Sobre este tema hay mucha información en la red, los aeropuertos no son un buen sitio para instalar una estación meteorológica por todo lo expresado antes, la mayoría de dichas estaciones no cumplen las normas de la NOAA para su adecuada ubicación debido principalmente a que su función es la de servir al aeropuerto y a las necesidades de la navegación aérea FAA, esa función si la cumplen pero no están pensadas para formar parte de la red mundial que mide la temperatura del mundo
¿Normas de la NOAA?, ¿y a mí qué las normas de la NOAA?. Las normas que hay que cumplir son las de la OMM, y las estaciones de los aeropuertos generalmente cumplen las especificaciones de la OMM sobradamente. Y en ocasiones mucho mejor que otras supuestamente mejor situadas. Además, lo que dices de que su función es servir al aeropuerto y a la navegación aérea, por lo menos en España, no es exacto. Me explico: una cosa son los sensores que se utilizan para la información aeronáutica; para hacer los METAR y tal, y otros diferentes, con otras especificaciones, los que se utilizan para la meteorología sinóptica y la climatología. Los sensores aeronáuticos tienen que estar situados en cabeceras, y los otros en su jardín meteorológico, eso para empezar.
Normas NWS NOAA
Proper Siting
The COOP network has provided climate and weather data for over 100 years. Consistency of the measurements is an attribute of the network, and it has been maintained by rare and/or gradual change, and established standards for exposure, of instruments over the life of the network.
In order to preserve the integrity of the network, NWS has established standards for equipment, siting, and exposure.
Temperature sensor siting: The sensor should be mounted 5 feet +/- 1 foot above the ground. The ground over which the shelter [radiation] is located should be typical of the surrounding area. A level, open clearing is desirable so the thermometers are freely ventilated by air flow. Do not install the sensor on a steep slope or in a sheltered hollow unless it is typical of the area or unless data from that type of site are desired. When possible, the shelter should be no closer than four times the height of any obstruction (tree, fence, building, etc.). The sensor should be at least 100 feet from any paved or concrete surface.
Precipitation gauge siting: The exposure of a rain gauge is very important for obtaining accurate measurements. Gauges should not be located close to isolated obstructions such as trees and buildings, which may deflect precipitation due to erratic turbulence. To avoid wind and resulting turbulence problems, do not locate gauges in wide-open spaces or on elevated sites, such as the tops of buildings. The best site for a gauge is one in which it is protected in all directions, such as in an opening in a grove of trees. The height of the protection should not exceed twice its distance from the gauge. As a general rule, the windier the gauge location is, the greater the precipitation error will be.
http://www.nws.noaa.gov/om/coop/standard.htmSobre el tema del lamentable estado de las estaciones meteorologicas y de la mala ubicación de las mismas..
"Then there was the “upgrade” to automated surface observing systems at airports. ASOS27
was designed mainly for aviation purposes. It has an error tolerance of +/-0.9F for air temperature.
Temperature Sensor’s Range, Accuracy, and Resolution
During recent decades there has been a migration away from old instruments read by trained observers. These instruments were in shelters that were properly located over grassy surfaces and away from obstacles to ventilation and heat sources.
Today we have many more automated sensors located on poles cabled to the forecast stations or airports where they can be monitored or transmitted.
27 http://www.nws.noaa.gov/asos/aum-toc.pdf.
During recent decades there has been
a migration away from old instruments read by trained observers.
28
The installers of these instruments were often equipped with nothing more than a shovel. They were on a tight schedule and with little budget. They often encountered paved driveways or roads between the old sites and the buildings. They were in many cases forced to settle for installing the instruments close to the buildings, violating the government specifications in this or other ways.
Pielke and Davey (2005) found a majority of stations, including climate stations in eastern Colorado, did not meet WMO requirements for proper siting.
They extensively documented poor siting and land-use change issues in numerous peer-reviewed papers, many summarized in the landmark paper Unresolved issues with the assessment of multi-decadal global land surface temperature trends28
(2007).
In a volunteer survey project, Anthony Watts and his more than 650 volunteers www.surfacestations.org found that over 900 of the first 1067 stations surveyed in the 1221 station US climate network did not come close to meeting the specifications. Only about 3% met the ideal specification for siting. They found stations located next to the exhaust fans of air conditioning units, surrounded by asphalt parking lots and roads, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat. They found 68 stations located at wastewater treatment plants, where the process of waste digestion causes temperatures to be higher than in surrounding areas. In fact, they found that 90 percent of the stations fail to meet the National Weather Service’s own siting requirements that stations must be 30 meters (about 100 feet) or more away from an artificial heating or reflecting source.
The average warm bias for inappropriately-sited stations exceeded 1 C° using the National Weather Service’s own criteria, with which the vast majority of stations did not comply." extraido de aqui
Hay 111 páginas sobre el tema.http://scienceandpublicpolicy.org/images/stories/papers/originals/surface_temp.pdfmas:
"This paper documents various unresolved issues in using surface temperature trends
as a metric for assessing global and regional climate change. A series of examples ranging
from errors caused by temperature measurements at a monitoring station to the
undocumented biases in the regionally and globally averaged time series are provided. The
issues are poorly understood or documented and relate to micrometeorological impacts
due to warm bias in nighttime minimum temperatures, poor siting of the instrumentation,
effect of winds as well as surface atmospheric water vapor content on temperature trends,
the quantification of uncertainties in the homogenization of surface temperature data, and
the influence of land use/land cover (LULC) change on surface temperature trends.
Because of the issues presented in this paper related to the analysis of multidecadal surface
temperature we recommend that greater, more complete documentation and quantification
of these issues be required for all observation stations that are intended to be used in such
assessments. This is necessary for confidence in the actual observations of surface
temperature variability and long-term trends."
Citation: Pielke, R. A., Sr., et al. (2007), Unresolved iss
http://pielkeclimatesci.files.wordpress.com/2009/10/r-321.pdf
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