Add AO_index (#56)

repo_name: SAM_index

people:  Willi Rath (<wrath@geomar.de>)

http_path_remote: https://git.geomar.de/data/SAM_index

git_path_remote: git@git.geomar.de:data/SAM_index

repo_description: |

    Marshall Southern Annular Mode (SAM) Index (Station-based)

    <https://climatedataguide.ucar.edu/climate-data/marshall-southern-annular-mode-sam-index-station-based>

prefixes: data doc

data:

    - url: "http://www.nerc-bas.ac.uk/public/icd/gjma/newsam.1957.2007.txt"

      prefix: data

      file_name: sam.1957.current.txt

      method: !!python/name:data_repo_renderer.CurlSingleFile

doc:

    - url: "https://climatedataguide.ucar.edu/climate-data/marshall-southern-annular-mode-sam-index-station-based"

      file_name: climatedataguide.ucar.edu_climate-data_marshall-southern-annular-mode-sam-index-station-based.html

      prefix: doc

      method: !!python/name:data_repo_renderer.CurlSingleFile

    - url: "http://journals.ametsoc.org/doi/pdf/10.1175/1520-0442%282003%29016%3C4134%3ATITSAM%3E2.0.CO%3B2"

      file_name: Marshall_2003.pdf

      prefix: doc

      method: !!python/name:data_repo_renderer.CurlSingleFile