of the ionosphere-thermosphere-mesosphere (ITM) system (50 to 𝐴𝐴 ∼ 1,000 km) is now well established. GWs are excited by flow over topography, instabilities in the mean flow, spontaneous emission, and convection. Due to their exponential growth with height prior to dissipation, and with favorable propagation conditions, GWs are capable of transferring significant energy and momentum from the troposphere and stratosphere into and throughout the ITM. The present paper is concerned with GWs generated by monsoon-driven convection from the equator to 𝐴𝐴 40 • S, particularly in the context of their wider role as a global-scale GW source to the overlying ITM system.From the system perspective, there is interest in knowing the global climatological distribution of GW forcing near the 50-km "gateway" to the ITM, by analogy with our current knowledge of the solar tidal spectrum at the 𝐴𝐴 ∼ 90-100 km gateway to the ionosphere-thermosphere (IT) system enabled by wind and temperature measurements from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission (e.g., Oberheide et al., 2011). The Cloud Imaging and Particle Size (CIPS) instrument on the AIM satellite provides a first opportunity to obtain a global perspective of GW forcing at the base of the ITM (Randall Abstract A new data set consisting of Rayleigh Albedo Anomaly variance 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝑣𝑣 data resulting from measurements by the Cloud Imaging and Particle Size instrument on the Aeronomy for Ice in the Mesosphere satellite is introduced, and is used to illustrate the lower-mesospheric ( 𝐴𝐴 ∼ 50-55 km) gravity wave (GW) response to tropospheric convection during Southern Hemisphere monsoon season (December-February). The 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝑣𝑣 correspond to GWs with vertical wavelengths 𝐴𝐴 𝐴 15 km and horizontal wavelengths between about 23 and 600 km. It is shown that these scales encompass most of the convectively generated GW spectrum at 𝐴𝐴 ∼ 50-55 km altitude due to both plume overshoot and diabatic heating, and include those GWs most likely to impact the overlying ionosphere-thermospheremesosphere system. The GWs originate from convective sources associated with the African and South American land masses, the maritime continent/Australia, and the South Pacific Convergence Zone. The regions of enhanced convection are identified according to half-hourly rainfall rate (RR) distributions from the Global Precipitation Measurement mission. The GW 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝑣𝑣 exhibits spatial, inter-monthly, and inter-annual variabilities connected with RR and propagation conditions. A ∼ 𝐴𝐴 15 • southward shift of longitudinal structures in 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝑣𝑣 with respect to RR longitudinal structures is interpreted in terms of wave focusing toward the middle atmosphere summer easterly jet core. For the South American Monsoon System, a linear regression analysis shows 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝑣𝑣 variability to be expressible in terms of upperstratosphere zonal wind speeds (correlation coefficient R = −0.91) with magnitude of RR playing a much lesser role (R = 0.16).

Wind measurements from the Michelson Interferometer for Global High‐resolution Thermospheric Imaging (MIGHTI) instrument on the Ionospheric CONnections (ICON) mission provide new insights into the semidiurnal tidal spectrum in the thermosphere, covering latitudes 9°S–39°N and altitudes 100–280 km altitude throughout 2020. Latitude vs. day of year (DOY) variability of solar semidiurnal tides SE2, S0, SW1, SW2, SW3, and SW4 at 250 km are presented for the first time, and evaluated relative to similar results at 106 km. Using daytime‐only data, height vs. latitude and height vs. DOY variability of SE2, S0, SW1. SW3, and SW4 amplitudes and phases are depicted for the first time, revealing the effects of a dissipative thermosphere on the vertical evolutions of these tidal structures. SW2 is absent from these depictions due to potential aliasing by zonal mean winds. The above results are considered in light of the Climatological Tidal Model of the Thermosphere (CTMT), which is based on fits to tidal winds and temperatures from the Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics mission between 80 and 120 km during 2002–2008, and extrapolated to an altitude of 400 km based on modeled tidal structures propagating in a dissipative thermosphere, but without in situ sources of excitation due to tide‐tide or tide‐ion drag nonlinear interactions. On the basis of comparisons with the CTMT and other characteristics revealed in the MIGHTI tidal structures, it is concluded that in situ sources exist for S0, SW1, SW2, and SW3 in the thermosphere above about 200 km.

Broadly speaking, the Global Monsoon System (GMS) is the tropical response of the coupled atmosphere-land-ocean-cryosphere-biosphere system to the annual variation of solar radiative forcing (e.g., see review by Wang et al. [2011], and references therein). Associated with this solar-driven divergent circulation (Trenberth et al., 2000) that is modulated by land-sea differences are "wet summer" and "dry winter" seasons that migrate between the hemispheres. Consequently, given the availability of satellite-based global measurements of precipitation, rainfall rates (RR) are often used to quantify the latitude-longitude and seasonal distribution of the GMS, either through the use of empirical orthogonal functions or by depicting the "annual range (AR)" of precipitation in some way. AR refers to the local summer-minus-winter precipitation, that is, June-July-August (JJA) minus December-January-February (DJF) precipitation in the Northern Hemisphere (NH) and DJF minus JJA in the Southern Hemisphere (SH).Also contained within the GMS, and closely associated with high RR, are regions of intense convection, updrafts, and latent heating that serve as excitation sources for gravity waves (GW). In this paper, we apply the concept of AR to satellite-based measurements of outgoing long-wave radiation (OLR) to delineate the global distribution and variability of convectively generated GWs associated with the GMS as a whole. The major focus is to explore the vertical extension of the GMS to higher altitudes in the form of GWs, including the effects of filtering and Doppler-shifting of the GWs by the background wind field. GW responses at 30 km, 50 km, 70 km, and 90 km altitude are in the form of GW momentum fluxes (GWMFs) estimated from limb temperature measurements during 2016-2020 made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite (Ern et al., 2011(Ern et al., , 2018. The time period is specifically chosen to overlap with measurements of convectively forced GWs from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite (Randall et al., 2017) at 50 km altitude. The CIPS/AIM measurements were the focus of a similar study by Forbes et al. (2021), which, however, is confined to the SH and involves a different scale of GWs than those considered here.

“Ultra‐fast” Kelvin waves (UFKWs) serve as a mechanism for coupling the tropical troposphere with the mesosphere, thermosphere and ionosphere. Herein, solutions to the linearized wave equations in a dissipative thermosphere in the form of “Hough Mode Extensions (HMEs)” are employed to better understand the vertical propagation of the subset of these waves that most effectively penetrate into the thermosphere above about 100 km altitude; namely, UFKWs with periods ≲4 days, vertical wavelengths (λz) ≳30 km, and zonal wavenumber s = −1. Molecular dissipation is found to broaden latitude structures of UFKWs with increasing height while their vertical wavelengths (λz) increase with latitude. Collisions with ions fixed to Earth's magnetic field (“ion drag”) are found to dampen UFKW amplitudes, increasingly so as the densities of those ions increase with increased solar flux. The direct effect of ion drag is to decelerate the zonal wind. This leads to suppression of vertical velocity and the velocity divergence, and related terms in the continuity and thermal energy equations, respectively, that lead to diminished perturbation temperature and density responses. Access is provided to the UFKW HMEs analyzed here in tabular and graphical form, and potential uses for future scientific studies are noted.

Measurements of CO2, Ar and N2 densities from the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution Mission (MAVEN) between 150 and 200 km altitude during 2015–2022 are analyzed to reveal diurnal (DW1), semidiurnal (SW2) and terdiurnal (TW3) solar‐synchronous tides in Mars thermosphere. Multi‐year‐mean tidal perturbations on a diurnal‐ and zonal‐mean background, corrected for solar flux variations, are reported as a function of latitude (48°S–48°N), altitude and solar longitude (Ls). The DW1, SW2 and TW3 amplitudes at for example, 180 km altitude are of order 90%–120%, 15%–20%, and ≲10% for CO2 and Ar, and roughly 2/3 these values for N2, the latter presumably due to the difference in molecular weight from the other species. Through examination of vertical phase progressions, DW1 is concluded to be mainly excited in situ, but SW2 and TW3 contain significant contributions from tides propagating upward from lower altitudes. By analogy with studies for Earth's thermosphere, the DW1 amplitudes and phases are thought to reflect the combined influences of thermal expansion and vertical winds. Points of agreement and disagreement with DW1, SW2, and TW3 amplitudes and phases derived from the Mars Climate Database are noted and interpreted.