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mliukis on new_granule_format
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Hello! I have a quick question and for some reason I can't seem to figure it out...
I can see how to download (both through the NSIDC's website and programmatically) the annual Greenland velocity mosaics and the scene pair velocities, but I'm struggling to find the monthly ice sheet mosaics. Is there an obvious place that I am missing (or piece of code) that we can use to download them?
Thanks for any help you can provide!
For Julia nerds and the Julia-curious, ITS_LIVE has a new Julia package for exploring the data:
You can plot data for your glacier with 4 lines of code:
julia> Using Pkg; Pkg.add(“ItsLive”) julia> lat = [59.925]; lon = [-140.620] julia> C = ItsLive.getvar(lat, lon, ["mid_date","date_dt","v","satellite_img1"], ItsLive.catalog()) julia> p = ItsLive.plotbysensor(C,"v")
Hi everyone - I hope I'm in the right place to ask questions about the ITS_LIVE Antarctic monthly elevation data! I'd really appreciate some help with these questions.
1) Could you possibly state the difference between the downloaded files (a) 'NETCDF: "ANT_G1920V01_GroundedIceHeight":h' and (b) 'NETCDF: "ANT_G1920V01_GroundedIceHeight":dh'? And why does (a) appear to show significantly less spatial coverage than (b)?
2) What does each 'Band' correspond to when I click identify results in QGIS? Does it correspond to data from one individual month - therefore starting from January 1985? (Please see in the above photos to the right hand side of the screen to see what I'm referring to)
3) Is there a recommended way in which to extract the data on QGIS? For instance, for extracting the data at points every 200m down a plotted line, it gives this (c) when extracting values from (b). I'm using 'Points along geometry' in the QGIS toolbox, and it appears to only extract 'angle' values as shown below. I used this toolbox for extracting velocities from the ITS_LIVE velocity dataset, and it worked - is there another recommended tool to use?
@nilssonj @alex-s-gardner @tlohde --> Thanks for your help so far, I've definitely made progress! I hope its ok to ask a few more questions?
@tlohde thank you, that's certainly greatly improved my methodology for the extracting data from the ITS_LIVE velocity dataset (I have tried and tested and it works!)
@alex-s-gardner that's perfect, I've downloaded, tried and tested the tool, and it works! But could you please clarify something for me?
(b) https://postimg.cc/v1JPFS0L : data taken from a pixel at the margin of Pine Island Glacier from the "dh" file, with the "h" file overlaid.
With this tool, it gives me the results in (b) which I can extract into excel for plotting. But if you'd take a look at the graph towards the bottom of the screen, what does the y-axis refer to? For instance, in 2004 it is ~25.0m above what variable? Or in 2020 it is -13.2m below what variable?
(Also, apologies as I would have sent this message in the above reply thread - but there appeared no easy way to format my reply as compared to when I post a new thread)
Hello ITSLIVE team. A question about uncertainty.
Create seasonal (or monthly, or annual) velocity profiles along a centreline.
vx/y_error. Moreover, it does not take the error associated with that particular time slice.
vy_errorterms are functions of time, and do not vary spatially.
I have two measures of uncertainty one, measuring the uncertainty across space, the other time.
How best to combine these? Do they to be combined?
Happy to provide more detail if required. And I hope the above is intelligible. Thank you, ed
Hi ITS_LIVE team,
Thank you very much for publish the great ITS_LIVE glacier velocities product.
I'm Yuzhe Wang from Shandong Normal University, China. We're using the surface velocities at East Rongbuk Glacier (28.05N, 86.93E) in Everest to compute the basal firction parameters inverted by an ice flow model.
Although the 240m HMA product provided the annual velocities from 1985, it is still too coarse for individual glacier modelling. We tried to use the 120m time-averaged product which is relatively appropriate for our study. However, we have no idea about the time information.
Could you please, by any chance, help me confirm which period do you choose to compute the averaged velocities on East Ronbuk Glacier?
Thank you very much.
In case anyone missed the announcement of V2 data:
The NASA ITS_LIVE (https://its-live.jpl.nasa.gov) team has analyzed over a petabyte of radar and optical satellite data to find slight distortions between image-pairs caused by surface motion, creating a detailed record of flow for every glacier on Earth. The data is easily accessed through an interactive widget that generates publishable quality figures within seconds:
Take a minute to discover a new glacier surge, watch glaciers slow in winter across the planet, or tour the Antarctic "doomsday" glaciers of Pine Island and Thwaites.
I just learned of this great resource and am getting familiar with it, but I have a few questions:
1) I assume that the annual velocities take into account leap years, correct? For example, the annual velocity for non-leap years would be for a period of 365 days, while the annual velocity for leap years would be for a period of 366 days. Is this correct?
2) I assume the Its_Live online map and downloaded data are referenced to the WGS84 datum. Is that correct?
3) When I enter a lat/long coordinate into the Global Glacier Velocity Point Data Access map, I enter the coordinate as decimal degrees to 7 decimal places. It then tells me that I have entered an invalid value and that the valid value should be to only 1 decimal place. But then when I export and download the data for the point that I entered (to 7 decimal places), the file name of the downloaded data shows the lat/long to 4 decimal places. It appears that the Its_Live map app is rounding off my 7-decimal coordinate values to 4 decimal places and then returning the data for the 120-meter grid cell in which the 4-decimal place coordinate is located. Is this correct?
data_epsg, which I have entered below. Does anyone have a workaround for this? Thanks!
File ~/notebooks/datacube_tools.py:83, in DATACUBETOOLS.find_datacube_catalog_entry_for_point(self, point_xy, point_epsg_str) 79 break 81 if cubefeature: 82 # find point x and y in cube native epsg if not already in that projection ---> 83 if point_epsg_str == cubefeature["properties"]["data_epsg"].split(":")[-1]: 84 point_cubexy = point_xy 85 else: KeyError: 'data_epsg'
Hi there! I am an undergrad student at Lancaster University currently working on my dissertation. Part of this involves looking to analyse velocity data for Upernavik Isstrom (NW Greenland), which ITS_LIVE seems perfect for. However, i'm having some issues working with the data, specifically getting velocity rasters loaded into ArcGIS (3.0).
I have tried creating velocity rasters using both the 'Make NetCDF Raster Layer' and 'Make Multidimensional Raster Layer' tools, but both to no avail. The former tool does create a layer but doesn't display anything, regardless of symbology choices. The latter tool does display a layer, but with very coarse detail - only velocities of 240, 480, 960, and 1920 m/y are shown. No attempt to modify symbology changes this. See example:
Oddly, QGIS displays the layers as expected. See example:
I was wondering if anyone has any experience successfully loading velocity rasters into ArcGIS, or could shed any light on this situation?
v_errorinstead. What exactly does
v_errorrepresent? Standard deviation of a speed measurement or uncertainty of that under a certain confidence level?
I'd like to share some code I wrote for downloading datacubes on custom date/spatial extent (for both yearly and sub-yearly datacubes), tracking specific pixel displacements, and calculating surface strain rates.
Most of it is a GUI, you should be able to run the notebooks without having to dive in the code or understand all of it.
I hope it is useful to some people, let me know if I can help in any way with it ! Just follow the instructions and it should work :)
Also I hope I'm not trespassing any rule by sharing homemade code here. If I am, please let me know and I will delete my message/link. Thank you !