Radiosonde observations of high-latitude planetary waves in the lower atmosphere

Abstract

The characteristics of high-latitude planetary waves (PWs) in the troposphere and lower stratosphere (TLS) are studied by using the data from radiosonde observations during 1998 to 2006 at three Alaskan stations in USA (Nome, 64.50°N, 165.43°W; McGrath, 62.97°N, 155.62°W; Fairbanks, 64.82°N, 147.87°W). It is found that strong PWs exist in two regions. One is around tropopause, and the other is in the polar night jet (PNJ) in winter. The PW activities are rather intermittent, and their lifetimes are no longer than two months. Among three perturbation components in zonal and meridional winds and temperature, the temperature disturbance amplitude is the smallest, and the amplitude for the meridional wind component the largest. Around the tropopause, quasi 5-, 10-, and 16-day PW activities can be observed simultaneously. Among these PW components, the quasi 5-day and 10-day PW are the weakest and strongest, respectively. Moreover, PWs around the tropopause are complex and no obvious season variability can be observed. However, in the PNJ, the higher region, only obvious quasi 10-day and 16-day PWs remain, with smaller amplitudes than those around the tropopause. And significant PWs in the PNJ occur only in winter. By calculating the refractive index for PWs, it is found that there is a persistent reflection layer around 11 km, which is thick in summer and becomes thin or even disappears in winter, revealing that PWs in the stratosphere can only occur in winter. PWs in the 2003/2004 winter at the three stations are analyzed in detail. It is found that for the focused observation duration, the quasi 10-day and quasi 16-day waves exist mainly in the troposphere and stratosphere, respectively. The quasi 10-day wave is a standing wave in the vertical direction, with vertical wavelength about 12 km in the temperature component and larger than 26 km in the meridional component. Moreover, the tropospheric quasi 10-day wave propagates westward with the zonal numbers between 2 and 4. The quasi 16-day wave is also a standing wave in the vertical direction with vertical wavelength larger than 20 km, and seems to be a stationary wave in the horizontal direction. planetary waves, troposphere and lower stratosphere, radiosonde Citation: Wang R, Zhang S D, Yi F. Radiosonde observations of high-latitude planetary waves in the lower atmosphere. Sci China Earth Sci, 2010, 53: 919-932,

Global climatological variability of quasi-two-day waves revealed by TIMED/SABER observations

“…Satellites can almost provide whole global wind fields, temperature and atmospheric compositions from the upper troposphere to the lower thermosphere. For example, the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) can measure the lower atmospheric temperature (He et al, 2009;Yang and Zou, 2012); the Upper Atmospheric Research Satellite/High Resolution Doppler Imager (UARS/HRDI) measures temperature, zonal and meridional wind, water vapor and ozone concentration in the middle and upper atmosphere (Wu et al, 1993(Wu et al, , 1996; the Thermosphere Ionosphere Mesosphere Energetics Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) is used for temperature measurements in the upper atmosphere (Xu et al, 2007a, b); and the line-of-sight (LOS) winds can be surveyed by the Microwave Limb Sounder (MLS) on Aura (Tunbridge et al, 2011). Satellite observations contribute greatly to our knowledge of global morphology of QTDWs.…”

“…Periods of PWs are usually between 2 and 30 days (Vincent, 1990). A PW event usually lasts several periods, and always exhibits seasonality and discontinuity (Vincent, 1984;Wang et al, 2010). Therefore, the window for spectral analysis is set to be 30 days.…”

“…Therefore, the window for spectral analysis is set to be 30 days. During summertime, the QTDW was proved to be the strongest PW in the MLT (Muller, 1972;Roger and Prata, 1981;Wu et al, 1993;Harris and Vincent, 1993;Harris, 1994;Garcia et al, 2005;Palo et al, 2007;McCormack et al, 2009), and thus it is taken as the primary topic of this paper. In addition, most of our attention is paid to the summertime in the altitude range from 70 to 90 km and from 30 • S (N) to 50 • S (N) in latitude, where intense QTDWs recur regularly (Muller, 1972;Muller and Nelson, 1978;Craig et al, 1980;Salby, 1981;Meek et al, 1996;Garcia et al, 2005;Tunbridge et al, 2011).…”

“…Primary periods of the PWs contain quasi-two-day, quasi-five-day, quasi-ten-day and quasisixteen-day waves (Jacobi et al, 1998;Wang et al, 2010). The most prominent component in the MLT is the quasitwo-day wave (QTDW), which is able to affect horizontal wind and temperature in the middle atmosphere (Palo et al, 1999).…”

“…The most prominent component in the MLT is the quasitwo-day wave (QTDW), which is able to affect horizontal wind and temperature in the middle atmosphere (Palo et al, 1999). Amplitudes of QTDWs in temperature and wind can reach 12 K (Tunbridge et al, 2011) and 60 m s −1 (Wu et al, 1993). Traces of QTDWs can also be found in atmospheric H 2 O, carbon monoxide, OH emission, and height of the F2 layer (Wu et al, 1993;Randel, 1994;Forbes and Zhang, 1997;Limpasuvan and Wu, 2003;Limpasuvan et al, 2005;Tunbridge et al, 2011;Pedatella and Forbes, 2012).…”