug Oct 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Categories Air quality Antarctic Arctic AVHRR Aviation AWIPS II Calibration Anomalies Cloud Top Cooling Convective Initiation Fire detection Fog detection General interpretation GOES sounder GOES 10 GOES 11 GOES 12 GOES 13 GOES 14 GOES 15 GOES R Google Earth Heavy rain flooding Historical Hydrology Lightning Marine weather McIDAS V Meteosat MODIS MTSAT Other Satellites POES Red Green Blue RGB images Satellite winds Severe convection Suomi NPP Synthetic satellite imagery Training Tropical cyclones VIIRS Volcanic activity Web Map Server

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2008/09 (2012-11-14)
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  • August « 2008 « CIMSS Satellite Blog
    southerly component Note that the surface features on the GOES 13 animations exhibit less image to image movement compared to both GOES 11 and GOES 12 improvements to the GOES 13 spacecraft Image Navigation and Registration INR system include the use of star trackers to provide more precise image navigation data GOES 12 GOES 13 visible images The smoke was easier to identify using 250 m resolution MODIS true color imagery from the SSEC MODIS Today site below and this smoke was also evident on the MODIS Aerosol Optical Depth product MODIS true color image The Denver National Weather Service forecast discussion mentioned the smoke AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 315 PM MDT THU AUG 28 2008 AVIATION VFR CONDITIONS TO CONTINUE THROUGH TONIGHT SMOKE OVER AREA HAS BEEN CREATING SOME SLANT VISIBILITY PROBLEMS UPON APPROACH AS WELL AS TAKE OFFS BUT NO CONCERNS WITH SURFACE VISIBILITY IT DOESN T APPEAR THAT SURFACE VISIBILITY WILL BE REDUCED While there were a couple of pilot reports of haze aloft over the region around 18 00 UTC at altitudes of 11 500 and 14 000 feet below the surface visibilities only dropped to 6 miles at Boulder KBJC and 7 miles at Denver KDEN during the afternoon hours and remained around 10 miles at other surrounding airports AWIPS images of the MODIS visible channel Posted in Air quality Aviation GOES 11 GOES 12 GOES 13 MODIS Comments Off Running a forecast model with locally downloaded satellite data August 27th 2008 McIDAS V images of CRAS model Precipitable Water pre forecast spin up MODIS instruments see here as well on board NASA s Terra and Aqua satellites offer high resolution multi banded views of the Earth s atmosphere Information from the channels can be used to derive total precipitable water in regions where clouds do not exist as explained here In the present case MODIS TPW is compared to colocated TPW values in a CRAS model run that is centered on the direct broadcast MODIS ground station site at SSEC Where the values differ mixing ratios are adjusted so that the model value more closely matches the satellite observed TPWs Lapse rates are preserved in the adjustment Satellite observed TPWs are available only in clear fields of view cloud initializations however are adding information where clouds are observed The case above imagery produced using McIDAS V shows the 12 hour pre forecast spin up for the model with an initial time of 12 00 UTC on 25 August 2008 Six different MODIS orbits that were received at the SSEC direct broadcast ground station between 00 00 UTC and 12 00 UTC directly affect the initial model fields that are derived from GFS output Note how the addition of MODIS data moistens the atmosphere in and around the remains of Tropical Storm Fay over the south central US and also moistens the atmosphere over the Pacific Ocean west of California This method is used to introduce satellite information downloaded locally into

    Original URL path: http://cimss.ssec.wisc.edu/goes/blog/archives/date/2008/08 (2012-11-14)
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