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I'm processing BUFR products from Eumetsat and I would like to ask for your help about the following descriptors:

002028 SEGMENT SIZE AT NADIR IN X DIRECTION
002029 SEGMENT SIZE AT NADIR IN Y DIRECTION

My problem is that I don't know how to interpret their values.

For example in ASR (All sky radiance) product from MSG, I have this subset in the first message of the bufr file:

:Subset 1
:
:     1  001007               57  SATELLITE IDENTIFIER [CODE TABLE]
:     2  001031              254  IDENTIFICATION OF ORIGINATING/GENERATING CENTRE: [CODE TABLE]
:     3  002020              333  SATELLITE CLASSIFICATION [CODE TABLE]
:
     4  002028            48000  SEGMENT SIZE AT NADIR IN X-DIRECTION [M]
:     5  002029            48000  SEGMENT SIZE AT NADIR IN Y-DIRECTION [M]
:     6  004001             2015  YEAR [A]
:     7  004002                2  MONTH [MON]
:     8  004003               27  DAY [D]
:     9  004004               20  HOUR [H]
:    10  004005               45  MINUTE [MIN]
:    11  004006                0  SECOND [S]
:    12  005001         23.46664  LATITUDE (HIGH ACCURACY) [DEG]
:    13  006001         -59.6647  LONGITUDE (HIGH ACCURACY) [DEG]
:    14  030021             3712  NUMBER OF PIXELS PER ROW [NUMERIC]
:    15  030022             3712  NUMBER OF PIXELS PER COLUMN [NUMERIC]
:    16  010002          missing  HEIGHT [M]
:    17  020082               62  AMOUNT SEGMENT CLOUD FREE [%]
:    18  008012                1  LAND/SEA QUALIFIER [CODE TABLE]
:    19  020082                0  AMOUNT SEGMENT CLOUD FREE [%]
:    20  008012          missing  LAND/SEA QUALIFIER [CODE TABLE]
:    21  020081               38  CLOUD AMOUNT IN SEGMENT [%]
:    22  008003                8  VERTICAL SIGNIFICANCE (SATELLITE OBSERVATIONS) :[CODE TABLE]
:    23  020081               38  CLOUD AMOUNT IN SEGMENT [%]
:    24  008003                9  VERTICAL SIGNIFICANCE (SATELLITE OBSERVATIONS) :[CODE TABLE]
:    25  020081                0  CLOUD AMOUNT IN SEGMENT [%]

As you can see, in this subset we have a single point with a LATITUDE and LONGITUDE. I interpret a subset as a description of a single segment and as above this segment has a single coordinates and a single value for a certain data type. So I get that segment = pixel. And so pixel has a dimension of 48000m x 48000m as written in the subset. Is this right? Why I read also:

:    14  030021             3712  NUMBER OF PIXELS PER ROW [NUMERIC]
:    15  030022             3712  NUMBER OF PIXELS PER COLUMN [NUMERIC]

If a pixel has the dimension above we can't have an image size of 3712 x 3712. Also I know that MSG has a pixel resolution of 3km x 3km and 1km x 1km not 48km x 48km.

Any ideas please?

  • 1 bufr pixel = 16x16 MSG pixel :) – Marco Ciaramella May 7 '15 at 12:58
  • 2
    Hi Marco, could you please post your solution as an Answer instead of adding "SOLVED" to your title? When you post your answer, you can click the green tick to close this question off (note: you will have to wait 2 days from when you first posted your question). – Joseph May 7 '15 at 12:59
2

Solved with:

1 bufr pixel = 16x16 MSG pixel, then the size is (3712 / 16) x (3712 / 16) = 232 x 232 pixels :)

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