Middle and upper-atmospheric wave structures in the vicinity of a subtropical jet stream

April 4th, 2016 |

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images, with ECMWF model maximum wind isotachs [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images, with ECMWF model maximum wind isotachs [click to enlarge]

A strong (120-knot) subtropical jet stream was moving eastward across the Gulf of Mexico during the 03 April – 04 April 2016 period. During the overnight hours between these 2 days, a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0753 UTC (above) revealed a large packet of arc-shaped mesospheric airglow waves south of the axis of the jet stream (as indicated by isotachs of the maximum tropospheric wind speed from the ECMWF model). Note how there were no cloud features which corresponded to these waves in the 0753 UTC VIIRS Infrared Window (11.45 µm) image; since the Moon was in the waning Gibbous phase (at 13% of Full), there was very little lunar illumination of cloud features, so airglow — essentially the “night glow” emitted from a variety of high-altitude (80-105 km) gases (primarily the sodium layer) near the mesopause — was allowing these high-altitude waves to be detected using the sensitive Day/Night Band (reference: “Suomi satellite brings to light a unique frontier of nighttime environmental sensing capabilities”).

During the subsequent daytime hours on 04 April, more interesting (tropospheric) waves were seen in the vicinity of this subtropical jet stream — small packets of waves that were propagating westward, against the ambient flow –one over Florida/Georgia/South Carolina, and another over South Texas. Unfortunately, these features fall into the “What the heck is this?” blog category, so no coherent explanation of them can be offered at this time.

GOES-13 Water Vapor (6.5 µm) images, with ECMWF model maximum wind isotachs [click to play animation]

GOES-13 Water Vapor (6.5 µm) images, with ECMWF model maximum wind isotachs [click to play animation]

An interesting question from Shea Gibson:

3 Responses to “Middle and upper-atmospheric wave structures in the vicinity of a subtropical jet stream”

  1. Shea Gibson says:

    10hPa had upper vorticity opposite the subtropical jet aloft. What about an outside chance they could be nacreous strata? Only other thing I could think of is higher up where noctilucent sublimation just caught with enough light at the right angle might be showing up.

  2. Scott Bachmeier says:

    Interesting ideas Shea — I confess to knowing little (if anything) about the atmosphere above about 100 hPa, so those seem like feasible explanations.

  3. Dziban303 says:

    Is it just me, or do the waves seem to start precisely along the coasts and retain the shape of the coastline as they propagate? That doesn’t strike me as a high-altitude phenomenon, but I study rocks, so what do I know

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