Thermospheric inter-annual variability and its potential connection to ENSO and stratospheric QBO

Abstract

Using a 46-year-long dataset of the thermospheric density during 1967-2012, we examined the inter-annual variability in the thermosphere at 400 km and its potential connection to El-Nino Southern Oscillation (ENSO) and stratospheric Quasi-Biennial Oscillation (QBO). Wavelet analysis reveals two major modes of the thermosphere inter-annual oscillation, with the slower mode having an average period of ~64 months and the faster mode of ~28 months. The slower mode bears high coherence with the ENSO during 1982-2012, while the faster mode is found to vary coherently with the QBO around 1972QBO around , 1982QBO around and 2002. Further examination reveals that the coherence between QBO and the faster mode is significantly influenced by their common coherent variation with the solar flux, while high coherence between the slower mode and ENSO is much less contaminated. Therefore, we conclude that the 28-month periodicity in thermospheric density may be caused by both QBO and solar radiation, whereas the 64-month periodicity possibly arises mainly from ENSO processes, with little/small contribution from solar radiation.

Raman modes inPbcaenstatite (Mg2Si2O6): an assignment by quantum mechanical calculation to interpret experimental results

“…Among the DFT based calculations, the thermodynamic properties and phase transition of MgSiO 3 at high pressure were calculated in a pure GGA simulation. [21] Here we discuss the results of new simulations of Raman spectra of orthoenstatite from first principles, by means of CRYSTAL14, [22] employing the hybrid Hamiltonian WC1LYP, [1] which is particularly suitable to calculate modes wavenumbers, as demonstrated for C2/c pyroxenes, like diopside, jadeite and spodumene [23][24][25] and in the À1 plagioclase albite. [26] Full Raman spectra are simulated, and the peak assignment is discussed in comparison with computational and experimental literature; the contribution of each atom to the vibration is assessed performing a building unit decomposition of the vibrational modes and by means of isotopic substitutions.…”

El Niño–Southern Oscillation effect on ionospheric tidal/SPW amplitude in 2007–2015 FORMOSAT-3/COSMIC observations

“…Ionospheric plasma density structures are highly variable on broad range of temporal and spatial scales, and the solar activity and lower atmosphere forcing are the major drivers. The El Niño-Southern Oscillation (ENSO) oceanatmosphere coupling phenomenon is one of the significant sources of variability in the thermosphere (Gurubaran et al 2005;Lieberman et al 2007;Liu 2012, 2013;Warner and Oberheide 2014;Liu 2016;Liu et al 2017;Sun et al 2018). However, studies on the ENSO signature in the ionosphere are rare and challenging (Pedatella and Forbes 2009;Pedatella and Liu 2013;Chang et al 2018) due to the complex nature of the atmosphere-ionosphere-solar system.…”

The non–storm time corrugated upper thermosphere: What is beyond MSIS?

“…Using a 46 year long data set of the thermospheric density during 1967–2012, Liu [] examined the interannual variability of the thermosphere density. Two major oscillation modes were revealed, with the slower mode having an average period of ∼64 months and the faster mode of ∼28 months.…”

“…Thick contours enclose regions of greater than 95% significance level. The arrows indicate the relative phase relationship between the time series, right: in phase; left: antiphase; down: Nino3/QBO leading Δ ρ by 90°; and up: Δ ρ leading Nino3/QBO by 90° [from Liu , ].…”