Abstract
A new high‐spatial resolution camera on the International Space Station used OH nightglow in the H‐band to image the ground at an ∼ ${\sim} $70 m pixel footprint over an ∼ ${\sim} $280 km swath and maintained this resolution during its 1.5 s exposure. Near 0405 UT on 28 September 2022 moon down images obtained over the eyewall of the category 4 Hurricane Ian revealed short‐horizontal wavelength (∼ ${\sim} $5 km) instabilities with even finer scale (∼ ${\sim} $1–2 km) perpendicular structures, similar to those identified in recent modeling. Images taken (∼ ${\sim} $10 s apart) are used to separate these tropospheric features from atmospheric gravity waves (AGWs) imaged at ∼ ${\sim} $87 km. Geostationary Operational Environmental Satellite 16 (GOES‐16) data were used to estimate the altitudes of the tropospheric features. Available auxiliary data were used to show that the AGWs plausibly originated from close to Ian's eyewall 1–2 hr earlier.
Plain Language Summary
Just before landfall of the category 4 Hurricane Ian around 0405 UT on 28 September 2022 a new and unique camera on the International Space Station was able to simultaneously capture at very high spatial resolution the wave structure near the top of the clouds at 12–17 km, and high above that at ∼ ${\sim} $87 km, near the mesopause, the coldest region of the Earth's atmosphere. The high‐altitude imagery is possible because the Earth's atmosphere naturally emits light at ∼ ${\sim} $87 km that both illuminates the clouds below and is also affected by atmospheric gravity waves (AGWs), generated by the hurricane, that subsequently propagate to higher altitudes. This new imagery revealed very fine‐scale instability structure in Ian's clouds never seen before at this resolution and AGWs at ∼ ${\sim} $87 km that were generated about 1–2 hr earlier, probably by dynamic processes near the eyewall of the hurricane.
Key Points
H‐band imagery reveals dynamics with high‐spatial resolution at hurricane cloud tops and in the airglow independent of lunar illumination
Short scale waves in the cloud imagery include structures that are consistent with secondary instabilities of Kelvin‐Helmholtz Instabilities
Gravity waves plausibly generated by dynamic processes at the Hurricane Ian eyewall