Surface Automatic Meteorological Observations: Portuguese Experience and Future Perspectives

The early experience of the Portuguese Meteorological Institute (IM) regarding Surface Automatic Meteorological Stations (SAMS) refers about a couple of stations installed in the late 70's. Due to the coastal conditions of the Atlantic capes where these stations were installed there was large maintenance difficulties, which caused a high rate of failures. As a result and also because of the high costs of electronics, power supply and housing, the project was abandoned.

In the early 90's a new and more ambitious project started to build up for the progressive implementation of a national network of SAMS. These stations should lead to improve the observing frequency and data quality, comparing to classical systems, and serve both climate and synoptic purposes. Other key objective was to overcome the personnel difficulties, either at climatological stations by gradually replacing part of those stations with SAMS (type II) and also at some synoptic stations by improving time coverage during certain periods of the day (i.e. nighttime) by installing type I SAMS. So, these two sub-networks, should allow for a time resolution of data archive of the order of 10 minutes, and that hourly data should be available in real-time and should include weather parameters like visibility and clouds. The solution for this was the inclusion of a computer terminal at type I stations to allow the Observers to introduce the results of visual observations and validate SAMS data. The system should also allow for the automatic transmission of alarm messages at pre-defined thresholds.

Those simple definitions became into very complex tasks when setting-up such a network-system. During the first years of the network operation there was large communication problems and software failures and in addition IM faced with other big needs, such as the development of new procedures for data processing at central level and the need to arrange local people to make regular maintenance of the stations and give them adequate training. Main conclusions are presented.

With these experiences in mind and considering the latest needs IM is developing a study, in order to prepare the next project, focusing on network re-design, on new kinds of sensors, on adjustments to processing algorithms and on improvements to the communications and power supply systems. Preliminary results are showed.

The seek of a more complete and better surface network and the need to supply the more demanding users, leads us to consider some different approaches when improving the network. This means that we can improve an existing network by creating new sub-networks or changing existing ones, once the technical aspects like sitting, infrastructures, sensors and data processing, and also communications and maintenance, are carefully arranged to comply with specific purposes, for example, coastal stations must have an adequate spatial distribution and the sensors and infrastructures must be specially prepared for a harsh environment.