Quasi‐two‐day wave structure, interannual variability, and tidal interactions during the 2002–2011 decade

Abstract

In this paper we employ Thermosphere Ionosphere Mesosphere Energetics Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry temperature measurements from 20 to 120 km and between about ±72° latitude to investigate several aspects of the quasi‐two‐day wave (QTDW) during the 2002–2011 decade, including interannual variability of its seasonal‐latitudinal structure, its penetration into the lower thermosphere, and various wave‐wave interactions. We focus on two components of the QTDW: the westward‐propagating component with zonal wave number s=3 (TDW3), and the eastward‐propagating component with s=−2 (TDE2). TDW3(TDE2) has maximum amplitudes during 2003, 2004, and 2011(2006 and 2011) and both waves have their lowest amplitudes during the deep solar minimum years of 2008–2009. TDW3 and to some degree TDE2 penetrate with significant amplitudes up to 120 km altitude, well into the region where neutral winds generate electric fields through the dynamo mechanism. A new “longitude subdivision method (LSM)” is presented that enhances temporal resolution of TDW3 and enables the determination of 9.6 h and 16 h waves that result from nonlinear interaction between TDW3 and/or TDE2 and diurnal migrating (DW1) and semidiurnal migrating (SW2) tides. Evidence is presented for westward‐propagating 9.6 h and 16 h waves with s=5 and s=4, respectively, and a zonally symmetric (s=0) 9.6 h wave. The s=5(s=0) wave only occurs as a result of nonlinear interaction between SW2 and TDW3(TDE2), whereas the s=4 wave can result from interaction of TDW3 with DW1 or of TDE2 with SW2. We payed special attention to possible aliasing between different waves.

Meteor radar quasi 2-day wave observations over 10 years at Collm (51.3° N, 13.0° E)

“…Craig and Elford (1981) explored phase locking relative to the sun and suggested nonlinear interactions with diurnal tides. This is also supported by recent studies (e.g., Huang et al, 2013a;Moudden and Forbes, 2014;Walterscheid et al, 2015). A possible correlation of QTDW amplitudes with the 11-year solar cycle has been found by Jacobi et al (1997), who explained this finding by a stronger mesospheric wind shear during solar maximum.…”

Quasi two day wave‐related variability in the background dynamics and composition of the mesosphere/thermosphere and the ionosphere

“…The QTDW structure is known to be manifested simultaneously in both wind and temperature fields in numerical experiments [ Palo et al , 1999; Chang et al , 2011a], as well as in observations such as that using the Microwave Limb Sounder (MLS) aboard the Earth Observing System by Limpasuvan and Wu [2009], and in SABER and TIDI by Gu et al [2013]. QTDW temperature amplitudes have also been used extensively in past studies due to the availability of temperature soundings over a broad vertical domain from instruments such as SABER [ Palo et al , 2007; Chang et al , 2011b; Moudden and Forbes , 2014] and MLS [ Limpasuvan and Wu , 2009; Tunbridge et al , 2011], thus providing a large body of past work for intercomparison. Our results for the QTDW using SABER are consistent with these past studies.…”

“…We select an altitude of 85 km, which is close to the altitude of the lower QTDW amplitude peak at the mesopause and is more easily resolved than the secondary peak in the lower thermosphere near 110 km [ Moudden and Forbes , 2014]. Raw SABER temperature soundings at 85 km are binned into an overlapping geographic latitude × altitude grid of 2.5°×2.5 km.…”

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

“…Those planetary waves represent "normal mode" or "resonant" oscillations of the atmosphere (e.g., Salby 1984). Global climatology of 2-, 5-, 10-and 16-day waves has been established by satellite measurements, e.g., Gu et al (2013), Moudden and Forbes (2014) for 2-day waves; Wu et al (1994) If the amplitude of the planetary waves is sufficiently large in the dynamo region, they will drive ionospheric currents and affect geomagnetic perturbations on the ground. Even if the planetary waves dissipate before they reach the dynamo region, they can still interact with tides and mean flow in the middle atmosphere, which will affect the upward propagation of tides to the dynamo region, and thus affect the ionospheric dynamo (e.g., Liu et al 2010;Chang et al 2011).…”