1. NASA‐GISS: data.giss.nasa.gov/gistemp
2. NCDC:www.ncdc.noaa.gov/oa/climate/research/anomalies/index.html
3. HadCRU:hadobs.metoffice.com
4. BakerCB HelfertM. U.S. Climate Reference Network (USCRN): a unique national long‐term climate monitoring network.12th Conference on Integrated Observing and Assimilation Systems for Atmosphere Oceans and Land Surface (IOAS‐AOLS) New Orleans 20–24 January 2008.