documenting the recent climate

RECENT CLIMATE

DOCUMENTING the

CLIMATOLOGICAL STATIONS

Are categorized by the World Meteorological Organization (WMO) as “principal and ordinary; precipitation stations for specific purposes. In the US, official climatological records are collected from a variety of stations, and observations are taken both paid and unpaid observers. Daily accumulated precipitation and maximum and minimum temperature are measured at almost all stations.

1. The principal climatological station network for local

climatological data (LCD) stations defines climate for about 275 major

cities and towns.

The major climate –observing networks now operated by U.S national Oceanic and Atmospheric Administration (NOAA) include the following:

2. The co-op network defines the baseline climate for the United States

using about 5200 temperature stations and 7400 precipitation stations.

The major climate –observing networks now operated by U.S national Oceanic and Atmospheric Administration (NOAA) include the following:

3. The hourly precipitation data (HPD) network about 3000 stations

establishes baseline rainfall records for hydrologic purposes.

The major climate –observing networks now operated by U.S national Oceanic and Atmospheric Administration (NOAA) include the following:

4. The historical climate network (HCN) of 1215 temperature and precipitation stations is definite

network for documenting climate variations and change.

The major climate –observing networks now operated by U.S national Oceanic and Atmospheric Administration (NOAA) include the following:

INSTRUMENTATIONS

COTTON REGION

INSTRUMENT SHELTER

Standard medium sized Cotton Region shelter for housing temperature and humidity sensors. Height of the shelter is 4 ft. (1.12 m). Height of the thermometers is approximately 5.5 ft. (1.68m)

RAIN GAUGEPLASTIC SHELTER

and

The smaller plastic shelter houses the newer thermistor-based maximum-minimum temperature system (MMTS) of the U.S. National Weather Service.

INSTRUMENTATION

The World Meteorological Organization (WMO) has established requirements for instrument shelters in which temperature and humidity sensors are housed. The National Weather service has described the shelter, and provided instructions for the exposures and installation of its instrument.

INSTRUMENTATION

In addition to the standard mercury thermometer and maximum and minimum thermometers, temperature sensors are available that use thermocouples, resistance elements, thermistors, and electric diodes and transistors.

WIND MEASUREMENT

Wind is simply air in motion relative to the surface of the earth. The standard level for wind measurements is 10m (32.8ft) above the ground over level open terrain, but many observations are taken at nonstandard levels. This creates serious problems of homogeneity, since the wind typically increase rapidly through the lowest few meters of the atmosphere.

It has its own dynamic characteristics. The choice of the measurement technique

depends on the application.

STANDARD WIND VANES

WIND INSTRUMENTS

PROPELLER ANEMOMETERS

CUP ANEMOMETERS

RADIATION MEASUREMENT

Surface measurements of radiation is far less common and more difficult than measurements of the standard meteorological parameters.Consequently, the quality of the climatological radiation data is less reliable. Instruments for measuring radiation are designed to measure the intensity of radiant energy over broad or narrow spectral band.

RADIATION MEASUREMENT

the radiation fluxes of interest maybe divided into fluxes with wavelength less than 4. 0µm (short-wave solar radiation) and fluxes whose wavelength is more than 4. 0µm (long wave terrestrial radiation). The short wave solar radiation can in turn be subdivided into ultraviolet (uv, between .2 and 0.38µm), visible (0.38 to 0.75µm), and infrared (greater than 0.75µm radiation).

RADIATION MEASUREMENT

The generic term radiometer refers to any instrument for measuring radiation, regardless of its special characteristics and its mode of operation. The WMO classification of radiation instruments identifies five basic types.

NET RADIOMETER

PYRHELIOMETERPYRANOMETER

PYRRADIOMETER PYRGEOMETER

NET PYRRADIOMETER

RADIATION INSTRUMENTS

Measures global solar radiation- that is, the short-wave radiation received on a horizontal surface from sun and sky. Use of a masking device to screen out the sun’s direct beam

allows measurement of the diffuse component of solar radiation.

PYRANOMETER

NET RADIOMETER

PYRHELIOMETERPYRANOMETER

PYRRADIOMETER PYRGEOMETER

NET PYRRADIOMETER

RADIATION INSTRUMENTS

Measures only the direct beam component of the solar radiation, i.e.,

the solar radiation received on a horizontal surface

PYRHELIOMETER

NET RADIOMETER

PYRHELIOMETERPYRANOMETER

PYRRADIOMETER PYRGEOMETER

NET PYRRADIOMETER

RADIATION INSTRUMENTS

Measures the total short-wave and long-wave radiation incident on a

horizontal plane.

PYRRADIOMETER

NET RADIOMETER

PYRHELIOMETERPYRANOMETER

PYRRADIOMETER PYRGEOMETER

NET PYRRADIOMETER

RADIATION INSTRUMENTS

Measures the long-wave atmospheric radiation on a horizontal upward-facing

black surface at ambient air temperature.

PYRGEOMETER

NET RADIOMETER

PYRHELIOMETERPYRANOMETER

PYRRADIOMETER PYRGEOMETER

NET PYRRADIOMETER

RADIATION INSTRUMENTS

Measures total (short-wave and long-wave) net radiation lux through a

horizontal plane

NET PYRRADIOMETER AND NET RADIOMETER

RADIATION MEASUREMENT

In addition to these five general terms, trade names are often attached to specific instruments. To ensure the reliability and compatibility of radiation measurements on an international and national scale, the WMO has established a system of world, regional, and national centers that provide facilities, maintain equipment, and conduct comparisons.

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