READER observations

The READER data set is continuously being revised as more observations are acquired, however as with any data set we expect READER to contain errors.

The observations come from a variety of sources, each having its own probability of error. Real-time data is provided through the WMO Global Telecommunications System (GTS). Today, most of this is electronic, but early data was often read by observers, transmitted by voice over HF radio and hand punched onto telex tape. Each step could lead to the generation of errors and omissions. National operators may subsequently supply the complete data set in electronic form after local verification and on occasion re-calibration (the preferred means for inclusion in READER), but it is still subjected to further quality control to identify possible errors; not all are detected. On occasion, particularly for older observations, no synoptic observations are available, however a monthly mean from a CLIMAT message has been provided. Little verification is possible for these values. Finally errors may occur during compilation of the READER database. We welcome independent verification of the values presented here, and would particularly welcome contribution of the original synoptic data in order to provide uniform treatment for all stations. In addition to these issues, we note that the actual location of observing points at Antarctic stations, and indeed the location of the stations themselves, often changes over time.