Monitoring mountain precipitation – difficulties in practice

Power availability is the big challenge at 900 m elevation.  The Wildland mountain observatory on Druim nam Bo benefits from a 60 W solar panel and a wind turbine generator, with 220 Ah of battery capacity.

Ben Pickering’s disdrometer, pictured here in the foreground, needs 1 A of current, so sometimes there isn’t enough to go around.  A low voltage disconnect (LVD) stops the power to the disdrometer when reserves get too low – leading to this icing-up spectacle on 19th November – while the weather station continues unabated.  Since then, conditions have improved, so hopefully laser radiation is once again analyzing the precipitation – solid and liquid – as it falls.

Big thaw at the weekend

After 10 days of continually freezing conditions at the Wildland mountain observatory on Druim nam Bo, warm air on Saturday brought a thaw to high altitudes – and significant melt.  Some 41.2 mm of snowmelt was recorded through the rain gauge.  The ground had been frozen and gradually climbed above zero – escaping from freezing some 16 hours after the air temperature.

Water level in the adjacent pond rose some 5 cm, soil moisture content rose from 2% to 18% – though the initially low value may be a reflection of freezing conditions.  The rise in pond level began 2 hours after thaw began to be recorded by the rain gauge.