GRACILE: A comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

Abstract

Abstract. Gravity waves are one of the main drivers of atmospheric dynamics. The spatial resolution of most global atmospheric models, however, is too coarse to properly resolve the small scales of gravity waves, which range from tens to a few thousand kilometers horizontally, and from below 1 km to tens of kilometers vertically. Gravity wave source processes involve even smaller scales. Therefore, general circulation models (GCMs) and chemistry climate models (CCMs) usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified. For this reason, comparisons 5 with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases.We present a gravity wave climatology based on atmospheric infrared limb emissions observed by satellite (GRACILE).GRACILE is a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere 10 using Broadband Emission Radiometry (SABER). Typical distributions (zonal averages and global maps) of gravity wave vertical wavelengths and along-track horizontal wavenumbers are provided, as well as gravity wave temperature variances, potential energies and absolute momentum fluxes. This global data set captures the typical seasonal variations of these parameters, as well as their spatial variations. The GRACILE data set is suitable for scientific studies, and it can serve for comparison with other instruments (ground based, airborne, or other satellite instruments) and for comparison with gravity wave distri-15 butions, both resolved and parametrized, in GCMs and CCMs.

Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

“…Additionally, these calculations are an average estimate over the entire flight path, and localized MFs due to stronger phases over the mountains and directly in the lee of the mountains likely have larger associated MFs. Regardless of this, the spectral MF calculations show MF values that are larger than the average background MF values previously measured by radars and satellites, which have ranged from ~1 to 20 m 2 /s 2 (Ern et al, ; Fritts et al, , ; Fritts & Vincent, ; Murphy & Vincent, ; Nakamura et al, ; Reid et al, ; Tsuda et al, ; Vincent & Reid, ; Wang & Fritts, ). This finding is qualitatively in good agreement with Hertzog et al (), who showed that MW events are particularly intermittent and strong events can carry very large MFs.…”

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

“…; Ern et al . ) suggest that, for the same season, altitude and geographic regions as the peaks in TC‐associated GW activity, typical mean levels of momentum flux are ∼0.5 mPa over the whole of each region, compared to basin‐ total estimates of the same order for TCs. While some fraction of the GWs included in these reference averages will be from TCs, and even allowing for the possibility that the bulk of the time‐mean TC‐associated momentum flux is concentrated in short bursts with much higher local values, the additional momentum flux suggested by my results to be attributable to TCs specifically is small, and is thus very unlikely to be a major factor in the overall circulation.…”

Orographic Primary and Secondary Gravity Waves in the Middle Atmosphere From 16‐Year SABER Observations

“…The maximum value of 130% occurs during June and September but not during July and August. This might be related to the fact that the GW generation over the oceans from spontaneous emission is strongest during July and August (Figures 13 and 14 of Ern et al, ). This imposes a stronger zonal‐mean component of the GW activity during July–August.…”