Impact of abrupt stratospheric dynamical change on Tropical Tropopause Layer Eguchi, N. 1, K. Kodera 2,3 and T. Nasuno 4 1: Kyushu University, 2: Nagoya University 3MRI, 4:JAMSTEC 1

Contents 2 1.Stratospheric Sudden Warming (SSW) 2.Abrupt Stratospheric Dynamical Change in early winter Summary & Discussion

Warming convergence Cooling by Upward motion & Kelvin-response Meridional circulation is enhanced Cirrus Schematic Figure: Impact of stratospheric change associated with Stratospheric Sudden Warming (SSW) on Tropics ※ Stratospheric Sudden Warming ※ The location of center of convection depends on the condition of troposphere, e.g., suitable seasonal and intra-seasonal convective latitudinal band. We have studied the effect of stratospheric circulation change on tropical troposphere through Tropical Tropopause Layer (TTL). 3 Kodera and Yamada (2004) Eguchi and Kodeta (2007) Eguchi and Kodera (2010) Kodera, Eguchi et al. (2012)

Case for SSW in January 2009 Kodera, Eguchi, Lee, Kuroda and Yukimoto (JMSJ, 2010) 4 From Walker-cell to Hadley-cell Before onset of SSWAfter onset of SSW 200hPa

Case for SSW in September 2007 Eguchi and Kodera (SOLA, 2010) 5 Before onsetAfter onset

Case for SSW in September 2007 Western Pacific Eq. Africa S.America Eguchi and Kodera (SOLA, 2010) 6 Cold

7 Abrupt warming in the tropical stratosphere 2011

8 Contrast with SSW event Abrupt warming in early winter 2011

Temporal variation in TTL (i)(ii)(iii) (i)(ii)(iii) 11/112/112/31 11/112/112/31 68 hPa 82 hPa 100 hPa 121 hPa 146 hPa IWC 100 hPa O hPa *anomaly from linear trend WV (i) Downward motion in stratosphere (ii) Transitional period of downward motion (iii) Downward motion in troposphere 9

10 Modulate Madden-Julian Oscillation (MJO) At this case, the MJO stopped to move to eastward. In contrast, the MJO after the SSW event in 2009 was occurred and moved to eastward

SSW 2011 abrupt warming EOS MLS deseasonalize water vapor mixing ratio 21hPa 177hPa

Summary & Discussion 12 1.The sudden stratospheric dynamical change affects on the tropical troposphere and TTL. 2.The variables in the TTL are affected by both changes of troposphere and stratosphere, the magnitude of effect depends on background conditions in troposphere (convective activity) and stratosphere (QBO). 3.It is still not known why the convection becomes active or suppression after the sudden stratospheric dynamical change. − TTL becomes unstable -> higher convection −Easy to see the effect during the period when longitudinal contrast in troposphere is less.

13 Thank you! I need some sleep…

14 Just arisen SSW impact!

stratospheric momentum forcing simplified GCM experiment (Thuburn and Craig, 2000) Cumulus heating Tropopause height N 90S EQ 90N 90S EQ Eastward Westward Eastward Westward