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AMR Experimental Product              		    *
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The Advanced Microwave Radiometer (AMR) experimental product (EXP) is a research grade product that supplements information provided on the Jason-2 Geophysical Data Records (GDRs). The product contains enhanced wet troposphere path delays (PDs) within 25 km from land, a radiometer land flag for the enhanced PDs, and rain and ice flags derived exclusively from the radiometer.  The primary purpose of the product is for users to test these new fields. 

The file naming convention is equivalent to the Jason-2 GDR with "AMR_EXP" added.  If the file is made from the GDR product it will contain "GPN."  If it is made from the Interim GDR (IGDR) product, it will contain "IGN."  However, typically the product will be provided only as a supplement to the GDR. The time, latitude and longitude fields included in the file are identical to those on the Jason-2 I/GDR, and the number of records in each pass file is the same as on the GDR.  An example file name is below:

JA2_GPN_AMR_EXP_2PTP001_001_20080712_012005_20080712_021617.nc

Details about the file contents and a sample header from a file are provided below.

All questions/comments/feedback about the product should be directed to Shannon Brown (Shannon.T.Brown@jpl.nasa.gov).


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Enhanced Wet Tropospheric Path Delay           *
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The enhanced wet troposphere path delay is identical to the rad_wet_tropo_corr field on the GDR greater than approximately 25 km from land.  Near the coast, an improved near land wet path delay algorithm is applied to improve the performance up to the coast.  
The algorithm error when applied to the AMR is estimated to be less than 0.8 cm up to 15 km from land, less than 1.0 cm within 10 km from land, less than 1.2 cm within 5 km from land and less than 1.5 cm up to the coastline. This is estimated from detailed simulations and validated by comparisons with measured AMR data.  

Full details can be found in:

Brown, S. "A Novel Near-Land Radiometer Wet Path Delay Retrieval Algorithm:  Application to the Jason-2/OSTM Advanced Microwave Radiometer", submitted to IEEE Trans. Geosci. Rem. Sens. March 2009



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Enhanced Wet Tropospheric Path Delay Land Flag              *
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The enhanced radiometer PD land flag that is included with the product is applicable to only the enhanced PD product.  The flag will be 1 (invalid) when the radiometer boresight is centered on the coastline and remain 1 when the radiometer is over land.  The flag will be 0 (valid) if at least half of the radiometer footprint is ocean.  The radiometer land flag on the GDR is valid only for the GDR PD and not the enhanced PD.

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Radiometer Sea Ice Flag          *
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The sea ice flag indicates if the radiometer path delay measurement should be considered invalid due to sea ice contamination.  This flag is applicable to both the GDR PD and the new enhanced PD.  The sea ice flag is 0 if the measurement is valid and 1 if the measurement is invalid due to sea ice.

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Radiometer Rain Flag        *
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The rain ice flag indicates if the radiometer path delay measurement should be considered invalid due to rain contamination.  This flag is applicable to both the GDR PD and the new enhanced PD.  The rain flag is 0 if the measurement is valid and 1 if the measurement is invalid due to rain.


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Header output from a AMR EXP file         *
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netcdf F:\AMR\JA2_Level1B\Jan282009_recal_GDRv0\AMR_NL_files\GDR_LD_merge\JA2_GPN_AMR_EXP_2PTP004_057_20080812_234341_20080813_003954 {
dimensions:
	time = 3251 ;
variables:
	double time(time) ;
		time:units = "seconds" ;
		time:description = "seconds since 1/1/2000 00:00:00" ;
		time:scale_factor = 1. ;
	int lat(time) ;
		lat:units = "degrees_north" ;
		lat:description = "Latitude [-90:90]" ;
		lat:scale_factor = 1.e-006 ;
	int lon(time) ;
		lon:units = "degrees_east" ;
		lon:description = "Longitude [0:360]" ;
		lon:scale_factor = 1.e-006 ;
	short rad_wet_tropo_corr_epd(time) ;
		rad_wet_tropo_corr_epd:units = "m" ;
		rad_wet_tropo_corr_epd:description = "Enhanced Wet Tropo Path Delay;  wet path delay is identical to rad_wet_tropo_corr on GDR > ~25 km from land, but uses improved algorithms for coastal path delays" ;
		rad_wet_tropo_corr_epd:scale_factor = 0.0001 ;
		rad_wet_tropo_corr_epd:Fill_value = 32767s ;
	byte rad_sea_ice_flag(time) ;
		rad_sea_ice_flag:units = "/" ;
		rad_sea_ice_flag:description = "AMR Sea Ice Flag (0=no ice, 1=ice); Ice flag is 1 when GDR wet path delay or enhanced wet path delay radiometer product is invalid due to sea ice contamination" ;
		rad_sea_ice_flag:scale_factor = 1. ;
		rad_sea_ice_flag:Fill_value = 127b ;
	byte rad_rain_flag(time) ;
		rad_rain_flag:units = "/" ;
		rad_rain_flag:description = "AMR Rain Flag (0=no rain, 1=rain); Rain flag is 1 when GDR wet path delay or enhanced wet path delay radiometer product is invalid due to rain contamination" ;
		rad_rain_flag:scale_factor = 1. ;
		rad_rain_flag:Fill_value = 127b ;
	byte rad_epd_land_flag(time) ;
		rad_epd_land_flag:units = "/" ;
		rad_epd_land_flag:description = "AMR Enhanced Wet Tropo Path Delay Land Flag (0=no land, 1=land); Enhanced PD land flag is 1 when radiometer enhanced wet path delay product is invalid due to land contamination contamination" ;
		rad_epd_land_flag:scale_factor = 1. ;
		rad_epd_land_flag:Fill_value = 127b ;
}