The dynamical signal in stratospheric temperatures from satellites Changes 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 Note, additional co-authors Based on novel method that Susan, Qiang and Pu Lin started with MSU data (1) NOAA-ESRL, (2) CIRES-CU, (3) CSU Fort Collins, (4) NCAR, (5) U. NSW, Aus. (6) U. Washington Thanks to Craig Long and Roger Lin (NOAA - data); Bill Randel & Fei Wu (NCAR - data); Eric Ray, Bob Portmann, Sean Davis (NOAA - discussions)

Outline Dynamical (Brewer-Dobson) temperature signal The MSU/SSU temperature data Horizontal patterns and interannual variability from Brewer-Dobson circulation Long-term changes and the B-D circulation Summary Two results sections: Interannual variability L-T changes

How do we get a dynamical temperature signal? COOLS HEATS Opposite-sense anomalies from stronger/weaker than average Expansion -> cooling Compression -> warming Holton et al. 1995

Annual temperature cycle - Asymmetric wave driving = maximum wave driving (NH winter) (> 30°S/N) Ann cycle in extratropics (50%)… …balanced in tropics (50%) (30°S – 30°N) MSU T4 analysis from Yulaeva et al. 1994

Temperature data: MSU and SSU Microwave/Stratospheric sounding units Monthly/zonal mean anomalies, 1979-2005 Tropical tropopause Polar tropopause Randel et al. 2009

Horizontal patterns and interannual variability (De-trended data) Highlight de-trended data

Winter correlations: Spider on the mirror High lats (>50N) and tropics High lats (>50S) and tropics NH, DJF SH, JJA SSU 27 SSU 26 SSU 25 Pairs of lines (tropics and high latitudes) for each satellite channel, for NH winter (DJF) and SH winter (JJA). Data are normalized to mean = 0 and std dev = 1. Dotted lines show timing of El Chichon and Mt Pinatubo. Line pairs are significantly anti-correlated. Anomalies persist in vertical MSU T4 1979 2005 1979 2005 Individual signals of SH 2002 winter, ENSO, others….? Young et al. in prep

Tropics-S/N Pole correlations by month Local correlation with… > 60° N > 60° S SSU 27 Out-of-phase in hemispheric winter (B-DC signal) SSU 26 In-phase in NH summer (weak in SH summer) Altitude SSU 25 Local monthly time series correlation with NH/SH high latitudes Shading where |r| > ~ 0.4 (t-test signif at 95% level) Still looking at in-phase NH summer - “seasonal memory” / NOy perhaps…? MSU T4 Young et al. in prep

Brewer-Dobson circulation signals 1979-2005 See also Fu et al. (in review) for MSU discussion

Tropical/extratropical linear trends, 1979-2005 SSU 27 ? Changes in Tropics and extratropics balance  adiabatic process ? SSU 26 Altitude = B-DC strengthening? SSU 25 Black line = global mean; extratropics is avg poleward of 30°N/S Where tropical and extratropical trends deviate from global mean Note April-May plot Distorted SH pattern due to ozone hole cooling = B-DC weakening? MSU T4 April  May Young et al. in prep

B-DC seasonality change / weakening SSU 27 SSU 26 B-DC seasonality change / weakening B-DC strengthening Altitude SSU 25 Trend and trend-mean trend - highlight latitudinal structure Persistence in vertical Long-term strengthening tendency robust to (e.g.) 2002 and volcanoes MSU T4 Ozone-related cooling Young et al. in prep

Consistency with radiosonde trend Satellites on the left; radiosondes on the right MSU T4 pattern not reproduced in IPCC AR4 models (see Fu et al.) Young et al. in prep

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”? Temperature data Ozone data Subtract F10.7cm regression

Summer correlations: “seasonal memory”? Temperature data Ozone data High lat-tropical T correlation from ozone? O3 anomalies persist through, e.g., NOy transport (Tegtmeier et al. 2008) Subtract F10.7cm regression