ACSPO SSTs off the Oregon Coast

September 14th, 2021 |
ACSPO SST values derived from VIIRS data, 12-14 September 2021, at times indicated (Click to enlarge)

Clear skies to the west of Oregon and California in the past two days have allowed VIIRS data (VIIRS — the Visible-Infrared Imaging Radiometer Suite flying on both Suomi-NPP and NOAA-20) to produce compelling imagery of the Sea Surface using Advanced Clear Sky Processing for Ocean (ACSPO) algorithms. VIIRS imagery is downlinked at the Direct Broadcast site at the UW-Madison; data are processed using CSPP. Purple values are just a bit cooler than 50º F; Yellow values are in the mid-60s ºF.

ACSPO estimates of SSTs are important over the Pacific Northwest because the Level 2 SST GOES-16 product is not computed near the GOES-16 limb. Level 2 Clear Sky mask is not computed out to the limb, as shown below, and GOES-16 SSTs (Full-Disk only products) are not computed out to the edge of the Clear Sky mask! So, if you want satellite-derived SSTs (GOES-17 Level 2 products are not yet widely available), Polar-Orbiting data are the way to go.

GOES-16 Level Clear Sky Mask (white=clouds; black=no clouds) and derived SSTs, 1600 UTC on 14 September 2021 (Click to enlarge)

AWIPS-ready ACSPO SST files are available from via an LDM feed from CIMSS.

Actinoform clouds near Hawai’i

June 30th, 2020 |

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) revealed 3 cyclonically-rotating actinoform cloud structures that were moving west-southwestward toward the Hawaiian Islands on 30 June 2020 (surface analyses).

A closer look at the northernmost actinoform feature showed it moving over Buoy 51000 (located northeast of Hawai’i) around 04 UTC on 01 July — there was somewhat of an increase in 1-minute wind speeds and wind gusts as it approached, but no obvious perturbation was seen in the air pressure (it appeared to have arrived during the typical ~12-hourly drop in pressure).

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

A sequence of 3 hourly (at 0010, 0110 and 0210 UTC) panoramic camera views from Buoy 51000 (below) suggested that there were rain showers reaching the ocean surface beneath one of the actinoform’s radial arms at 0210 UTC (GOES-17 Visible image).

Sequence of 3 hourly (at 0010, 0110 and 0210 UTC) panoramic camera views from Buoy 51000 [click to enlarge]

Sequence of 3 hourly panoramic camera views from Buoy 51000, at 0010, 0110 and 0210 UTC [click to enlarge]

True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) VIIRS images from NOAA-20 and Suomi NPP as visualized using RealEarth (below) provided a detailed view of 2 of the actinoform clouds. The radial arms that comprised the cloud features remained within the marine boundary layer, so they exhibited fairly warm cloud-top infrared brightness temperatures.

True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

Plots of rawinsonde data from Hilo, Hawai’i (below) indicated that the marine boundary layer was strongly capped by a temperature inversion at an altitude of 1.3-1.5 km (where the air temperature was around +15ºC — which was very close to the minimum cloud-top infrared brightness temperatures exhibited by the actinoform clouds).

Plots of rawinsonde data from Hilo, Hawai'i [click to enlarge]

Plots of rawinsonde data from Hilo, Hawai’i [click to enlarge]

Other examples of actinoform clouds have been shown in May 2019, March 2008, March 2007 and June 1997.

Fog/stratus along the New England coast

July 24th, 2018 |

GOES-16 Total Precipitable Water product [click to play animation | MP4]

GOES-16 Total Precipitable Water product [click to play animation | MP4]

The GOES-16 (GOES-East) Total Precipitable Water product (above) showed a northerly/northwesterly flow of tropical moisture toward New England during the day on 24 July 2018, with TPW values in the 1.0 to 1.6 inch range moving toward the region. As this moist air moved over relatively cool water — as indicated by Aqua MODIS Sea Surface Temperature values generally in the 60s F on the previous day (below) — areas of marine boundary layer fog/stratus developed.

Aqua MODIS Sea Surface Temperature product from 23 July [click to enlarge]

Aqua MODIS Sea Surface Temperature product from 23 July [click to enlarge]

1-minue Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (below) revealed interesting patterns in the resulting marine layer fog/stratus — for example, bow shock waves along the eastern edges of Nantucket Island and Cape Cod, and narrow clear swaths to the lee of some of the smaller islands off the coast of Maine.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Fog/stratus over Lake Michigan

June 30th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface reports [click to play animation | MP4]

As a warm and very humid air mass (surface analyses) moved northward across the relatively cool waters of Lake Michigan on 30 June 2018, GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed complex interactions of the resulting fog/stratus with coastlines and islands — features such as “bow shock waves” and internal reflections of waves off the northern end of the lake could be seen.

A 30-meter resolution Landsat-8 false-color Red-Green-Blue (RGB) image viewed using RealEarth (below) provided a very detailed view of the fog/stratus structure over the northern end of the lake.

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

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

The Aqua MODIS Sea Surface Temperature product at 1734 UTC (below) showed SST values in the middle 60s to around 70ºF across the southern end of Lake Michigan (the southern lake buoy reported a water temperature of 66ºF), transitioning to SST values around 60ºF mid-lake. The northern lake buoy reported a water temperature of 54ºF — much colder than the surface air dew points that were in the low to middle 70s F, which explained the more widespread coverage of lake fog/stratus farther north.

Aqua MODIS Sea Surface Temperature product, with plots of surface and buoy reports [click to enlarge]

Aqua MODIS Sea Surface Temperature product, with plots of surface and buoy reports [click to enlarge]