Dynamical Coupling between high and low latitude regions during sudden stratospheric warming event (Case study of 2009 and 2013 event) Vinay Kumar 1,S. K. Dhaka 1,R. K. Choudhary 2,Shu-Peng Ho 3,M. Takahashi 4,and S. Yoden 5 1 Department of Physics, University of Delhi, Delhi, India 2 Space Physics Laboratory, VSSC, Trivanduram, India 3 University Corporation for Atmospheric Research, Boulder, Colorado, USA 4 AORI, University of Tokyo, Japan 5 Kyoto University, Japan World Weather Open Science Conference 16-21 August 2014, Montreal, Canada
Objective Stratospheric sudden warming (SSW) is one of the most dramatic phenomena in the stratospheric atmosphere over northern polar region. This event is strongest manifestation of dynamical coupling in the stratosphere- troposphere system. How the temperature alters at different latitudes and longitudes sections during such events needs to be understood SSW phenomena may have impact on temperature of cold point tropopause (T-CPT) (?), and latitudinal range of impact?. Due to that water vapor budget, traces gases and circulation pattern may be changed. Here we will provide case study of January 2009 polar vertex splitting SSW event with record breaking temperature after 1989
Data Used COSMIC/FORMOSAT 3 Satellite (Radio Occultation) Data from 2007 to 2013 The mission is called the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) in the United States and the Formosat Satellite Mission 3 (FORMOSAT 3) in Taiwan. The mission was Launched on April 14, 2006. Comparison of occultations from different satellites missions Mission Total Atmospheric Occultations COSMIC (July 2006- May 2012) 32,64,812 SAC-C (March 2006- May 2012) 4,11,937 CHAMP (May 2001-Sep 2008) 3,99,968
About 500 and 25 daily COSMIC RO vertical profiles are available in the tropics (30 S 30 N) and polar region (80 N-90 N), respectively. NH COSMIC Radiosondes FormoSat-3/COSMIC: ~ daily 2500 Radio Occultation profiles worldwide Global coverage of data during May 2007 by FormoSat-3/COSMIC for 30 N-30 S SH
Characteristics of GPS RO Data With the ability of performing both during rising and setting number of occultations produce approximately 2,500 soundings per day. Such a remarkable near real time data with wide spatial coverage, high vertical resolution (100m), high accuracy (equivalent to <1 K; average accuracy <0.1 K) and almost uniform global coverage over the globe have never been available to atmospheric scientific community. Validation COSMIC data already validated with NCEP, JRA 25, and UK Met Office (MetO) data sets [P. Kishore et al., 2009, JGR] Global coverage of data from surface to 40 km height. No satellite to satellitebias
Result and Discussion To understand the variability in temperature structure during and after 2009 SSW event
(Km) ( C) A rapid increase in the temperature take place at 40 km nearly 16 January and the warm anomalies propagates downwards. After By the SSW22 January the cooling the can temperature be observed at 40 at Km 40 Kmis from increases 13 February by 40 C to 20and Marchthewhose warming peak value phases occurs extended in mind up to of this 22km. time spam However the maximum temperature increase (58 C) can be observed nearly 30km After SSW the temperature at 40 km is cooled by -80 C that is double (10hPa). in amplitude the warming and -40 C less than the temperature before SSW. While at 30 Km temperature equivalent to before SSW event. Results evidenced the different dynamical behavior of upper stratosphere and the lower stratosphere (< 30 km).
Recovery of SSW event Is SSW followed by cold phase? Or This cold phase is normal seasonal temperature?
Temperature observations using COSMIC during 2007-2011 Zonal Averaged (80-90 N) Temperature 1-40 km altitude Monthly averaged Data Study of Sudden stratospheric warming (SSW) followed by Cold temperature during 2009 unprecedented Extended plots up to Dec 2013
Daily Temperature variation during winter (Jan April) 2007-2011 3:00 pm, 11 July 2014, Geophysics deptt, Kyoto University 10
Contd../ Daily Temperature variation during winter (Dec April) 2011-2013 2012 2013 2014 3:00 pm, 11 July 2014, Geophysics deptt, Kyoto University 11
Effect of SSW on tropopause height and its temperature in polar region
With the presence of warm anomalies at tropopause level, H-CPT decreased by 3.5 km with 12 C increase in T-CPT. SSW produces an extension of 3.5 km to stratospheric region, while tropospheric region shrunk.
Effect of SSW over tropical region
when sudden stratospheric warming event occur at 40 Km of polar region at the same time, the 40 km temperature in the tropics shows a decline and the cold anomaly propagates downward The downward propagated warming anomalies can be observed at tropical region during the cooling anomalies propagation at polar region after SSW event.
Effect of SSW on tropopause height and its temperature in tropical region
During Warm Phase Declining and mounting in T-CPT and H-CPT can be observed over tropical region during SSW. The T-CPT is decreased by 3 C with increase in height.4 km due to cool anomalies Tropical atmosphere become quite unstable during the time spam of polar SSW event. 40% change in stability occurs in the tropical tropopause region due to the SSW event SSW effects the T-CPT and H-CPT in tropical region
Fine scale structure of zonally averaged T-CPT at each 2.5 latitude band from 30 N to 30 S (latitudinal variation) ~ 2 C (a)blue color represents temperature 01 to 15 Jan 2009, red color denotes period of cold anomalies in the tropical tropopause region (04 to14 February 2009), (b) Variation of H- CPT before (blue) and after (red) the occurrence of SSW.
Fine scale structure of zonally averaged sharpness of T-CPT from 30 N to 30 S. Blue color represents period before occurrence of SSW (01 to 15 Jan 2009), while red color denotes the peak period 623 of SSW (18-29 Jan 2009). Stp is defined as the change in vertical temperature gradient across the tropopause
SSW 2013 Dec 12 April 13 3:00 pm, 11 July 2014, Geophysics deptt, Kyoto University 20
Tropical tropopause variability during 2013 SSW
Fine scale structure of zonally averaged T-CPT at each 2.5 latitude band from 30 N to 30 S (latitudinal variation) for 2013 SSW
Lat-long sectors of temperature anomalies, on 2.5 x5 grid map, from 50 N to 50 S when cooling occurs at 40 km it can be seen mainly between 10 S-40 N but with non-uniform meridional extension beyond 20 N At 25 km, cooling can be observed in both hemispheres from 45 N45 S with uniform meridional structure
Brief Summary SSW event disturbs the polar and tropical stratospheric circulation pattern and this newly emerged pattern takes its own time to settle down. Stratospheric and tropospheric region have shown certain unique changes after the event. Polar region SSW is followed by downward propagated cool anomaly, which is quite stronger than warm phase in upper stratosphere (>30 km). A rapid atmospheric response is identified between polar and tropical region possibly through strong meridional circulation.
These warm (cool) and cool (warm) anomalies are not found to limited in stratospheric region but penetrate more deeply up to tropopause. Both polar and tropical tropopause temperature and height is found to be influence by these anomalies. It is seen that the influence of SSW event does not confined to only tropical region in the northern hemisphere rather it crosses the equator and appears in the southern hemisphere up to 40 S. The 2009 SSW event seems to be the strongest one in recent years and COSMIC data provided a much clearer picture on the atmospheric dynamics during this event.
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