The dynamical signal in stratospheric temperatures

from satellitesChanges and interannual variability (1979-2005)

Paul J Young1,2, S Solomon1, D W J Thompson3, K H Rosenlof1,

J-F Lamarque1,2,4, S C Sherwood5, Q Fu6

Thanks to Craig Long and Roger Lin (NOAA - data); Bill Randel & Fei Wu (NCAR - data); Eric Ray, Bob Portmann, Sean Davis (NOAA - discussions)

(1) NOAA-ESRL, (2) CIRES-CU, (3) CSU Fort Collins, (4) NCAR, (5) U. NSW, Aus. (6) U. Washington

Outline

1. Dynamical (Brewer-Dobson) temperature signal

2. The MSU/SSU temperature data

3. Horizontal patterns and interannual variability from

Brewer-Dobson circulation

4. Long-term changes and the B-D circulation

5. Summary

How do we get a dynamical temperature signal?

Holton et al. 1995

COOLSHEATS

Opposite-sense anomalies from stronger/weaker than average

Annual temperature cycle - Asymmetric wave driving

MSU T4 analysis from Yulaeva et al. 1994

Ann cycle in extratropics (50%)…

…balanced in tropics (50%)

(> 30°S/N)

(30°S – 30°N)

= maximum wave driving (NH winter)

Temperature data: MSU and SSU

Tropical tropopause

Polar tropopause

Randel et al. 2009

Microwave/Stratospheric sounding units

Monthly/zonal mean anomalies, 1979-2005

Horizontal patterns and interannual variability

(De-trended data)

Winter correlations: Spider on the mirror

Young et al. in prepIndividual signals of SH 2002 winter, ENSO, others….?

NH, DJF

1979 2005 1979 2005

SH, JJA

High lats (>50S) and tropics

SSU 27

SSU 26

SSU 25

MSU T4

High lats (>50N) and tropics

Tropics-S/N Pole correlations by month

Out-of-phase in hemispheric winter (B-DC signal)

In-phase in NH summer (weak in SH summer)

Young et al. in prep

Alti

tud

e

SSU 27

SSU 26

SSU 25

MSU T4

Local correlation with… > 60° N > 60° S

Brewer-Dobson circulation signals

1979-2005

See also Fu et al. (in review) for MSU discussion

Tropical/extratropical linear trends, 1979-2005

Young et al. in prep

Changes in Tropics and extratropics balance

adiabatic process

= B-DC strengthening?

= B-DC weakening?

?

?

Alti

tud

e

SSU 27

SSU 26

SSU 25

MSU T4

April May

Young et al. in prep

Ozone-related cooling

B-DC seasonality change / weakening

B-DC strengthening

B-DC strengthening

Alti

tud

e

SSU 27

SSU 26

SSU 25

MSU T4

Young et al. in prep

Consistency with radiosonde trend

Summary

• Wintertime B-D signal clear through the vertical

• “Seasonal memory” in NH summer? (model?)

• Satellites/radiosondes & adiabatic arguments change in strength/seasonality of B-DC over last ~30 years

• Evidence for long term tendency? Still looking at decadal patterns, but appears winter strengthening is robust

Extras – “seasonal memory”

Summer correlations: “seasonal memory”?

Subtract F10.7cm regression

Temperature data Ozone data

Summer correlations: “seasonal memory”?

Subtract F10.7cm regression

Temperature data Ozone data

High lat-tropical T correlation from ozone?

O3 anomalies persist through, e.g., NOy transport (Tegtmeier et al. 2008)