SWESARR Tutorial
Contents
SWESARR Tutorial¶

- Introduce SWESARR
- Briefly introduce active and passive microwave remote sensing
- Learn how to access, filter, and visualize SWESARR data
Quick References¶
What is SWESARR?¶
- Description from Batuhan Osmanoglu.
- Airborne sensor system measuring active and passive microwave measurements
- Colocated measurements are taken simultaneously using an ultra-wideband antenna
SWESARR gives us insights on the different ways active and passive signals are influenced by snow over large areas.
Active and Passive? Microwave Remote Sensing?¶
Passive Systems¶
All materials can naturally emit electromagnetic waves
What is the cause?

Material above zero Kelvin will display some vibration or movement of particles
These moving, charged particles will induce electromagnetic waves
If we’re careful, we can measure these waves with a radio wave measuring tool, or “radiometer”

Radiometers see emissions from many sources, but they’re usually very weak
It’s important to design a radiometer that (1) minimizes side lobes and (2) allows for averaging over the main beam
For this reason, radiometers often have low spatial resolution
✏️ Radiometers allow us to study earth materials through incoherent averaging of naturally emitted signals
Active Systems¶
While radiometers generally measure natural electromagnetic waves, radars measure man-made electromagnetic waves
Transmit your own wave, and listen for the returns
The return of this signal is dependent on the surface and volume characteristics of the material it contacts

✏️ Synthetic aperture radar allows for high spatial resolution through processing of coherent signals
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SWESARR Sensors¶
SWESARR Frequencies, Polarization, and Bandwidth Specification
Center-Frequency (GHz) |
Band |
Sensor |
Bandwidth (MHz) |
Polarization |
---|---|---|---|---|
9.65 |
X |
SAR |
200 |
VH and VV |
10.65 |
X |
Radiometer |
200 |
H |
13.6 |
Ku |
SAR |
200 |
VH and VV |
17.25 |
Ku |
SAR |
200 |
VH and VV |
18.7 |
K |
Radiometer |
200 |
H |
36.5 |
Ka |
Radiometer |
1,000 |
H |


SWESARR Coverage¶
Below: radiometer coverage for all passes made between February 10 to February 12, 2020
SWESARR flights cover many snowpit locations over the Grand Mesa area as shown by the dots in blue

Reading SWESARR Data¶
SWESARR’s SAR data is organized with a common file naming convention for finding the time, location, and type of data

Accessing Data: SAR
SAR Data Example¶
# Import several libraries.
# comments to the right could be useful for local installation on Windows.
from shapely import speedups # https://www.lfd.uci.edu/~gohlke/pythonlibs/
speedups.disable() # <-- handle a potential error in cartopy
import requests # !conda install -c anaconda requests
# raster manipulation libraries
import rasterio # https://www.lfd.uci.edu/~gohlke/pythonlibs/
from osgeo import gdal # https://www.lfd.uci.edu/~gohlke/pythonlibs/
import cartopy.crs as ccrs # https://www.lfd.uci.edu/~gohlke/pythonlibs/
import rioxarray as rxr # !conda install -c conda-forge rioxarray
import xarray as xr # !conda install -c conda-forge xarray dask netCDF4 bottleneck
# plotting tools
from matplotlib import pyplot # !conda install matplotlib
import datashader as ds # https://www.lfd.uci.edu/~gohlke/pythonlibs/
import hvplot.xarray # !conda install hvplot
# append the subfolders of the current working directory to pythons path
import os
import sys
swesarr_subdirs = ["data", "util"]
tmp = [sys.path.append(os.getcwd() + "/" + sd) for sd in swesarr_subdirs]
del tmp # suppress Jupyter notebook output, delete variable
from helper import gdal_corners, join_files, join_sar_radiom