# Is There Data Describing the Velocity of Different Heights of a Glacier?

I'm looking for glacier data that provides the velocity at different heights within a glacier. So, ideally I would like data that includes not only velocity at the surface, but also velocity at at different distances below the surface. Figure 2 on page 5 here made me think that I could find velocity at different height values for some glacier. Am I interpreting this graph incorrectly? I'm very new to glaciology.

I read up on the use of inclinometers, which I think could be used to get the type of measurements that I want (again, I'm very new to this, so I could be wrong). However, I searched the databases here, and here and I could not find any data like what I'm looking for. I can find the surface velocity for the different glaciers, but not the velocity at different depths below the surface of the glaciers.

1. Does data giving ice velocity at different heights within the glacier exist?

2. Do we have this type of data for a glacier that could be modeled as a parallel sided slab on slope problem? My main purpose is that I would like some real-world velocity vs $$z$$-coordinate (height) data that I can plot for the parallel-sided slab on slope problem.

Even if you can't tell me where to find this data just knowing if there's a possibility it exists would be very helpful. Thanks!

• @trondhansen can you explain further why you think searching plasticity might help please? I'm very new to all of this. Thanks! Commented Feb 26, 2023 at 19:10

There are many measurements presented in the literature of the velocity profile of a glacier. However, since all profiles will to some extent be dependent on local conditions, I am not sure how useful they will be. A simple alternative would then be to follow the flow profile presented by Nye (1952) where the velocity at some depth u_z in a glacier is related to the surface u_s as (using pseudo-LaTeX syntax):

u_z - u_s = 2A/(n-1) (rga)^n H^(n+1)


where A is a viscosity related constant (site specific), n = 3, r is the density of ice (900 kg/m^3), g is the gravitational constant, a is the surface slope of the glacier and H is the thickness of the glacier.

The equation allows you to produce a velocity profile from a given set of values of surface slope and ice thickness related to a surface velocity.

Reference:

Nye, J.F. 1952. Mechanics of glacier flow. Journal of Glaciology, 2 (12), 82–93.

• Thank you very much for your response. This is an interesting formula that I had not come across yet. I am looking for a way to see this data independent of the assumptions of the Glen Flow Law though. This was my purpose for trying to find real world data. You mentioned that there are many measurements presented in the velocity profile of a glacier. Does this mean you have seen data giving velocities of a glacier at different depths within the glacier? Again thank you! Commented Feb 24, 2023 at 16:12