On the Roles of Advection and Solar Heating in Seasonal Variation of the Migrating Diurnal Tide in the Stratosphere, Mesosphere, and Lower Thermosphere

Abstract

The migrating diurnal tide (DW1) presents a unique latitudinal structure in the stratosphere, mesosphere, and lower thermosphere. In this paper, the physical mechanisms that govern its seasonal variation are examined in these three regions using the 31. 5-year (1979-2010) output from the extended Canadian Middle Atmosphere Model (eCMAM30). DW1 annual variation in the stratosphere is mainly controlled by the short-wave heating in the high latitudes, but by both the short-wave and adiabatic heating in the low latitudes. In the mesosphere, linear and nonlinear advection play important roles in the semiannual variation of the tide whereas short-wave heating does not. In the lower thermosphere, the annual variation of DW1 is mainly governed by the short-wave heating and linear advection. This study illustrates the complexity of the main physical mechanisms modulating the seasonal variations of DW1 in different regions of the atmosphere.

Statistical Modeling of Tidal Weather in the Mesosphere and Lower Thermosphere

“…The reason for varying range of stronger correlation as a function of height in eCMAM is unknown. One possible reason is that DW1 presents a different latitudinal structure in the stratosphere due to trapped Hough modes (Gu & Du, , Figure ). The Hough mode composition in the stratosphere is more complicated than that in the MLT region where the symmetric Hough mode (1, 1) is dominant.…”

Interannual Variability of the 12‐hr Tide in the Mesosphere and Lower Thermosphere in 15 Years of Meteor‐Radar Observations Over Rothera (68°S, 68°W)

“…Nonlinear interactions between tides and planetary waves play a significant role in the behavior of the 12‐hr tide, and therefore the relationship to the solar cycle may be in part due to changes in planetary wave activity as a result of changing solar flux (Baumgaertner et al., 2005; Salby & Callaghan, 2004). A change in planetary wave activity could change the generation of migrating tidal modes, which are thought to be forced mainly by nonlinear interactions between tides and planetary waves, generating secondary waves, which include the nonmigrating tidal modes (Beard et al., 1999; Gu & Du, 2018; Palo et al., 2007; Teitelbaum & Vial, 1991).…”

Numerical Prediction of the Migrating Diurnal Tide Total Variability in the Mesosphere and Lower Thermosphere

“…DW1 is known to have a strong semi‐annual oscillation in the mesosphere and lower thermosphere (MLT) region with larger amplitudes during the equinoxes than the solstices (Gan et al., 2014; Hays et al., 1994; Lieberman et al., 2007; McLandress, 2002a, 2002b). A different seasonal variation pattern of DW1 (annual variation with a maximum in the summer hemisphere) is present in the stratosphere (Gu & Du, 2018; Mukhtarov et al., 2009; Sakazaki et al., 2013; Zeng et al., 2008). DW1 in the thermosphere is characterized by an annual variation with a maximum in the summer (Gu & Du, 2018; Jones et al., 2014).…”

“…DW1 in the thermosphere is characterized by an annual variation with a maximum in the summer (Gu & Du, 2018; Jones et al., 2014). The latitudinal structures of DW1 are quite different in the three atmospheric regions as well (Gu & Du, 2018).…”

“…A different seasonal variation pattern of DW1 (annual variation with a maximum in the summer hemisphere) is present in the stratosphere (Gu & Du, 2018; Mukhtarov et al., 2009; Sakazaki et al., 2013; Zeng et al., 2008). DW1 in the thermosphere is characterized by an annual variation with a maximum in the summer (Gu & Du, 2018; Jones et al., 2014). The latitudinal structures of DW1 are quite different in the three atmospheric regions as well (Gu & Du, 2018).…”