RESEARCH DATA: ICP WEATHER STATION DATA

Weather Station Data Observations and Calculations

A weather station on the roof of the NASA Goddard Institute for Space Studies observes daily weather conditions for our location. Data are recorded at 30-minute intervals and include the following observations: temperature, humidity, wind speed, wind direction, rain, and barometric pressure.

Weather Variables

The variables provided in the data set are listed below followed by brief explanations for each measurement/calculation.

Temperature, High and Low Temperatures

The temperature reading is sampled from the station every 15 seconds during each 30-minute interval. The recorded observation for an interval in the data set is the average of the readings during that 30-minute time period. The highest and lowest readings observed during an interval are recorded as its High and Low Temperatures.

Temperature-Humidity Index (THI)

This index is derived from the observed outside temperature and humidity. It is intended as a measure of the "apparent" temperature, i.e, how the temperature feels, depending on the amount of water vapor in the air. The derivation is based on R.G. Steadman's temperature-humidity scale and apparent temperature (1979; see reference below). The index only applies to temperatures ranging from 68°F (20°C) to 125°F (51°C).

Relative Humidity

The ratio of the actual amount of water vapor in the air to the amount of water vapor that air can hold (saturated) at the same temperature and pressure. The relative humidity is reported in percent.

Dew point temperature

The temperature to which air must be cooled for saturation to occur, keeping pressure and water vapor constant.

Wind Speed, Direction, and High Wind Speed

Speed and direction of the wind are sampled from the station every 15 seconds during each 30-minute interval. The recorded observations in the data set are the averages of their respective samplings. During an interval, the first wind speed reading is recorded as the "high", and subsequent readings are compared to the initial value, replacing it if greater.

Wind Chill

The average temperature and average wind speed during each time interval are used to calculate wind chill.

Rain

Rainfall is recorded as the amount observed per time interval in the data set. To get the total daily rainfall, add all the values for the entire day.

Barometric Pressure

Barometric pressure is observed and the value recorded (in inches) every 30 minutes.

References

• Schneider, S.H., editor in chief. 1996. Encyclopedia of Climate and Weather. Oxford University Press: NY.
• Steadman, R.G. 1979. The Assessment of Sultriness. Part I: A Temperature-Humidity Index Based on Human Physiology and Clothing Science. Journal of Applied Meteorology, 18, 861-873.
• WeatherLink User's Guide and Technical Reference Manual. 1998. Davis Instruments Corporation: CA.
• Williams, J. 1997. The Weather Book. Vintage Books/Random House: NY.