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Level-3 12.5 km Sea Ice Data Fields

The following notations are used throughout this document:

Int8 8-bit (1-byte) signed integer
Int16 16-bit (2-byte) signed integer
NT2 Enhanced NASA Team algorithm
BBA Bootstrap Basic Algorithm

North polar grids are 608 pixels by 896 pixels.
Northern Hemisphere masks are 608 pixels by 896 pixels.
South polar grids are 632 pixels by 664 pixels.

North Polar Grids
Field Name
Data Type
Description
Scale Factor
SI_12km_NH_18V_ASC Int16 18.7 GHz horizontal daily average Brightness Temperatures (Tbs) (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_18V_DSC Int16 18.7 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_18V_DAY Int16 18.7 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_18H_ASC Int16 18.7 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_18H_DSC Int16 18.7 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_18H_DAY Int16 18.7 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_23V_ASC Int16 23.8 GHz vertical daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_23V_DSC Int16 23.8 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_23V_DAY Int16 23.8 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_23H_ASC Int16 23.8 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_23H_DSC Int16 23.8 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_23H_DAY Int16 23.8 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_36V_ASC Int16 36.5 GHz vertical daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_36V_DSC Int16 36.5 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_36V_DAY Int16 36.5 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_36H_ASC Int16 36.5 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_36H_DSC Int16 36.5 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_36H_DAY Int16 36.5 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_89V_ASC Int16 89.0 GHz vertical daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_89V_DSC Int16 89.0 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_89V_DAY Int16 89.0 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_89H_ASC Int16 89.0 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_89H_DSC Int16 89.0 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_89H_DAY Int16 89.0 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_NH_ICECON_ASC Int16 Sea ice concentration daily ascending average

Value
Description
0 Open Water
1 to 100 Percent Ice Concentration
120 Land Mask
Not Applicable (N/A)
SI_12km_NH_ICECON_DSC Int16 Sea ice concentration daily descending average

Value
Description
0 Open Water
1 to 100 Percent Ice Concentration
120 Land Mask
N/A
SI_12km_NH_ICECON_DAY Int16 Sea ice concentration daily average

Value
Description
0 Open Water
1 to 100 Percent Ice Concentration
120 Land Mask
N/A
SI_12km_NH_ICEDIFF_ASC Int16 Sea ice concentration daily ascending average using the difference between BBA and NT2 algorithms

Value
Description
0 Open Water
1 to 100 or -1 to -100 Percent difference between algorithms*
120 Land Mask
200 to 300 Missing NT2 value (200+BBA)**
-200 to -300 Missing BBA value (-200-NT2)**
-310 Out-of-range value in V12 data***
N/A
SI_12km_NH_ICEDIFF_DSC Int16 Sea ice concentration daily descending average using the difference between BBA and NT2 algorithms

Value
Description
0 Open Water
1 to 100 or -1 to -100 Percent difference between algorithms*
200 to 300 Missing NT2 value (200+BBA)**
-200 to -300 Missing BBA value (-200-NT2)**
-310 Out-of-range value in V12 data***
N/A
SI_12km_NH_ICEDIFF_DAY Int16 Sea ice concentration daily average using the difference between BBA and NT2 algorithms

Value
Description
0 Open Water
1 to 100 or -1 to -100 Percent difference between algorithms*
200 to 300 Missing NT2 value (200+BBA)**
-200 to -300 Missing BBA value (-200-NT2)**
-310 Out-of-range value in V12 data***
N/A
SI_12km_NH_SNOWDEPTH_5DAY Int16 5-day running average of snow depth (cm) based on current day and previous 4 days

Value
Description
110 Missing Data
120 Land Mask
130 Open Water
140 Multiyear Sea Ice
150 Variability in Snow Depth
160 Snow Melt
N/A

* Positive values 1 to 100% represent the difference in concentration where NT2 is greater than BBA and negative values -1 to -100% represent the difference in concentration where BBA is greater than NT2.

** The difference values need input from both the NT2 and BBA sea ice concentration algorithms. These new values indicate when one of these is missing. If there is a valid BBA value and missing NT2, it takes on the value 200+BBA. Likewise, a valid NT2 and missing BBA takes on the value -200-NT2. A difference value of 200 means the BBA was open water and the NT2 was missing; a value of 225 means the BBA was 25% and the NT2 was missing. A value of 300 means BBA was 100 and NT2 was missing. The normal range of difference values is -100 to 100.

*** An out-of-range value for the sea ice concentration difference field was introduced in Validated 12 (V12) AMSR-E 12.5 km sea ice data when data from the BBA were missing. The value was -310, whereas the standard value when BBA data are missing is -200 to -300. With V13 data, the data were updated to correct this issue. However, as past data will not be reprocessed, users should be mindful of this out-of-range value when working with data prior to 27 August 2010.

 

Northern Hemisphere Masks

Beginning with Version 12 data, the Northern Hemisphere sea ice and snow melt masks used for the snow depth on sea ice parameter are stored within the 12.5 km product (AE_SI12). The following table describes the mask contents of the HDF files.

Description of Sea Ice and Snow Melt Masks
Field Name Data Type Description Dimensions Scale Factor
date Int16 The processing date (year/month/day) of the masks. 3 n/a
initialization year Int16 The first year in which the mask was set, or reset, to begin processing. 1 n/a
multiyear mask Int16 A multiyear sea ice mask. 608 x 896 n/a
variability 5day Int16 A running 5-day snow melt mask corresponding to the running 5-day snow melt product. 608 x 896 n/a

 


South Polar Grids
Field Name
Data Type
Description
Scale Factor
SI_12km_SH_18V_ASC Int16 18.7 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 kelvin (K)		 Multiply data values by 0.1 to obtain units in kelvin (K)
SI_12km_SH_18V_DSC Int16 18.7 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_18V_DAY Int16 18.7 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_18H_ASC Int16 18.7 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_18H_DSC Int16 18.7 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_18H_DAY Int16 18.7 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_23V_ASC Int16 23.8 GHz vertical daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_23V_DSC Int16 23.8 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_23V_DAY Int16 23.8 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_23H_ASC Int16 23.8 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_23H_DSC Int16 23.8 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_23H_DAY Int16 23.8 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_36V_ASC Int16 36.5 GHz vertical daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_36V_DSC Int16 36.5 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_36V_DAY Int16 36.5 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_36H_ASC Int16 36.5 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_36H_DSC Int16 36.5 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_36H_DAY Int16 36.5 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_89V_ASC Int16 89.0 GHz vertical daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_89V_DSC Int16 89.0 GHz vertical daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_89V_DAY Int16 89.0 GHz vertical daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_89H_ASC Int16 89.0 GHz horizontal daily average ascending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_89H_DSC Int16 89.0 GHz horizontal daily average descending Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_89H_DAY Int16 89.0 GHz horizontal daily average Tbs (K)
Valid range: approximately 50 to 300 K		 Multiply data values by 0.1 to obtain units in K
SI_12km_SH_ICECON_ASC Int16 Sea ice concentration daily ascending average

Value
Description
0 Open Water
1 to 100 Percent Ice Concentration
110 Not Calculated
120 Land Mask
N/A
SI_12km_SH_ICECON_DSC Int16 Sea ice concentration daily descending average

Value
Description
0 Open Water
1 to 100 Percent Ice Concentration
110 Not Calculated
120 Land Mask
N/A
SI_12km_SH_ICECON_DAY Int16 Sea ice concentration daily average

Value
Description
0 Open Water
1 to 100 Percent Ice Concentration
110 Not Calculated
120 Land Mask
N/A
SI_12km_SH_ICEDIFF_ASC Int16 Sea ice concentration daily ascending average using the difference between BBA and NT2 algorithms

Value
Description
0 Open Water
1 to 100 or -1 to -100 Percent difference between algorithms*
110 Not Calculated
120 Land Mask
200 to 300 Missing NT2 value (200+BBA)**
-200 to -300 Missing BBA value (-200-NT2)**
-310 Out-of-range value in V12 data***
N/A
SI_12km_SH_ICEDIFF_DSC Int16 Sea ice concentration daily descending average using the difference between BBA and NT2 algorithms

Value
Description
0 Open Water
1 to 100 or -1 to -100 Percent difference between algorithms*
110 Not Calculated
120 Land Mask
200 to 300 Missing NT2 value (200+BBA)**
-200 to -300 Missing BBA value (-200-NT2)**
-310 Out-of-range value in V12 data***
N/A
SI_12km_SH_ICEDIFF_DAY Int16 Sea ice concentration daily average using the difference between BBA and NT2 algorithms

Value
Description
0 Open Water
1 to 100 or -1 to -100 Percent difference between algorithms*
110 Not Calculated
120 Land Mask
200 to 300 Missing NT2 value (200+BBA)**
-200 to -300 Missing BBA value (-200-NT2)**
-310 Out-of-range value in V12 data***
N/A
SI_12km_SH_SNOWDEPTH_5DAY Int16 5-day running average of snow depth (cm) based on current day and previous 4 days

Value
Description
110 Not Calculated
120 Land Mask
130 Open Water
140 Multiyear Sea Ice
150 Variability in Snow Depth
160 Snow Melt
N/A

* Positive values 1 to 100% represent the difference in concentration where NT2 is greater than BBA and negative values -1 to -100% represent the difference in concentration where BBA is greater than NT2.

** The difference values need input from both the NT2 and BBA sea ice concentration algorithms. These new values indicate when one of these is missing. If there is a valid BBA value and missing NT2, it takes on the value 200+BBA. Likewise, a valid NT2 and missing BBA takes on the value -200-NT2. A difference value of 200 means the BBA was open water and the NT2 was missing; a value of 225 means the BBA was 25% and the NT2 was missing. A value of 300 means BBA was 100 and NT2 was missing. The normal range of difference values is -100 to 100.

*** An out-of-range value for the sea ice concentration difference field was introduced in Validated 12 (V12) AMSR-E 12.5 km sea ice data when data from the BBA were missing. The value was -310, whereas the standard value when BBA data are missing is -200 to -300. With V13 data, the data were updated to correct this issue. However, as past data will not be reprocessed, users should be mindful of this out-of-range value when working with data prior to 27 August 2010.

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