Get Climate Teleconnection Indices

Import time series of climate teleconnection indices from the United States National Weather Service (NWS)/National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC) website found here: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml.

Downloadable indices include:
get_ao retrieves Arctic Oscillation (AO), sometimes called the Northern Annular Mode (NAM).

get_aao retrieves Antarctic Oscillation (AAO), sometimes the Southern Annular Mode (SAM).

get_nao retrieves North Atlantic Oscillation (NAO).

get_pna retrieves Pacific North-American Pattern.

INPUT ARGUMENTS: none

OUTPUTS: (example for the AAO)
aao_ind = daily AAO index values
aao_dates = date vector

EXAMPLE:
[aao_ind,aao_dates] = get_aao;
figure
plot([aao_dates(1) aao_dates(end)],[0 0],'k'); hold on
plot(aao_dates,aao_ind,'b')
datetick
xlim([aao_dates(1) aao_dates(end)])
box off
text(0,.9,' Antarctic Oscillation Index','units','normalized')