search

wmo-im / BUFR4

BUFR edition 4
MIT License
27 stars 9 forks source link

Proposal for new BUFR table entries for Sentinel-6 Michael Freilich #15

Closed erget closed 4 years ago

erget commented 4 years ago

Branch

https://github.com/wmo-im/BUFR4/tree/issue-15

Summary and purpose

This document proposes new BUFR entries in order to represent altimeter data from Sentinel-6 Michael Freilich.

Action proposed

The meeting is requested to approve the contents for inclusion within the next update to the WMO Manual on Codes.

Discussions

Sentinel-6 Michael Freilich is due to be launched in the autumn of 2020. In order to ensure the standardized exchange of data from the radiometer mission, a number of BUFR table entries have been developed and are proposed here for adoption.

Detailed proposal

Add the following sequence 3-40-019 “Altimeter product” to BUFR Table D/01:

Table references Element name
3-40-020 Satellite general values
3-40-021 General radiometer values
3-40-022 Altimeter model values
3-40-023 Altimeter main values

Add the following sequence 3-40-020 “Satellite general values” to BUFR Table D/01:

Table references Element name
0-01-007 Satellite identifier
0-02-019 Satellite instruments
0-05-044 Satellite cycle number
0-01-096 Station acquisition
0-05-040 Orbit number
0-01-040 Processing centre id code
0-25-061 Software identification and version number
0-25-182 L1 processing flag
0-25-183 L1 processing quality
0-25-181 L2 processing flag
0-25-184 L2 product status
0-08-075 Ascending/descending orbit qualifier
0-25-090 Orbit state flag
3-01-011 Date
3-01-013 Time
0-04-007 Seconds within a minute (microsecond accuracy)
3-01-021 Latitude and longitude (high resolution)
0-05-063 Spacecraft roll
0-05-064 Spacecraft pitch
0-05-066 Spacecraft yaw
0-10-081 Altitude of cog above reference ellipsoid
0-10-082 Instantaneous altitude rate

Add the following sequence 3-40-021 “General radiometer values” to BUFR Table D/01:

Table references Element name
0-40-012 Radiometer data quality flag
0-08-077 Radiometer sensed surface type
1-04-000 Delayed replication
0-31-001 Delayed descriptor replication factor
0-02-153 Satellite channel centre frequency
0-12-063 Brightness temperature
0-12-065 Standard deviation brightness temperature
0-40-013 Radiometer brightness temperature interpretation flag
0-07-002 Height or altitude
0-11-098 Wind speed from radiometer

Add the following sequence 3-40-022 “Altimeter model values” to BUFR Table D/01:

Table references Element name
0-08-029 Surface type
2-01-137 Change data width
2-02-129 Change data scale
0-06-021 Distance
2-02-000 Reset scale
2-01-000 Reset width
0-10-087 Ocean depth/land elevation
0-40-024 Meteorological map availability
0-07-002 Height or altitude
0-25-126 Model dry tropospheric correction
0-25-128 Model wet tropospheric correction
0-40-011 Interpolation flag
0-07-002 Height or altitude
0-11-095 U-component of the model wind vector
0-11-096 V-component of the model wind vector
0-10-088 Total geocentric ocean tide height (solution 1)
0-10-089 Total geocentric ocean tide height (solution 2)
0-10-090 Long period tide height
0-10-092 Solid earth tide height
0-10-093 Geocentric pole tide height
0-10-098 Loading tide height geocentric ocean tide solution 1
0-10-099 Loading tide height geocentric ocean tide solution 2
0-10-100 Non-equilibrium long period tide height
0-25-127 Inverted barometer correction
0-40-014 High-frequency fluctuations of the sea-surface topography correc
0-01-030 Numerical model identifier
0-10-085 Mean sea-surface height
0-01-030 Numerical model identifier
0-10-085 Mean sea-surface height
0-10-086 Geoid's height
0-10-096 Mean dynamic topography
0-10-103 Mean dynamic topography accuracy
0-21-169 Ice presence indicator
0-13-055 Intensity of precipitation
0-25-165 Ionospheric correction from model on specific band

Add the following sequence 3-40-023 “Altimeter main values” to BUFR Table D/01:

Table references Element name
0-25-095 Altimeter state flag
0-40-023 Auxiliary altimeter state flags
0-08-074 Altimeter echo type
3-40-024 1 Hz C and Ku band values
3-40-024 1 Hz C and Ku band values
3-40-024 1 Hz C and Ku band values
3-40-025 20 Hz C and Ku band values

Add the following sequence 3-40-024 “1 Hz C and Ku band values” to BUFR Table D/01:

Table references Element name
0-22-080 Waveband central frequency
0-08-076 Type of band
0-25-190 Altimeter echo processing mode
0-10-102 Sea-surface height anomaly
0-22-189 Specific band ocean range
0-22-191 Rms of specific band ocean range
0-22-130 Number of valid points for specific band
0-25-167 Specific band net instrumental correction
0-25-163 Altimeter ionospheric correction on ku band
0-15-012 Total electron count per square metre
0-25-164 Radiometer wet tropospheric correction
0-13-090 Radiometer water vapour content
0-13-091 Radiometer liquid content
0-25-166 Sea state bias correction on specific band
0-07-002 Height or altitude
0-11-097 Wind speed from altimeter
0-21-183 Specific band corrected ocean backscatter coefficient
0-21-184 Std specific band corrected ocean backscatter coefficient
0-22-134 Number of valid points for specific band backscatter
0-21-122 Attenuation correction on sigma-0 (from tb)
0-21-186 Specific band automatic gain control
0-21-187 Rms specific band automatic gain control
0-21-188 Number of valid points for specific band automatic gain control
2-01-131 Change data width
0-21-185 Specific band net instrumental correction for agc
2-01-000 Reset width
0-22-179 Specific band significant wave height
0-22-131 Rms specific band significant wave height
0-22-132 Number of valid points for specific band significant wave height
0-22-133 Specific band net instrument correction for significant wave height
0-21-144 Altimeter rain flag
0-25-191 Altimeter tracking mode
0-21-143 Ku band rain attenuation
0-10-101 Squared off-nadir angle of the satellite from waveform data
0-25-112 Band specific altimeter data quality flag
0-25-113 Band specific altimeter correction quality flag
0-33-092 Band specific ocean quality flag

Add the following sequence 3-40-025 “20 Hz C and Ku band values” to BUFR Table D/01:

Table references Element name
0-08-049 Number of observations
0-22-080 Waveband central frequency
0-08-076 Type of band
0-25-190 Altimeter echo processing mode
1-46-021 Replication
3-01-011 Date
3-01-013 Time
0-04-007 Seconds within a minute (microsecond accuracy)
3-01-021 Latitude and longitude (high resolution)
0-10-081 Altitude of cog above reference ellipsoid
0-10-082 Instantaneous altitude rate
0-08-029 Surface type
2-01-137 Change data width
2-02-129 Change data scale
0-06-021 Distance
2-02-000 Reset scale
2-01-000 Reset width
0-25-191 Altimeter tracking mode
0-21-071 Peakiness
0-01-030 Numerical model identifier
0-10-085 Mean sea-surface height
0-01-030 Numerical model identifier
0-10-085 Mean sea-surface height
0-40-011 Interpolation flag
0-10-088 Total geocentric ocean tide height (solution 1)
0-10-089 Total geocentric ocean tide height (solution 2)
0-25-164 Radiometer wet tropospheric correction
0-07-002 Height or altitude
0-25-126 Model dry tropospheric correction
0-25-128 Model wet tropospheric correction
0-10-102 Sea-surface height anomaly
0-22-189 Specific band ocean range
0-25-167 Specific band net instrumental correction
0-25-163 Altimeter ionospheric correction on ku band
0-21-183 Specific band corrected ocean backscatter coefficient
2-01-131 Change data width
0-21-185 Specific band net instrumental correction for agc
2-01-000 Reset width
0-22-179 Specific band significant wave height
0-22-133 Specific band net instrument correction for significant wave height
0-22-146 Ocog range
0-21-189 Corrected OCOG* backscatter coefficient
0-13-163 Snow water equivalent
2-02-126 Change data scale
0-22-046 Sea ice fraction
2-02-000 Reset scale
0-13-117 Snow density (liquid water content)
0-13-013 Total snow depth
0-25-112 Band specific altimeter data quality flag
0-25-113 Band specific altimeter correction quality flag
0-33-092 Band specific ocean quality flag

Add the following elements to BUFR Table B/40:

Descriptor Name Units Scale Reference Width
0-21-189 Corrected OCOG* backscatter coefficient (negative reference) dB 2 -32768 16
0-22-179 Specific band significant wave height (negative reference) M 3 -500 16

Notes:

jbathegit commented 4 years ago

Hi Daniel - a reminder that Y > 191 means a descriptor is local, so your proposed new FXY numbers 0-21-192, 0-22-192 and 3-40-192, 3-40-193, ..., 3-40-198 all need to be adjusted to put them into the WMO standard range where Y <= 191.

erget commented 4 years ago

Hi Jeff, yes, you're right - the thought here was that there might be number clashes so we'd discuss the sequences and then when they're ok have the Secretariat assign the final numbers.

SimonElliottEUM commented 4 years ago

It was a cunning plan on my part. It doesn't matter which numbers we get - I though it might be helpful to have them assigned by the Secretariat

marijanacrepulja commented 4 years ago

Hi Daniel, Many thanks for BUFR templates.

erget commented 4 years ago

Hi @marijanacrepulja , I've answered your questions point-by-point below:

Could we not include satellite name in the name of the BUFR template since the same template will be used for other altimeters.

This is fine, I have updated the sequence names accordingly.

Would't it better if the following elements are moved from the "3-40-197 “Sentinel-6 Michael Freilich 1 Hz C and Ku band values" part to the "3-40-194 “Sentinel-6 Michael Freilich radiometer values"...

Those descriptors are proposed for 3-40-197 because the retrieved values use the radiometer brightness temperatures and the altimeter's Sigma0, so they should remain in that sequence.

...why do we have twice 0-01-030 ... 0-10-085

The product will contain 2 MSS models in the product, this is to allow describing both of them.

In 3-40-194, could we use delayed replication

Yes, I have updated the sequence accordingly.

If element "0-21-122 Attenuation correction on sigma-0 (from tb)" is new, can we change sigma-0 to backscatter coefficient to be consistent with the other elements like: "0-21-183 Specific band corrected ocean backscatter coefficient"

0-21-122 already exists, we would prefer to reuse it.

chenxiaoxia2019 commented 4 years ago

@erget Hi, Daniel, I changed the FXY number of Corrected OCOG* backscatter coefficient (negative reference) from 0-21-192 to 0-21-189 and changed the FXY number of Specific band significant wave height (negative reference) from 0-22-192 to 0-22-179. And, I also changed from 340192 to 340018, 340193 to 340019, 340194 to 340020, 340195 to 340021, 340196 to 340022, 340197 to 340023, 340198 to 340024. More information about the CREX_Unit, CREX_Scale, CREX_DataWidth_Char, Status are needed. A branch for this issue is created. Please check it. Many thanks.

erget commented 4 years ago

@chenxiaoxia2019 I note the following changes:

and have updated the proposal accordingly.

I'm a bit confused about the CREX information - this is satellite data and thus we don't intend to disseminate it in CREX. What do you require exactly?

erget commented 4 years ago

@chenxiaoxia2019 I have reviewed the proposed changes in the associated PR. I didn't review every file but rather BUFR_TableD_en_40.csv and txt/BUFRCREX_TableB_en.txt but of course the changes in those files will need to extend to the other ones as well.

erget commented 4 years ago

@chenxiaoxia2019 I note also that there is a number clash in these tables - #10 already uses 3-40-018. I propose giving the IKFS-2 sequence described in that issue to use 3-40-023 but I leave it to you to make the final decision that will not produce a number clash.

For now, I'm producing sample data as described in this proposal, i.e. #10 and #15 are both using different definitions for 3-40-018.

erget commented 4 years ago

I've uploaded sample data - *.nc is the native file, *.bin is the same translated into BUFR.

marijanacrepulja commented 4 years ago

@chenxiaoxia2019 BUFR_TableD_en_40.csv still contains entries that need to be updated, please see below 40,Additional satellite report sequences,340018,(Altimeter product),,340193,Uuu,,,Operational 40,Additional satellite report sequences,340018,(Altimeter product),,340194,Vvv,,,Operational 40,Additional satellite report sequences,340018,(Altimeter product),,340195,www,,,Operational 40,Additional satellite report sequences,340018,(Altimeter product),,340196,Xxx,,,Operational

erget commented 4 years ago

I've corrected the issues found on the associated branch; it looks fine to me now.

marijanacrepulja commented 4 years ago

@erget I also found that lines below need to be updated 40,Additional satellite report sequences,340022,(Altimeter main values),,340023,Yyy,,,Operational 40,Additional satellite report sequences,340022,(Altimeter main values),,340023,Yyy,,,Operational 40,Additional satellite report sequences,340022,(Altimeter main values),,340023,Yyy,,,Operational 40,Additional satellite report sequences,340022,(Altimeter main values),,340024,Zzz,,,Operational

efucile commented 4 years ago

replace 3-40-018 with 3-40-xxx before validation of samples

erget commented 4 years ago

I have renamed 3-40-018 to 3-40-019, giving precedence to #10.

erget commented 4 years ago

Hi @marijanacrepulja I've uploaded new sample data, can you please re-confirm?

marijanacrepulja commented 4 years ago

Hi @erget, please see attached output of decoded sample. I have used table D from branch but haven't been able to check values, as there is no file to show what the decoded values should be.

W_XX-EUMETSAT-Darmstadt,SURFACE+SATELLITE,S6A+P4+L2+HR_C_EUMS_20170305065123_F01_000_000_20170305065238.bin_decoded.txt

I have now noticed with real numeration assigned, that template 3-40-023 “Altimeter main values” contains repetition of 3-40-24 three times. Could you please explain the reason.

I have request from our Research Department if could be possible to include 20-Hz wind speed values (21 of them). Many thanks

erget commented 4 years ago

@marijanacrepulja thank you very much!

The repetition of 3-40-024 is due to the use of 3 different algorithms: SAR, LRM & PLRM. This was agreed (prior to my involvement!) with colleagues from ECMWF, I believe in R&D, but I'm not sure who was involved.

Also, although we have space in the sequence for including 20-Hz wind speed values, these are not present in the original product - Sentinel-6 doesn't produce them. That's why you don't see them in these BUFR messages.

Is there anything else we should discuss or can we consider the product validated?

marijanacrepulja commented 4 years ago

@erget I believe we can consider the product validated. Thank you for the feedback.

erget commented 4 years ago

Perfect, thank you, then I am marking this template as validated.

amilan17 commented 4 years ago

SUMMARY: Add entry to Table B Class 21, add entry to Table B Class 22 and add entries to Table D Category 40.

amilan17 commented 4 years ago

Approved by FT 2020-2.