Category Archives: Terra

Lake Superior ship tracks

GOES-16

GOES-16 “Red” Visible (0.64 µm, left), Near-Infrared “Snow/Ice” (1.61 µm, center) and Shortwave Infrared (3.9 µm, right) images, with hourly surface wind barbs plotted in yellow [click to play animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.9 µm) images (above) revealed the presence of ship tracks across Lake Superior on 16 November 2017. Aerosols from the exhaust of ships cause a “cloud seeding effect”, which results in a higher concentration of smaller cloud droplets compared to the surrounding unperturbed clouds. These smaller cloud droplets are more effective reflectors of sunlight, resulting in a brighter white signature on the Snow/Ice imagery and a warmer (darker gray) signature on the Shortwave Infrared imagery.

A view of the entire lake — using similar Visible, Snow/Ice and Shortwave Infrared images from the Terra MODIS instrument — is shown below. In addition to the ship tracks, plumes from power plants and/or industrial sites can be seen in southern Ontario, streaming southward near Thunder Bay (station identifier CYQT) and southwestward near Upsala (CWDV); another plume was evident in northeastern Wisconsin, to the southeast of Eagle River (KEGV).

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

Isolated cirrus cloud feature over Louisiana

GOES-16 Visible (0.64 µm) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

GOES-16 Visible (0.64 µm) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

An isolated cloud feature moving east-southeastward across Louisiana on 10 November 2017 caught the attention of several people on Twitter — GOES-16 “Red” Visible (0.64 µm) images (above) showed the motion of this cloud during the 1317-2052 UTC period.

In a 3-panel comparison of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Cirrus” (1.37 µm) and “Clean” Infrared Window (10.3 µm) images (below), the strong signature (bright white) on the 1.37 µm imagery indicated that this feature was a cirrus cloud. The uncharacteristically-warm Infrared brightness temperatures exhibited by this feature were due to the fact that the thin cirrus allowed warmer thermal radiation from the surface to pass through the cloud and reach the satellite detectors.

GOES-16 Visible (0.64 µm, top), Near-Infrared

GOES-16 Visible (0.64 µm, top), Near-Infrared “Cirrus” (1.37 µm, middle) and “Clean” Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

Rawinsonde profiles from Lake Charles and Slidell, Louisiana at 12 UTC (below) showed the presence of a moist layer aloft (at an altitude around 9.5 km or 31,100 feet) — the cirrus cloud feature likely resided within this moist layer, which would explain why the cloud was slow to dissipate. Air temperatures within this moist layer were in the -40 to -50ºC range, and winds were from the west-northwest at speeds of 30-35 knots (which was consistent with the cloud motion seen on satellite imagery).

Rawinsonde data for Lake Charles and Slidell, Louisiana at 12 UTC on 10 November [click to enlarge]

Rawinsonde data for Lake Charles and Slidell, Louisiana at 12 UTC on 10 November [click to enlarge]

Even with the higher spatial resolution Infrared Window imagery (1 km, vs 2 km at the satellite sub-point for GOES-16) of Terra MODIS (below), the minimum Infrared brightness temperature of the cirrus cloud feature was still a relatively warm -31ºC.

Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Another interesting aspect of this small cirrus cloud is that it was casting a shadow to the north (due to the low November sun angle) — and the Terra MODIS Land Surface Temperature product (below) indicated that LST values were about 10 degrees F cooler within the shadow (low to middle 60s F) compared to adjacent sunlit ground (low to middle 70s F). That particular area was not normally cooler in terms of LST values (because of varying vegetation, soil type, a deep lake, etc.), since it did not show up as a cooler feature on the following day.

Terra MODIS Visible (0.65 µm) image and Land Surface Temperature product [click to enlarge]

Terra MODIS Visible (0.65 µm) image and Land Surface Temperature product [click to enlarge]

Additional images and ground-based photos of the cirrus cloud feature can be found on this AccuWeather blog.

Aircraft “hole punch” clouds over Wisconsin

GOES-16 Visible (0.64 µm, top) and Near-Infrared

GOES-16 “Red” Visible (0.64 µm, top) and Near-Infrared “Snow/Ice” (1.61 µm, bottom), with surface station identifiers plotted in yellow [click to play MP4 animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed a number of aircraft “hole punch” clouds over western Wisconsin on the morning of 10 November 2017.  These cloud features were caused by aircraft that were either ascending or descending through a layer of cloud composed of supercooled water droplets — cooling from wake turbulence (reference) and/or particles from the jet engine exhaust acting as ice condensation nuclei cause the small supercooled water droplets to turn into larger ice crystals (which then often fall from the cloud layer, creating “fall streak holes“). The darker gray appearance of the hole punch clouds on 1.61 µm images confirms that the features were composed of ice crystals (since ice is a strong absorber of radiation at that wavelength).

One isolated  hole punch cloud was also seen in 250-meter resolution Terra MODIS false-color Red-Green-Blue (RGB) imagery (source) over central Wisconsin around 16:52 UTC (below). In this type of RGB image (created using MODIS Bands 7/2/1), ice crystal clouds appear as shades of cyan, in contrast to supercooled water droplet clouds which appear as shades of white. With the low November sun angle, this cloud deck was casting a long shadow to the north — and sunlight filtering through the hole punch feature was brightening up a spot in the cloud shadow on the ground.

Terra MODIS false-color images [click to enlarge]

Terra MODIS false-color image [click to enlarge]

Lake effect and river effect clouds in northeastern Montana

GOES-16 "Red" Visible (0.64 µm, top) and Near-Infrared "Snow/Ice" (1.61 µm, bottom) images, with hourly plots of surface observations [click to play MP4 animation]

GOES-16 “Red”Visible (0.64 µm, top) and Near-Infrared “Snow/Ice” (1.61 µm, bottom) images, with hourly plots of surface observations [click to play MP4 animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

As arctic air began to spread eastward across Montana — where the coldest temperature in the US was -12ºF — behind an inverted trough (surface analyses) on 04 November 2017, GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed bands of “lake effect” (from Fort Peck Lake) and “river effect” (slightly upstream, from the Missouri River) clouds. On the Snow/Ice images, sow cover (and cold ice crystal clouds) appear as darker shades of gray, in contrast to supercooled water droplet clouds which are brighter white. Note that surface air temperatures at Glasgow (KGGW) and Jordan (KJDN) were generally in the 15 to 20ºF range.

A 1-km resolution Aqua (overpass times) MODIS Sea Surface Temperature product (below) indicated that SST values were still 50ºF and warmer (darker shades of green) in parts of Fort Peck Lake. Farther to the west, a deeper portion of the Missouri River exhibited SST values in the mid-40s F (cyan) — this area  was likely the source of the river-effect cloud features. The temperature difference between the surface air and the warmer lake/river water was therefore in the 30-35ºF range.

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product [click to enlarge]

In a toggle between 250-meter resolution Terra (overpass times) MODIS true-color (Bands 1/4/3) and false-color (Bands 7/2/1)  Red-Green-Blue (RGB) images from the MODIS Today site (below), the false-color image helps to highlight the bands of supercooled water droplet river effect and lake effect clouds (brighter white) — snow cover (and high-altitude ice crystal clouds) appear as shades of cyan.

Terra MODIS true-color and false-color RGB images [click to enlarge]

Terra MODIS true-color and false-color RGB images [click to enlarge]

A 30-meter resolution Lnndsat-8 false-color image (below) captured the dissipating remnants of the Missouri River cloud plume at 1800 UTC; a few cumulus cloud streets could also be seen over Fort Peck Lake, along the far eastern edge of the image swath.

Landsat-8 false-color image [click to enlarge]

Landsat-8 false-color image [click to enlarge]

Detection of low clouds on “Cirrus band” imagery

GOES-16 Visible (0.64 µm, top), Cirrus (1.37 µm, middle) and Infrared Window (10.3 µm, bottom) images [click to play animation]

GOES-16 Visible (0.64 µm, top), Cirrus (1.37 µm, middle) and Infrared Window (10.3 µm, bottom) images [click to play animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

The ABI “Cirrus” (1.37 µm) band is centered in a strong water vapor absorption spectral region — therefore it does not routinely sense the lower troposphere, where there is usually substantial amounts of water vapor. Hence, its main application is the detection of higher-altitude cirrus cloud features.

However, in areas of the atmosphere characterized by low amounts of total precipitable water, the Cirrus band can sense clouds (and other features, such as blowing dust) in the lower troposphere. Such was the case on 29 October 2017, when a ribbon of dry air resided over the northern Gulf of Mexico in the wake of a strong cold frontal passage; low-level stratocumulus clouds were very apparent on GOES-16 Cirrus band images (above). Also of note: cloud features associated with Tropical Storm Philippe could be seen east of Florida.

The three GOES-16 Water Vapor bands (Upper-level 6.2 µm, Mid-level 6.9 µm and Lower-level 7.3 µm) highlighted the pocket of dry air that was moving across the northern Gulf of Mexico on that day (below).

GOES-16 Upper-level Water Vapor (6.2 µm, top), Mid-level Water Vapor (6.9 µm, middle) and Lower-level Water Vapor (7.3 µm, bottom) images [click to play animation]

GOES-16 Upper-level Water Vapor (6.2 µm, top), Mid-level Water Vapor (6.9 µm, middle) and Lower-level Water Vapor (7.3 µm, bottom) images [click to play animation]

The MODIS instrument on Terra and Aqua has a 1.37 µm Cirrus band as well; 1619 UTC Terra images (below) also revealed the stratocumulus clouds (especially those over the northeastern Gulf, where the driest air resided). Conversely, note how the low cloud features of Philippe were not seen on the Cirrus image, since abundant moisture within the tropical air mass east of Florida attenuated 1.37 µm wavelength radiation originating from the lower atmosphere.

In addition, the VIIRS instrument — on Suomi NPP, and the upcoming JPSS series — has a 1.37 µm Cirrus band.

Terra MODIS visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Hourly images of the MIMIC Total Precipitable Water product (below) showed the ribbon of very dry air (TPW values less than 10 mm or 0.4 inch) sinking southward over the northern Gulf of Mexico. This TPW product uses microwave data from POES, Metop and Suomi NPP satellites (description).

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2017/10/tpw_17z.png

MIMIC Total Precipitable Water images [click to play animation]

Heavy rain in Florida

Aided in part by precipitation associated with Hurricane Irma, some areas of Florida have received record rainfall during the June-October 2017 period:

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

GOES-16 Visible (0.64 µm, left), Near-Infrared

GOES-16 Visible (0.64 µm, left), Near-Infrared “Vegetation” (0.86 µm, center) and Near-Infrared “Snow/Ice” (1.61 µm, right) images [click to play animation]

A comparison of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) showed that water was a strong absorber of radiation at 0.86 µm and 1.61 µm wavelengths — therefore wet ground, rivers, lakes and the oceans appeared dark in those images. This makes those two GOES-16 ABI spectral bands useful for identifying areas of flooding.

Two areas in Florida are noteworthy on the images: the St. Johns River in the northeast part of the state (where Moderate Flooding had been occurring), and parts of South Florida (which had just received an additional 1-5 inches of rain on  the previous day).

A closer look at those 2 areas using Terra MODIS Visible (0.65 µm) and Near-Infrared “:Snow/Ice” (1.61 µm) images are shown below.

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice” (1.61 µm) images, showing central and northeastern Florida [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice" (1.61 µm) images, showing southern Florida [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice” (1.61 µm) images, showing southern Florida [click to enlarge]

In stark contrast to the periods of heavy rain, a strong cold front brought clear skies and very dry air over Florida, as seen in MIMIC Total Precipitble Water product (below).

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]

This dry air evoked enthusiasm in least one South Florida resident:


Santa Ana winds in Southern California

GOES-16 Land Surface Temperature product, with hourly surface reports plotted in white [click to enlarge]

GOES-16 Land Surface Temperature product, with hourly surface reports plotted in white [click to enlarge]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

The GOES-16 Land Surface Temperature product (above, courtesy of Jordan Gerth, CIMSS) revealed a dramatic increase in the land surface temperature (or surface “skin temperature”) following the onset of easterly/northeasterly Santa Ana winds in Southern California’s Ventura County during the overnight and early morning hours of 24 October 2017. Between 06-14 UTC (11 PM-7 AM local time), the surface air temperature increased from 66-91ºF at Oxnard (KOXR), 75-90ºF at Point Mugu (KNTD) and 77-91ºF at Camarillo (KCMA). Surface wind gusts of 32 mph were recorded at Camarillo during this period, although 64 mph was reported at South Mountain (elevation 2350 feet)..

A warming trend in that same area was also evident in the MODIS Land Surface Temperature product (below), during the time between the Terra (0539 UTC) and Aqua (0951 UTC) overpasses — LST values ranged from the low 60s F (lighter shades of yellow) to the upper 80s and low 90s F (darker shades of red) in the higher elevations.

Terra and Aqua MODIS Land Surface Temperature product [click to enlarge]

Terra and Aqua MODIS Land Surface Temperature product [click to enlarge]

A similar warming signature was seen over Ventura County on GOES-16 Shortwave Infrared (3.9 µm) images (below) — although an even more pronounced Santa Ana wind warming signal was evident farther to the southeast over Orange County (where winds gusted as high as 69 mph); note how the warmer orange-enhanced infrared brightness temperatures surged southwestward toward the coast.

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

A number of record high temperatures resulted from this Santa Ana wind event:


Record high temperatures in the San Diego, California

Record high temperatures in the San Diego, California area

In fact, the highest temperature in the Lower 48 states that day was 108ºF at Miramar Naval Air Station and San Luis Obispo, California.

National Temperature extremes

National Temperature extremes

Ex-hurricane Ophelia over Ireland and the United Kingdom

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

After reaching Category 3 intensity over the eastern Atlantic Ocean on 14 October, Hurricane Ophelia (storm track) rapidly underwent transition to an extratropical storm which eventually spread high winds across much of Ireland and the United Kingdom on 16 October 2017. EUMETSAT Meteosat-10 upper-level Water Vapor (6.25 µm) (above) and lower-level Water Vapor (7.35 µm) images (below) revealed the familiar “scorpion tail” signature of a sting jet (reference). Hourly wind gusts (in knots) from primary reporting stations are plotted in red.

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Two sites with notable wind gusts were Cork, Ireland (67 knots at 0930 UTC) and Valley, UK (70 knots at 1500 UT), shown below. In fact, a wind gust of 103 knots (119 mph or 191 km/hour) was reported at the Fastnet Rock Lighthouse off the southwest coast of Ireland.

Time series plot of surface data from Cork, Ireland [click to enlarge]

Time series plot of surface data from Cork, Ireland [click to enlarge]

Time series plot of surface data from Valley, United Kingdom [click to enlarge]

Time series plot of surface data from Valley, United Kingdom [click to enlarge]

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Terra and Aqua MODIS true-color images [click to enlarge]

Terra and Aqua MODIS true-color images [click to enlarge]

In a toggle between Terra MODIS (overpass time around 1159 UTC) and Aqua MODIS (overpass time around 1345 UTC) true-color Red/Green/Blue (RGB) imagery (above), a somewhat hazy appearance was seen over the Irish Sea on the Terra MODIS image. This was due to an airborne plume of sand from the Sahara Desert (UK Met Office story).

In fact, blowing sand was observed about 3 hours later at Isle of Man, from 1520-1620 UTC — during that time period their surface winds gusted to 68 knots (78 mph), and surface visibility was reduced to 2.2 miles (below).

Time series plot of surface data from Isle of Man [click to enlarge]

Time series plot of surface data from Isle of Man [click to enlarge]

Increase in Turbidity near the Texas Gulf Coast following Hurricane Harvey

Terra MODIS True-Color imagery off the Texas Gulf Coast on 23 and 30 August, 2017 (Click to enlarge)

MODIS Today imagery from 23 August (pre-Harvey) (cropped) and 30 August (post-Harvey) (cropped), above, show an enormous increase in turbidity in the nearshore waters off the coast of Texas. Further, many of the rivers change their appearance to brown and flooding in the post-Harvey image. (River gauges in flood stage; Source)

A similar toggle using Suomi NPP VIIRS Imagery, from this site, also from 23 August and 30 August, is shown below. The increase in turbidity was due to a combination of strong winds and runoff from very heavy rainfall associated with the hurricane.

Suomi NPP True-Color imagery off the Texas Gulf Coast on 23 and 30 August, 2017 (Click to enlarge)

Suomi NPP VIIRS Products include a River Flood estimate, developed by Sanmei Li and others at George Mason University. The toggle below from RealEarth shows Suomi NPP VIIRS True Color at 1904 UTC, and the River Flood Product for the same time.

Suomi NPP VIIRS True-Color imagery off the Texas Gulf Coast, 1904 UTC on 30 August, 2017, and the Suomi NPP River Flood Product at the same time (Click to enlarge)

(Thanks to Bill Taylor and John Stoppkotte, NWS in N. Platte NE, for noting this!)

Hurricane Harvey makes landfall

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

As Hurricane Harvey moved across warm waters in the northwestern Gulf of Mexico (SST | OHC), it continued to intensify (ADT | SATCON) to a Category 4 hurricane just before making landfall (which occurred around 03 UTC on 26 August 2017, or 10 pm local time on 25 August). A GOES-16 Mesoscale Sector had been positioned over Harvey, providing images at 30-second intervals; some of these are shown with “Red” Visible (0.64 µm) images prior to sunset (below). A GOES-16 vs GOES-13 (GOES-East) Visible image comparison is available here.

GOES-16 Visible (0.64 µm) images, with hourly surface ports plotted in yellow (Click to play MP4 animation)

GOES-16 “Red” Visible (0.64 µm) images, with hourly surface ports plotted in yellow [click to play MP4 animation]

Hurricane Harvey had a large eye on GOES-16 “Clean” Infrared Window (10.3 µm) images at landfall, which persisted — albeit becoming smaller with time — for many hours after it moved inland (below). A longer-term animation of 5-minute GOES-16 Infrared Window images (covering the period 23-27 August) is available here.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

A sequence of 4 Infrared Window images, from Suomi NPP VIIRS and Terra/Aqua MODIS, covering the period 0419-0851 UTC (below) showed the shrinking eye and the erratic path of Harvey once it moved inland.

Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) Infrared Window images [click to enlarge]

Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) Infrared Window images [click to enlarge]

A recap of the torrential rainfall amounts and maximum wind gusts caused by Hurricane Harvey can be seen in the WPC Storm Summary.