Climate data elements (2023)

A climate data item is a measured parameter that helps indicate the climate of a specific place or region, e.g. B. Precipitation, temperature, wind speed and humidity. The descriptive terminology for climate data elements is:

Elementname- The full description of the item referred to in the weather station (e.g. maximum temperature).

element identification- It is an abbreviated identifier for the item, typically 4 characters long (e.g. TMAX (daily high temperature), TMIN (daily low temperature), PRCP (precipitation, etc.).

item duration- The interval between measurements of a data item. Typical data element durations available to the station could be monthly, daily, or hourly.

The following description of climate data elements is a summary of the material contained withinNational Weather Service Observing Manual No. 2, Cooperative Station Observations, IsWeather Station Handbook and Inter-Agency Guide for Wilderness Managers,and theGlossar der Meteorologie der American Meteorological Society.

Statistical analysis of climate data generates descriptive information reflecting average atmospheric conditions at a location and probabilities of extreme events occurring. Any statistical analysis of climate data must follow the rules of statistical analysis, mainly due to the limited number of samples available. An important rule for analyzing small samples requires a minimum of 30 samples. This is not to say that climate data with data less than 30 years old cannot be analyzed, but that some adjustment needs to be made to estimate what a set of 30 samples would yield.

air temperature- Temperature is a measure of how hot or cold the air is. It is measured on a specific temperature scale. Usually two scales are used. The Fahrenheit and Celsius temperature scales place the freezing point of water at 32/0 degrees and the boiling point at 212/100 degrees, respectively. The Fahrenheit scale is most commonly used in the US and Celsius in the rest of the world. Air temperature is usually measured with a maximum-minimum glass liquid thermometer mounted in a ventilated wooden box, or with an electronic sensor.

It is important that thermometers are protected from sunlight to avoid a falsely high reading of temperature. Instrument shelters are designed to remedy this problem. For more information on instrument shelters, see the Weather Station Handbook: An Interagency Guide for Wilderness Managers.

evaporation- Evaporation is the physical process by which a liquid changes to a gaseous state. Evaporation is affected by solar radiation, air temperature, vapor pressure, wind, and possibly atmospheric pressure. Evaporation varies with latitude, elevation, season, time of day, and sky conditions. Accurate evaporative readings require careful maintenance of a water evaporative pan. The water depth is measured daily and adjusted to any precipitation that may occur.

precipitation -Precipitation refers to all forms of water, liquid or solid, falling from the atmosphere and reaching the ground. Precipitation includes, but is not limited to, rain, drizzle, snow, hail, hail, sleet, and ice crystals. It is one of the most basic pieces of data collected by any weather station. Dew, frost and frost are excluded as they are the result of water vapor in the air condensing or freezing on a surface.

The standard US rain gauge has a mouth eight inches in diameter and about 30 inches in height. Non-logging gauges simply collect precipitation; the amount of precipitation must be measured by an observer. Recording gauges have instruments that record the time, duration, and intensity of precipitation. Most logging gauges store information on a piece of paper, which is usually changed weekly by an observer. Rainfall intensity and duration, useful information for many NRCS design activities, can be derived from information collected by rain gauges.

The most important factor in the precipitation measurement error is the wind. Strong winds during precipitation events can lead to significant discrepancies between actual and measured precipitation. Measurement errors can also arise from small amounts of dew, frost and frost being accidentally included in the total measured precipitation. Even with careful placement, all meters underestimate each otherrealÂPrecipitation, especially when it snows.

Breaking News- New snowfall is the incremental amount of snow that has fallen since the last observation of snow depth. The demarcation between fresh snow and old snow is a challenge. A snowboard (usually a sheet of plywood) can provide an artificial surface on top of existing snow. Snowboards are placed on old snow when there is a chance of fresh snow falling. After each observation of fresh snow, the table is cleaned and moved to a new location. The location of the panels and the location of the measurements are the biggest source of error when determining fresh snow.

snow depth- Snow depth is the actual snow depth on the ground at the time of measurement. Snow depth is usually measured daily and is determined to the nearest whole inch using a calibrated rod such as that used with the 8-inch non-registering rain gauge or a ruler or ruler. Snow should be measured at multiple locations and averaged to avoid errors caused by snowpack.

snow water equivalent- The water equivalent of snow is the water depth that would be obtained by melting the snow cover. The water equivalent of snow is continuously measured (weighed) by register gauges winterized with an antifreeze solution. For non-recording rain gauges, the snow collected by the standard rain gauge (without the funnel and tubes) is melted by adding a known amount of warm water. The total amount is then measured and the amount of warm water added is subtracted to obtain the observed water equivalent. Most snow water equivalent measurement errors are due to not selecting a representative site or to subtracting added water from the total catch.

soil temperature- Soil temperature measures the warmth or coldness of the soil. Soil temperature is very important for agriculture. Most seeds require a certain soil temperature to germinate. Ground temperatures are commonly measured at 2, 4, 8, 20, 40, 60, and 120 inches, with the 4 inch reading being the most commonly observed. Readings are generally observed and recorded daily. The maximum, minimum and current temperatures are generally recorded over 8 inches. At greater depths, where the temperature changes more slowly, only the current temperature is usually recorded. Different plant species have specific ranges of soil temperatures in which they will grow.

solar radiation, incoming- Incident solar radiation is the total electromagnetic radiation that the sun emits when it hits the earth. Much of the sun's radiation is absorbed by air molecules, reflected back into space, or refracted as it passes through the atmosphere. A pyrheliometer measures the direct solar radiation that penetrates the atmosphere unhindered. It consists of a closed radiation sensor element with a small opening through which direct sunlight enters. A pyranometer measures the combined incident direct solar radiation and diffuse radiation from the sky. It is mounted to see the whole sky. Both instruments can be connected to electronic recorders to record readings. Solar radiation sensors must be cleaned regularly and properly exposed to accurately measure solar radiation.

Wind- Wind is the movement of air relative to the earth's surface. Wind speed and direction, the two main elements, are generally measured using an anemometer and weathervane, respectively. Wind speed is usually measured in miles per hour; Direction is measured in degrees to the nearest ten (10 to 360), where 360 ​​degrees is north, 90 degrees east, 180 degrees south, and 270 degrees west. Wind measurement accuracy is mainly affected by the height of the sensor and nearby objects.