[airplane]
Sproles: We’re in the prairie central heartland of Montana of the
headwaters of the Missouri River, and we’re at the Central Agricultural Research
Center, which is Montana State University’s working agricultural research lab
here in the center part of the state. Part of NASA’s SnowEx is
to better understand what and what we cannot measure from the air
or from space to try to advance satellite remote sensing
of snow. Polamacki: Out here as you can see looking around
the snow that we’re studying out here is
hugely spatially variable. Sproles: You can have anywhere from, you know, as you can see
behind me, a lot of snow to no snow over very short distances.
And so how we can better quantify that from space is important.
Polamacki: Some really interesting questions that I think we’re getting at up here that we
wouldn’t be able to up in the mountains where we are normally working.
Feduschak: Today I have dug a few snow pits, taken some
measurements, been wrestling with technology as
always seems to be the case. Sproles: We’re using a range of techniques. We’re going
from old school techniques, like digging snow pits, where
we can really get detailed measurements of the snow and the snow properties
as we go with depth.
[natural sound] Sproles: We’re doing simple transects where we’re
measuring snow depth going across the whole landscape here
and then we’re using some pretty sophisticated techniques as well.
We’re using UAV’s, uncrewed aerial vehicles, or drones.
Polamacki: When I flying the drone earlier today, I was basically just
taking many, many photos of the ground from up high
to get really high resolution measurements with our
camera of the patchiness of the snow. We can throw
all of those photos together in a piece of photogrammetry
software, stitch them together into a three-dimensional model. We can
basically select any point in this giant field and
determine what the snow depth was. It’s a way
for us to cover a lot of ground pretty quickly.
Mullen: Today I’m collecting albedo measurements from a UAV.
Albedo is essentially how reflective
the surface is. It tells us both
how much energy coming from the Sun the surface is reflecting, but more
importantly with regards to snow, it tells us how much energy that
snow is absorbing, which allows us to kind of determine
how fast it’s going to melt and allows us to better predict
runoff quantities for water resource modeling.
Rizza: We’re looking to use the lidar data to map the snow surfaces.
and ultimately be able to calculate snow volumes and water
content. Lidar is an active sensing technology
and so it’s a laser that gets shot out of the sensor. It bounces off
a surface, whether that be the ground or, in this case, the snow surfaces,
bounces back to the sensor and that measurement is recorded very precisely to give us
very accurate distance measurement. The biggest challenge
I’d say is the cold and the wind. The wind is always a challenge
for us with a drone in particular. Sproles: It’s an extremely
hard environment to work in, it’s harsh, it’s windy, things blow around. But that’s just
the nature of where we’re working. Mitchell: Most of the
agriculture on this landform and in the surrounding area is dry land
agriculture, meaning they don’t use flood or pivot irrigation.
So we’re curious how significant this snow is to
the soil water, which then turns into crop water.
Sproles: Prairies and grasslands occupy about ten percent
of the Earth’s land surface, so that’s a lot of land, right?
And of that land surface, about 30 percent of it has seasonal snow, meaning that
it doesn’t snow once a year, but you have accumulation and melt periods throughout.
Feduschak: As kind of biomes are moving north, these prairies and
the water that they hold are going to become increasingly important
for human habitation and food production.
And so getting an idea of how much snow is on the landscape,
how that snow is changing, when it’s melting, where it’s going
is really important for us to understand, and it’s definitely one
of the big gaps in our understanding of snow
as we stand today. [music]