Monitoring the Health of
U.S. In Situ Networks

The on-going project to monitor the health of many weather and climate observing networks will be addressing many U.S.in situ networks. These include:

• Health of the NWS Cooperative Observer Network (COOP)
  Relying primarily on volunteers, most of the several thousand COOP observers record weather observations once per day.

• Health of the NOAA Climate Reference Network (CRN)
  The newest of the U.S. in situ observing networks, CRN focuses on producing very high quality observations. For example, to insure against a bias in the data originating from faulty thermometers, each CRN station's instumentation includes three independent thermometers.

• Automated Surface Observing Systems (ASOS)
  The approximately 900 commissioned ASOS stations operate primarily at airports. These stations provide a wide variety of observations on time scales as frequent as 1 minute.

U.S. in situ networks to be addressed in the future:

• The U.S. Historical Climatology Network (USHCN)
  The USHCN is a subset of the Cooperative Observers Network. Stations that make up the USHCN were carefully selected with a view towards long-term data quality. Data for these stations have been adjusted to account for biases introduced when stations moved or when a different type of thermometer was installed.