Focus on tropical convection (OLR), and zonal and global - - PowerPoint PPT Presentation

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Focus on tropical convection (OLR), and zonal and global - - PowerPoint PPT Presentation

Mar 11, 2023 170 likes •371 views

Tropical-Extratropical interaction during YOTC Klaus Weickmann, NOAA/ESRL/Physical Sciences Division Edward Berry, NOAA/NWS Dodge City, Kansas Focus on tropical convection (OLR), and zonal and global atmospheric angular momentum (AAM)

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SLIDE 1
  • Focus on tropical convection (OLR), and zonal

and global atmospheric angular momentum (AAM)

  • Major events with forecast implications

– May 2008 - MJO and severe storm outbreak USA – SON 2008 - Boreal fall intraseasonals (MJO, GWO*): The return of La Nina – XT initiation of DJFMA 2008-09 MJO activity? – Atmospheric Rivers and eq. Kelvin Waves: FM09 – A warming equatorial Pacific Ocean: MAM 2009

Tropical-Extratropical interaction during YOTC

Klaus Weickmann, NOAA/ESRL/Physical Sciences Division Edward Berry, NOAA/NWS Dodge City, Kansas

*GWO - global wind oscillation

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SLIDE 2

GWO

retrogression

MJOs

seasonal split flow

SSW

“truncated” Oct 08 MJO

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SLIDE 3

H Momentum sink events: NH winter 2008-09

Flux convergence of AAM ( top); AAM (bottom) Anomalies (colors); mean seasonal cycle (contours)

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SLIDE 4

red – May 08 blue – JJA 2008 green – SON 2008 gray – DJF 2009 black – MAM 2009

~4-5 MJOs?

Apr 09 May 08 Sep-Oct 08 Dec-Jan 09

OLR, 200 and 850 mb winds: 15N - 15S

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SLIDE 5

L L L H H H L L

250 mb vector wind anomalies

May 2008 MJO

16 May 2008 22 May 2008 7-8-1 transitions Frequent Model Failures?

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SLIDE 6

Rise in AAM SON 2008 mainly result of GWO and mountain forcing

Boreal fall intraseasonals: the return of La Nina

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SLIDE 7

XT initiation of DJFMA 2009 MJO activity?

5s-15s 5s-15s

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SLIDE 8

L

H

H

L

H H

H H L H H L L H L L H L L L

150 mb vector wind anomalies just before MJO initiation

14-20 Dec 2008 6-12 Mar 2009 Dec Jan Feb Mar Apr

Mar 12 Dec 19

26 Dec 2008

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SLIDE 9

TOTAL OLR 5N-15N Jan-Jun 2008 Jan-Jun 2009

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SLIDE 10

L L L L H L H

22 Feb 2009 3 Mar 2009 250 mb wind anoms

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SLIDE 11

Slow eastward movement of convection and early March breakdown of NH wintertime jet stream

red – May 08 blue – JJA 2008 green – SON 2008 gray – DJF 2009 black – MAM 2009

Strong MJOs weak MJOs

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SLIDE 12

L L H H

L

H H L H

L

L

250 mb seasonal mean wind and OLR anomalies DJF 2009 vs MAM 2009 W W W W E E 19-26 Mar 09 surface wind

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SLIDE 13

SUMMARY

  • May-June 2008 MJO
  • Boreal Fall 2008 intraseasonals

– “truncated” Oct MJO La Nina – 15 Oct, 15 Nov Indian Ocean convective flareups – circulation retrogression (Dec 08, cold USA)

  • Initiation of DJ09 and MA09 MJOs?
  • SSW, major cold outbreak USA Jan 09
  • Slow eastward movement of convection

– contribution to early March 09 “split flow”?

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SLIDE 14

13 Oct 2008 15 Oct 2008 29 Oct 2008

AWB 1/2

  • - --
  • H

H H H H H H L L

12 Oct 2008

H H H L L L L L L L L L L

AWB 3

+ + + +

tendency = - (transports) + torques

global zonal

H

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SLIDE 15
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SLIDE 16

Dec Jan Feb Mar Apr

Mar 12 Dec 19

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SLIDE 17

Zonal Mean AAM: 2008-09

Dec Jan Feb Mar Apr

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SLIDE 18

GWO

07 08 09

MJO

07 08 09

JJA 2008 DJF 2009

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SLIDE 19

26 Dec 2008 3 Jan 2009

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SLIDE 20

12 Mar 2009 16 Mar 2009 19 Mar 2009