Multidecadal Measurements of UTLS Gravity Waves Derived From Commercial Flight Data

Abstract

Gravity waves (GWs) are key drivers of atmospheric dynamics, with major impacts on climate and weather processes. However, they are challenging to measure in observational data, and as a result no large-area multidecadal GW time series yet exist. This has prevented us from quantifying the interactions between GWs and long-timescale climate processes. Here, we exploit temperatures measured by commercial aircraft since 1994 as part of the In-Service Aircraft for a Global Observing System (IAGOS) atmospheric chemistry research program to produce a novel 26-year time series of upper troposphere/lower stratosphere (UTLS) GW measurements across most of the Northern Hemisphere. We analyze 90,342 flight hours (76.2 million flight kilometers) of data, typically at a temporal resolution of seconds and with high temperature precision. We show that GW activity in the Northern Hemisphere UTLS is consistently strongest north of and above the upper tropospheric jet. We also show that GW sources not typically observed in stratospheric data but assumed in model schemes, such as the Rocky Mountains, are visible at these altitudes, suggesting that wave momentum from these sources is deposited specifically between ∼200 and 50 hPa. Our data show no significant impact of the Quasi-Biennial Oscillation, the Northern Annular Mode, or climate change. However, we do see strong evidence of links with the El Niño-Southern Oscillation, which modulates the measured GW signal by ∼25%, and weak evidence of links with the 11-year solar cycle. These results have important implications for atmospheric process modeling and for understanding large-scale climate teleconnections. Plain Language Summary We use 26 years of temperature measurements, made by commercial aircraft flying routine passenger and freight routes, to measure and understand small-scale atmospheric waves ("gravity waves"). These waves play many vital roles in the atmosphere, and they are critically important to understanding and predicting weather and climate. However, due to their small size, they are extremely difficult to study at typical flight altitudes using any other method. Our data provide the longest large-area record of gravity waves from any dataset, with 76 million flight kilometers of measurements made since 1994. We see strong evidence that El Niño affects the behavior of these small waves over northern Europe and central Asia, many thousands of kilometers away from the Pacific Ocean. We also see weak evidence that the waves may be affected by the 11-year cycle of solar intensity. Our results provide a unique window on the interactions between small-scale atmospheric behavior and long-time scale climate dynamical processes and have important implications both for improving atmospheric models and for understanding long-distance climate teleconnections.

Comparing Gravity Waves in a Kilometer‐Scale Run of the IFS to AIRS Satellite Observations and ERA5

“…The locations of the peaks in amplitude in AIRS and the resampled models are consistent with Hindley et al. (2020) and Wright and Banyard (2020). The maximum mean amplitudes in IFS 1 (Figure 7c) and IFS 2 (Figure 7d) are a factor of 2.72 and 2.81 lower than in AIRS respectively, so the mean of the maximum mean amplitudes for the 1 km IFS run is a factor of 2.77 lower than in AIRS, averaging the results from the two resampling methods.…”

“…(2020). GWs in this region have previously been shown to be strongly visible in AIRS (Hindley et al., 2020) and aircraft (Wright & Banyard, 2020) observations, but not in limb sounder observations (Ern et al., 2018; Geller et al., 2013). This may suggest a strong role for the GWs with long vertical and short horizontal wavelengths that this model should be well configured to accurately resolve.…”

“…The region is likely to contain numerous sources of orographic GW activity generated by surface flow over mountain ranges, such as the Abakanski Khrebet Mountain range, the Ural mountains, the Pamir mountains and other hotspots as observed by Hoffmann et al (2013) and Hindley et al (2020). GWs in this region have previously been shown to be strongly visible in AIRS (Hindley et al, 2020) and aircraft (Wright & Banyard, 2020) observations, but not in limb sounder observations (Ern et al, 2018;Geller et al, 2013). This may suggest a strong role for the GWs with long vertical and short horizontal wavelengths that this model should be well configured to accurately resolve.…”

Dynamical and surface impacts of the January 2021 sudden stratospheric warming in novel Aeolus wind observations, MLS and ERA5

“…ERA5 data can be obtained from the Copernicus Climate Data Store, https://cds.climate.copernicus.eu/ (Copernicus, 2021). The code used to produce the analyses and figures has been archived at https://doi.org/10.5281/zenodo.4638273 (Wright et al, 2021).…”