MIRS Ice Concentration Products over the Great Lakes

January 20th, 2020 |

MIRS Lake Ice Concentration (as a percentage) from NOAA-20 ATMS at 0735 UTC on 19 January 2020 (Click to enlarge)

CIMSS is now providing via LDM MIRS Lake Ice Products over the Great Lakes. These data are created using the Community Satellite Processing Package (CSPP) Software and NOAA-20/Suomi-NPP ATMS data downlinked at the Direct Broadcast Antennas in Madison WI. Imagery is shown above from 0735 UTC on 19 January 2020; the image below is from 0717 UTC on 20 January 2020, from NOAA-20, about 24 hours later, and then from 0808 UTC on 20 January 2020, from Suomi NPP (although it is labeled as NOAA-20). A great benefit of these microwave products is that they are not affected by persistent cloud cover that is common over the Great Lakes in winter.

MIRS Lake Ice Concentration (as a percentage) from NOAA-20 ATMS at 0717 UTC on 20 January 2020 (Click to enlarge)

MIRS Lake Ice Concentration (as a percentage) from NOAA-20 ATMS at 0806 UTC on 20 January 2020 (Click to enlarge)

Ice concentration estimates from microwave are very strongly influenced by view angle. Make certain in your comparisons (if you are trying to ascertain changes in lake ice coverage during Lake-Effect Snow events, for example) that you understand this! If the footprint sizes are similar, a comparison to different passes is valid; if the footprint sizes differ, the effects of view angle must be considered. Orbital paths can be viewed here (NOAA-20 it passed right over Lake Erie at 0722 UTC on 20 January; Suomi-NPP passed over Duluth at 0812 UTC on 20 January). In the two examples above, note how ice cover estimates differ over Lake Ontario. In the later example, from ATMS on Suomi-NPP, Lake Ontario is far closer to the limb; the ATMS footprint is much larger and the estimate of lake ice concentration is affected. This toggle compares the VIIRS Day Night band image to the ATMS observations; Lake Ontario is close to the limb for NPP’s pass over western Lake Superior at this time.

For instructions on how to access these data, please contact the blogpost author. Many thanks to Kathy Strabala and Lee Cronce, CIMSS, for their work in making these data available. Click here for short video explaining MIRS Ice Concentration).

Added: A consequence of the relatively poor resolution of ATMS (compared to, say, AMSR-2 on GCOM) is that a footprint in the Great Lakes will often not be over only water or over only land. A mixed surface (land and water within the ATMS footprint) means that the ice concentration algorithm will struggle to interpret the signal and reach the right solution. Best resolution from ATMS occurs near the sub-satellite point (from 15-50 km, depending on the frequency), and that’s where this product give the best information. (Thanks to Chris Grassotti, NOAA/CISESS for this information)

Cold air over the Upper Midwest

December 10th, 2019 |

GOES-16

GOES-16 “Clean” Infrared Window (10.35 µm) images, with select minimum temperatures as of 12 UTC [click to play animation | MP4]

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) showed pockets of cold surface brightness temperatures — darker blue represented the -30 to -35ºC (-22 to -31ºF) range — over parts of North Dakota during the 4 hours leading up to sunrise on 10 December 2019. As of 12 UTC, the coldest locations in the US (including Alaska) were Rugby and Watford City, North Dakota with -22ºF; however, Grand Forks International Airport later dropped to -25ºF at 1245 UTC.

With the cold and dry arctic air mass in place across the Upper Midwest, GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor imagery (below) was able to sense the thermal contrast between cold, snow-covered land surfaces and the still-unfrozen reservoirs along the Missouri River in North Dakota and South Dakota.

 GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) images, with rawinsonde sites indicated in yellow [click to play animation | MP4]

GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) images, with rawinsonde sites indicated in yellow [click to play animation | MP4]

GOES-16 Water Vapor weighting functions calculated using 12 UTC rawinsonde data from Aberdeen, SD (below) showed the downward shift of the peak pressures for all 3 spectral bands — with some contributions of radiation originating from the surface indicated for both the 7.3 µm and 6.9 µm bands.

GOES-16 Water Vapor weighting functions calculated using 12 UTC rawinsonde data from Aberdeen, SD [click to enlarge]

GOES-16 Water Vapor weighting functions calculated using 12 UTC rawinsonde data from Aberdeen, SD [click to enlarge]

According to the climatology of Precipitable Water for Aberdeen SD (below), the 12 UTC value of 0.06 inch tied the record minimum value for that date/time. The 12 UTC sounding at Bismarck ND failed at a pressure level near 400 hPa — but the PW value of 0.05 inch calculated from that data would be slightly less than the record minimum value of 0.06 inch for that date/time.

Climatology of Precipitable Water for Aberdeen, SD [click to enlarge]

Climatology of Precipitable Water for Aberdeen, SD [click to enlarge]

On a NOAA-20 VIIRS Visible (0.64 µm) image with plots of available NUCAPS sounding locations (below), soundings northeast of Bismarck KBIS and southeast of Aberdeen KABR are denoted by 1 and 2, respectively.

NOAA-20 VIIRS Visible (0.64 µm) image, with plots of available NUCAPS sounding locations [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) image, with plots of available NUCAPS sounding locations [click to enlarge]

Plots of the NOAA-20 NUCAPS sounding profiles northeast of Bismarck KBIS and southeast of Aberdeen KABR around 19 UTC are shown below. Precipitable Water values calculated for these two soundings remained quite low, at 0.03 inch and 0.04 inch.

NOAA-20 NUCAPS sounding profile northeast of Bismarck (Point 1) [click to enlarge]

NOAA-20 NUCAPS sounding profile northeast of Bismarck KBIS (Point 1) [click to enlarge]

NOAA-20 NUCAPS sounding profile southeast of Aberdeen KABR (Point 2) [click to enlarge]

NOAA-20 NUCAPS sounding profile southeast of Aberdeen KABR (Point 2) [click to enlarge]

GOES-16

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

Examples of “river effect” cloud plumes — produced by cold air flowing across deep, relatively warm water in some of the Missouri River reservoirs — were evident in GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images over North Dakota (above) and South Dakota (below).

GOES-16 "Red" Visible (0.64 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

Lake-effect, river-effect and bay-effect cloud bands producing snowfall

November 13th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm), “Clean” Infrared Window (10.35 µm) and Day Cloud Phase Distinction RGB images on 07 November [click to play animation | MP4]

During the course of multiple intrusions of arctic air across the Lower 48 states during early November 2019, a variety of lake-effect, river-effect and bay-effect cloud features were generated — many of which produced varying intensities of snowfall. GOES-16 (GOES-East) “Red” Visible (0.64 µm), “Clean:” Infrared Window (10.35 µm) and Day Cloud Phase Distinction Red-Green-Blue (RGB) images on 07 November (above) showed lake-effect clouds streaming south-southeastward across Lake Superior. The Day Cloud Phase Distinction RGB images (in tandem with the Infrared images) helped to highlight which cloud features had glaciated and were therefore more capable of producing moderate to heavy lake-effect snow; the dominant band yielded 5-10 inches of snowfall in the central part of northern Michigan.

On 11 November, GOES-16 Nighttime Microphysics RGB images (below) displayed lake-effect clouds originating from the still-unfrozen waters of Fort Peck Lake in northeastern Montana — these clouds did produce a brief period of light snowfall downstream at Glendive (KGDV). On this particular morning, the lowest temperature in the US occurred in north-central Montana, with -30ºF reported north of Rudyard.

GOES-16 Nighttime Cloud Phase Distinction RGB images on 11 November [click to play animation | MP4]

GOES-16 Nighttime Microphysics RGB images on 11 November [click to play animation | MP4]

On 12 November, cold air moving southward across the Lower Mississippi Valley produced horizontal convective roll clouds which were evident in GOES-16 Nighttime Microphysics RGB and subsequent Visible images after sunrise (below) — one of these narrow cloud bands was likely enhanced by latent heat fluxes as it passed over the comparatively-warm waters of the Mississippi River, and produced accumulating snowfall in downtown Memphis. Note that since Memphis International Airport KMEM was located just east of the cloud band, no accumulating snow was reported there (only a brief snow flurry around 1430 UTC).

GOES-16 Nighttime Microphysics RGB and "Red" Visible (0.64 µm) images on 12 November [click to play animation | MP4]

GOES-16 Nighttime Microphysics RGB and “Red” Visible (0.64 µm) images on 12 November [click to play animation | MP4]

Aqua MODIS Sea Surface Temperature values along parts of the Mississippi River were as warm as the mid-40s F (below).

MODIS Sea Surface Temperature product at 1848 UTC on 12 November; rivers are plotted in red [click to enlarge]

Aqua MODIS Sea Surface Temperature product at 1848 UTC on 12 November; rivers are plotted in red [click to enlarge]


On 13 November, as the cold air was moving off the US East Coast, GOES-16 Infrared images (below) revealed bay-effect cloud plumes which developed over Chesapeake Bay and Delaware Bay — the Chesapeake Bay plume produced brief periods of light snow at Oceana Naval Air Station in Virginia Beach KNTU from 06-10 UTC (and possibly contributed to snowfall farther south at Elizabeth City, North Carolina KECG).

GOES-16 "Clean" Infrared Window (10.35 µm) images on 12 November [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images on 12 November [click to play animation | MP4]

Terra MODIS Sea Surface Temperature values in Chesapeake Bay and Delaware Bay were in the lower to middle 50s F where the bay-effect cloud plumes were originating (below).

Terra MODIS Sea Surface Temperature product and Visible (0.65 µm) image at 1613 UTC [click to enlarge]

Terra MODIS Sea Surface Temperature product and Visible (0.65 µm) image at 1613 UTC [click to enlarge]

Gridded NUCAPS in AWIPS, part II

November 12th, 2019 |

NUCAPS horizontal plots of 850-hPa temperature, 1643-1705 UTC on 12 November 2019, and the NUCAPS Sounding Availability plots (Click to enlarge)

As noted in this post from October, horizontal fields of thermodynamic variables that have been derived from NUCAPS vertical profiles are now available in AWIPS. The fields give a swath of observations derived from infrared and microwave sounders in regions of the troposphere where observations by Radiosondes happen only occasionally. In this case, NUCAPS observed the strong cold front moving southward into the north Atlantic. Temperatures over eastern Canada at 850 hPa were in the teens below 0 Celsius, and in the teens (Celsius) out over the Atlantic.

850-hPa Temperatures derived from NUCAPS Soundings, 1653 UTC on 12 November 2019 (Click to enlarge)

Lower-tropospheric temperatures are an important variable to know when early-season cold airmasses are cold enough that the temperature difference between 850 hPa and surface water bodies — such as rivers and lakes — is sufficient to support Lake (or River) Effect clouds and precipitation. River-effect flurries hit mid-town Memphis on the 12th of November, and the 0.86 “Veggie” image (0.86 µm, this wavelength was chosen because land/water contrasts are large in it) image, below, shows a band extending from the Mississippi River in northwest Tennessee southward into central Memphis. NUCAPS data at 850 on this day showed 850-mb temperatures around -10 C at 0900 UTC.

GOES-16 0.86 “Veggie” Band (0.86 µm) imagery, 1346 UTC on 12 November 2019 (Click to enlarge). Shelby County in Tennessee is outlined, and the arrow points to a River-Effect snow band that dropped flurries over mid-town Memphis.