Quantifying the global impact of tropical cyclone‐associated gravity waves using HIRDLS, MLS, SABER and IBTrACS data

Abstract

Tropical convective systems are major sources of atmospheric gravity waves (GWs). These waves are a key driver of global atmospheric circulation, especially in the middle and upper atmosphere. Tropical cyclones (TCs) such as hurricanes and typhoons are particularly dramatic examples of such systems, and are therefore potentially significant individual sources of GWs. To investigate this effect, GW observations from three satellite limb sounders in the vicinity of TCs are produced and analysed. By statistically combining 15 years of GW observations from 1,379 individual TCs represented in the International Best Track Archive for Climate Stewardship, it is shown that TCs are associated with a 15% increase of GW amplitudes over background and a 25% increase in measured momentum fluxes, primarily during the period immediately before the TC. It is further shown that this additional contribution is small relative to other GW‐generating processes, and thus that individual TCs do not have a large quantitative effect on the dynamics of the middle and upper atmosphere as a whole. Thus, it is concluded that accurate modelling of TC‐generated short vertical wavelength GWs need not be a development priority for the next generation of weather and climate models. The results also demonstrate that stronger GW activity is associated with TCs that will later develop into hurricane‐intensity storms than is observed for those that will not, and thus that better space‐based monitoring of stratospheric GW activity could be a useful tool to help improve the forecasting of strong hurricane events in the presence of obscuring tropospheric cloud.

Stratospheric Gravity Waves as a Proxy for Hurricane Intensification: A Case Study of Weather Research and Forecast Simulation for Hurricane Joaquin

“…This phenomenon is particularly prominent for the strongest GW events. This result agrees with observational results found by Hoffmann et al (2018) [Hoffmann et al, 2014], and MLS [Wright, 2019]), it is possible to monitor significant changes in TC intensity by observing GWs with passive infrared and microwave sounders. This proxy is particularly useful when a cloud canopy obscures the direct view to the TC center for other instruments.…”

“…based on 13.5 years of AIRS observations andWright (2019) based on 17 years of MLS, SABER, and HIRDLS observations of TC-induced GWs. Moreover, the correlation between the intensity changes of stratospheric GWs activities and the hurricane is more significant when the time lag is considered.Measuring the internal structure and dynamics of TCs from space-based infrared sensors is typically not possible because the dense cloud coverage due to the TCs block the view of the instrumentation below cloud top.…”

“…Using 13.5 years of Atmospheric Infrared Sounder (AIRS) observations of stratospheric GWs, Hoffmann et al (2018) found a statistically robust correlation that more intensive stratospheric GWs are observed during the intensification of TCs than during weakening. Wright (2019) presented a study of TC-induced GWs using the microwave limb sounder (MLS), the Sounding of the atmosphere using broadband emission radiometry (SABER), and the high-resolution dynamics limb sounder (HIRDLS). Despite different GW spectrum ranges revealed by the sounders, Wright (2019) found a similar result that GW amplitudes steadily increase before TCs reaching peak intensity.…”

“…Wright (2019) presented a study of TC-induced GWs using the microwave limb sounder (MLS), the Sounding of the atmosphere using broadband emission radiometry (SABER), and the high-resolution dynamics limb sounder (HIRDLS). Despite different GW spectrum ranges revealed by the sounders, Wright (2019) found a similar result that GW amplitudes steadily increase before TCs reaching peak intensity. However, these relationships require further verification due to the coarse time and space sampling of these satellite observations.…”

Influences of the Mid‐Latitude Westerly Trough on Stratospheric Gravity Waves Generated by Typhoon Lekima (2019)

“…Typhoon is a kind of mesoscale weather system with strongly organized convection development (e.g., Ming et al., 2008; Nolan & Zhang, 2017; Wright, 2019). It occurs especially in the region of the Northwestern Pacific Basin, which is the most active tropical cyclone basin on earth.…”