1. VIPLab QA Data Filtering Process

2. Ranking Codes CODE Description 1 Ideal Data, Good and Useful 2
Good to Marginal 3
Marginal to Questionable 4
Snow 5
Cloud 6
Estimated 7
NO DATA

3. MODIS Flags and Data Variable Data Cloud State Bit 0-1: 00 = Clear
01 = Cloudy
10 = Mixed
11 = not set, assumed clear
Cloud Shadow?
Bit 2: 1=Yes, 0=No
Pixel adjacent to Cloud (Not used)
Bit 13: 1=Yes, 0=No
Aerosol Quantity
Bit 6-7:
00 = Climatology
01 = Low
10 = Average
11 = High
Snow/Ice
Bit 12: 1=Yes, 0=No
Cirrus detected (Not used)
Bit 8-9:
00 = None
01 = Small
View Angle
Pixel Information, Degrees
(Solar Zenith Angle)

4. AVHRR Flags and Data Variable Data Cloudy? Bit 1: 1=yes, 0=no
Cloud Shadow?
Bit 2: 1=yes, 0=no
Aerosol Quantity
N/A
Snow/Ice
N/A (processing)
View Angle
Pixel Information, Degrees
(Solar Zenith Angle, View Zenith Angle)

5. Decision Tree – Data Filtering
START
Data valid No
Rank =7
Yes
Yes
IsCloudy
Rank=5 No
Yes
IsSnow
Rank=4 No
Yes
Yes
Cloud
Shadow
Low Aerosol & Vz<30 No No
Low Aerosol No
Yes No
Vz<=30
Yes
Rank=1
Rank=2
Rank=3
Rank=2

6. AVHRR Screening / Decision Tree
START No
isData
Rank =7
Yes
Yes
IsCloudy
Rank=5 No
Cloud
Shadow
Yes No
Vz<=30 No
Cloud Shadow &Vz>30
Rank=2
Yes
Rank=1
Rank=3