# Presentation: 915280

## RS_Vis_1

**Notes:**
When the Apollo astronauts became the first humans to look back on the Earth from space, we all came to the realization that we are, indeed, alone on “Spaceship Earth,” surrounded by a hostile environment.  Here we see the parts of the Earth System; hydrosphere, atmosphere, lithosphere, and cryosphere, and we see fully, for the first time, the interconnectedness of all these parts of the Earth’s environment.

We realize that we can no longer study atmosphere, for example, in isolation from the rest of the Earth’s systems, but must consider how atmospheric processes affect, and are affected by, all other parts of the system.

## RS_Vis_2

**Notes:**
Remote sensing gives us a perspective that ground-based measurements cannot.  Here, in this AVHRR composite image, we have a “synoptic” view of the land forms of North America, a view available only through remote sensing.

## Slide 3

**Notes:**
Landsat images allow us to study large areas of the Earth at one time.  In this true-color image of Cleveland, Ohio, covering 60 km x 60 km, we see the interactions of water, natural and developed land covers, and we can appreciate the effects that humans have had on the processes in the environment at this scale.

## Slide 4

**Notes:**
Each GLOBE school or franchise is provided with a 15 km x 15 km Landsat image centered on its reported location.  This is the school’s GLOBE Study Site.  

In this 15 km x 15 km view of a portion of the previous Cleveland image, we see in great detail the various land covers present. 

## Slide 5

**Notes:**
GLOBE also provides a “false-color Infrared” print of the GLOBE Study Site.  Using the near and middle-infrared wavelengths from the Landsat sensors, we can better distinguish vegetated land covers.

The image is also provided in electronic form, on disk, to be manipulated with the Software “MultiSpec,” available from Purdue University.  See the Toolkit section of the GLOBE Teachers Guide. 

## “GLOBE Study Site”

- “GLOBE Study Site”
- 15 km x 15 km

- Hydrology Site

- School

- Weather Site

- Biology Site

- Qual/Quan Land Cover Sites

- Soil
- Mois.
- Site

- The “GLOBE Study Site, 15 x 15
- km (512 x 512 pixels) centered on
- the school, contains the various
- study sites for atmosphere, soils,
- hydrology and biometry/land cover.
- Schools _may_ select measurement sites outside of this 15 x 15 km areas, and separate imaging can be provided.

- Soil Characterization

- RS_Vis_5

**Notes:**
This schematic representation of the 15 km x 15 km GLOBE Study Site represents the different types of measurement sites that GLOBE schools establish.

Schools are not limited to sites within this area, but may establish sites outside it.  Separate images may be obtained for such sites.   Contact the GLOBE Help Desk.

## RS_Vis_6

**Notes:**
This visual shows the locations, in the electromagnetic spectrum, of the five Landsat sensor channels included in a GLOBE school image.  Landsat actually has sensors for 7 channels, but in GLOBE we only use these 5.

## RS_Vis_7

**Notes:**
A more detailed look at the locations of the 5 GLOBE Landsat channels.  Wavelengths in this visual are measured in “microns,” where 

	1 μ = 0.000001 m  (one-millionth of a meter)

## How will this pixel appear in the image?

**Composition of a Pixel**

- RS_Vis_8

**How will this pixel appear in the image?**

**Notes:**
This pixel helps to illustrate why single-pixel features are very difficult to identify in a satellite image.  Here we have a single pixel, size unimportant, containing four different land cover types.

How will this pixel appear in an image?  It will look like the “weighted average” of all its contents, each contributing according to its brightness (reflectance) and how much of the pixel it occupies.

## Composition of a Pixel

**Composition of a Pixel**

- RS_Vis_9

**Notes:**
This slide illustrates the contribution of each land cover type in the pixel to the weighted average of the pixel.  Buildings, for example, occupy 15% of the pixel, and have a reflectance of 90.  Therefore, they contribute 15% of 90, or 13.5 units of reflectance to the pixel’s overall reflectance.

Similarly, each land cover component makes its contribution to the overall reflectance of the pixel.

The total of all these contributions is a brightness of 58.5 units.

## Composition of a Pixel

**Composition of a Pixel**

- RS_Vis_10

**Notes:**
With a brightness of 58.5 units, this pixel would look like a vegetated area.

So, to be certain we know what we are looking at, land cover sites must be at least 90 m x 90 m, or 3 pixels by 3 pixels, and homogeneous in land cover.

## RS_Vis_12

**Notes:**
This is a sample land cover map of a watershed in Virginia, keyed to the MUC System of Land Cover identification.  It was produced from a Landsat image.

## RS_Vis_13

**Notes:**
This image of the same watershed shows the various soil types in the area.  We can use these to study the relationship between soil types and land cover types.

## RS_Vis_14

**Notes:**
This is an update of the GLOBE GPS image with some corrections, showing the locations of the principal satellite types orbiting the Earth.