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National Aeronautics and Space Administration. Analysis of S’COOL Data: An Introductory Tutorial. http://scool.larc.nasa.gov. www.nasa.gov. Finding the Data. Under the first cloud, Select Step 4: Database. Selecting the data. Interact with the data Just yours All OR….

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slide2

Findingthe Data

Under the

first cloud,

Select

Step 4:

Database

slide3

Selecting the data

  • Interact with the data
    • Just yours
    • All

OR…

slide4

Selecting the data

  • Download all S’COOL and CERES matches (as of Aug. 2004)
slide5

Selecting the data

  • Get ideas for data analysis

a) This tutorial

b) Excel file 1

c) Excel file 2

slide6

Review the Results

4. Read our analysis of the S’COOL and CERES data

-We will be happy to post results of student studies here too!

slide7

Search Options

  • Choose a date range

And/Or

  • Choose a lat/long region

And/Or

  • Choose a country

And/Or

  • Choose results with satellite data
slide8

Submit Query Request

It may take a few minutes to process the search.

  • Hit Submit when ready
slide9

Search Results - Ground Only

The student report

A graphic representation

slide10

Search Results - Ground + SatelliteA No Cloud Case

The student report

Excellent Agreement!

The satellite report

slide11

Search Results - Ground + Satellite

  • Of course, the reports from the ground and the satellite may not always agree
  • The next few slides illustrate a few examples
    • Sometimes the disagreement makes sense
    • Sometimes the disagreement does not make sense
  • You can look at your own observations to
    • Quantify the agreement
    • Find and further study cases that don’t make sense
slide12

Search Results - Ground + SatelliteCloudy Case - I

The student report

Very good Agreement!

Only opacity

(a subjective measure from the ground) does not match

The satellite report

slide13

Search Results - Ground + SatelliteCloudy Case - II

The student report

Near disagreement

Cloud Cover differs by one category. May be off only a few percent.

The satellite report

slide14

Search Results - Ground + SatelliteCloudy Case - III

The student report

Interesting disagreement

Satellite cannot see clouds under opaque top layer

The satellite report

slide15

Search Results - Ground + SatelliteCloudy Case - IV

The student report

Interesting disagreement

Satellite cannot detect sparse, thin, high clouds

The satellite report

slide16

Search Results - Ground + SatelliteCloudy Case - V

The student report

Puzzling disagreement

Student comments indicate extensive cloudiness

The satellite report

slide17

Analyzing the Data - Cloud Cover

  • So far we have talked about 6 cases (no cloud case, and cloudy cases I, II, III, IV, and V). How could we summarize these?

Low cloud

Mid-level cloud

High cloud

All

3/6

50%

5/6

83%

4/6

67%

 2/6

33%

slide18

Analyzing the Data - Cloud Cover

Low cloud

Mid-level cloud

High cloud

All

3/6

50%

5/6

83%

4/6

67%

 2/6

33%

Cloud Cover is important to understanding the Earth’s Energy Budget, since clouds both reflect sunlight and modulate emission of heat from the Earth.

slide19

Analyzing the Data - Cloud Cover

  • What if we look at total cloud cover (Low + Mid + High)?

-Need to decide how to combine levels - do they overlap?

-Use a middle value for ground classes (i.e., 5-50 = 27.5%)

*No overlap assumed

slide20

Analyzing the Data: How Many Cloud Layers

Number of Cloud Layers

Ground

Observations

Cloud Layers are of particular interest when comparing the passive satellite view of the Earth from space with the report of human observers on the ground who can distinguish different cloud layers and types.

Satellite Observations

3/6 = 50% agree completely

3/6 = 50% off by one class

slide21

Analyzing the Data: Which Cloud Levels

Cloud Levels seen from Ground

Cloud Levels seen from Satellite

LM = Low + Mid. etc

Cloud Levels are of interest for the same reason, since human observers on the ground can distinguish cloud levels better than the top-level satellite view.

3/6 = 50% agree completely

slide22

Analyzing the Data

  • Of course, these 6 correspondences were hand-picked to illustrate interesting comparisons.
  • What happens if we look at all the data?
  • Let’s start with the two-week period (Sept. 1-15, 2002) that includes these examples.

It also tells you how many data points were found = 245.

At the bottom of the search page, you will

find directions, a key to the file, and a link to get the data.

slide23

The Downloaded .bin File

  • The file you get will have a name like

11301239.grn.bin

    • Decoding:
      • 1130 is the date (Nov. 30 in this case) you download the file.
      • 1239 is a time stamp from when you requested the file
      • grn means Ground
      • .bin was chosen as the extension so that most browsers will automatically download the file when you click on the link
slide24

Inside the .bin file

  • The .bin file is an ASCII (text) file.
  • Each line contains the student report and, if available, the corresponding satellite retrieval information.
  • The lines are very long and will wrap in most text editors (see below).
  • Fields are tab-separated, so that the file can be imported into a spreadsheet program like Excel.
slide25

Importing into Excel

  • There are several ways to import data into Excel. If you already know how, skip this page.
    • Open Excel
    • Under the File menu, choose Open
    • Find the .bin file you downloaded to your computer. (you may have to Enable: All Documents in the Open menu)
    • Open the file. A Text Import Wizard should start.
    • Delimited is default. Next.
    • Tab is default. Next.
    • Finish. File should appear as on next page.
slide26

The file in Excel - I

Row 1: Variable Name

Row 2: Units

Row 3: Blank

Row 4…: Data

The key lets you interpret the entries in these columns (see slide 22).

You may notice

other blank lines.

These have to do

with line feeds, and can be deleted or

ignored.

slide27

The file in Excel - II

Scrolling to the right in the file, you will find the satellite entries, or the notation NAY (Not Available Yet)

If the satellite saw no cloud in a level it will be left blank.

slide28

Analyzing data

  • Now that you have the file open in Excel, you can save it as an Excel workbook, then do all sorts of analyses.
  • See the two Excel files (refer to slide 5) for some examples and ideas
  • If you discover anything interesting, share it with the S’COOL Team!
slide29

National Aeronautics and Space Administration

Langley Research Center

Hampton, VA 23681

www.nasa.gov