did we expect a disturbed stratosphere in 2009-10? qbo-east ? (holton & tan 1980) el nino ?...
Post on 20-Dec-2015
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Did we expect a disturbed stratosphere in 2009-10?
QBO-EAST ? (Holton & Tan 1980) EL NINO ? (Ineson and Scaife, 2009; Bell et al 2009) SOLAR MINIMUM ? (Labitzke & Van Loon 1988; Kodera and Kuroda 2002) TREND ? (Chartlon et al 2008; Bell et al 2010) ... all fit with a weaker-than-average polar vortex
QBO
90N
30h
Pa T
empe
ratu
re
QBO- east
Key features of stratospheric flow:
Minor warming – early DecemberStrong vortex until mid-January – major stratospheric sudden warming (SSW)Weak, disturbed vortex late winter – persistent easterlies over polar cap
North Pole temperature at 10hPa ZMZW at 60N 10hPa
Courtesy Andrew Charlton-Perez http://www.met.reading.ac.uk/research/stratclim/current/
Minor Major
ZMZW 60-90N
Pres
sure
Pres
sure
Dec-01 Jan-01 Feb-01 Mar-01Dec-15 Jan-15 Feb-15
NAM index
Dec-01 Jan-01 Feb-01 Mar-01Dec-15 Jan-15 Feb-15
NAO
Dec-01 Jan-01 Feb-01 Mar-01Dec-15 Jan-15 Feb-15
ERA-
40 o
pera
tiona
l ana
lysi
s
- 08-12-2009 - lower stratospheric
split
Strong mid-winter (Dec – Jan)
- 01-02-2010 - displacement SSW
event
Courtesy Andrew Charlton-Perez
ZMZW 60-90N
Pres
sure
Pres
sure
Dec-01 Jan-01 Feb-01 Mar-01Dec-15 Jan-15 Feb-15
NAM index
Dec-01 Jan-01 Feb-01 Mar-01Dec-15 Jan-15 Feb-15
NAO
Dec-01 Jan-01 Feb-01 Mar-01Dec-15 Jan-15 Feb-15
ERA-
40 o
pera
tiona
l ana
lysi
s
•growth in vertical EP-flux is pre-blocking •Was it driven by PNA-type pattern?
•Wave-2 confined to lower stratosphere
• January blocking precedes SSW•Also strong PNA-like pattern, no NAO •Low EP flux (10hPa) in late winter due to persistence of easterly anomalies in
lower stratosphere
16 NOV 16 DEC 16 JAN 16 FEB 16 MAR 16 APR
EP-flux vector (10hPa, 60N)
16 NOV 16 DEC 16 JAN 16 FEB 16 MAR 16 APR
Vertical EP-flux (100hPa)
EQ
90N
Tropospheric precursors?
NOV 500hPa Z’