Analysis of Analysis of S’COOL Data: S’COOL Data:
An An Introductory Introductory
TutorialTutorial
Analysis of Analysis of S’COOL Data: S’COOL Data:
An An Introductory Introductory
TutorialTutorialhttp://scool.larc.nasa.govhttp://scool.larc.nasa.govhttp://scool.larc.nasa.govhttp://scool.larc.nasa.gov
National Aeronautics and Space Administration
www.nasa.gov
FindingFinding the the DataDataUnder thefirst cloud,
SelectStep 4:Database
Selecting Selecting the datathe data
1. Interact with the dataa) Just
yoursb) All
OR…
1. Interact with the dataa) Just
yoursb) All
OR…
Selecting Selecting the datathe data
2. Download all S’COOL and CERES matches (as of Aug. 2004)
2. Download all S’COOL and CERES matches (as of Aug. 2004)
Selecting Selecting the datathe data
3. Get ideas for data analysis
a) This tutorial
b) Excel file 1
c) Excel file 2
3. Get ideas for data analysis
a) This tutorial
b) Excel file 1
c) Excel file 2
Review Review the the ResultsResults4. Read our
analysis of the S’COOL and CERES data-We will be happy to post results of student studies here too!
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 country
And/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 + Search Results - Ground + SatelliteSatelliteA No Cloud CaseA No Cloud CaseThe student report
Excellent Excellent Agreement!Agreement!
The satellite report
Search Results - Ground + Search Results - Ground + SatelliteSatellite
• 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
• 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 + Search Results - Ground + SatelliteSatelliteCloudy Case - ICloudy Case - IThe student report
The satellite 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 + Search Results - Ground + SatelliteSatelliteCloudy Case - IICloudy Case - IIThe 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.
The satellite report
Search Results - Ground + Search Results - Ground + SatelliteSatelliteCloudy Case - IIICloudy Case - IIIThe The student student reportreport
Interesting Interesting disagreementdisagreement
Satellite cannot Satellite cannot see clouds under see clouds under opaque top layeropaque top layer
The satellite reportThe satellite report
Search Results - Ground + Search Results - Ground + SatelliteSatelliteCloudy Case - IVCloudy Case - IVThe student report
Interesting Interesting disagreementdisagreement
Satellite cannot Satellite cannot detect sparse, detect sparse, thin, high cloudsthin, high clouds
The satellite report
Search Results - Ground + Search Results - Ground + SatelliteSatelliteCloudy Case - VCloudy Case - VThe student report
Puzzling Puzzling disagreementdisagreement
Student comments Student comments indicate extensive indicate extensive cloudinesscloudiness
The satellite report
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 0 0 PC Cl PC 0 0 0 PC 0
Grd Sat
0 0 MC MC 0 0 PC 0 0 0 0 0
Grd Sat
0 0 PC PC 0 0 PC Ov Cl 0 0 0
3/63/6
50%50%
5/65/6
83%83%
4/64/6
67%67%
2/62/6
33%33%
Grd Ground
Sat Satellite
0 No Cloud
Cl Clear
PC Partly Cloudy
MC Mostly Cloudy
OV Overcast
Analyzing the Data - Cloud CoverAnalyzing the Data - Cloud Cover
Low cloudLow cloud Mid-level cloudMid-level cloud High cloudHigh cloud AllAll
Grd Sat
0 0 0 0 PC Cl PC 0 0 0 PC 0
Grd Sat
0 0 MC MC 0 0 PC 0 0 0 0 0
Grd Sat
0 0 PC PC 0 0 PC Ov Cl 0 0 0
3/63/6
50%50%
5/65/6
83%83%
4/64/6
67%67%
2/62/6
33%33%
Grd Ground
Sat Satellite
0 No Cloud
Cl Clear
PC Partly Cloudy
MC Mostly Cloudy
OV Overcast
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%)
• 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 Satellite
Cl Clear
PC Partly Cloudy
MC Mostly Cloudy
OV Overcast
Grd Ground
Sat Satellite
0 No Cloud
Cl Clear
PC Partly Cloudy
MC Mostly Cloudy
OV Overcast
Analyzing the Data: How Many Cloud Analyzing the Data: How Many Cloud LayersLayers
GroundGround
ObservationsObservations
Sa
telli
te
Sa
telli
te
Ob
se
rva
tio
ns
Ob
se
rva
tio
ns 0 1 >1
0
1
>1
3/6 = 50% agree completely3/6 = 50% agree completely
3/6 = 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 Analyzing the Data: Which Cloud LevelsLevels
Clr Low Mid LM Hi LH MH LMH
Clr Low
Mid
LM
Hi LH
MH
LMH
Cloud Levels seen from GroundCloud Levels seen from Ground
Clo
ud
Lev
els
seen
fro
m S
atel
lite
Clo
ud
Lev
els
seen
fro
m S
atel
lite
3/6 = 50% agree completely3/6 = 50% agree completely
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.
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, 2002) that includes these examples.
• 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 willfind directions, a key to the file, and a link to get the data.
The Downloaded .bin The Downloaded .bin FileFile• 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
• The file you get will have a name like11301239.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
Inside the .bin fileInside 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.
• 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.
Importing into ExcelImporting into Excel• There are several ways to import data into
Excel. If you already know how, skip this page.1. Open Excel2. Under the File menu, choose Open3. Find the .bin file you downloaded to your
computer. (you may have to Enable: All Documents in the Open menu)
4. Open the file. A Text Import Wizard should start.
5. Delimited is default. Next.6. Tab is default. Next.7. Finish. File should appear as on next page.
• There are several ways to import data into Excel. If you already know how, skip this page.1. Open Excel2. Under the File menu, choose Open3. Find the .bin file you downloaded to your
computer. (you may have to Enable: All Documents in the Open menu)
4. Open the file. A Text Import Wizard should start.
5. Delimited is default. Next.6. Tab is default. Next.7. Finish. File should appear as on next page.
The file in Excel - IThe file in Excel - I
The key lets you interpret the entries in these columns (see slide 22).
Row 1: Variable Name
Row 2: Units
Row 3: Blank
Row 4…: Data
You may notice other blank lines.These have to dowith line feeds, and can be deleted orignored.
The file in Excel - IIThe 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.
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!
• 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