Flooding in the Missouri/Mississippi/Ohio River basins

January 2nd, 2016 |

Aqua MODIS false-color RGB images on 19 December 2015 and 02 January 2016 [click to enlarge]

Aqua MODIS false-color RGB images on 19 December 2015 and 02 January 2016 [click to enlarge]

A comparison of 250-meter resolution Aqua MODIS false-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site on 19 December 2015 and 02 January 2016 (above) showed large increases in the width of portions of the Missouri/Mississippi/Ohio Rivers (as well as many of their tributaries and surrounding lakes) during that 14-day period. These false-color images use MODIS bands 7/2/1 as the R/G/B components — water appears as varying shades of darker blue. Some light snow cover (shades of cyan) can also be seen in the upper left corner of the 02 January image.

A comparison of Aqua MODIS true-color (created using bands 1/4/3) and false-color (created using bands 7/2/1) RGB images on 02 January (below) demonstrated the advantage of the false-color imagery for detection of the extent of river and lake flooding. The high sediment content of the area lakes and rivers made them appear as varying shades of tan to brown on the true-color image, making their boundaries more difficult to distinguish from the similar shades of the surrounding bare ground surfaces. (Note: when GOES-R is launched in late 2016, similar spectral bands on the ABI instrument will allow the creation of these types of true-color and false-color RGB images)

Aqua MODIS true-color and false-color RGB images on 02 January 2016 [click to enlarge]

Aqua MODIS true-color and false-color RGB images on 02 January 2016 [click to enlarge]

A more detailed view of flooding across the eastern portion of the MODIS images (in southern Indiana and northern Kentucky) was provided by 30-meter resolution Landsat-8 false-color imagery, as visualized using RealEarth (below). A magnified view of the Evansville, Indiana / Owensboro, Kentucky area can be seen here.

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

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

Maps of total observed precipitation and departure from normal (below) during the same 14-day period as the 2 MODIS false-color images shown at the top of the blog post revealed that widespread areas received upwards of 8-10 inches of rainfall, which was 6-8 inches above normal for that 2-week period of time.

19 December 2015 to 02 January 2016 total precipitation and departure from normal [click to enlarge]

19 December 2015 to 02 January 2016 total precipitation and departure from normal [click to enlarge]

As a result of water runoff from the heavy precipitation, new records for maximum river gauge height were set for the Mississippi River at Cape Girardeau, Missouri and Thebes, Illinois (below).

River gauge plot for the Mississippi River at Cape Girardeau, Missouri [click to enlarge]

River gauge plot for the Mississippi River at Cape Girardeau, Missouri [click to enlarge]

River gauge for the Mississippi River at Thebes, Illinois [click to enlarge]

River gauge for the Mississippi River at Thebes, Illinois [click to enlarge]

Additional information is available from the NWS Paducah.

Toxic Algal Bloom in Western Lake Erie

August 4th, 2014 |
Terra MODIS True Color Imagery (click to play animation)

Terra MODIS True Color Imagery (click to play animation)

As happened in 2011, an algae bloom is ongoing over Lake Erie. The current bloom has contaminated at least one water intake for Toledo, Ohio’s municipal water supply with microcystin, a cyanobacter that when ingested can damage the liver and nauseate people. (There is also significant danger to pets). A series of true-color images (from 4 July, 1 August and 4 August) taken from the MODIS Today website, above, (combining visible channels at 0.6465 µm [red], 0.5537 µm [green] and 0.4656 µm [blue]) shows changes in the water color over the past month. (Image Source: MODIS Today) Some changes are apparent over western Lake Erie that are associated with the toxic bloom.

The algal growth is more readily apparent in the false-color imagery below. This red/green/blue image is constructed with 2.1143 µm imagery as ‘red’, 0.8567 µm imagery as ‘green’ and 0.6465 µm imagery as ‘blue’. The animation including scenes from 4 July, 1 August and 4 August shows dramatic growth between 1 and 4 August. Near-infrared channels — such as 0.8567 µm — are sensitive to energy reflected by algae.

Terra MODIS True Color Imagery (click to play animation)

Terra MODIS True Color Imagery (click to play animation)

A series of True-Color images for six days this Spring/Summer is here. The increase in algae in the western part of Lake Erie is apparent, but it seems that the outbreak this year is less wide-spread than the outbreak in October of 2011. A series of False-Color images is here.

[Update, 5 August 2014: Toledo’s water supply has been deemed safe to drink]

Ice jam flooding along the Yukon River in Galena, Alaska

May 28th, 2013 |
Suomi NPP VIIRS 1.61 µm

Suomi NPP VIIRS 1.61 µm “snow/ice discrimination channel” images

A sequence of AWIPS images of Suomi NPP VIIRS 1.61 µm near-IR “snow/ice discrimination channel” data covering the period from 13:47 UTC on 27 May to 23:24 UTC on 28 May 2013 (above) showed the effects of ice jam flooding along the Yukon River in the vicinity of Galena, Alaska (station identifier PAGA). In addition to snow and ice, water is also a strong absorber at the 1.61 µm near-IR wavelength — so it appears darker on the images. This dark signature of water inundation can be seen increasing in areal coverage during that 1.5 day period. This flooding forced the evacuation of aruond 300 residents of Galena, as many homes were extensively damaged by the flooding.

A comparison of Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm “land/water discrimination channel”, and 1.61 µm “snow/ice discrimination channel” images at 21:43 UTC on 28 May (below) showed that the Yukon River downstream of Galena was still snow/ice covered (appearing brighter white on the 0.64 µm and 0.86 µm images). Meanwhile, the darker signature of floodwaters near and upstream of Galena was evident to some extent on the 0.86 µm image, but was even more pronounced on the 1.61 µm image. The Yukon River ice jam flooding in the Galena area occurred about a week after similar ice jam floding occurred much farther upstream in the Fort Yukon area.

Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm land/water discrimination channel, and 1.61 µm snow/ice discriminatioon channel images

Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm land/water discrimination channel, and 1.61 µm snow/ice discriminatioon channel images

Flooding along the Yukon River in Alaska

May 20th, 2013 |
Suomi NPP VIIRS 1.61 µm near-IR "snow/ice channel" images

Suomi NPP VIIRS 1.61 µm near-IR “snow/ice channel” images

A comparison of AWIPS images of Suomi NPP VIIRS 1.61 µm “snow/ice discrimination channel” data from 19 May and 20 May 2013 (above) revealed the areal extent of flooding along the Yukon River upstream of the Fort Yukon (station identifier PFYU) area in northeastern Alaska. Both ice and water are strong absorbers at the 1.61 µm wavelength, so they appear very dark on the images. The flooding along the Yukon River began as a surge of ice and water moved through the Eagle, Alaska (station identifier PAEG) area on 17 May, then continued downstream to produce major flooding in the Circle, Alaska area on 19 May (Circle is located about halfway between PAEG and PFYU). An ice jam had formed about 12 miles upstream of Fort Yukon, which then impounded the flow of ice and water that had flooded Circle, leading to the increased flooding seen upstream of Fort Yukon on 20 May.

A comparison of Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm “land/water discrimination channel”, and 1.61 µm “snow/ice discrimination channel” at 20:52 UTC on 20 May (below) showed how the 0.86 µm and 1.61 µm images can be used to identify the darker flooded portions of the Yukon River that are not apparent on the 0.64 µm visible image.

Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm "land/water" channel, and 1.61 µm "snow/ice channel" images

Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm “land/water” channel, and 1.61 µm “snow/ice channel” images