HRly MEAN is the average of the preceding 60 1-minute values. Each element value and the hourly mean is given in a six-digit field including a minus sign for negative values, or a blank for positive values. Missing data spaces are padded with 99999. No alteration of logical record length is required for different types of computers. Codes for sources of digital magnetometer data in the WDC system not only indicate the source organization, but also show whether the data are average values or point data.
Different organizations process their higher time resolution observations in different ways.
Some may filter and smooth the observations. If the method used to obtain 1-minute average values is important to a user, the WDC will assist in determining the exact procedure applied. Often only timely variations data are needed to support special research campaigns and digital values may be transmitted from regular observatory sites via satellite relay platforms. Values from special networks such as the IMS chains are variations only. Attempts are made to check the absolute output of these instruments but usually no systematic absolute observations are possible or they are later replaced by adopted standard observatory digital values.