Philippe Keckhut, Chantal Claud, Bill Randel

Upper stratospheric trends

Topics

- lidar / SSU- Trend estimates- Other data sets- Solar effect

NDACC Lidars

Station Latitude Longitude Operating since

Hohenpeissenberg 47,80°N 11,02°E 1987

OHP:

Obs de Haute-Provence

43,93°N 5,71°E 1979

Table Mountain Facility 34,04°N 117,70°W 1988

Hawaï 19,54°N 155,58°W 1993

La Réunion 21,80°S 55,5°E 1994

TMF lidarhas much larger cooling trends: step wise 2-3

Hohenp. lidarhas positive residual trends: anomalies in 98-00 and biais

OHP lidarhas negligible residual trend

?

comparison of lidar andSSU trends for 1988-2005

Notes:

Satellite trends are small for this period.Trends are changing

Large statistical uncertaintiesfor the lidars (only shown forOHP curve, but similar forother stations).

Table Mountain is an outlier(strong cooling, as seen inthe time series)Hohenpeisenberg also

TMF. OHP. Hohenp.

A new temperature trend assessment should

• Assess trends• Time• Altitudes• Latitudes• Accuracy

• trends accuracy• temporal continuity, data consensus

• Highlighted what is new / 2001• Trend behavior:

• Changing trends• Existing series:

• new, • combining (SSU/AMSU) • and stopping one (FUB, rocket)

• What is required for future trends: recommendations

Summer OHP Lidar temperature trends

Linear1979-1997

Linear1979-2005

Linear term of a non linear

analysis1979-2005

Quadratic term1979-2005

Trends updated with rocket sondes 1969-1995

Rockets and lidar

Heiss (81°N)

Temperature climatology above Dumont D’Urville (Antarctica)

-20

-15

-10

-5

0

5

1-02 5-02 9-02 1-03 5-03 9-03 1-04 5-04 9-04

Time (month-years)

Temperature deviations

(°Celsius)

0

5

10

15

20

25

30

1979 1982 1985 1988 1991 1994 1997 2000 2003

Time (years)

Occurrence of cold

events (%)

Nov-April Aug.-Oct.

Occurrence of T < 190K ECMWF-RS at 100hPa for 1995-2000

Response to the 11-year solar cycle

US Rocket sites

Tropics Sub-tropics Mid-latitudes

Kekchut et al., 2005

Response to the 11-year solar cycle

Lidar 44°N

Summer WinterKeckhut et al., 2005

Response to the 11-year solar cycle

±70°

SSU at 6 hPa

1979-1998

Keckhut et al., 2005

Mechanistic simulations of the atmospheric solar response

• Response depends on Planetary Waves activity

• Response is highly non-linearClim*1.5

Clim*1.8

Clim*2.2

3D Rose/Reprobus model at SA

Hampson et al., 2005

Variations with Longitude

25 km25 km

37 km37 km

49 km49 km

Ref: Hampson et al. 2007Ref: Hampson et al. 2007