
File Format Basics
MOD08_E3 product files are stored in Hierarchical Data Format (HDF).
HDF is a multiobject file format for sharing
scientific data in multiplatform distributed environments.
HDF files should only be accessed through HDF library subroutine and function calls,
which can be downloaded from the HDF web site.
Each of the 739 gridded statistical fields
within the HDF file is stored as a Scientific Data Set (SDS).
Only a subset of statistics outlined in the Statistic List (see below)
are computed for each parameter.
MOD08_E3 Parameter List
Parameters derived from MOD04_L2
AEROSOL: LAND & OCEAN (Y.KAUFMAN)
1. Scattering_Angle

Derived from the MOD04_L2 SDS "Scattering_Angle".

2. Optical_Depth_Land_And_Ocean

Derived from the MOD04_L2 SDS "Optical_Depth_Land_And_Ocean".

3. Optical_Depth_Ratio_Small_Land_And_Ocean

Derived from the MOD04_L2 SDS "Optical_Depth_Ratio_Small_Land_And_Ocean".

4. Reflected_Flux_Land_And_Ocean

Derived from the MOD04_L2 SDS "Reflected_Flux_Land_And_Ocean".

AEROSOL: LAND ONLY (Y.KAUFMAN)
5. Corrected_Optical_Depth_Land

Derived from the MOD04_L2 SDS "Corrected_Optical_Depth_Land".
Note that this parameter group contains three joint histograms for optical depth computed using 0.47 vs 0.55 microns, 0.47 vs 0.66 microns, and 0.55 vs 0.66 microns at 5x5 intervals for each.

6. Optical_Depth_Ratio_Small_Land

Derived from the MOD04_L2 SDS "Optical_Depth_Ratio_Small_Land".

7. Mass_Concentration_Land

Derived from the MOD04_L2 SDS "Mass_Concentration_Land".

8. Angstrom_Exponent_Land

Derived from the MOD04_L2 SDS "Angstrom_Exponent".

9. Transmitted_Flux_Land

Derived from the MOD04_L2 SDS "Transmitted_Flux_Land".

10. Reflected_Flux_Land

Derived from the MOD04_L2 SDS "Reflected_Flux_Land".

11. Mean_Reflectance_Land_All

Derived from the MOD04_L2 SDS "Mean_Reflectance_Land_All".
The parameter has three spectral band solutions
(.47, .66, and 2.13 microns)
Two groups of statistics are available in MOD08,
one group is associated with QA for .47 microns,
the other is associated with QA for .66 microns.
The parameter groups are called Mean_Reflectance_Land_All_QA47
and Mean_Reflectance_Land_All_QA66, respectively.

AEROSOL: OCEAN ONLY (D.TANRE)
12. Mass_Concentration_Ocean

Derived from the MOD04_L2 SDS "Mass_Concentration_Ocean ".

13. Effective_Optical_Depth_Average_Ocean

Derived from the MOD04_L2 SDS "Effective_Optical_Depth_Average_Ocean".

14. Optical_Depth_Ratio_Small_860_Ocean

Derived from the MOD04_L2 SDS "Optical_Depth_Ratio_Small_Ocean_0.86micron".
There are two solutions (dimensions), one for best and one for average.
(The now defunct parameter "Optical_Depth_Ratio_Small_Ocean" was derived at 0.55
and was replaced by this parameter in Spring 2002.)

15. Effective_Radius_Ocean

Derived from the MOD04_L2 SDS "Effective_Radius_Ocean".

16. Cloud_Condensation_Nuclei_Ocean

Derived from the MOD04_L2 SDS "Cloud_Condensation_Nuclei_Ocean".

17. Angstrom_Exponent_1_Ocean
18. Angstrom_Exponent_2_Ocean

Derived from the MOD04_L2 SDS "Angstrom_Exponent_1_Ocean"
and "Angstrom_Exponent_2_Ocean", respectively.

19. Asymmetry_Factor_Average_Ocean

Derived from the MOD04_L2 SDS "Asymmetry_Factor_Average_Ocean".

20. Backscattering_Ratio_Average_Ocean

Derived from the MOD04_L2 SDS "Backscattering_Ratio_Average_Ocean".

21. Transmitted_Flux_Average_Ocean

Derived from the MOD04_L2 SDS "Transmitted_Flux_Average_Ocean".

22. Reflected_Flux_Average_Ocean

Derived from the MOD04_L2 SDS "Reflected_Flux_Average_Ocean".

23. Optical_Depth_by_models_ocean

Derived from the MOD04_L2 SDS "Optical_Depth_by_models_ocean".
The parameter has solutions at 9 models.

Parameters derived from MOD05_L2
WATER VAPOR (B.GAO)
24. Water_Vapor_Near_Infrared_Clear
25. Water_Vapor_Near_Infrared_Cloud

Derived from the MOD05_L2 SDS "Water_Vapor_Near_Infrared"
and aggregated into a clear or cloud category
from the MOD05_L2 SDS "Quality_Assurance_Near_Infrared".

Parameters derived from MOD06_L2
CIRRUS DETECTION (B.GAO)
26. Cirrus_Reflectance
27. Contrail_Reflectance

Derived from the MOD06_L2 SDS "Cirrus_Reflectance"
and aggregated into a cirrus or contrail category
from the MOD06_L2 SDS "Cirrus_Reflectance_Flag".

28. Cirrus_Fraction_SWIR
29. Contrail_Fraction_SWIR

Derived from the MOD06_L2 SDS "Cirrus_Reflectance_Flag"
and aggregated into a cirrus or contrail category
from the MOD06_L2 SDS "Cirrus_Reflectance_Flag".
This flag differentiates between BadData, NonCirrus,
Cirrus, or Contrail at 1km resolution.

CLOUD TOP PROPERITES (P.MENZEL)
30. Cloud_Top_Temperature
31. Cloud_Top_Temperature_Day
32. Cloud_Top_Temperature_Night

Derived from the MOD06_L2 SDS "Cloud_Top_Temperature"
and aggregated into Day or Night categories
from the MOD06_L2 SDS "Cloud_Mask_5km".

33. Cloud_Top_Pressure
34. Cloud_Top_Pressure_Day
35. Cloud_Top_Pressure_Night

Derived from the MOD06_L2 SDS "Cloud_Top_Pressure"
and aggregated into Day or Night categories
from the MOD06_L2 SDS "Cloud_Mask_5km".

36. Cloud_Effective_Emissivity
37. Cloud_Effective_Emissivity_Day
38. Cloud_Effective_Emissivity_Night

Derived from the MOD06_L2 SDS "Cloud_Effective_Emissivity"
and aggregated into Day or Night categories
from the MOD06_L2 SDS "Cloud_Mask_5km".

39. Cloud_Phase_Infrared
40. Cloud_Phase_Infrared_Day
41. Cloud_Phase_Infrared_Night

Derived from the MOD06_L2 SDS "Cloud_Phase_Infrared"
and aggregated into Day or Night categories
from the MOD06_L2 SDS "Cloud_Mask_5km".
The various dimensions of the Histogram Counts statistic
corresponds to clear = 0, water = 1 or 5, ice = 2 or 4, mixed = 3, and uncertain = 6.
Note that categories 4 and 5 were eliminated in a year 2000 L2 code delivery.

42. Cloud_Fraction_Infrared
43. Cloud_Fraction_Infrared_Day
44. Cloud_Fraction_Infrared_Night

Derived from the MOD06_L2 SDS "Cloud_Fraction"
and aggregated into Day or Night categories
from the MOD06_L2 SDS "Cloud_Mask_5km".

45. Cirrus_Fraction_Infrared
46. High_Cloud_Fraction_Infrared

Derived from the MOD06_L2 SDS "Quality_Assurance_5km"
The SDS's are an interpretation of the Retrieval Processing Path Flags:
Cirrus/NoCirrus or HighCloud/NoHighCloud.

CLOUD OPTICAL PROPERTIES (M.KING)
47. Cloud_Optical_Thickness_Water
48. Cloud_Optical_Thickness_Ice
49. Cloud_Optical_Thickness_Undetermined
50. Cloud_Optical_Thickness_Mixed_Phase
51. Cloud_Optical_Thickness_Combined

Derived from the MOD06_L2 SDS "Cloud_Optical_Thickness"
and aggregated into Cloud Phase categories
(water, ice, undetermined, mixed, combined)
from the MOD06_L2 SDS "Quality_Assurance_1km".
Note that the liquid water cloud parameter contains three joint histograms for COT vs Cloud Effective Radius, COT vs Cloud Top Temperature, and COT vs Effective Emissivity at 11x10, 11x12, and 11x10 intervals, respectively; and the ice cloud parameter also contains the same three joint histograms but at 11x12, 11x10, and 11x10 intervals, respectively.

52. Cloud_Effective_Radius_Water
53. Cloud_Effective_Radius_Ice
54. Cloud_Effective_Radius_Undetermined
55. Cloud_Effective_Radius_Mixed_Phase
56. Cloud_Effective_Radius_Combined

Derived from the MOD06_L2 SDS "Effective_Particle_Radius"
and aggregated into Cloud Phase categories
(water, ice, undetermined, mixed, combined)
from the MOD06_L2 SDS "Quality_Assurance_1km".
Note that the liquid water cloud parameter contains two joint histograms for CER vs Cloud Top Temperature and CER vs Effective Emissivity at 10x12 and 10x10 intervals, respectively; and the ice cloud parameter also contains the same two joint histograms but at 12x10 and 12x10 intervals, respectively.

57. Water_Path_Liquid
58. Water_Path_Ice
59. Water_Path_Undetermined
60. Water_Path_Mixed_Phase
61. Water_Path_Combined

Derived from the MOD06_L2 SDS "Water_Path"
and aggregated into Cloud Phase categories
(water, ice, undetermined, mixed, combined)
from the MOD06_L2 SDS "Quality_Assurance_1km".

62. Cloud_Fraction_Water
63. Cloud_Fraction_Ice
64. Cloud_Fraction_Undetermined
65. Cloud_Fraction_Mixed_Phase
66. Cloud_Fraction_Total

Derived (and aggregated into Cloud Phase categories:
water, ice, undetermined, mixed, combined)
from the MOD06_L2 SDS "Quality_Assurance_1km".
The SDS's are an interpretation of the
Retrieval Processing Path Flags (decision tree outcome)
that is determined from the Cloud Mask, IR and SWIR tests.

67. Cloud_Fraction_SWIR_Water
68. Cloud_Fraction_SWIR_Ice
69. Cloud_Fraction_SWIR_Undetermined
70. Cloud_Fraction_SWIR_Total

Derived (and aggregated into Cloud Phase categories:
water, ice, undetermined, combined)
from the MOD06_L2 SDS "Quality_Assurance_1km".
The SDS's are an interpretation of the
Determination of Cloud Phase from the SWIR test only.
Note that as of March 2001, the SWIR algorithm is still under development,
so these SDS parameters contain all missing data.

Parameters derived from MOD07_L2
ATMOSPHERE PROFILE (P.MENZEL)
71. Total_Ozone

Derived from the MOD07_L2 SDS "Total_Ozone".

72. Total_Totals

Derived from the MOD07_L2 SDS "Total_Totals".

73. Lifted_Index

Derived from the MOD07_L2 SDS "Lifted_Index".

74. K_Index

Derived from the MOD07_L2 SDS "K_Index".

75. Atmospheric_Water_Vapor
76. Atmospheric_Water_Vapor_Low
77. Atmospheric_Water_Vapor_High

Derived from the MOD07_L2 SDS's
"Water_Vapor, "Water_Vapor_Low", and "Water_Vapor_High", respectively.
The keywords "Low" and "High" refer to the lower and higher
portions of the atmospheric column. Note that the parameter
"Water Vapor" is also refered to as "Precipitable Water".

MOD08_E3 Statistic List
A number of statistical summaries are computed, depending on the science parameter being considered.
Statistics for a given Level2 measurement might include:
Simple Statistics of the Mean
 Mean_Mean
 Mean_Min
 Mean_Max
 Mean_Std
Mean of the Standard Deviation
 Std_Deviation_Mean
QA Weighted Statistics
 QA_Mean_Mean
 QA_Mean_Std
 QA_Mean_Min
 QA_Mean_Max
 QA_Std_Deviation_Mean
Histograms of the quantity within each grid box
 Histogram_Counts
Histograms of the confidence placed in each measurement
 Confidence_Histograms
Mean and Standard Deviation of the Fraction of pixels that satisfy some condition (e.g. cloudy, clear)
 FMean
 FStd
Total number of observations (pixels) within each grid box
 Pixel_Counts
Parameters of LogNormal Distributions
 Log_Mean_Mean
 Log_Mean_Std
 Log_Mean_Min
 Log_Mean_Max
 Log_Std_Deviation_Mean
Parameters of QA Weighted LogNormal Distributions
 QA_Log_Mean_Mean
 QA_Log_Mean_Std
 QA_Log_Mean_Min
 QA_Log_Mean_Max
 QA_Log_Std_Deviation_Mean
Regressions and/or Histograms derived from comparing one science parameter to another, statistics may be computed for a subset that satisfies some condition
 Regression_Slope
 Regression_Intercept
 Regression_R_Squared
 Regression_Mean_Square_Error
 Joint_Histogram_vs_Effect_Radius
 Joint_Histogram_vs_Temperature
 Joint_Histogram_vs_Emissivity
 Joint_Histogram_47vs55
 Joint_Histogram_47vs66
 Joint_Histogram_55vs66
Statistic Computation Details
Below are more details on the computation of each statistic:
For the daily product, assume that x1, x2, …, xn represent the retrieved pixel values of a Level2 parameter over a 1 x 1 degree grid box, Qi is the quality flag for each retrieved pixel value, and wi is the weighting factor (1 for the daily case), then the simple statistics are defined as:
In these equations, (1) will be referred to as the 'regular' mean, (2) as the QA weighted mean, (3) as the regular standard deviation, (4) as the QA weighted standard deviation, (5) as the minimum, and (6) as the maximum.
The simple statistics also include daily log regular mean, log standard deviation, log QA mean, and log QA standard deviation. These log quantities are calculated as shown in equations (1  4), except that x1, x2, …, xn are replaced by their logarithms.
Regression statistics, based on the pixels within each 1 by 1 degree grid cell, includes the slope, intercept, meansquarederror (MSE), and the coefficient of determination (R2).
The histograms and joint histograms report the counts of the pixels falling into predetermined numerical intervals.
The pixel counts are used to represent the number of pixels for the parameters which do not have QA flags, while the confidencehistogramscounts are used to represent the number of counts for each parameter that falls within each QA bin (e.g., questionable, good, very good, and total).
