Each USCRN station has three thermometers which report independent temperature measurements each hour. These three observed temperature value are used to derive a single official USCRN temperature value for the hour. This single value is sometimes a median and sometimes an average of various combinations of the three observed values, depending on information about which equipment is functioning reliably. For the details of how this single value is computed, see the Official USCRN Temperature Algorithm. Each station transmits the three independent observed values; the computation of the official USCRN temperature value is done after these values arrive at NCDC. The discussion below describes the details of the three observed values.

Each station has three Thermometrics platinum resistance thermometers, each of which is housed in its own Met One 076B 7308 aspirated solar shield. Each thermometer measures the temperature (in degrees Celsius) every 2 seconds. Every 5 minutes the station datalogger computes the average of these 2-second values, giving 12 5-minute averages for each thermometer:

T_i^k = average of 2-second values for i-th 5-minute period in the hour, i=1,...,12. [k is the thermometer number (1, 2, or 3).]

1. T^k_avg = average (°C) of T^k₁, ..., T^k₁₂
2. T^k_stdev = standard deviation of T^k₁, ..., T^k₁₂
3. T^k_min = minimum (°C) of T^k₁, ..., T^k₁₂
4. T^k_mintime = time at which the above minimum occurred
5. T^k_max = maximum (°C) of T^k₁, ..., T^k₁₂
6. T^k_maxtime = time at which the above maximum occurred
7. T^k₁₂ (°C)

In addition to the above thermometer values, the station also measures the speed of the fan in each aspirated shield. As the shield's fan rotates, a contact closes and generates a pulse twice per rotation. The datalogger counts these pulses every two seconds. Every hour these 2-second values are averaged to obtain an average number of pulses per second for the hour. The hourly data stream from the station thus include the following values (one value for each of the three sensors):

FS^k = average of 2-second pulse rates for the hour, in pulses per second, for shield number k = 1,2,3.

For more details about the temperature sensor and measurements, see the Air Temperature Sensor Summary. For more details about the aspirated shield, see the Aspirated Shield Summary.

Each USCRN station measures precipitation with a Geonor T-200B precipitation gauge. This gauge produces several independent observed precipitation measurements each hour. These observed values are used to derive a single official USCRN precipitation value for the hour. For the details of how this single value is computed, see the Official USCRN Precipitation Algorithm. Each station transmits the observed values; the computation of the official USCRN precipitation value is done after these values arrive at NCDC. The discussion below describes the details of the observed values.

The Geonor T-200B uses a collection bucket which is suspended by three vibrating wire strain gauges. Each wire, when excited with 12V DC, vibrates with a frequency relative to the weight in the collection bucket. The gauge is surrounded by a small wind/snow shield, and a controlled heater device is attached to the gauge to prevent ice buildup. The station datalogger measures the frequency of each vibrating wire and converts it to a gauge depth (in mm) each hour on the hour, at 15 minutes past the hour, at 30 minutes past the hour, and at 45 minutes past the hour. The hourly data stream contains the following values 12 for each wire k = 1,2,3 (a total of 36 values):

1. P^k₁ = precipitation (mm) for 1st 15 minutes of the hour
2. P^k₂ = precipitation (mm) for 2nd 15 minutes of the hour
3. P^k₃ = precipitation (mm) for 3rd 15 minutes of the hour
4. P^k₄ = precipitation (mm) for 4th 15 minutes of the hour
5. P^k_tot = precipitation total (mm) for hour
6. D^k₄ = gauge depth (mm) at end of 1st 15 minutes of the hour
7. D^k₄ = gauge depth (mm) at end of 2nd 15 minutes of the hour
8. D^k₄ = gauge depth (mm) at end of 3rd 15 minutes of the hour
9. D^k₄ = gauge depth (mm) at end of 4th 15 minutes of the hour
10. F^k_avg = average wire frequency for the hour
11. F^k_min = minimum wire frequency for the hour
12. F^k_max = maximum wire frequency for the hour

A Hydrological Services Tipping Bucket Rain Gauge Model TB-3 is installed at some sites for comparison purposes only. Its data are not quality controlled and are not considered official USCRN precipitation readings.

An Apogee Instruments IRTS-P infrared temperature sensor measures the infrared ground surface temperature (in degrees Celsius) at each station. The datalogger samples the sensor every two seconds. Every five minutes these two-second samples are averaged to obtain 5-minute values. Each hour the station's data stream contains:

1. IR_avg = average (°C) of the 12 5-minute values for the hour
2. IR_stdev = standard deviation of the 12 5-minute values for the hour

A Kipp & Zonen SP Lite Pyranometer measures solar radiation (watts per meter squared, W/m²) at each station. The datalogger samples the sensor every two seconds. Every five minutes these two-second samples are averaged to obtain 5-minute values. Each hour the station's data stream contains:

1. SR_avg = average (W/m²) of the 12 5-minute values for the hour
2. SR_stdev = standard deviation of the 12 5-minute values for the hour

A Met One Model 014A anemometer measures wind speed (in meters per second) at each station. The datalogger samples the anemometer every two seconds. Every five minutes these two-second samples are averaged to obtain 5-minute values. Each hour the station's data stream contains:

1. WS_avg = average (meters/sec) of the 12 5-minute values for the hour
2. WS_stdev = standard deviation of the 12 5-minute values for the hour

In addition to the above elemental observations, the hourly data stream from each station includes the following values:

1. FGBV = Battery voltage for fan and GOES transmitter battery
2. FGBV_full = Battery voltage for fan and GOES transmitter battery under full load
3. DLBV = Battery voltage for datalogger
4. DLDO = Number of minutes in this hour that the datalogger door was open

In summary, the hourly data stream from each station contains the following values. (In the table below, you can click on a value to jump to the place in this page where it is described in more detail).