Lab 2: Understand Geographic Data

Accomplishment statement:

Further explored two important applications within ArcGIS: ArcCatalog and ArcMap. ArcCatalog is effective in  previewing, documenting, and organizing data. Moreover, use of ArcCatalog can help with understanding the importance of coordinate systems and projections. Fixing misaligned and improperly referenced data is also achievable through ArcCatalog. Composite images can be created by using remote sensed data and analyzing the different bands.

A guideline for fixing misaligned and improperly referenced data: 

1. In order to verify that all ArcGIS shapefiles has the same spatial data properties, you will need to first preview each shapefile in ArcCatalog to check if all data are similar (right click on each file on ArcCatalog and go to Properties).
2. Make sure the coordinate reference system is the same for each file, which is found next to the bold Spatial Reference header. (Ex: Canada_Lambert_Comfornal_Conic)
3. Drag files into Table of Contents as layers. If there are any different projections, convert all layers into the common projection first before analysis.
4.  Look to make sure that all information is displayed properly on the map. If there are any files that have missing spatial reference they might not appear on the map. If this happens, follow steps i. and ii. to realign the layers.
   1. You will need to find out what the coordinate system of the data is from the data provider in order to apply it your data so that it aligns with the map
   2. Using ArcCatalog, find the coordinate system that the data provider used and apply it to the layer. Under the section ‘XY coordinate system’ you can then select the Geographic Coordinate System you would like for the layer. Units of measurement and datum can also be adjusted in the properties menu.
5. The new layer could now be projected and added to the map as it can be aligned to the rest of the data.

The advantages to using remotely sensed Landsat data for Geographic Analysis

Since remotely sensed Landsat data is on a 16-day cycle by sensors on a satellite reflected by solar radiation, it creates a highly detailed visual image of the area. Landsat data would also be useful for geographical analysis because of it’s ability to observe change of land over time as well as different wavebands of radiation which are usually unseen by the naked eye. For example, Landsat data would be incredibly useful for researching the global recession of glacier ice as glaciers retreat throughout the globe. Specifically, if landsat data was used to monitor the retreat  of glaciers in Glacier National Park, that could prove to be very useful in explaining the impacts of global climate change. You would need to precisely select various times within the year and different seasons and monitor the glaciers at those dates every year at those specific dates and times in order to be able to gauge what the change in the movement of glaciers are. For example, a team of researchers from Ege University in Turkey and NASA’s Goddard Space Flight Center analyzed four decades of Landsat satellite data to monitor the major decline in glacial area  in Mount Suphan. There, they saw discovered that the glacier that previously resided there has lost more than 75 percent of its initial area since the 1970s. Thus Landsat data can provide quantitative and accurate analysis on the recession of glaciers between various periods of time by examining the detailed imagery at those particular dates and times.