Saturday, 6 June 2015

Temperatures are sooo much warmer near the ground!

Last year I set up temperature sensors, 1m above ground, 5cm above ground and just below the ground surface at one site near camp at Lake Hazen and logged the hourly temperature for the whole summer. The results are really quite interesting.
Temperature sensor set up 1m and 5cm above ground and
at ground level at Lake Hazen in 2014
Firstly even though there is 24 hour sun and the sun is approximately the same height above the horizon over the 24 hour period, the temperatures do go through a daily cycle; warmer during the "day" and colder at "night". It surprised me at first but then I realised that during the "night" the sun's rays have a lot further to reach the ground at "night" because the sun is on the other side of the world.

Temperatures at Lake Hazen in 2014 were much warmer
close to the ground and during the "day"
even though there is 24 hours of daylight.
Secondly the temperature near the ground, where the plants grow,  is much warmer than the temperature measured at 1m above the ground, where weather station temperatures are measured. This is part of the reason why Arctic plants never grow very tall, it is just sooo much warmer near the ground! Many of the plants create their only little micro-environment by forming a hemi-spherical cushion to maximise the heat and nutrients the plant receives.

The cushion forming tufted saxifrage (Saxifraga cespitosa)
makes its own microenvironment

I had temperature sensors set up at both Iqaluit and Lake Hazen last year and one thing I have found through my analysis is that during the middle of the growing season, July, the average temperature at 5cm above ground at Lake Hazen is pretty much the same as at Iqaluit even though the two locations are over 18° of latitude apart. However, the temperatures at Iqaluit tend to get much warmer during the day and dip lower at night than at Lake Hazen.

Comparison of 2014 temperatures 5cm above ground at
Lake Hazen sites (dotted lines) and Iqaluit sites (solid lines).
The average temperatures are the similar at Lake Hazen and Iqaluit
but Iqaluit temperatures very more during over a 24 hour period  

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