analysis of s’cool data: an introductory tutorial

Analysis of Analysis of S’COOL Data: S’COOL Data:

An Introductory An Introductory TutorialTutorial

http://scool.larc.nasa.govhttp://scool.larc.nasa.gov

National Aeronautics and Space Administration

www.nasa.gov

FindingFinding the Datathe Data

Click on the For Participants

tab

Finding the Data

Next click on: 4. Database

Selecting Selecting the datathe data

1. Interact with the data

a) Just yoursb) All

OR…


2. Download data matches by spacecraft name and date.


3. Get ideas for data analysis

a) This tutorialb) Excel file 1c) Excel file 2

Review Review the the ResultsResults

4. Read our analysis of the S’COOL and CERES data-We will be happy to post results of student studies here too!

Search Search OptionsOptions

• Choose a date range

And/OrAnd/Or• Choose a

lat/long region

And/OrAnd/Or• Choose a

countryAnd/OrAnd/Or• Choose

results with satellite data

Submit Submit Query Query RequestRequest

• Hit Submit when ready

It may take a few minutes to process the search.

Search Results - Ground OnlySearch Results - Ground Only

The student report

A graphic representation

Search Results - Ground + SatelliteSearch Results - Ground + SatelliteA No Cloud CaseA No Cloud Case

The student report

Excellent Excellent Agreement!Agreement!

The satellite report

Search Results - Ground + SatelliteSearch 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

Search Results - Ground + SatelliteSearch Results - Ground + SatelliteCloudy Case - ICloudy Case - I

The student report


Very good Very good Agreement!Agreement!

Only opacityOnly opacity(a subjective (a subjective measure from measure from the ground) the ground) does not matchdoes not match

Search Results - Ground + SatelliteSearch Results - Ground + SatelliteCloudy Case - IICloudy Case - II

The student report

Near Near disagreementdisagreement

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


Search Results - Ground + SatelliteSearch Results - Ground + SatelliteCloudy Case - IIICloudy Case - III

The The student student reportreport

Interesting Interesting disagreementdisagreement

Satellite cannot Satellite cannot see clouds under see clouds under opaque top layeropaque top layer

The satellite The satellite reportreport

Search Results - Ground + SatelliteSearch Results - Ground + SatelliteCloudy Case - IVCloudy Case - IV

The student report

Interesting Interesting disagreementdisagreement

Satellite cannot Satellite cannot detect sparse, detect sparse, thin, high cloudsthin, high clouds


Search Results - Ground + SatelliteSearch Results - Ground + SatelliteCloudy Case - VCloudy Case - V

The student report

Puzzling Puzzling disagreementdisagreement

Student observations Student observations indicate extensive indicate extensive cloudinesscloudiness


Analyzing the Data - Cloud CoverAnalyzing 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 cloudLow cloud Mid-level cloudMid-level cloud High cloudHigh cloud AllAll

Grd

Sat

0 0 MC MC 0 0

PC 0 XX0 0 0 0

XXXXXXXX

3/63/6 50%50%

5/65/6 83%83%

4/64/6 67%67%

2/62/6 33%33%

Grd

Ground

Sat Satellite0 No CloudCl ClearPC Partly

CloudyMC Mostly

CloudyOV Overcast

Grd

Sat

0 0 0 0

PC Cl XXPC 0 XX0 0

PC 0 XX

Grd

Sat

0 0 PC PC 0 0

PC 0 XX0 0 Cl 0 XX

Analyzing the Data - Cloud CoverAnalyzing 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 cloudLow cloud Mid-level cloudMid-level cloud High cloudHigh cloud AllAll

Grd

Sat

0 0 MC MC 0 0

PC 0 XX0 0 0 0

XXXXXXXX

Grd

Ground


CloudyMC Mostly

CloudyOV Overcast

Grd

Sat

0 0 0 0

PC Cl XXPC 0 XX0 0

PC 0 XX

Grd

Sat

0 0 PC PC 0 0

PC 0 XX0 0 Cl 0 XX

Cloud Cover is important to understanding the Earth’s Energy Budget, since clouds both reflect sunlight and

modulate emission of heat from the Earth.

Analyzing the Data - Cloud CoverAnalyzing 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%)Case Grd* (%) Sat*

(%)1 0. 0. 2 PC+MC = 100. 100. 3 PC = 27.5 2.35 4 PC+PC+PC=82.5 100. 5 Cl = 2.5 0 6 PC = 27.5 0

**No overlap assumedNo overlap assumed

Grd

Ground

Sat SatelliteCl ClearPC Partly

CloudyMC Mostly

CloudyOV Overcast

Grd

Ground


CloudyMC Mostly

CloudyOV Overcast

Analyzing the Data: How Many Cloud LayersAnalyzing the Data: How Many Cloud Layers

GroundGroundObservationsObservations

Sate

llite

Sa

telli

te

Obs

erva

tions

Obs

erva

tions

0 1 >1

0 1

>1

3/6 = 50% agree completely3/6 = 50% agree completely3/6 = 50% off by one class3/6 = 50% off by one class

Number of Cloud Layers

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.

Analyzing the Data: Which Cloud LevelsAnalyzing the Data: Which Cloud Levels

Clr Low

Mid

LM Hi LH MH LMH

Clr Low

MidLMHi LHMH

LMH

Cloud Levels seen from GroundCloud Levels seen from Ground

Clo

ud L

evel

s se

en fr

om S

atel

lite

Clo

ud L

evel

s se

en fr

om S

atel

lite

3/6 = 50% agree completely3/6 = 50% agree completely

LM =

Low

+ M

id. e

tc

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.

Analyzing the DataAnalyzing 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, 2008,

that includes these examples.

At the bottom of the search page, you will find directions, a key to the file, and a link to get the data.* This can be found at the bottom of the comparison report request.

It also tells you how many data points were found = 336.

The Downloaded .xls FileThe Downloaded .xls File• The file you get will have a name like

12070812.grn.xls– Decoding:

• 1207 is the date (Dec. 07 in this case) you download the file.

• 0812 is a time stamp from when you requested the file (8:12 am in this case)

• grn means Ground• .xls was chosen as the extension so that most

browsers will automatically download the file when you click on the link

Inside the .xls fileInside the .xls file• The .xls file is a Microsoft Excel 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).

The file in Excel - IThe file in Excel - IRow 1: Variable NameRow 2: UnitsRow 3: BlankRow 4…: Data

You may notice other blank lines.These have to dowith line feeds, and can be deleted orignored.

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

The file in Excel - IIThe file in Excel - IIScrolling 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.

Analyzing dataAnalyzing 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!

National Aeronautics and Space Administration

Langley Research Center

Hampton, VA 23681

www.nasa.gov

analysis of s’cool data: an introductory tutorial

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