Features of the seasonal variation of the semidiurnal, terdiurnal and 6-h components of ozone heating evaluated from Aura/MLS observations

Abstract

Abstract. This paper presents the thermal forcing of the semidiurnal, terdiurnal, and 6-h components of the migrating tide induced by ozone heating in stratosphere and lower mesosphere. The heating as a function of local time is determined from the global ozone observed by the Microwave Limb Sounder on the Aura satellite. The harmonic components of the heating rates of the semidiurnal, terdiurnal and the 6-h periodicities are calculated using the Strobel/Zhu parameterized model and then decomposed into Hough modes. Seasonal variations of each harmonic component and its Hough modes are presented. For all three tidal components, the majority of the annual mean O 3 heating projects onto symmetric modes. The semiannual variation is a prominent signal in almost all of the symmetric Hough modes near the stratopause. The strongest annual variation takes place in the asymmetric modes. The results also show that, during the solstice season, the maximum forcing of the diurnal and terdiurnal component occurs in the summer hemisphere while the maximum forcing of the semidiurnal and 6-h components occurs in the winter hemisphere. The global mean ozone density and the tidal components of the ozone heating rate are different between December-January and June-July. The asymmetry in the heating is primarily due to the 6.6 % annual variation in the solar energy input into the Earth's atmosphere due to the annual variation of the Sun-Earth distance.

Tidal wind mapping from observations of a meteor radar chain in December 2011

“…[30] The Hough modes from the classical tidal theory are orthogonal and complete covering from pole to pole [Xu et al, 2012]. However, in this paper, it should be pointed out that the stations of the IGGCAS meteor radar chain locate at the middle-and low-latitudes in the Northern Hemisphere.…”

“…Recently, the space-borne observations, such as the Wind Imaging Interferometer and High Resolution Doppler Imager on board the UARS, and the TIMED Doppler Interferometer on board the Thermosphere-Ionosphere-Mesosphere Energetic and Dynamics (TIMED) spacecraft, revealed a wealth of information on the global structure of upper atmospheric tides [Manson et al, 2002a;Oberheide et al, 2006Oberheide et al, , 2007Pancheva et al, 2009b;Shepherd et al, 1999;Wu et al, 2006]. Owing to the virtue of their global coverage, they are capable of providing both the latitudinal and longitudinal structures of any tides from the space-borne measurements; this makes it possible to distinguish the migrating and nonmigrating tides and to decompose different Hough modes Lu, 2008a, 2008b;Mukhtarov et al, 2009;Xu et al, 2012;Xu et al, 2011;Zhang et al, 2006].…”

A note on apparent solar time and the seasonal cycle of atmospheric solar tides

“…Xu et al . () showed that the symmetric mode of semidiurnal stratospheric ozone heating minimizes in June–July (see their Fig. 11).…”

“…The smaller A 2 in boreal summer vs. winter is understandable largely as a consequence of the eccentricity of the Earth's orbit -the Sun-Earth distance is over 3% shorter at perihelion (in early January) than at aphelion (in early July) resulting in nearly 7% annual modulation of the effective solar flux reaching the top of the atmosphere. Xu et al (2012) showed that the symmetric mode of semidiurnal stratospheric ozone heating minimizes in June-July (see their Fig. 11).…”

What causes seasonal variation of migrating diurnal tide observed by the Mars Climate Sounder?

“…The symmetric modes are (1, 1), (1, 3), (1, 5), (1, 7)… and (1, À2), (1, À4), (1, À6), (1, À8)…, while the antisymmetric modes are represented by (1, À1), (1, À3), (1, À5), (1, À7)… and (1, 2), (1, 4), (1, 6), (1, 8)…. Hough functions are useful for expansion of tidal fields (e.g., Φ in equation (2)) to investigate their latitudinal distribution and vertical propagation [Zurek, 1976;McLandress, 2002c;Takahashi et al, 2006], and the thermal heating (J in equation (3)) of various atmospheric compositions to estimate their effects in tidal excitation [Lindzen, 1968;McLandress, 2002c;Xu et al, 2012]. In the next section, we use the 16 sets of Hough functions shown in Figure 1 to decompose MDT extracted from MCS temperature field to explore their composition characteristics and the seasonal variations.…”