• Technical Help
  • GIS Climate Search Site
  • A Note about Cookies
• Utah Climate Center Data Types
  • COOP Data
  • GSOD Data
  • AWOS Data
  • Calculations
  • Current Weather Conditions
  • Change Location
• GOES Satellites
• Calculation of Normals

A Geographic Information System (GIS) search engine for data retrieval (http://climate.usurf.usu.edu/products/data.php) is provided to facilitate the access of climate data. The governing philosophy of the UCC is to provide all levels of climate data starting with basic observations coupled with flexibility for data output. Presently, the GIS search engine can access three climate datasets / data types: those of the Cooperative Observer Program (COOP), the Global Summary of Day (GSOD),and the Automated Weather Observing System (AWOS). The COOP and GSOD datasets are static in the sense that staff at the UCC download the data at regular intervals when made available by government institutions, e.g., the National Climatic Data Center (NCDC). The third dataset (AWOS) is dynamic; i.e., data is automatically ingested into the database in near real-time from the UNIDATA Internet Data Distribution system.

USU's climate database was designed from the ground up to support the instantaneous dissemination of COOP, GSOD and AWOS climate data. Specialized schemas were designed to support each data type, and implemented compression algorithms, using relations, significantly reduce the data cluster size and also increase the speed at which data is accessed. Running on a PostgreSQL engine allowed us to implement clustering with various indices that helps provide a query return time of less than 3 seconds for 95% of queries expected by visitors to the system. This is a significant improvement over the past system design and gives users instant access to climate data from the mid 1800's to just a few hours ago with only a few mouse clicks.

The Utah Climate Center GIS Climate Search site uses cookies to store user session information. A cookie is a small text file saved on your hard drive that is used to remember information during the session and the next time you visit the site. The cookie does not contain any information that can be used to personally identify the user. It simply contains a session number that points to a table in a database that stores all queries being made. If the cookie is deleted (or expires), the user can no longer retrieve information from the session (e.g., the list of data requests made). The cookie is also used to remember session information such as map positions, selected stations, and time periods. For this reason, it is recommended that cookies are enabled when using this site. Cookies from this site are set to automatically expire after a week.

Cooperative Observer Program. This data set has been used in countless climatological studies, legal litigation, insurance claims, and other various research applications. The data contains various parameters consisting of the previous day’s maximum and minimum temperatures, snowfall, and 24-hour precipitation totals that are initially obtained from state universities, state cooperatives, and the National Weather Service (NWS). Currently, there are approximately 8,000 active stations with cooperative observers, known as cooperative observing stations, but data are in these files for approximately 23,000 stations for various years. Selected Summary of the Day data from related file DSI-3210 for National Weather Service "first order" or principal climatological stations and "second order" stations have also been included in this file. The COOP database is updated monthly.

The record period and number of stations varies among the states. Most states began collecting data during 1948, but some began as early as 1946. Prior to 1948, most of these data were collected through cooperative agreements with state universities and other state organizations. Many years of records were digitized with some going as far back as the 1850s. It must be noted that NCDC has the observations from the time the station opened, but the NWS has the current data. Official surface weather observation standards can be found in the Federal Meteorological Handbook.

Global Summary of Day. This database contains summarized data which have been extracted from surface synoptic weather observations, exchanged on the Global Telecommunications Systems (GTS). The National Meteorological Center (NMC) of NOAA maintains an archive file of the complete surface synoptic reports which are received from the GTS. The Climate Analysis Center (CAC) extracts portions of these NMC archive files, performs an automated decode of extreme temperatures and accumulated precipitation according to WMO code manuals, and performs limited automated validation of the parameters. The data for all reporting stations are summarized on a daily basis to satisfy current operational requirements related to the assessment of crop and energy production. The GSOD database is updated monthly.

Automated Weather Observing System. The AWOS is a suite of approximately 600 U.S. stations, which measure, collect, and broadcast weather data to help meteorologists, pilots, and flight dispatchers prepare and monitor weather forecasts and plan flight routes. The AWOS data set records hourly data from this suite of stations and contains data for wind speed, direction, temperature, rain, and other climatological phenomenon. It should be noted that not all stations report information every hour and there may be time periods for some stations without data. NOTE: All times reported in the AWOS data set is ZULU (GMT). There are no offsets for local time zones.

The evapotranspiration computed is the so-called reference crop evapotranspiration or reference evapotranspiration, denoted as ET _o. The reference surface is a hypothetical grass reference crop. The reference surface closely resembles an extensive surface of well-watered green grass of uniform height that is actively growing and completely shading the ground.

Temperature data are widely available at COOP stations; hence, several reference evapotranspiration equations are available in which temperature is the only required input variable. Of the temperature-based equations for computing ET_o, the Hargreaves ET _o equation is calculated here for the COOP dataset. The equation has the form:

ET_o = 0.0023 (T_mean + 17.8) (T_max - T_min)^0.5 R_a

Where,

ET_o – is the reference evapotranspiration in millimeters per day. T_mean – is the monthly mean temperature (T_max + T_min) / 2 in degrees Celsius. T_min – is the daily minimum temperature in degrees Celsius. T_max - is the daily maximum temperature in degrees Celsius. R_a – is the extraterrestrial radiation in millimeters per day.

As a note of caution, the Hargreaves equation has a tendency to under-predict under high wind conditions (greater than 6 – 7 miles per hour) and to over-predict under conditions of high relative humidity.

Further explanatory details are in the Utah Climate book. An updated version will soon be available through the Utah Climate Center.

On the sidebar of the Utah Climate Center home page are current weather climate data and information. These data are automatically calculated and display current climate information including temperature, “feels like” temperature, wind speed and direction, barometric pressure, visibility, dewpoint temperature, relative humidity, and daily precipitation. Below current weather conditions, other useful information is also displayed such as the current phase of the moon and exposure time before frostbite and/or heat stroke warning levels.

Below current weather conditions, other useful information is also displayed, such as:

• Record High and Low Temperatures
• Record Precipitation
• Normal (average) High and Low Temperatures
• Normal (average) Precipitation
• Current Phase of the Moon
• Warning levels of exposure time before frostbite and/or heat stroke.

NOTE: “Precip. Today” is a measure of the amount of precipitation (rain, melted snow, sleet, etc.) that has been recorded since 12:00 a.m. local time.

By clicking Change Location, two methods of changing the location are presented."Station Map" displays a google map interface which can be used to select a station within the desired location. "Enter Station ID" gives the option of entering a station's ID. The station ID must be known in order to use this method. It is recommended that first time users use the google map interface. Note that the station id can be found here by simply hovering the cursor over a station. Make note of this ID for future reference. If the station ID has known or has been obtained from the google map interface. The location can be changed by entering the station ID.

A Geostationary Operational Environmental Satellite, or GOES Satellite, is a satellite which is placed on a geosynchronous orbit around the Earth's equator. This means that the satellite is orbiting the Earth at a rate equal to the rate of the Earth's rotation. Therefore, the satellite remains at the same position over the Earth at all times. There are two GOES Satellites used on this site: one positioned over the western US, and another positioned over the eastern US.

GOES Satellites have several channels, each of which are used to measure different aspects of the atmosphere. The channels used here are visible, infrared (IR), and water vapor.

The visible channel measures the intensity of solar radiation which has been reflected by terrestrial objects such as clouds, the ground, etc. The higher the intensity of a reflected solar radiation the whiter the image will appear on the map. Thick clouds have a higher reflectivity than thin clouds and will show up better on a visible image. Snowpack on the surface also has a high reflectivity and will thus make it difficult to differentiate between clouds and snow on the map. Because the visible image is based on reflected solar radiation it is only useful during daylight hours.

The infrared (IR) channel measures the intensity of radiation emitted by terrestrial objects at a wavelength of about 10-11 micrometers. Radiation emitted at these wavelengths is known as "window IR" and is less likely to be absorbed by other atmospheric gases before reaching the satellite. Using blackbody radiation laws, the intensity of the radiation is translated into a temperature value. Higher temperature values are shown as darker colors on the map while colder temperatures are shown as whiter colors. The IR imagery can be used to determine cloud-top temperature and consequently can give a general idea of the cloud-top height. A lighter-colored cold temperature value on an IR image indicates a high cloud-top height. A darker-colored warm temperature value, on the other hand, indicates a low cloud-top height. The IR channel can only measure the radiation emitted from the top of the clouds or other terrestrial objects. Therefore, the thickness of a cloud layer on the IR imagery cannot be determined.

The water vapor channel is also an IR image; however, it is sensitive to emitted radiation at a wavelength of about 6-7 micrometers. Water vapor in the atmosphere effectively absorbs radiation at these wavelengths. This absorption decreases the intensity of radiation that reaches the satellite and therefore reduces the temperature value sensed by the satellite. It can then be inferred that a higher temperature value on a water vapor image indicates a dry area and a lower temperature value indicates a moist area. On a water vapor image higher temperature values are indicated by darker colors and colder temperature values by whiter colors. The water vapor image gives a good look at the movement of air and inferred moisture content in the upper and mid-level portions of our atmosphere, including areas where clouds are not present. Low-level moisture content cannot be inferred from the water vapor channel because the radiation emitted at those levels is greatly or entirely absorbed by the time it reaches the satellite.

The calculations for normal values found in the Period Of Record (POR) reports are based on data from 1971-2000. Because many weather stations have an incomplete set of data throughout this period it was necessary to adopt a method whereby the normal calculation would give the best representation of how much data was available from the 30-year normal period for a particular station. The letters "A" through "G" and "M" are attached to each normal value according to how much data was available for the calculation of the normal.

The WMO establishes that normal values should be arithmetic means calculated for each month of the year from the daily data. To qualify, temperature data, soil temperatures and evapotranspiration must fit the following rule: "if more than 3 consecutive daily values are missing or more than 5 daily values in total in a given month are missing, the monthly mean should not be computed and the year-month mean should be considered missing." This is referred to as the "3/5" rule. For total precipitation, degree-days and "days with" calculations no missing days are allowed.

Once the year-month values that qualify are determined, a similar "3/5" rule is also applied to each month of the year over the 30-year normal period. This is done to determine if the normal value for a given month can be designated with a normal code of "A". For instance, to meet the WMO standard, a value of a monthly element, such as normal mean temperature for May, with a normal code of "A" can have no more than 3 consecutive, or 5 in total, midding mean temperature values for any of the months of May in between 1971 and 2000.

If a month does not meet the "3/5" rule standard it is not given a normal code of "A". Rather, it is given a normal code of "B" through "G" or "M" based simply on the number of valid year-month values found for each month over the 30-year normal period. The following chart illustrates the standards for the assignment of normal codes:

Considering the 1971-2000 normal period, if, for example, the month of January were missing for the years of 1981, 1985, 1988, 1989, and 1993, the normal code of "A" would be assigned because no more than 3 consecutive and 5 total years are missing. However, if the month of January were missing for the years of 1981, 1985, 1986, 1987, and 1988, the normal code of "B" would be assigned because more than 3 consecutive years are missing but no more than 5 years are missing (i.e. there are still 25 valid years available for calculation of the normal.)

The annual normal values are calculated based on the final normal values given for each month. The normal code assigned to the annual value is equal to the monthly normal code representing the least degree of completeness. For example, if the months of January-November all had a normal code of "C" but December had a normal code of "D" then the annual normal value would be given a normal code of "D".