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Longer-Term Trends Dian Seidel SPARC Temperature Trends Panel Meeting 19-21 July 2006 Abingdon

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Longer-Term Trends. Dian Seidel SPARC Temperature Trends Panel Meeting 19-21 July 2006 Abingdon. Outline. Datasets Considerations for our paper Recently published results Possible approaches for our paper. Datasets. Radiosonde Rocketsonde (Chantal?) Berlin Analysis (Ulrike) - PowerPoint PPT Presentation

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Page 1: Longer-Term Trends

Longer-Term Trends

Dian Seidel

SPARC Temperature Trends Panel Meeting

19-21 July 2006 Abingdon

Page 2: Longer-Term Trends

Outline

• Datasets

• Considerations for our paper

• Recently published results

• Possible approaches for our paper

Page 3: Longer-Term Trends

Datasets

• Radiosonde

• Rocketsonde (Chantal?)

• Berlin Analysis (Ulrike)

• Reanalysis (not considering)

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Considerations

• Summarize published results and/or make new calculations?

• What can we learn (or report) that we didn’t know circa Ramaswamy et al. (Rev. Geophys. 2001)?– Effect of homogeneity adjustments on trends (Lanzante et al.

2003; Free et al., JGR 2005; Thorne et al., JGR 2005; CCSP 2006)

– Time-segmented trends (Seidel and Lanzante, JGR 2004; Ramaswamy et al., Science 2006)

– Details of volcanic signal (Free and Angell, JGR 2002; Santer et al., JGR 2001; above studies)

– Statistical issues (Nishizawa and Yoden, JGR 2005)

• Use only homogeneity-adjusted datasets?

Page 5: Longer-Term Trends

Radiosonde Datasets 1958-present(Update of 3/2005 Reading Report)

• Hadley Atmospheric Temperature (HadAT)– UK Met Office (Thorne et al. JGR 2005)– 9 levels, including 300, 200, 150, 100, 50, and 30hPa – Gridded product – Adjustments based on Lanzante et al. (2003) and neighbor comparisons– Available now at http://hadobs.metoffice.com/hadat/

• Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC)– NOAA (Free et al. JGR 2005)– 16 levels, including 300, 250, 200, 150, 100, 70, 50 and 30 hPa– Two datasets:

• Large-scale (~30 deg bands) anomaly time series based on Lanzante et al. (2003) adjustments through 1979, then first-difference method and metadata

• Station data with no adjustments post-1979, also 10-deg zonal data– Available now at http://www.ncdc.noaa.gov/oa/cab/ratpac/index.php

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RATPAC and HadAT Coverage

Source: CCSP report

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Source: CCSP reportNote great discrepancy between datasets in early years – RATPAC more variable, with larger Agung signal.

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Temperature Trends in the Lower Atmosphere

For further information on

CCSP Synthesis and Assessment Product 1.1

http://www.climatescience.gov/

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Note good agreement between sonde (and surface) datasets compared with satellite.

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Possible Approaches

• No discussion of pre-satellite errors– Pro: keeps paper shorter and more focused– Con: ignores developments with sonde data

• Text-only review of recent literature– Pro: addresses new developments without adding

much length– Con: doesn’t allow presentation of new analysis

• Text-with-figure(s) presentation of some pre-1979 observations– Pro: most thorough approach– Cons: longer paper, more work