Data · dataset · 2026
Historical SAM Variability. Part II: Twentieth-Century Variability and Trends from Reconstructions, Observations, and the IPCC AR4 Models
Listed in National Center for Atmospheric Research
This second paper examines the Southern Hemisphere annular mode (SAM) variability from reconstructions, observed indices, and simulations from 17 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) models from 1865 to 2005.
Description
Comparisons reveal the models do not fully simulate the duration of strong natural variability within the reconstructions during the 1930s and 1960s. Seasonal indices are examined to understand the relative roles of forced and natural fluctuations.
The models capture the recent (1957-2005) positive SAM trends in austral summer, which reconstructions indicate is the strongest trend during the last 150 yr; ozone depletion is the dominant mechanism driving these trends. In autumn, negative trends after 1930 in the reconstructions are stronger than the recent positive trend. Furthermore, model trends in autumn during 1957-2005 are the most different from observations.
Read the rest (2 more)
Both of these conditions suggest the recent autumn trend is most likely natural climate variability, with external forcing playing a secondary role. Many models also produce significant spring trends during this period not seen in observations. Although insignificant, these differences arise because of vastly different spatial structures in the Southern Hemisphere pressure trends.
As the trend differences between models and observations in austral spring have been increasing over the last 30 yr, care must be exercised when examining the future SAM projections and their impacts in this season.
Links
Get the data
- Publisher page n2t.org/ark:/85065/d78p61tz ↗
documentation · download · from data ucar edu
Where it is published
- data.ucar.edu /dataset/historical-sam-variability-part-ii-twentieth-century-v… ↗
National Center for Atmospheric Research dataset page
landing page · from data ucar edu
Catalogue records · 1
- CKAN API data.ucar.edu/api/3/action/package_show?id=b3c426ea-550e-4ccc-8d50-23061a0a6… ↗
metadata API · from data ucar edu
Topics
- From keywords
- Earth & Environmental Science · Ocean & Atmospheric Science
Provenance · 1 source records, 7 field assertions
| Source | Key | Last seen | Raw |
|---|---|---|---|
| National Center for Atmospheric Research | b3c426ea-550e-4ccc-8d50-23061a0a64ab | 12 d ago | JSON v1 |
| Field | Assertion | Extractor | Evidence |
|---|---|---|---|
| concepts[field].local:field:earth-environmental | mapping · data ucar edu | connector:data_ucar_edu@1.0.0 | |
| concepts[field].local:field:ocean-atmospheric | mapping · data ucar edu | connector:data_ucar_edu@1.0.0 | |
| created_date | source · data ucar edu | connector:data_ucar_edu@1.0.0 | |
| description | source · data ucar edu | connector:data_ucar_edu@1.0.0 | /notes |
| publication_date | source · data ucar edu | connector:data_ucar_edu@1.0.0 | |
| title | source · data ucar edu | connector:data_ucar_edu@1.0.0 | /title |
| updated_date | source · data ucar edu | connector:data_ucar_edu@1.0.0 |