ESA - Eduspace EN - Global Change

Coastal change

Danube Delta change detection Oil spills

Deforestation

Bardia National Park Congo River Basin Kameng-Sonitpur Elephant Reserve Kilimanjaro Rondonia Shillong and Guwahati

Ice

Antarctica 2003 Climate change and glaciers Glacier analysis using radar imagery Glacial retreat in the Alps Glacier Ice Flow Monitoring of glaciers in the Himalayas Remote sensing of ice and snow

Urbanisation

Cairo City of Kathmandu Córdoba Himalayas Kathmandu Valley Lagos

Vegetation

Annapurna Conservation Area Lost in the Andes Ngorongoro Conservation Area Niger Inland Delta Vegetation in South America

Example

The following images show the different degrees of reflection at different wavelengths for glaciers on Svalbard. They depict how the satellite sensor sees the area in different wavelength sections.

True colour satellite image of Brøggerhalvøya, Svalbard, Norway

The image of the red channel shows the reflection in the red part of the electromagnetic spectrum

Image of the Near InfraRed channel

Image of the ShortWave InfraRed channel

Number of pixels with a certain reflection in the red, NIR and SWIR channels

In sum, snow and ice have a very high reflection in visible wavelengths (white colour), decreased reflectance towards the NIR, and even lower values of reflectance at the SWIR. Snow and ice are thus nearly black in the SWIR, a type of radiation humans are not able to see with the naked eye.

Questions

1. Fill in the following table by marking, for each snow/ice type, if its reflectance is high, medium or low in the VIS, NIR and SWIR regions of the spectrum. An example is given for snow in the VIS.

Snow Firn Glacier
ice Dirty
glacier
ice

VIS NIR SWIR VIS NIR SWIR VIS NIR SWIR VIS NIR SWIR

High
reflectance X

Medium
reflectance

Low
reflectance

2. Print out the above colour, VIS, NIR and SWIR images. Place a transparency on one of the four and try to outline some areas with snow, firn and ice. When you are finished, put the transparency on the other images and compare how you outline the areas on these.

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Remote sensing of ice and snow

Background

Ice – a special substance Optical properties of ice and snow

Exercises

Introduction Purpose of the exercise Exercises