5-minute CONUS Sector GOES-16 (GOES-East) True Color RGB images + Nighttime Microphysics RGB images from the CSPP GeoSphere site (above) showed large smoke plumes produced by 2 wind-driven grass fires in central Nebraska (just north of North Platte) on 26 February 2024. The burn scar associated with the larger (southernmost) fire was very apparent, as a west-to-east oriented swath of darker brown shades. After sunset, the hot fire signatures showed up as clusters of darker purple pixels in Nighttime Microphysics RGB imagery.

In a toggle between Suomi-NPP VIIRS True Color RGB and False Color RGB images valid at 1950 UTC (above), a more detailed view of the burn scar was seen in the True Color RGB image — with the hot thermal signatures of active fires exhibiting brighter shades of pink to red. The head of the fire was close to the Lincoln County / Custer County line at that time. A sequence of 3 VIIRS Shortwave Infrared (3.74 µm) images from NOAA-20 and Suomi-NPP (below) provided a high-resolution view of how quickly the fire’s leading edge moved eastward in a time span of about 1 hour and 40 minutes. The VIIRS data used to create these images were received and processed using the CIMSS/SSEC Direct Broadcast ground station.

1-minute Mesoscale Domain Sector GOES-16 Fire Temperature RGB images along with the Fire Power, Fire Mask and Fire Temperature derived products (below) provided a closer view of the southern grass fire thermal signature and its rapid eastward run toward (and eventually across) the Lincoln County / Custer County line (the Fire Power, Fire Mask and Fire Temperature derived products are components of the GOES Fire Detection and Characterization Algorithm FDCA). Distinct thermal signatures of the fire were evident beginning at 1644 UTC — which advanced quickly eastward due to winds gusting as high as 42 knots (49 mph) at North Platte (KLBF).

Parts of this fast-moving grass fire burned very hot at times — in fact, a cursor sample of GOES-16 Fire Temperature RGB and Fire Mask at 2000 UTC (below) showed that the fire exhibited a maximum 3.9 µm infrared brightness temperature of 138.71ºC (which is the saturation temperature of the GOES-16 ABI Band 7 detectors). The Fire Mask product helps to quickly identify such “Saturated Fire” pixels by highlighting them as bright yellow. In addition, maximum Fire Power values exceeded 2500 MW.

The #Nebraska #fire from GOES-16 True Color RGB and 3.9um temps overlaid with the KLNX (North Platte) radar data. Base reflectivity shows the smoke plume, along with the 3D vertical cross section and 20dBZ isosurface (anywhere 20dBZ is detected across elevation angles). #mcidas pic.twitter.com/qo95yeVyxP

— Robert Carp (@rmcarp) February 26, 2024

During the following nighttime hours, a toggle between Suomi-NPP (mislabeled as NOAA-20) VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images (above) showed the area of the grass fire at 0808 UTC (2:08 AM CST) on 27 February. Due to ample illumination from the Moon — which was in the Waning Gibbous phase, at 92% of Full — darker areas of burned grassland could be seen, extending just across the Lincoln County / Custer County border. Although most of the fire had ended (since wind speeds decreased dramatically after sunset), a few clusters of warmer pixels remained along the perimeter of the burn scar.

 

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The GXS is the sounder that is proposed to be part of the GeoXO constellation of satellites that will launch starting in the 2030s as a replacement to the GOES-R satellites. (Note: GOES-U is now scheduled to launch no earlier than mid-May 2024). Beyond the GXS uses of radiance assimilation into global and regional models, there will be many applications associated with nowcasting. This post highlights one related to convection. What kind of capabilities will the GXS bring? That’s shown in the animation above. The left-hand imagery shows the theta_e(500) – theta_e(850) values computed from simulated sounder data: The extra fine spatial resolution (1-km) nature run (XNR1K) from the ECMWF model was averaged over the Sounder field of view (FOV), and a radiative transfer model was used to create Top of Atmosphere (TOA) radiances at all GXS sounder channels. Subsequently, temperature/moisture profiles were retrieved from these simulated sounder TOA observations using a deep neural network model. The retrievals are derived based on GXS radiances only (no NWP forecast used as first guess or background). Theta-e values at 850 hPa, 500 hPa were calculated from the retrieved T/Q profiles. The right-hand imagery shows theta_e(500) – theta_e(850) values calculated from the averaged XNR1K profiles (averaged to the Sounder field of view), which are used here as truth for validation.

There is remarkable similarity between the two fields, meaning the sounder data can give accurate estimates of potential instability, that is, theta_e(500) – theta_e(850). If theta_e is decreasing strongly with height, atmospheric lift will lead to the rapid release of instability driven by strong latent heat release. In the animation above, strong convection develops near the strong negative values of theta_e(500) – theta_e(850) (red values); you can also see stable regions (in green/blue) near strong convection where cool downdrafts have stabilized the atmosphere. That’s also apparent in the shorter animations below: 2000 UTC on 6 September – 0000 UTC on 7 September and 0200 UTC – 0545 UTC on 7 September. The simulated GXS data here can alert a forecaster to where convection might (or might not) soon occur. There is a marked tendency for the convection to occur near gradients of potential instability.

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The following figure shows forecast model output estimates of precipitation at 1700, 1800 and 1900 UTC on 6 September 2019. The focus here is on the convection moving from Kansas into Nebraska, circled in purple. Figures below that describe how the convection relates to sounder-derived potential instability.

Convection develops at the leading edge of the diagnosed instability, the boundary between deep reds and yellows. The model output and sounding-consistent retrievals based on the model output show pools of stability near the developing convection (yellows and greens in the enhancement).

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GOES-16 (GOES-East) Split Window Difference (10.3-12.3 µm) along with SO2 RGB and Ash RGB images (above) displayed signatures of volcanic clouds produced by a sequence of eruptions of Popocatépetl in Mexico on 21 February 2024. Although these volcanic clouds apppeared to be predominantly ash-dominated (shades of pink to magenta in the Ash RGB, and shades of blue in the SO2 RGB), there were brief indications of an SO2-ash mixture — in a toggle between the 2 RGB image types at 1846 UTC (below), note the shades of green near the volcano summit (suggestive of SO2 dominance) and shades of orange in the Ash RGB with shades of pink to red in the SO2 RGB (suggestive of an ash/SO2 mixture) a few miles downwind of the summit.

GOES-16 Nighttime Microphysics RGB + daytime True Color RGB images (below) showed the west-southwest transport of the volcanic cloud (shades of pink to magenta) during the nighttime hours into the next morning, followed by additional volcanic cloud pulses that moved to the southwest during the afternoon hours

For the afternoon eruption phase that began around 1700 UTC, GOES-16 False Color RGB, Ash Height, Ash Effective Radius and Ash Loading products from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) indicated that the (predominantly ash) cloud reached heights of 6-7 km at times, with the ash consisting of generally small particles at relatively low levels of ash loading.

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On the following day (22 February), GOES-16 Split Window Difference along with SO2 RGB and Ash RGB images (above) showed the volcanic clouds produced by 2 additional eruptive periods — with the first cloud drifting southward, followed by the additional clouds drifting to the east-southeast.

During these eruptions, there were more notable indications of an SO2-ash mixture — for example, in a toggle between the 2 RGB image types at 1701 UTC (below), note the darker shades of orange in the Ash RGB along with brighter shades of pink to violet in the SO2 RGB (suggestive of an ash/SO2 mixture) immediately east of the volcano summit.

GOES-16 Nighttime Microphysics RGB + daytime True Color RGB images (below) showed the southward transport of volcanic clouds during the nighttime hours into the following morning, with additional volcanic cloud pulses that moved to the east during the afternoon hours.

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The ‘manati’ website (https://manati.star.nesdis.noaa.gov/) is a helpful NOAA/NESDIS/STAR website that includes different observations from Polar-Orbiting satellites including, as shown above, Altimetric Observations of Significant Wave Height. Observations from three different satellites are shown in the image, including Jason3 (0718-0722 UTC), Cryosat (0610-0614 UTC) and Sentinel-3A (0927-0930 UTC). This post will help you anticipate where tomorrow’s observations from these satellites will occur. In other words, if you know where the observations are today, can you guess where they will be tomorrow (or the next day?)

To answer this question, I downloaded the Two-Line-Element files (using the ‘SATCAT’ ability at celestrak.org) and used NAVDISP commands in McIDAS-X. The imagery below shows 3 consecutive days of JASON-3 orbits over the south Pacific. Based on this figure, the orbit for ‘tomorrow’ — in blue — will be later and to the west of ‘today’s orbit (in red) and the even further west and later on the day after tomorrow. (Note that ‘Day 2’ below corresponds to the Jason orbit shown above). From day to day, Jason-3 orbits cover a swath that is farther and farther west, and later in the day.

Sentinel-3A orbits evolve differently, as shown below. The Day 2 orbit is farther east and earlier than the Day 1 orbit. The blue line labeled 09:28 below is also shown in the image at the top of this blog post. From day to day, Sentinel orbits cover a swath that is farther and farther east, and earlier in the day.

Cryosat orbits are also different. The figure below shows 4 days of orbits. Comparing the two orbits ‘Today’ and ‘Tomorrow’ shows that tomorrow’s orbit is about an hour earlier than today’s and farther east. Look at the ‘Red’ orbit that moves through Fiji at 0700 UTC on Day 1; on Day 2, there is an orbit through American Samoa at 0613 UTC (as also shown in the figure up top). Note on Day 3, however, that a near-overlap of the Day 1 orbit is occurring through Fiji.

Use this information to anticipate where tomorrow’s overpass will be (or where yesterday’s overpass was!) when you’re looking at the Significant Wave Height.

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