Leibniz Institute of Atmospheric Physics, Schlossstr. 6, Kühlungsborn, Germany b)

Transcription

1 Neutral air density variations during strong planetary wave activity in the mesopause region derived from meteor radar observations G. Stober a), C. Jacobi b), V. Matthias a), P. Hoffmann a), M. Gerding a) a) Leibniz Institute of Atmospheric Physics, Schlossstr. 6, Kühlungsborn, Germany b) Leipzig Institute for Meteorology, Stephanstr. 3, Leipzig, Germany 24/08/2012 5th NDMC

2 Outline specular meteor observations - climatologies sporadic Meteors and shower meteors planetary wave temperature and wind meteor ablation and meteor ablation model neutral density variation (Meteor radar, MLS) 24/08/2012 5th NDMC

3 Radar measurements SKiYMET meteor radar position in the sky: range, elevation, azimuth, altitude electron line density meteor entry velocity radial drift velocity of ambipolar plasma radiant activity maps cosmic noise Collm 51.3 N / 13 E 24/08/2012 5th NDMC

4 Specular meteor observation 24/08/2012 5th NDMC

5 Specular meteor observations width of meteor layer meteor peak flux altitude (MPFA) defining a width of the meteor layer MPFA meteor peak flux altitude related to background neutral atmospheric density 24/08/2012 5th NDMC

6 angular distribution 2h Specular meteor observations radiant activity 12h Continuous flux of sporadic and shower meteors into the Earth s atmosphere 24/08/2012 5th NDMC

7 Meteor climatology Quadrantids Geminids 24/08/2012 5th NDMC

8 Meteor climatology 24/08/2012 5th NDMC

9 Meteor Peak Flux Altitude What causes these wave like patterns of the MPFA? astrophysical origin atmospheric origin 24/08/2012 5th NDMC

10 Sporadic meteor sources merged measurements of one year data Southern hemispheric sources difficult to observe activity of sources changes with season only meteor showers cause short time events 24/08/2012 5th NDMC

11 Sporadic Meteor bulk velocity Geminids Meteor bulk velocity Meteor bulk velocity Meteor shower are clearly seen as a spike in the meteor velocity distribution Sporadic velocity distribution has apart from time of high meteor shower activity a peak around km/s 24/08/2012 5th NDMC

12 Meteor sporadic bulk velocity weak trend of the bulk meteor velocity and MPFA Meteor showers indicate a small contamination (GEM, QUA) No obvious coincidence of MPFA wave structure in the bulk meteor velocity 24/08/2012 5th NDMC

13 Temperature Winter 2009/10 MLS over Juliusruh PW activity in the temperature from MLS, Lidar and MR SSW event clearly visible at all three latitudes 24/08/2012 5th NDMC

14 Wind Winter 2009/10 24/08/2012 5th NDMC

15 Meteor Ablation Total meteoric mass input into atmosphere between t/d. Strong mass velocity selection effect detectability of radar depends on meteor velocity 24/08/2012 5th NDMC

16 Meteor ablation model Ablation altitude defined by atmospheric friction NRLMSIS-00 reference atmosphere radar calibrated known electron line densities e - /m Meteor ablation model linked to MAGMA 24/08/2012 5th NDMC

17 Neutral density variation Conversion of MPFA to neutral air density variation with a meteor ablation model 24/08/2012 5th NDMC

18 MPFA vs MR temperature Phase jump Phase jump between temperature wave and MPFA indicates onset of SSW event 24/08/2012 5th NDMC

19 MPFA and zonal wind SSW Almost perfect anti-correlation between zonal wind and MPFA SSW event at the End of January leads to a phase jump of the PW 24/08/2012 5th NDMC

20 MPFA and neutral density variation MLS satellite and MR show a similar PW pattern of the neutral air density variation Amplitude difference due to altitude difference (likely) MPFA and geometric altitude variation of retrieval level show also same pattern 24/08/2012 5th NDMC

21 Conclusion Strong PW activity in the winter season 2009/10 in the wind, temperature and MPFA at three different latitudes relatively good agreement of MLS temperature, lidar and MR temperatures SSW event leads to a phase jump of the PW and is accompanied by a decrease of the MPFA Neutral air density variations explain wave structure of MPFA by using a meteor ablation model Almost perfect anti-correlation between zonal wind and MPFA/neutral air density variation 2010 (January) SSW event stronger at mid-latitudes than at polar latitdues 24/08/2012 5th NDMC