NCDC Data Dictionary
Straight from the documentation:
DATA FIELDS / FORMATS Each station file contains fixed-width formatted fields with a single set of subhourly (5-minute) data per line. A summary table of the fields and a detailed listing of field definitions/column formats are shown below. Please be sure to refer to the "Important Notes" section below for essential information. All subhourly data are calculated over the 5-minute period *ending* at the UTC/LST times shown. Please note that the stations Local Standard Time is always used, regardless of its Daylight Savings status. Field# Name Units --------------------------------------------- 1 WBANNO XXXXX 2 UTC_DATE YYYYMMDD 3 UTC_TIME HHmm 4 LST_DATE YYYYMMDD 5 LST_TIME HHmm 6 CRX_VN XXXXXX 7 LONGITUDE Decimal_degrees 8 LATITUDE Decimal_degrees 9 AIR_TEMPERATURE Celsius 10 PRECIPITATION mm 11 SOLAR_RADIATION W/m^2 12 SR_FLAG X 13 SURFACE_TEMPERATURE Celsius 14 ST_TYPE X 15 ST_FLAG X 16 RELATIVE_HUMIDITY % 17 RH_FLAG X 18 SOIL_MOISTURE_5 m^3/m^3 19 SOIL_TEMPERATURE_5 Celsius 20 WETNESS Ohms 21 WET_FLAG X 22 WIND_1_5 m/s 23 WIND_FLAG X 1 WBANNO [5 chars] cols 1 -- 5 The station WBAN number. 2 UTC_DATE [8 chars] cols 7 -- 14 The UTC date of the observation. 3 UTC_TIME [4 chars] cols 16 -- 19 The UTC time at the end of the 5-minute observation period. For example, 0420 designates the observational period starting just after 0415 and ending at 0420; and 0000 designates the last 5-minute period of the previous day. 4 LST_DATE [8 chars] cols 21 -- 28 The Local Standard Time (LST) date of the observation. 5 LST_TIME [4 chars] cols 30 -- 33 The Local Standard Time (LST) time at the end of the 5-minute period (see UTC_TIME description). 6 CRX_VN [6 chars] cols 35 -- 40 The version number of the station datalogger program that was in effect at the time of the observation. Note: This field should be treated as text (i.e. string). 7 LONGITUDE [7 chars] cols 42 -- 48 Station longitude, using WGS-84. 8 LATITUDE [7 chars] cols 50 -- 56 Station latitude, using WGS-84. 9 AIR_TEMPERATURE [7 chars] cols 58 -- 64 Average temperature, in degrees C. See Notes F and G. 10 PRECIPITATION [7 chars] cols 66 -- 72 Total amount of precipitation, in mm. See Notes F and H. 11 SOLAR_RADIATION [6 chars] cols 74 -- 79 Average global solar radiation received, in watts/meter^2. 12 SR_FLAG [1 chars] cols 81 -- 81 QC flag for the average global solar radiation measurement. See Note I. 13 SURFACE_TEMPERATURE [7 chars] cols 83 -- 89 Average infrared surface temperature, in degrees C. See Note J. 14 ST_TYPE [1 chars] cols 91 -- 91 The type of infrared surface temperature measurement: 'R' denotes raw (uncorrected); 'C' denotes corrected; and 'U' is shown if the type is unknown/missing. See Note J. 15 ST_FLAG [1 chars] cols 93 -- 93 QC flag for the surface temperature measurement. See Note I. 16 RELATIVE_HUMIDITY [5 chars] cols 95 -- 99 Relative humidity average, as a percentage. See Note K. 17 RH_FLAG [1 chars] cols 101 -- 101 QC flag for the relative humidity measurement. See Note I. 18 SOIL_MOISTURE_5 [7 chars] cols 103 -- 109 Average soil moisture (volumetric water content in m^3/m^3) at 5 cm below the surface. See Note M. 19 SOIL_TEMPERATURE_5 [7 chars] cols 111 -- 117 Average soil temperature at 5 cm below the surface, in degrees C. See Note M. 20 WETNESS [5 chars] cols 119 -- 123 The presence or absence of moisture due to precipitation, in Ohms. High values (>= 1000) indicate an absence of moisture. Low values (< 1000) indicate the presence of moisture. 21 WET_FLAG [1 chars] cols 125 -- 125 QC flag for the wetness measurement. See Note I. 22 WIND_1_5 [6 chars] cols 127 -- 132 Average wind speed, in meters per second, at a height of 1.5 meters. 23 WIND_FLAG [1 chars] cols 134 -- 134 QC flag for the wind speed measurement. See Note I. IMPORTANT NOTES: A. All fields are separated from adjacent fields by at least one space. B. Leading zeros are omitted. C. Missing data are indicated by the lowest possible integer for a given column format, such as -9999.0 for 7-character fields with one decimal place or -99.000 for 7-character fields with three decimal places. D. Subhourly data are calculated over the 5-minute period which *ends* at the time shown. E. There are no quality flags for these derived quantities. When the raw data are flagged as erroneous, these derived values are not calculated, and are instead reported as missing. Therefore, these fields may be assumed to always be good (unflagged) data, except when they are reported as missing. F. The 5-minute values reported in this dataset are calculated using multiple independent measurements for temperature and precipitation. G. USCRN/USRCRN stations have multiple co-located temperature sensors that make 10-second independent measurements used for the average. H. USCRN/USRCRN stations use a weighing bucket gauge outfitted with three redundant, but independent, load cell sensors to monitor gauge depth. As a supplement, a disdrometer (wetness sensor) is used to detect wetness. I. Quality control flags indicate the following: 0 denotes good data, 1 denotes field-length overflow, and 3 denotes erroneous data. J. On 2013-01-07 at 1500 UTC, USCRN began reporting corrected surface temperature measurements for some stations. These changes impact previous users of the data because the corrected values differ from uncorrected values. To distinguish between uncorrected (raw) and corrected surface temperature measurements, a surface temperature type field was added to the data product. The possible values of the this field are "R" to denote raw surface temperature measurements, "C" to denote corrected surface temperature measurements, and "U" for unknown/missing. K. All USCRN stations now report 5-minute relative humidity averages, however the two Asheville, NC stations reported only hourly RH values until 2007-02-22. L. USRCRN stations do not measure solar radiation, surface temperature, relative humidity, wind speed or soil variables, so those fields are shown as missing data. M. USCRN stations have multiple co-located soil sensors that record independent measurements. The soil values reported in this dataset are calculated from these multiple independent measurements. Soil moisture is the ratio of water volume over sample volume (m^3 water/m^3 soil). N. In accordance with Service Change Notice 14-25 from the National Weather Service, NCDC stopped providing data from the 72 Southwest Regional Climate Reference Network (USRCRN) stations on June 1, 2014. The historical data for these stations remain available.