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Data Quality Evaluation for ICESat-2 Significant Wave Height across the Great Lakes Region

Linfeng Li, Mengfan Yu

EAS 644

School of Environment and Sustainability

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Objective of the study

Examine the data quality of significant wave height measured by satellite ICESat-2 within the Great Lakes by using buoys observations

How much it can be consistent with data from buoys?

Fill the gap of winter wave measurements

No buoy data during winter

NDBC - Station 41063 Recent Data (noaa.gov)

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Satellite ICESat-2

Main mission

ICESat-2 measures the height of a changing Earth surface.

Height of glaciers, sea ice, forests, lakes and more.

ATL13

Inland water surface height, one of ICESat-2 products, consists of along-track water surface height, slope and so forth, including significant wave height.

Source: ICESat-2 (nasa.gov)

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Download data

Source: | National Snow and Ice Data Center (nsidc.org)

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Extract data

HDF5 file

.

dataframe

.

csv file

Concatenate

one dataframe

Export

Extract

dataframe

.

Filter

Hierarchical Data Format

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Extraction

This function is used to get the file path of all the HDF5 datasets within a specified folder where they are stored.

Up to 604 HDF5 datasets in total ( 4/1/2021 - 5/31/2022 )

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Extraction

Longitude

Latitude

Time

Significant wave height

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Filter out data points outside of the Great Lakes region

�

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Filter

convex polygon

concave polygon

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Filter

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Monthly Plots

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The Amount of Data�

Temporal Distribution

Less data during winter

More data during summer

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Data Pairing

Buoy Distribution

National Data Buoy Center
Seagull - Great Lakes Observing System

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Data Pairing

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Data Pairing

This function searches the satellite data point which is the closest to a buoy, and record the minimum distance.

A series of data points from satellite

A buoy

the buoy

The closest satellite data point

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Data Pairing

This function calculates the great-circle distance between two points on a sphere based on their latitudes and longitudes.

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Fill in the Buoy SWH Data

This part of code involves parsing text on buoy dataset websites.

https://www.ndbc.noaa.gov/view_text_file.php?filename=45007h2021.txt.gz&dir=data/historical/stdmet/

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Spatial Plots

https://storymaps.arcgis.com/stories/c21ec2b22eaf4d779e0b5443b1008510

556 data pairs for comparison

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Statistical Results

https://storymaps.arcgis.com/stories/c21ec2b22eaf4d779e0b5443b1008510

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Key Takeaways

It is necessary to examine the usability of the satellite data.
HDFView is a helpful tool for viewing the file structure and metadata.
Python is used to extract data, filter data and make plots .
How much data is available depends on seasons.
Data of significant wave height is available from ICESat-2 during winter but constrained to unfrozen area.
We compared the data from the satellite and buoys by high wave events.

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Next Steps

The significant wave height data gained from ICESat-2 will be applied to examine the accuracy of WAVEWATCH III model predictions.

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Source: www.nasa.gov

Thank you!�Any Questions?