In mid-April 2026, Super Typhoon Sinlaku became a significant weather event as it traversed the North Pacific Ocean, bringing heavy rain and flooding to the Mariana Islands. The storm achieved “violent typhoon” status, the highest on the Japan Meteorological Agency scale, comparable to a category 5 storm on the Saffir-Simpson wind scale. Meteorologists noted that Sinlaku was among the few tropical cyclones of such intensity occurring early in the year.
Sinlaku rapidly intensified before making landfall, showing effects that extended into the upper atmosphere. Satellite imagery from the NOAA-20 satellite’s Visible Infrared Imaging Radiometer Suite (VIIRS) displayed atmospheric gravity waves emanating from the typhoon. These waves, reflecting airglow in the mesosphere, mimic ripples on the surface of water resulting from sunlight-excited atoms and molecules that emit light to release energy.
The release of latent heat near the cyclone’s eye contributed to convection and created elevated cumulonimbus clouds. These “hot towers” can result in waves that propagate into higher atmospheric layers. An analysis of past cyclones suggested that gravity waves often arise during the intensification period of storms. Sinlaku strengthened from a category 2 to a category 5 storm just 24 hours before the satellite imagery capture.
Joan Alexander, a senior research scientist at NorthWest Research Associates, stated, “We’re seeing waves propagating radially and upward, in a cone-like shape.” She noted the presence of nearly complete rings in the mesospheric airglow above the storm. The relatively calm stratospheric winds at Sinlaku’s latitude during this period may have aided in preserving these waves.
Conditions were favorable, as the Moon was about 25 percent illuminated on April 12, allowing some reflected light to be visible without overshadowing the airglow signal. Sinlaku’s gravity waves were also detected at lower altitudes by NASA’s Atmospheric Infrared Sounder (AIRS) on the Aqua satellite, with ongoing effects visible in observations taken on April 14.
The monitoring of atmospheric gravity waves created by tropical cyclones holds practical implications for storm tracking. Alexander expressed interest in utilizing gravity waves to assess storm intensification, particularly over open ocean areas. Furthermore, it is important to include stratospheric processes in weather models since they can influence long-term forecasts, particularly regarding winter weather in the Northern Hemisphere.
Gravity waves might also impact space weather, as they can lead to traveling ionospheric disturbances and plasma bubbles that disrupt satellite signals and radio communications. Laura Holt, also a senior research scientist at NorthWest Research Associates, highlighted the significance of a single tropical cyclone event for space weather phenomena.
Source: science.nasa.gov.
