Lab - Remote Sensing with RADAR Imagery

Learning Objective

The purpose of Lab 11 is to familiarize you with interpreting radar imagery. Upon completion of this lab you should be aware of the usefulness and difficulties of radar imagery in remote sensing applications.

Outline:

Submission requirements

Materials (click to download)

Data Name	Description
GEOG111_Lab2Questions.docx	Handout to turn in

You are answering the questions (laid out in the word doc above and also included in the tutorial below) as you work through the lab. Use full sentences as necessary to answer the prompts and submit it to blackboard. Copy the folder Chapter 12, which contains the following GeoTIFF datasets from NASA’s Earth Observatory: * Bakken_vir_2012317_geo.tif, a VIIRS image showing a section of northwestern North Dakota at night * russia_tmo_2012170_fires_geo.tif, a MODIS image showing fires in Siberia * samerica_vir_2012202_geo.tif, a VIIRS image showing a section of the South American eastern coastline at night * irene_amo_2011238_geo.tif, a MODIS image showing Hurricane Irene * Newzealand_amo_2017317_geo.tif, a MODIS image showing an algal bloom off the coast of New Zealand * The folder also contains the following KML dataset from the University of Wisconsin’s Space Science and Engineering Center: * Daily_MODIS_May3, a series of MODIS images covering the United States from May 3, 2017

Guide

Background Information • Acronym – “Radio Detection And Ranging” • “Ranging” refers to measurement of time delay • Active system – generates own source of energy to acquire return • Signal representative of radar backscatter • Low backscatter = darker area • High backscatter = brighter area • 3 types of active radar scanners: o Doppler o Plan Position Indicator o SLAR (this lab focuses on SLAR)

Capabilities • Can measure distance from antenna to land surface features • Ability to detect frequency & polarization shifts • Can be used in almost any weather (helpful in tropical climates) • Independent of solar illumination • Can penetrate clouds, some snow, some soil, some vegetation providing crisp topographic information

What determines return signal? • Wavelength used • Polarization • Geometry • Surface Characteristics (Book page 220, Section 7.10)

Wavelengths Used

Band Designations Wavelengths Ka .75 – 1.18 cm K 1.18 – 1.67 cm Ku 1.67 – 2.40 cm X 2.40 - 3.75 cm C 3.75 - 7.5 cm S 7.5 - 15 cm L 15 - 30 cm UHF 30 - 100 cm P 77- 107 cm **Radar originated as a military endeavor during WWII. Because of its military origins, the band designations were assigned arbitrarily to ensure security and therefore don’t hold any specific meaning.

SLARgeom.png

ll radar collection occurs in slant range, therefore geometric errors exist

• Radar layover o radar measures all distance with respect to time elapsed between transmission & reception o at near range, top of tall object closer to antenna than is its base o top appears closer (appears to lean) o analogous to relief displacement

FrontSLARgeom.png

Geometry of SLAR • SLAR = Side-Looking Airborne Radar • Depression angle – angle between upper edge of beam & horizontal extension of plane • Near range – edge nearest airplane (more scale compression) • Far range – edge farthest from airplane • Slant range – direct distance from object to antenna (high distortion; object appear curved) • Ground range – represents correct scaling of distances; preference for interpretation because it minimizes distortion

Wrapping up

There is no need to save anything from this lab, so when done you can simply close without saving. Submit your answers to the questions on blackboard.