Comparison of 8-day average MODIS SST (left) and 07 September MODIS SST (right)

A comparison of the MODIS 8-day average Sea Surface Temperature (SST) ending on 06 September 2011 (above, left) with the MODIS SST product on 07 September 2011 (above, right) revealed a dramatic cooling of the near-shore waters just off the east coastline of Lake Michigan. Persistent strong northerly daytime winds (gusting in the 20-30 mph range) induced an upwelling of colder water from below the surface, with 07 September values as cold as 6.8ºC (44ºF) at one location (Latitude/Longitude 43.63 North/81.96 West) — compared to the previous 8-day average SST of 22.8ºC (73ºF) at that same location. Unfortunately, the MODIS Cloud Mask that is applied to the SST product mistakenly identifies the strongest SST gradient as a cloud, and blanks out the SST product along the far western fringe of the ribbon of colder water.

AWIPS images of MODIS 0.65 µm visible channel and 11.0 µm IR channel data (below) showed greater detail in the ribbon of colder waters, with a series of eddies forming along the northern edge of the feature. Since no Cloud Mask is applied to the IR image, the full westward extent of the cold water feature can be seen.

MODIS 0.65 µm visible channel and 11.0 µm IR channel images

A sequence of four MODIS 11.0 µm IR images (below) shows the evolution of the eddy features along the western edge of the cold water. Note that the land surfaces exhibit cool IR brightness temperatures (blue to cyan color enhancement) on the first 2 night-time images (03:10 UTC and 07:21 UTC, or 10:10 pm and 2:21 am local time), but on the 2 daytime images (16:45 UTC and 18:27 UTC, or 11:45 am and 1:27 pm local time) urban areas and regions with less dense vegetation heat up and exhibit much warmer IR brightness temperatures (orange to red color enhancement). However, the Lake Michigan IR brightness temperatures generally remain constant during this time period.

MODIS 11.0 µm IR images

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS. In addition, the VISIT training lesson “MODIS Products in AWIPS” is available to help users understand these products and their applications to weather analysis and forecasting.

GOES-13 10.7 µm IR images (click image to play animation)

AWIPS images of GOES-13 10.7 µm IR data (above; click image to play animation) showed the progression of two long-lived Mesoscale Convective Systems (or “derechos”) on 11 July 2011 — one moving southeastward from the Dakotas and Minnesota, and another moving northeastward from Nebraska. These two MCS features were responsible for a large number of severe weather reports (SPC: 10 July reports | 11 July reports).

Note the elongated band of cirrus that developed  behind the departing MCS feature, curving across parts of Iowa, Nebraska, Kansas, and Colorado toward the end of the IR image animation above — this striated cloud band marked the location of a well-defined deformation zone. Areas of light to moderate turbulence aloft are often present in association with such deformation zones, as was seen by the number of pilot reports overlaid on a GOES-13 6.5 µm water vapor channel image at 17:45 UTC (below).

GOES-13 6.5 µm water vapor channel image + pilot reports of turbulence

The GOES-13 sounder Total Precipitable Water (TPW) derived product (below; click image to play animation) showed that abundant moisture (TPW values of 50-60 mm or 2.0 to 2.4 inches, violet color enhancement) was in place ahead of the storms as they moved rapidly eastward.

GOES-13 sounder Total Precipitable Water product (click to play animation)

A closer view of GOES-13 10.7 µm IR images with overlays of the Automated Overshooting Top Detection product (below; click image to play animation) revealed a number of overshooting tops, with the minimum cloud top IR brightness temperature of -81ºC occurring over eastern Iowa at 09:45 UTC. The overshooting tops were very evident after sunrise on GOES 0.63 µm visible channel imagery, as they cast shadows upon the thunderstorm anvil tops below (11:45 UTC visible image + overshooting top detection product comparison).

GOES-13 10.7 µm IR images + Overshooting Top Detection (click to play animation)

A set of three comparisons of 1-km resolution POES AVHRR 10.8 µm IR images with their corresponding 4-km resolution GOES-13 10.7 µm IR images (below) demonstrated the value of improved spatial resolution for more accurate detection of the location and magnitude of the coldest cloud tops on severe thunderstorms. On the 08:22 UTC, 08:47 UTC, and 11:37 UTC POES AVHRR images, the coldest cloud top IR brightness temperatures were -84ºC, -90ºC, and -85ºC, respectively (the coldest GOES-13 IR brightness temperatures were -78ºC for all three of those times). Note that the apparent northwestward displacement of cloud features on the GOES-13 images is a result of parallax error due to the large viewing angle from the geostationary satellite.

1-km resolution POES AVHRR 10.8 µm IR and 4-km resolution GOES-13 10.7 µm IR images

1-km resolution POES AVHRR 10.8 µm IR and 4-km resolution GOES-13 10.7 µm IR images

1-km resolution POES AVHRR 10.8 µm IR and 4-km resolution GOES-13 10.7 µm IR images

Very strong surface winds were observed along and in the wake of the well-defined bow echo seen on radar — peak wind gusts included 74 mph at Dubuque, Iowa, 75 mph at Chicago Midway Airport, and 85 mph at Michigan City, Indiana. These strong winds created a seiche across southern Lake Michigan (Seiche Warning | NWS Chicago event summary), with oscillations in water levels seen at Calumet Harbor, Illinois, Milwaukee, Wisconsin, and Holland, Michigan.

MIMIC Total Precipitable Water (TPW) product

The National Hurricane Center initiated Invest 91 to monitor the potential development of a subtropical or even possibly a tropical cyclone over the western Atlantic Ocean on 20 April 2011. AWIPS images of the MIMIC Total Precipitable Water (TPW) product (above; click image to play animation) showed that a tongue of moisture was being advected northward from the band of higher moisture along the Inter-Tropical Convergence Zone (ITCZ) — and this moisture plume was being wrapped into the circulation of the developing disturbance.

A closer look at the MIMIC TPW product at 14:00 UTC along with an overlay of ASCAT scatterometer winds (below) revealed a well-defined cyclonic circulation at the surface, with gale force winds within the northwest quadrant of the storm.

MIMIC TPW product + ASCAT surface winds + Surface analysis

GOES-13 0.63 µm visible channel images

Animations of GOES-13 0.63 µm visible channel images (above) and GOES-13 10.7 µm IR channel images (below) from the CIMSS Tropical Cyclones site continued to show very well-defined cyclonic circulations associated with the feature on 22 April 2011.

GOES-13 10.7 µm IR images

GOES-13 6.5 µm water vapor channel images (below) indicated that dry mid-tropospheric air was wrapping into the system from the south and east.

GOES-13 6.5 µm water vapor channel images

A comparison of AWIPS images of the POES AVHRR 0.86 µm visible channel with ASCAT scatterometer surface wind data (below) revealed the development of deep convective elements just to the north of the low-level circulation center.

POES AVHRR 0.86 µm visible image + ASCAT scatterometer surface winds

A sequence of three POES AVHRR 0.86 µm visible channel images (below) showed the evolution of the convective elements associated with the disturbance during the day.

POES AVHRR 0.66 µm visible channel images

GOES-11 0.65 µm visible channel images (click image to play animation)

McIDAS images of GOES-11 0.65 µm visible channel data (above; click image to play animation) showed a number of well-defined ship condensation trails (or “ship tracks”) propagating southward within the marine boundary layer stratocumulus cloud field over the eastern North Pacific Ocean on 31 March 2011.

A comparison of AWIPS images of 1-km resolution POES AVHRR 0.86 µm visible channel data and the corresponding 1-km resolution POES AVHRR Cloud Particle Effective Radius product (below) revealed that the ship tracks were composed of slightly smaller particles (lighter cyan color enhancement) than the surrounding stratocumulus clouds that they were embedded within. Note that many of the ship tracks could not be seen on the visible image within the more overcast stratocumulus cloud deck that covered the southern portion of the image — but their detection was possible using the Cloud Particle Effective Radius product.

POES AVHRR 0.63 µm visible and Cloud Particle Effective Radius product images

As can be seen below, the ship track features did not show up very well in 1-km resolution images of the POES AVHRR Cloud Type product (showing liquid type clouds, cyan color enhancement), the Cloud Top Temperature product (showing temperatures around +10º C, green color enhancement), or the Cloud Top Height product (showing cloud tops around 2-3 km, purple color enhancement).

POES AVHRR Cloud Type product

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Height product

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

GOES-13 10.7 µm IR images (click image to play animation)

AWIPS images of GOES-13 10.7 µm IR data (above; click image to play animation) showed the development of two strong Mesoscale Convective Systems over the Gulf of Mexico on 28 March 2011. These storms prompted  the Storm Prediction Center to issue Severe Thunderstorm Watch #70 and #71 for the threat of  strong winds and large hail — however, no reports of severe weather were received from these particular storms.

The MODIS Sea Surface Temperature (SST) product from the previous day (below) revealed that the northern edge of the Gulf of Mexico Loop Current (warmer SST values in the upper 70s to around 80º F, red color enhancement) was located near the areas of development of these two Mesoscale Convective Systems — raising the question as to the role that this warmer water may have played in their initiation. In addition, an overlay of the High Resolution Real-Time Global Sea Surface Temperature (RTG_SST_HR) model SST failed to capture the warmer tongue of SSTs located to the east of the main core of the Loop Current.  MODIS SST values were 2-3 degrees F warmer than the model SST values in the eastern warm tongue feature — and 3-4 degrees F cooler within the main core of the Loop Current.

MODIS SST product + RGT_SST_HR model SST analysis

=================================

MODIS SST product + MODIS 11.0 µm IR images

A comparison of the MODIS SST product with MODIS 11.0 µm IR images of the first MCS (above) along with a similar comparison of the MODIS SST with a combination of MODIS 11.0 µm IR and POES AVHRR 10.8 µm IR images (below) showed the development of each MCS in the general proximity of the areas of warmer SST values associated with the Loop Current.

MODIS SST + MODIS 11.0 µm IR + POES AVHRR 10.8 µm IR images

A comparison of a 4-km resolution GOES-13 10.7 µm image with the corresponding 1-km resolution POES AVHRR image (below) demonstrated the value of higher spatial resolution for locating the colder cloud top IR brightness temperatures associated with overshooting tops of intense deep convection. The coldest IR temperature on the GOES-13 image was -71º C, compared to -80º C on the POES AVHRR image.

GOES 10.7 µm IR image + POES AVHRR 10.8 µm IR image

CIMSS participation in GOES-R Proving Ground activities includes making a variety of  MODIS and POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

GOES-13 0.63 µm visible channel imagery (click image to play animation)

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the development of a batch of cumulus clouds over the central Gulf of Mexico during the day on 13 February 2011. Other features of interest on the visible imagery include the rapidly-melting snow cover over the portions of the southern Plains, and a few small smoke plumes drifting northeastward due to fires burning in some of the Gulf Coast states.

A comparison of AWIPS images of the 1-km resolution MODIS 0.65 µm visible channel and the corresponding MODIS Sea Surface Temperature (SST) product (below) indicated that this area of cumulus development was occurring over the warmer waters of the Gulf of Mexico “Loop Current”, where SST values were as warm as 78º F (darker orange color enhancement). As a seasonally cool northeasterly flow of air moved across the warmer Loop Current, enough instability was generated to lead to the formation of shallow cumulus clouds.

MODIS 0.65 µm visible image + MODIS Sea Surface Temperature product

About 3 hours later, a similar comparison of a 1-km resolution POES AVHRR 0.63 µm visible image with the corresponding POES AVHRR Sea Surface Temperature product (below) showed a few more cumulus lines forming over the northern portion of the Loop Current, with the cumulus cloud field becoming more dense in the southern portion.

POES AVHRR 0.63 µm visible image + POES AVHRR Sea Surface Temperature product

GOES-13 0.63 µm visible channel images (click image to play animation)

A long lake effect snow band became well-organized and stretched nearly the entire length of Lake Ontario on 20 January 2011. The cloud band was very evident on McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation). As the lake band moved onshore, it produced light to occasionally moderate snow at a few inland locations across central New York. In addition, if you look closely in the far northeastern portion of the lake you can also see ice floes that were drifting slowly eastward.

An AWIPS image of 1-km resolution MODIS 0.65 µm visible channel data (below) showed a more detailed view of the lake effect snow band feature. On the corresponding 1-km resolution MODIS Sea Surface Temperature (SST) product, relatively warm SST values as high as 40º F (lighter blue color enhancement) could be seen on either side of the cloud band.

MODIS 0.65 µm visible channel image + MODIS Sea Surface Temperature product

A comparison of the MODIS 0.65 µm visible image with the corresponding 3.7 µm shortwave IR image (below) indicated that there was a significant amount of solar reflection off the center portion of the cloud band, suggesting a cloud composed of supercooled water droplets (darker gray enhancement) — perhaps with a very thin veil of cirrus cloud spreading out over the top of the supercooled water droplet clouds. At the time of the MODIS images, Fulton, New York (station identifier KFZY) was reporting moderate snow with a reduction in surface visibility to 0.5 mile.

MODIS 0.65 µm visible image + MODIS 3.7 µm shortwave IR image

However, the 4-km resolution MODIS Cloud Phase product (below) indicated that a good portion of the center of the cloud band had glaciated (salmon color enhancement), although this thin area of ice cloud was surrounded by a great deal of mixed phase (darker gray) or uncertain (lighter gray) and also water phase (blue color enhancement) cloud.

MODIS Cloud Phase product

GOES-11 0.65 µm visible channel images

McIDAS images of GOES-11 0.65 µm visible channel data (above) revealed some interesting cloud features over the far eastern North Pacific Ocean on 17 September 2010: (1) a large “hole” in the stratoculumus cloud field, which contained an intersecting pattern of ship condensation trails (or “ship tracks”), and (2) a subtle train of von Karman vortices extending downwind of Guadeloupe Island off the coast of Baja California. These cloud features were propagating southeastward, due to northwesterly winds within the marine boundary layer.

The pattern of ship tracks on the corresponding GOES-11 3.9 µm shortwave IR images (below) displayed a darker (warmer) signature — this was caused by the reflection of incoming solar radiation off the tops of the ship track plumes (which were composed of rather small water droplets compared to the surrounding stratocumulus clouds) during the day when the sun angle was high. Note how this “dark/warm signal” disappeared at the end of the shortwave IR image animation, when the sun angle became lower in the early evening hours.

GOES-11 3.9 µm shortwave IR channel images

A bit more detail can be seen in AWIPS images of the MODIS 0.65 µm visible channel, the 3.7 µm shortwave IR channel, and the 11.0 µm IR window channel data (below). Note how the ship tracks exhibited very little signal in the IR window image, since that channel is not sensitive to the reflection of solar radiation.

MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR window images

MODIS Sea Surface Temperature product + RTG_SST Hi-Res model analysis

The image comparison above shows “before” and “after” views of the axis of the Gulf Stream off the southeast coast of the US. The “before” view is the Sea Surface Temperatue (SST) analysis from the RTG_SST High Resolution model at 00:00 UTC on 02 September 2010 (before Hurricane Earl arrived) — the axis of the Gulf Stream can be taken to be the wide  ribbon of SST values of 84º F and warmer.

The “after” view is an AWIPS image of the 1-km resolution MODIS Sea Surface Temperature product at 16:03 UTC on 03 September 2010 (after Hurricane Earl had passed). One can see the effect that Hurricane Earl had on the axis of the Gulf Stream, with warm and cold eddies of water — the red colors on the MODIS image are SST values in the middle 80s F, while the blue colors are SST values in the upper 70s F.

Terra and Aqua MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) showed Hurricane Earl moving along the East Coast of the US on 03 September. Note the increased amount of sediment flowing off the coast of North Carolina and South Carolina, due to heavy rainfall and strong offshore winds.

Terra and Aqua MODIS true color RGB images (displayed using Google Earth)

Recent news articles (such as this one) have noted the unusual warmth present in the surface waters of the Great Lakes. Clear skies over the western Great Lakes on Sunday 8 August allowed MODIS instruments to measure sea surface temperatures, and the warm temperatures are plain to see. These warm temperatures have persisted for some time, and 5-day plots for the Buoy in central Lake Michigan (buoy 45007), northern Lake Michigan (buoy 45002), and the center of Lake Superior (buoy 45001) all confirm the MODIS readings: unusual warmth in the Lakes. In fact, many of the lake surface temperature readings are near the top of the 4th quartile in the statistical distribution (see data here for buoy 45001 and here for buoy 45007).

Data from the AVHRR on board the NOAA series of satellites show similarly warm temperatures. Here is an afternoon image from NOAA-19 from 8 August.