Plumes of blowing dust and salt in Bolivia

July 7th, 2020 |

GOES-16 True Color RGB images (credit: Tim Schmit, ASPB/CIMSS) [click to play animation | MP4]

GOES-16 True Color RGB images (credit: Tim Schmit, ASPB/CIMSS) [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) displayed widespread plumes of blowing dust and salt originating from Salar de Uyuni in southwestern Bolivia on 07 July 2020. These aerosol sources are located within an elevated plateau with altitudes of 11-12,000 feet (3.3-3.6 km) — and similar episodes of blowing dust/salt are not uncommon during the austral winter (reference).

A longer animation of GOES-16 Dust RGB images (below) showed the continued eastward transport of dust/salt plumes for a few hours after sunset.

GOES-16 Dust RGB images (credit: Tim Schmit, ASPB/CIMSS) [click to play animation | MP4]

GOES-16 Dust RGB images (credit: Tim Schmit, ASPB/CIMSS) [click to play animation | MP4]

A sequence of GOES-16 Natural Color RGB, Dust RGB and Split Window Difference (10.3 µm – 12.3 µm) images from AWIPS (below) provided a less detailed view of the plumes — the spatial resolution of Full Disk GOES imagery in AWIPS is reduced to 6 km.

GOES-16 Natural Color RGB, Dust RGB and Split Window Difference (10.3 µm – 12.3 µm) images [click to play animation | MP4]

GOES-16 Natural Color RGB, Dust RGB and Split Window Difference (10.3 µm – 12.3 µm) images [click to play animation | MP4]

Winds across that region increased on 07 July as an intensifying subtropical jet streak was passing just to the north/northeast, as shown in plots of 700 hPa geopotential height and integrated water vapor transport from this site (below). Clouds associated with this jet streak could be seen in the northern portion of the GOES-16 images above.

Plots of 700 hPa geopotential height and integrated water vapor transport [click to enlarge]

Plots of 700 hPa geopotential height and integrated water vapor transport [click to enlarge]

Plots of rawinsonde data from Antofagasta, Chile at 12 UTC on 06, 07 and 08 July (below) showed the increase in northwesterly 700 hPa winds to 40 knots on 07 July. Antofagasta is located about 300 miles southwest of the Salar de Uyuni region.

Plots of rawinsonde data from Antofagasta, Chile at 12 UTC on 06, 07 and 08 July [click to enlarge]

Plots of rawinsonde data from Antofagasta, Chile at 12 UTC on 06, 07 and 08 July [click to enlarge]

Posted in GOES-16, Red-Green-Blue (RGB) images | No Comments »

Blowing dust in southern Bolivia

July 4th, 2020 |

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images (credit: Tim Schmit, ASPB/CIMSS) [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed plumes of blowing dust originating from dry river beds along portions of the Río Grande O Guapay and Río Parapetí in southern Bolivia on 04 July 2020. Strong northerly winds developed across that region, just east of the axis of a deepening trough of low pressure.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 as visualized using RealEarth (below) provided a more detailed view at the blowing dust plumes.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

A plot of surface report data from Viro Viru International Airport, Santa Cruz de la Sierra — located not far to the north of the blowing dust plumes — showed northerly winds gusting as high as 36 knots (41 mph) at 20 UTC (below).

Plot of surface report data from Viro Viru International Airport [click to enlarge]

Plot of surface report data from Viro Viru International Airport [click to enlarge]

Thanks to Santiago Gassó for pointing out these dust features.

Posted in Air quality, GOES-16, NOAA-20, RealEarth, Red-Green-Blue (RGB) images, Suomi NPP, VIIRS | No Comments »

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.

Posted in GOES-17, Marine weather, NOAA-20, RealEarth, Red-Green-Blue (RGB) images, Suomi NPP, VIIRS | No Comments »

Saharan Air Layer dust reaches the Lesser Antilles, Puerto Rico and the Gulf of Mexico

June 21st, 2020 |

GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Dust RGB images, with surface reports plotted in white [click to play animation | MP4]

GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Dust RGB images, with surface reports plotted in white [click to play animation | MP4]

The major Saharan Air Layer dust outbreak (previously discussed here and here) continued its westward progression — and on 21 June 2020, GOES-16 (GOES-East) Split Window Difference (10.3 µm – 12.3 µm) and Dust RGB images (above) showed signatures of the dust (shades of tan to light brown in Split Window Difference, and shades of magenta in Dust RGB images) as it moved over the Lesser Antilles, the eastern  Caribbean Sea and Puerto Rico. Surface reports at Port of Spain, Trinidad and Tobago (plot | data) indicated a drop in visibility below 1/2 mile for several hours, until some of the airborne dust was scavenged by convective precipitation; farther to the north, dust restricted the visibility to 3 miles at Barbados (plot | data). At San Juan, Puerto Rico (plot | data) the surface visibility only dropped to 7 miles, as most of dust remained aloft.

GOES-16 True Color RGB images created using Geo2Grid (below) showed the characteristic tan hues of the dust plume during daylight hours (1000-2200 UTC).

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

===== 22 June Update =====

GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Aerosol Optical Depth images, with surface reports plotted in white [click to play animation | MP4]

GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Aerosol Optical Depth images, with surface reports plotted in white [click to play animation | MP4]

On 22 June, GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Aerosol Optical Depth (AOD) images (above) showed that the SAL dust had continued moving west, overspreading Puerto Rico, Hispaniola and much of the Caribbean Sea. Widespread AOD values of 1.0 to 1.8 were seen across that region.

A closer look at GOES-16 Split Window Difference and AOD images centered over Puerto Rico (below) revealed that the surface visibility was reduced to 3 miles at two sites in eastern Puerto Rico — and an AOD value of 2.0 was noted just south of San Juan TJSJ at 2201 UTC. The visibility was further reduced to 2-3 miles at nearby islands.

GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Aerosol Optical Depth images, with surface reports plotted in white [click to play animation | MP4]

GOES-16 Split Window Difference (10.3 µm – 12.3 µm) and Aerosol Optical Depth images, with surface reports plotted in white [click to play animation | MP4]



GOES-16 True Color RGB images (below) depicted the thick plume of dust.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

A 9-day animation of a GOES-16 Split Window Difference “Saharan Air Layer product” covering the period 13-22 June 2020 (below) displayed the westward progress of the SAL plume (darker red to shades of white) across the Atlantic Ocean.

GOES-16 Split Window Difference "Saharan Air Layer product", 13-22 June [click to play animation | MP4]

GOES-16 Split Window Difference “Saharan Air Layer product”, 13-22 June [click to play animation | MP4]

===== 24 June Update =====

GOES-16 True Color RGB (daytime) and Dust RGB (nighttime) images, 08-24 June [click to play MP4 animation]

GOES-16 True Color RGB (daytime) and Dust RGB (nighttime) images, 08-24 June (credit: Tim Schmit, ASPB/CIMSS)  [click to play MP4 animation]

A 17-day animation of GOES-16 True Color RGB (daytime) and Dust RGB (nighttime) images during the period from 08-24 June (above) showed that (1) the primary strong SAL dust plume eventually reached the Gulf of Mexico on 24 June, (2) a second SAL dust plume emerged off the northwest coast of Africa on 22-23 June, and (3) the Dust RGB only exhibited a strong signature (brighter shades of magenta) for the most highly-concentrated areas of dust as they began to move westward off the coast of Africa — once the dust became more diffuse over the middle Atlantic, it lost a recognizable signature in the Dust RGB (while still retaining a good daytime signature in the True Color RGB).

A 12-day animation of GOES-16 Split Window Difference “Saharan Air Layer product” covering the period 13-24 June (below) also displayed the primary SAL plume reaching the Gulf of Mexico on 24 June, in addition to the secondary SAL plume emerging on 22-23 June.

GOES-16 Split Window Difference "Saharan Air Layer product", 13-24 June [click to play animation | MP4]

GOES-16 Split Window Difference “Saharan Air Layer product”, 13-24 June [click to play animation | MP4]

Posted in Air quality, GOES-16, Red-Green-Blue (RGB) images | No Comments »

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