Metadata for KJSG/EW5982 10/20/2014 City/State: Norman, Oklahoma Lat/Lon: 35.1893 N and 97.4611 W Elev: 1155 ft The site is located in Cleveland County approximately 2.6 miles south-southwest of downtown Norman and 19.5 miles south of Oklahoma City. The weather station is a Davis Vantage Pro2 with 24-Hour Fan Aspirated Radiation Shield. The station is attached to a mounting tripod on grass beneath the northwest outer canopy of a black walnut tree. It is approximately 27 ft from the nearest road, 33 ft from the nearest building, and 45 ft from the nearest pool. The temperature and dew point sensor is located at around 5 ft agl, with the tipping-bucket rain gauge at 6 ft agl. The anemometer is at around 12 ft agl. Data are wirelessly transmitted every minute to a console and Weatherlink datalogger. Data are uploaded to this website as KJSG, Weather Underground, and the CWOP as EW5982 every 5 minutes. CWOP uploads data to Mesowest and MADIS. There are also NWS-standard 8-inch and COCORAHS-standard 4-inch rain gauges located around 70 ft to the southeast of the Davis station. These gauges are situated between 2.5 to 4 ft agl. Rainfall accuracy compared to the Davis station widely varies, with the Davis instrument usually undercatching between 10-25% (especially during heavy rainfall events), when compared to the NWS and COCORAHS gauges. Approximately once per week, the raw 1-minute data are manually quality controlled and adjusted to fit NWS ASOS standards. These data are then combined with data from the manual instruments to produce monthly LCDs and records. Below is an explanation of each parameter. Temperature: The station senses temperature every 10 seconds. These 6, 10-second values are then averaged and stored once per minute. In QC, 5, 1-minute observations are averaged to produce a 5-minute averaged temperature ending at the last observation, in the same way NWS ASOS reports temperature/dew point. This 5-minute average is calculated for every minute, and used to produce the maximum and minimums for the 24-hr period from 12:00 AM to 11:59 PM CST, as well as the mean temperature for the day (an average of all 1440, 5-minute averaged observations). Relative Humidity/Dew Point: The station senses relative humidity every minute. Dew point values are calculated each minute from the RH value and the 1-minute averaged temperature. In QC, 5, 1-minute observations are averaged to produce a 5-minute averaged RH/Dew Point ending at the last observation, in the same way NWS ASOS reports temperature/dew point. This 5-minute average is calculated for every minute, and used to produce the maximum and minimums for the 24-hr period from 12:00 AM to 11:59 PM CST, as well as the mean for the day (an average of all 1440, 5-minute averaged observations). Wind Speed: The station senses wind every 2.5 seconds. These 24, 2.5-second values are averaged and stored once per minute. In QC, 2, 1-minute observations are averaged to produce a 2-minute averaged wind speed ending at the last observation, in the same way NWS ASOS reports wind speed. This 5-minute average is calculated for every minute, and used to produce the maximum and minimums for the 24-hr period from 12:00 AM to 11:59 PM CST, as well as the mean for the day (an average of all 1440, 2-minute averaged observations). It should be noted that the anemometer is located at a lower height than the 33 ft agl NWS ASOS standard with surrounding obstructions. Speeds are thus significantly lower than the NWS ASOS standard. Wind Gust: The highest value of wind sensed every 2.5 seconds. Wind Direction: The station senses wind every 2.5 seconds. These 24, 2.5-second values are averaged and stored once per minute as the dominant wind direction. The direction is stored to one of 16 compass points. This is converted to the nearest tens of degrees for use in QC'd monthly data. Barometric Pressure: The station senses pressure every 15 minutes. The station adjusts the pressure to sea-level. Daily high, lows, and means are derived from the 96, 15-minute observations. Rainfall: The station has an unheated tipping bucket which updates every 10 seconds. These 6, 10-second values are then summed and stored once per minute. In QC, all 1-minute observations are adjusted using the formula C = A * (1 + (0.6 * A)) where C = the calculated amount, and A = the accumulated amount. This is the same formula used by NWS ASOS to adjust for underreporting of heavy rainfall rates. The 1-minute adjusted observations are then summed for the 24-hr period from 12:00 AM to 11:59 PM CST to produce the daily rainfall total. Typically, the Davis station undercatches precipitation by 10-25% when compared to the NWS and COCORAHS gauges. The NWS standard rain gauge is considered the official precipitation total of record. Temperature Humidity Wind Index: Derived from the NWS Heat and Wind Chill Indices, this provides a combined index to be used year-round. The value is calculated once a minute. In QC, 5, 1-minute observations are averaged to produce a 5-minute averaged temperature ending at the last observation, in the same way NWS ASOS reports temperature/dew point. This 5-minute average is calculated for every minute, and used to produce the maximum and minimums for the 24-hr period from 12:00 AM to 11:59 PM CST, as well as the mean for the day (an average of all 1440, 5-minute averaged observations). Heating and Cooling Degree Days: Calculated each minute by using the 1-minute average temperature with a base of 65°F. In QC, 5, 1-minute observations are averaged to produce a 5-minute averaged degree day ending at the last observation. This 5-minute average is calculated for every minute. All 1440, 5-minute averaged observations are then summed for the day.