Regional Distribution of Mesospheric Small‐Scale Gravity Waves During DEEPWAVE

Abstract

The Deep Propagating Gravity Wave Experiment project took place in June and July 2014 in New Zealand. Its overarching goal was to study gravity waves (GWs) as they propagate from the ground up to ~100 km, with a large number of ground‐based, airborne, and satellite instruments, combined with numerical forecast models. A suite of three mesospheric airglow imagers operated onboard the NSF Gulfstream V (GV) aircraft during 25 nighttime flights, recording the GW activity at OH altitude over a large region (>7,000,000 km2). Analysis of this data set reveals the distribution of the small‐scale GW mean power and direction of propagation. GW activity occurred everywhere and during every flight, even over open oceans with no neighboring tropospheric sources. Over the mountainous regions (New Zealand, Tasmania, isolated islands), mean power reached high values (more than 100 times larger than over the waters), but with a considerable variability. This variability existed from day to day over the same region, but even during the same flight, depending on forcing strength and on the middle atmosphere conditions. Results reveal a strong correlation between tropospheric sources, satellite stratospheric measurements, and mesosphere lower thermosphere airglow observations. The large‐amplitude GWs only account for a small amount of the total (~6%), even though they carry the most momentum and energy. The weaker wave activity measured over the oceans might originate from distance sources (polar vortex, weather fronts), implying that a ducted mechanism helped for their long range propagation.

Stratospheric Gravity Wave Products from Satellite Infrared Nadir Radiances in the Planning, Execution, and Validation of Aircraft Measurements during DEEPWAVE

“…12c. This finding is consistent with the orographic gravity wave hot spot enhancement over the South Island observed from the NGV during DEEPWAVE (e.g., Pautet et al 2019). By contrast, 4.3 mm s T B j in the right column of Fig.…”

“…over the South Island during June-July 2014 of ;20%. Thus, this 2% Gisinger et al (2017) value is an order of magnitude smaller than our finding of orographic gravity wave occurrence rates based on AIRS 15 mm radiances, and also many times less than orographic gravity wave occurrence rates derived from ground-based and NGV observations over the South Island during DEEPWAVE (e.g., Kaifler et al 2015;Fritts et al 2016;Smith et al 2016;Kruse et al 2016;Jiang et al 2019;Pautet et al 2019). Since this Gisinger et al (2017) result implies that there were almost no deep orographic gravity waves to observe throughout DEEPWAVE from AIRS at 4.3 mm, in contrast to all other DEEPWAVE observations including our 15 mm AIRS products, here we look deeper into their results to identify possible sources of these large unexplained discrepancies.…”

“…Localized orographic gravity wave enhancements are also still seen over Young, Buckle, and Sturge Islands, and over coastal Antarctic mountain ranges. A new orographic enhancement is observed over the Auckland Islands, which eventually spurred a dedicated NGV research flight during DEEPWAVE (Pautet et al 2016;. A broader increase in 3 hPa s T B j also occurs over the Southern Ocean due to nonorographic gravity waves.…”

SOUTHTRAC-GW: An Airborne Field Campaign to Explore Gravity Wave Dynamics at the World’s Strongest Hotspot

“…DEEPWAVE was also the first comprehensive airborne mission studying GW dynamics up to the mesopause (∼100 km). To mention just a few outstanding results, DEEPWAVE provided insight into the relation between tropospheric forcing and GW activity in the middle atmosphere (Fritts et al 2016(Fritts et al , 2018Kaifler et al 2015;Bramberger et al 2017;Portele et al 2018), the horizontal propagation of OGW into the polar night jet (Ehard et al 2017), secondary wave generation in regions of strong MW breaking (Bossert et al 2017), the effect of the background atmosphere on GW propagation also in the absence of critical level filtering (Kruse et al 2016), the relative contribution of various parts of the GW spectrum to momentum fluxes (Smith et al 2016;Kruse 2017, 2018;Bossert et al 2018), and the general characteristics of both OGWs and NOGWs (Smith et al 2016;Smith and Kruse 2017;Eckermann et al 2016;Pautet et al 2016Pautet et al , 2019Jiang et al 2019). In the following Section 2, we describe the research aircraft and its instruments dedicated to the measurements of GW properties, along with the ground based measurements in the region.…”

Effects of Latitude-Dependent Gravity Wave Source Variations on the Middle and Upper Atmosphere

“…Their dynamical importance is increasingly appreciated in planetary atmospheres as well (Medvedev and Yigit, 2019, and the references therein). GWs have routinely been characterized by a number of observational techniques in the terrestrial middle atmosphere, including ground-based lidars (Chanin and Hauchecorne, 1981;Mitchell et al, 1991;Mitchell et al, 1996;Yang et al, 2008), radars (Vincent and Reid, 1983;Scheffler and Liu, 1985;Manson et al, 2002;Stober et al, 2013;Pramitha et al, 2019;Spargo et al, 2019), airglow imagers (Taylor, 1997;Frey et al, 2000;Pautet et al, 2019), space-borne instruments (Wu and Waters, 1996;Ern et al, 2004;Ern et al, 2005;Alexander and Barnet, 2007;Ern et al, 2011;John and Kumar, 2012;Ern et al, 2016), balloon flights (Hertzog et al, 2008), and a combination of airborne and ground-based instruments (e.g., Fritts et al, 2016). Various techniques of GW observations, their limitations, and advantages have been a central topic in the middle atmosphere science (Alexander et al, 2010;Geller et al, 2013).…”