Advancing Water Resources Research and Management

HPD data, further information

Initially from August 1948 to September 1951, data were keyed on punched cards by the regional Weather Records Processing Centers. Then the task was transferred to the National Climatic Data Center (NCDC) in Asheville, NC. The hourly precipitation data file was transferred from punched cards to magnetic tape (TD-9657) during the late 1960s. This data file was then converted to the element file structure during 1984.

Several recording (weighing) rain gage instruments were used in measuring hourly precipitation, but by September 1963 many Fischer-Porter precipitation gage instruments with automated readout, recorded on paper tape, were phased in. By early 1965, about 200 of these were in operation and they became the primary recording instrument. In 1996, there were approximately 2,400 Fischer-Porter gages in operation. The Universal Rain gage is the other primary instrument used to create this data file. It has an automated readout recorded on paper charts. In 1996, there were approximately 100 Universal Rain gage stations in the HPD system. Station and dates of commissioning of weighing rain gages are in the Station History listings available at the NCDC in Asheville, NC.

Fischer-Porter precipitation gages record data on punched paper tapes. A device known as the Mitron reader translates the data at NCDC. The Universal Rain gage records data on paper charts. The precipitation recorded on the charts is then digitized. The data from the Surface Climate Information Archive and Dissemination System (SCIADS) or primary stations is also entered into the TD3240.

Data before 1984 were converted from existing digital files (TD-9657) to the element structure format. These (historical) data were processed through a gross value check only. Beginning January 1984, the hourly precipitation data were processed through a completely revised system which produces the element structure database file. This system was further enhanced beginning with the January 1996 data month. The new interactive quality control system introduced many features. Data are subjected to new computer editing procedures reducing the manual handling of the data.

To make the pre-1996 data consistent with the January 1996 processing system, the historical data were re-processed in 1997. The rehabilitated data covered the 1900 through 1995 period and contained more than 53 million observations. Approximately 400 thousand inconsistencies were identified and corrected as a result of this effort. These inconsistencies were categorized into 22 error types. In addition to this effort, ?last look? quality assurance software was implemented on HPD data (post 1996) operationally sent to the archive each month. The ?last look? software uses similar checks as the rehabilitation software and should result in maintaining consistency between the historical data and operationally received data.

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