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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By now you probably already know that a total solar eclipse will traverse North America during the afternoon of April 8, 2024. There have been many stories in the media and previous blog entries here at the CIMSS Satellite Blog: Will it be Cloudy on April 8th (2024)? and GOES Cloud Climatology on April 8th.

The Washington Post liked our previous GOES cloud climatology image so much they created their own version from our data and of course it looks fantastic! They know how to make good science look good! Please check out their story. Thank you to the Washington Post’s Lauren Tierney for reaching out to us and highlighting the work of the CIMSS cloud science team.

This presented an opportunity to update our GOES climatology figure. Enterprise Cloud Products were produced using NOAA’s Clouds from AVHRR Extended (CLAVR-x) processing framework at the University of Wisconsin, CIMSS. It turns out we have data that covers part of Atlantic Canada. New Brunswick and Nova Scotia to be specific, mostly cut out of the previous version unfortunately. One of the primary goals of the CIMSS Satellite Blog is to educate people and we usually learn new things along the way. For example, the author recently learned about the Atlantic Time Zone (note the final time marked on the map is in Atlantic Daylight Time or ADT). This also prompted the author to figure out how to put Canadian Province and Mexican State borders on maps in Matlab, so we can help our neighbors a bit.

Some people have expressed an interest in seeing these climatology data with a prettier color enhancement. The Washington Post version is really fantastic, but here’s the same data with a progressive colormap:

Notice the totality part of the eclipse goes by pretty fast, from the Pacific Ocean, across Mexico, across the contiguous USA, and past Canada into the Atlantic Ocean in about 25-30 minutes! It also will pass right over Newfoundland, which unfortunately is outside the coverage area of our data. For any given location, totality only lasts a few minutes though the eclipse event is much longer than that. The National Centers for Environmental Information (NCEI) has an eclipse page with an interactive map from which you can get both their cloud climate analysis and the time/duration of the eclipse for many towns and cities in the USA (it’s not helpful for our neighbors). Our friends in Canada are getting ready too of course and you can find more information about viewing the eclipse in Canada from Dan Falk (@danfalk on X) and this neat YouTube video he made. Mexico seems likely to get the best cloud-free views and also the spot with the longest view of totality. For our Spanish speaking audience, you can learn more about the eclipse and what to expect in Mexico (probably clear skies! Longer duration eclipse) from this UnoTV YouTube video featuring Primoz Kajdic of Universidad Nacional Autonoma de Mexico.

You might be wondering what the difference is between our cloud climatology product and the NCEI one or any others you might see on the web? Ours is generated solely from GOES observations, a few hours from every April 8 from 1995-2023 and averaged. Some other cloud climatologies may include satellite observations, some do not, and some include other satellite platforms.

Going to see the eclipse? Remember to be safe! Don’t look at the sun directly without suitable eye protection! You maybe can get away with it during totality, but remember it doesn’t last long and ends rather suddenly. Let the SUVI stare at the sun, it’s built for that! Follow NASA’s safety guidelines.

Disclaimer on cloud climatology: this is not a real forecast and past clear or cloudy skies do not guarantee anything for April 8, 2024! You should check your local forecasts which are probably starting to get pretty accurate for clouds around April 6 and will be most accurate the morning of the eclipse. The eclipse itself can impact the amount of certain types of clouds. Most local meteorologists along the path are going to be paying attention to cloud cover, where good open places to view it will be, and what local plans are for schools, parks, etc. Be safe traveling to your view area!

Don’t miss it if you can help it! While partial solar eclipses are not too rare, total solar eclipses that go through your country are. For most of us in the U.S., it’s going to be a long time before we see another one. Alaska will see one in March 2033. Montana and North Dakota will see one in August 2044. The rest of the lower 48 will have to wait until August 2045 when an eclipse will traverse the contiguous U.S. from Florida to California. NASA has more information about future and past eclipses.

Finally, if you can’t see the eclipse, don’t fret. The web will be full of pictures from those who get the best cloud-free views. Check back here at the CIMSS blog where we will post animations of GOES ABI imagery of the shadow crossing CONUS and hopefully some SUVI animations of the full eclipse. We enjoy making images of solar eclipse shadows! For fun, here’s what an eclipse in 1984 with a similar, but more southern, path looked like from GOES-5:

Thanks to Frank Espenak of NASA Goddard Space Flight Center (GSFC) for the prediction data on the eclipse path, including times.

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