© by PSP Volume 16 – No 8. 2007 Fresenius Environmental Bulletin THE DESIGN, INSTALLATION AND OPERATION OF A FULLY COMPUTERIZED, AUTOMATIC WEATHER STATION FOR HIGH QUALITY METEOROLOGICAL MEASUREMENTS Haralambos S. Bagiorgas1*, Margarita N. Assimakopoulos2, Argiro Patentalaki1, Nikolaos Konofaos3, Demetrios P. Matthopoulos1 and Giouli Mihalakakou1 1 University of Ioannina, Department of Environmental and Natural Resources Management, 2 G. Sepheri Str., 30100 Agrinio, Greece. 2 University of Athens, Department of Physics, Division of Applied Physics, Laboratory of Meteorology, University Campus, Build. Phys V, 15784 Athens, Greece. 3 University of Patras, Computer Engineering and Informatics Department, 26500 Rio Patras, Greece. SUMMARY The design, installation and operation of an Automatic cause the data obtained from the device should be both ac- Weather Station (AWS) are described and analysed in the curate and compatible with the World Meteorological Or- present paper. This station of high endurance is easy to be ganization (WMO) standards. Moreover, the station’s main- installed and capable for long-time operation without sig- tenance is a hard process, time consuming and of high cost. nificant problems. The metadata of the station which are the characteristics of the instruments, electronic logic con- In general, AWS contains sensor-based equipment. Its trol and datalogging systems are described in detail, ac- sensors contain a conventional cup anemometer, wind vane, cording to the Guides of the World Meteorological Or- miniature temperature screen with wet and dry bulb plati- ganization (WMO). Moreover, a computer controlled envi- num resistance thermometers, solarimeter, net radiometer ronment is designed and implemented, with capabilities of and tipping bucket raingauge. Many researchers have dealt data acquisition and control with flexible and high perform- with this matter and a great improvement has been achieved ing software and hardware capabilities. The AWS can easily in accomplishing the technical characteristics of the mete- communicate, so directly as remotely, with some modifi- orological instruments [1-10] as well as in the communica- cations and both possibilities are examined in detail. Fi- tion part of the AWS and the data acquisition and process- nally, an evaluation procedure is presented and analyzed, ing [11-13]. Βesides, so far, significant new developments while the obtained results are used for testing the system. and operational experiences together with new observation The evaluation depicted the unique and well established technology have been presented. Today, as AWS are com- characteristics of the system and proved its potential ap- pletely automated, AWS may record weather conditions al- plication to meteorological data collection and calcula- most everywhere on the globe, even under extremely hard tion. conditions [14-16], hence, AWS networks of completely automated weather stations have been adopted [17-20]. There are many advantages of using AWS’s systems KEYWORDS: Automatic weather station, real-time communication data link, con- instead of customary stations, but the main are: monitoring trol software, direct communication, remote station. of data in sparse areas where human observations are not practical, continuously flux of data at frequent intervals and for any observation time, increase of coverage, elimination of the subjectivity in observations, cost reduction [10] etc. Of course, there are many difficulties in AWS’s operation, INTRODUCTION as the disagreement between the professional meteorologi- cal observer and the automated observations [21-23], espe- Real-time meteorological and environmental obser- cially in the type and the intensity of precipitation [24,25], vations can be provided by Automatic Weather Stations the inabilities in guaranteeing the renewal of the spare parts, (AWS), gathering data from a network through various a wear of the material, the lack of flexibility, an aging sys- communication channels. The design, installation and op- tem of transmission of the data, etc. [10] but these prob- eration of well-functional AWS is a challenging task be- lems decrease day by day. 948 © by PSP Volume 16 – No 8. 2007 Fresenius Environmental Bulletin Our AWS has been established in Western Greece, in The present paper has as main objective to emerge in- the center of the prefecture of Aitoloakarnania, in the city formation and guidance on the design, installation and op- of Agrinio, an urban area of about 100,000 habitants, which eration of an, easy to install and maintain, fully computer- is characterized by a rather complicated topography. In ized, automatic weather station for high quality meteoro- Western Greece the climate has the basic features of Greek logical measurements in an urban area. It also demonstrates climate (a typical Mediterranean climate): mild and rainy the “flexibility” and propriety of this station both for near, as winters, relatively warm and dry summers and, generally, well as for remote applications, with some appropriate modi- extended periods of sunshine throughout most of the year fications each time. Moreover, this paper presents a pro- [26]. Moreover, due to the influence of topography (great cedure for the validation of the station, so in case of direct mountain chains along the central part and other mountain- communication as in case of the remote station too, which ous bodies) on the air masses coming from the moisture had been achieved by comparison of the AWS’s data with sources of the central Mediterranean Sea, Western Greece these of a thermograph, barograph and other conventional has a more wet climate comparatively to the dry climate of recording devices of the Greek Meteorological Agency’s Attiki (Athens’ greater area) and East Greece in general, in- (EMY) station in Agrinio. This comparison verified both cluding sometimes some harsh phenomena (storms, floods, accuracy and reliability of the AWS. Finally, the present etc.) [27]. Despite of the particular climatological charac- paper depicts the general difficulties that erase in the estab- teristics of Agrinio area (such as Western Greece), there was lishment of an urban meteorological station, concerning the sparse meteorological data coverage, which led to the im- selection of the station’s position and the settlement of the perative need for an AWS that could monitor continuously sensors, for the station to be well representative for urban - and on regularly selected time steps - basic meteorologi- sites and in accordance to the WMO guidelines at the same cal parameters in order to provide a weather identification time. and determination as similar to a human observer as pos- sible, ultimately replacing the observer. AWS FOR DIRECT COMMUNICATION The descriptions in this paper AWS should be used for energy, environmental, agricultural and meteorological ap- Description of the equipment, plications, such as the estimation of the wind and solar communications link and power supply energy potential of the area, the investigation of urban heat Equipment: In planning a new AWS, the selection of island effect (in Agrinio region, which is recently highly equipment depends on the nature of the regular data that developed and urbanized), the calculation of the area’s are to be measured and on the site location. Consideration potential in ground cooling applications, etc. should also be given to whether the versatility of the sys- The wind energy potential in Western Greece was tem might be enhanced by future addition of further sen- evaluated from measurements of wind speed and direction sors. The range of sensors offered and similar equipment at four weather stations. Weibull parameters estimated by is wide and the selection of a well established set guaran- three different methods were used to estimate wind power tees trouble-free performance in the future. potential in this area [28]. Additionally, analysis of the “unit energy cost”, being the specific cost per kilowatt-hour ob- The various instruments making up the station involve tained for several wind turbines, at different hub heights, a datalogger, a temperature and humidity probe, a wind- has been carried out for every station [29]. sonic 2D anemometer, a tipping bucket raingauge, a baro- metric pressure sensor, a pyranometer, a soil temperature An aluminium nocturnal radiator, painted with appro- probe, a soil moisture probe, a pyrgeometer and a sunshine priate white paint, was established on the roof of the De- duration meter. Table 1 summarizes the instruments and partment of Environmental and Natural Resources Man- their specifications and characteristics, while technical de- agement in Agrinio, in Western Greece [30]. A both sim- tails, specifications, operation ranges and other special in- ple and accurate model for the prediction of the radiator formation for the instruments can be found in data sheets heat exchange performance was presented. The model, using available1 [31]. as input data some meteorological parameters from our AWS measurements, calculated with appropriate algorithms Communications Link: AWSs report observations by a the outlet temperature of the radiator. variety of formats, including telephone lines, radio mo- dems, mobile phone networks and satellite networks. The The station ought to serve in educational purposes as communications between the AWS and the data collection well, without compromising the systems integrity. More- agency should be: reliable, inexpensive (satellite telephone over,