The U.S. Climate Reference Network (CRN) is a National Oceanic and Atmospheric Administration (NOAA)-sponsored network and research initiative. The first and foremost objective of the USCRN instrument suite is to provide benchmark-quality air temperature and precipitation measurements free of time-dependent biases. The CRN configuration uses three separate aspirated shields each of which contains one Platinum-wire Resistance Thermometer (PRT) sensor to measure ambient air temperature. The primary instrument systems used in the Cooperative Observer network (COOP) include the Cotton Region Shelter (CRS) housing the Liquid-in-Glass thermometer and the Maximum and Minimum Temperature System (MMTS), both of which are non-aspirated systems. In this study, a comparison was conducted on temperature observations made by the COOP and CRN systems at co-located sites. The difference between the COOP and CRN systems are useful in constructing long-term homogeneous time series and in surface observing network integration.        

Figure 1.     T_max and T_min differences (COOP minus CRN) at co-located stations (within 10 km). Error bars represent 95% confidence limits of the mean bias. Data from 20 co-located sites are used  

Figure 1 shows an example of the COOP and CRN temperature difference at co-located sites. Spatial and temporal characteristics of the difference were analyzed and their dependence on solar and wind regimes and siting characteristics was investigated.