Housing for Miniature Data Loggers in the Field

Ole Humlum, The University Courses on Svalbard (UNIS), Norway.

General

Several modern miniature data loggers are constructed for harsh environments and may, for that reason, be placed directly in nature without encountering difficulties. Quite often, however, a need for physical protection (animals) or camouflage (humans) will make it necessary to provide a kind of housing for loggers. A very simple solution, which has proved itself useful in many arctic areas, is constructing a small cairn around the logger(s), as shown on the photo above.

Temperature loggers with external sensor

Temperature sensor installed inside small stone cairn, about 20 cm above the ground surface. 

Air temperature measurements usually require some kind of protection against direct solar radiation. In the case of measuring near ground surface air temperatures this protection may be provided by the logger cairn as shown in the photo above. The open structure of the cairn enables good ventilation but hinders direct radiation. In addition, turbulence created around the cairn often keep the thermistor free of snow burial during winter time. In this picture, a stone has been removed in order to show the position of of the temperature sensor inside the cairn. Top of cairn is rising about 20 cm over the general snow surface.

Precipitation loggers

Precipitation gauge (110 mm diameter; lower part of picture) installed flush with ground surface.

By tradition, standard precipitation gauges are positioned 2 m above the terrain surface. In cold-climate regions this often only applies during the summer, as the effective terrain surface moves up and down during the winter, in concert with the snow cover growth. In addition, in many geomorphic and botanical contexts, the precipitation at the terrain surface is of higher interest, relative to precipitation measured 2 m level above. 

Due to their small size, the Gemini precipitation loggers are ideal for measuring precipitation at the terrain surface. Often, the gauge may be installed flush with the ground surface (see picture above, gauge visible in lower part of picture), while the connecting 2 m cable allows for logger location in protective cairn at some convenient place nearby, without interfering with airflow around the precipitation gauge itself.

A drawback of installation at the ground surface is the risk of getting the rain gauge blocked by debris or fragments of vegetation, especially if operated in a windy environment. Therefore the rain gauge should be inspected and cleaned whenever possible.

Latest update: 11. November 2002.