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The NIWA peeps are well curious about the nigh-on unprecedented amount of frozen precipitation (read: snow) falling all over NZ.

snow!  greta point, looking towards the harbour(ish)

snow! greta point, looking towards the harbour(ish)

In Wellington, and as we speak: it’s snowing _in_ the CBD and also at sea level (Greta Point, for example).  This is pretty darned unusual*.  And the scientists are keen to get some data, from all of you, all over New Zealand!  Herewith the blurb:

How much snow is there at your place?

In real life I’m a hydrologist, and we don’t often get good data in New Zealand on snowfalls at low elevations. So I thought I’d try the internet!

If you want to, I’d be really interested to know how deep the snow is (and when you measured it), and which suburb/area you live in (& perhaps a post code?). I got a really helpful response in July 2011 – thanks everyone :)

Here’s one of my observations:

9.5 cm (average of 10 readings)
1030am on 25 July 2011
Burnside 8053

For me, the most interesting thing is the _average_ snow depth, rather than the deepest snow drift.

There is lots of detailed guidance on how to do scientific snow measurements, but here’s the simple story:

Be careful! Snow and ice surfaces are very slippery. Your safety is more important than data collection.

Put a ruler vertically into the snow down to the ground level, and read off how deep the snow is. Do it ten times, and take the average (or the median, if you have a lot of variability and enough time to sort your data).

Try to choose places that are typical. Not in the middle of snow drifts or valleys. Not right next to a building or fence.

If there are several days of snow, try to take measurements every day, during fine spells when it has stopped snowing.

If you are feeling ambitious, you might want to measure snow water equivalent too:

Measure the depth of snow at the place where you are going to sample the snow water equivalent

Find an old saucepan (or similar cylinder) with straight sides, and measure its (inside) diameter

Press the upsidedown saucepan vertically down into the snow until you reach the ground (snow may need to be compressed into the pan – that’s ok)

Pick up the saucepan and most of the snow should come with it. Pick up any snow that falls out and put it in the pan.

Melt all the snow in the pan, and measure the volume of water (e.g. with measuring jug).

Report back these pieces of information: Depth of snow (mm), diameter of pan (mm), volume of melted water (millilitres), Date, Time, Location

If you’re interested, the snow density in % units is the volume of water divided by the original volume of snow (typically in the range 10%-40%)

e.g. Depth of snow =180 mm, Diameter of pan =200mm, volume of melted water = 1620 mL. Snow volume is 5655 mL (=.001*180*Ï€*(200/2)^2). Density = 100*1620/5655 = 29%

For more help or detailed information, see http://www.erh.noaa.gov/gyx/measuring_snow.htm

PS: be very careful outside – only go where you feel safe.

There’s also a facebook group, available here.

So, go out!  Measure things!  Be a _part_ of science!  Post your measurements on the FB group or here as comments :)

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Related posts:

Waiology: Crowd-sourcing for snow depth data

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* Climate change, anyone?