Project update: initial images analyzed

Folks, here's a short update on where things stand with regard to the image analysis. Rudi pulled some of the SAR images that corresponded with the location and dates for which Matthew had given us photos of ice road crossings. The logic of this was that we know the road crossings are there and the photos were taken after snow melt and breakup, so that the crossing stands out, visually. We should be able to see them on the SAR imagery.

Well, yes and no. Upon initial inspection, we only found one of the crossings in the SAR image. The crossing appeared to be approximately the size of a single pixel, which would make automatic detection very difficult. We also aren't entirely sure if what we see in the image is grounded ice below the water surface (i.e. a significant amount of water is flowing over a deep ice dam) or whether it's an ice bridge that hasn't broken up at all.

Another thing was clear. From SAR, breakup may actually be a difficult time to detect the position of the ice bridge because both snow and soil are saturated with liquid water. While the two look very different visually, from SAR they look somewhat similar because the sensor is simply reflecting it's beam off the liquid water.

We decided to back up a few weeks. It may be easier to detect the position of the road and the bridge when the hard ice differs considerably from the surrounding snow in terms of reflectivity. The platform passes over the same exact spot every 24 days. We are going to look backwards from breakup every 24 days to see if we can get a strong fix on the road location. Then we'll dial back into the mosaics at the daily time step to see how the scene evolves during the snowmelt and breakup periods. This should give us a better sense of what we can see and what we can't see and if we can use this to parameterize a model for the ice melt on the tundra versus in the river.

Proposal to the Alaska Satellite Facility

Hi all. I just put together a short proposal to ASF to get permission to order these images. Here's a copy:

Proposal to the Alaska Satellite Facility for Use of SAR Imagery

Jessie Cherry and Rudi Gens, in collaboration with Matthew Whitman at the Bureau of Land Management

Project Objectives: to use SAR imagery to estimate depletion rates of ice roads across rivers on Alaska’s North Slope and anticipate fish passage concerns. The immediate goal is to determine whether ice road crossings over rivers can be identified in SAR imagery. A number of aerial photographs of river crossings will be compared to SAR images on the same day. First, we will determine whether the crossings can be identified in the images (either Fine Beam and/or Standard, depending on availability). Second, we will look for the crossings in SAR images before and after the days coincident with the aerial photographs. The depletion of the road over time at various locations will then be calculated from this time series of photographs.

Data requirements: SAR imagery (either Fine Beam and/or Standard, depending on availability) for the following 14 locations, on the specified dates. Where crossings can be identified, additional images will be ordered for the days before and after these dates. Total number of images required is anticipated to be around 50.

x1: N 70.71212 W 155.02818, 6/6/07
x2: N 70.74697 W 154.98183, 6/6/07
x3: N 70.81777 W 154.88462, 6/6/07
x4: N 70.76153 W 154.77462, 6/6/07
x5: N 70.75403 W 154.69775, 6/6/07
x6: N 70.75262 W 154.67673, 6/6/07
x7: N 70.74682 W 154.65602, 6/2/07
x8: N70.71097 W 154.64258, 6/6/07
x9: N 70.70875 W 154.69702, 6/6/07
x10: N 70.69568 W 154.73437, 6/6/07
x11: N 70.67855 W 154.78623, 6/6/07
x12: N 70.64778 W 154.84308, 6/6/07
x13: N 70.63357 W 154.94385, 6/4/07
x16: N 70.56215 W 155.36087, 6/4/07

Good.

Sounds like a plan, Matthew. I will make a list of the sites from your report where there are photos, at the very least, with exact locations and dates. I'll work with Rudi to see what we can get from those locations at those times.

thanks,
Jessie

Moving Forward: Suggestion

Matthew...great, thanks for the update on the bathymetry data...hope we get that eventually. I had an idea on a way to move forward for the time being. I was reading back through your report from 2007. I was thinking that Rudi and I could look at SAR imagery of the sites you photographed for this report. If we can identify the crossing from the image, then we could look at a time series around these dates to see if we can calculate the difference in the ablation/breakup of the crossing point compared to the snow and later the river near that point. So, for example at site X1 on June 6, 2007:
1. Can we see the crossing in the SAR image from that day?
2. If so, how does the snow and ice distribution from this point vary in the 4 weeks leading up to this day and through total breakup of the crossing point?
3. Can differential ablation/breakup be calculated empiracally between the ice road & crossing versus the unaffected tundra and river?

Does this sound like a reasonable approach to start with? If so, I'll make a list of locations for Rudi and see what we can find.

Thanks,
jessie

Bathymetry Data Update

Yet another update on the lake bathymetry data owned by ConocoPhillips. I was in a (unrelated) meeting with Caryn Rea (Conoco's environmental lead for AK) yesterday and she tells me the data transfer is being held up by their legal department due to an ongoing lawsuit regarding some offshore leasing (not sure what the connection is). She still says she is fully confident she will get us what we want (sooner rather than later) and is actively pursuing it. I've passed this kind of info on to you before, but now I am also more confident because those GIS coverages are also needed by myself and some other cooperators for a separate lake project in which Conoco is a major contributor. Caryn tells me I won't need any additional permissions to use the data for the remote sensing work and is very interested in the product that we (you) are pursuing for that. So, don't hold your breath, but I just wanted to pass on the latest.

Subscribing to comments

Hi, I also thought I'd let you know that blogger has a little flaw which forces you to subscribe to comments separately. If you click on a post comment, then scroll to the bottom and click on 'Subscribe by email', it will email comments to you. Or your RSS reader should catch them, if you use one.

thanks,
Jessie

Next Step & Fingers Crossed on CPAI data

Matthew,
that's great news that CPAI at least says they'll share the data. I hope it's true! Glad you like the bibliography. I, for one, learned more about the previous SAR studies on particular lakes...which is helpful. I think that's one reason that making a map of the sites of previous SAR/ground truth studies would be useful. So hopefully I'll get this done in the next month or so. And then hopefully we'll have these data from CPAI. I think we're on the right track/doing useful things.

Rudi and I are going to meet tomorrow and talk about the ASF holdings for airborne SAR...

Peter, what's the status on the INE project?

cheers!
Jessie