Algorithm Theoretical Based Document (ATBD) - CESBIO

SO-TN-ESL-SM-GS-0001
Issue 1.a
Date: 31/08/2006
SMOS level 2 processor
Soil moisture ATBD
Name Origin / meaning Action Notes size
SPARE to 16 7
Processing descriptors
byte
S_TREE_1 Branches of decision tree stage 1 1
S_TREE_2 Retrieval R2, R3 or R4 1
Total Bytes: 2
3.4.4.2 Data Analysis Product
This report is intended for specific users (such as ESLs). This is more than a simple log file for debugging purposes,
since the SMOS mission is very innovative and will require extensive analysis after launch.
The DAP exist for every L1c product ingested by the L2 SM processor. They should contain all relevant data for
performing algorithm improvements, fine tuning and performing validation and calibration. We could also foresee that
auxiliary input data for L1/L2 process could be improved in time with the analysis of this product.
2
For example, let us consider the case of RFI and its distribution in space and time. With both χ maps and residuals
distribution analysis, it is hoped to improve the auxiliary RFI map.
Unlike the UDP, where the content and structure should not depend on what algorithm is used (e.g. iterative inversion
of forward models vs. a possible direct statistical inversion), the DAP content and structure depend necessarily on the
adopted algorithm. For iterative retrieval, we anticipate the following characteristics and content.
The DAP consists of a list of variable-size data records. Each record is associated with unique ISEA node numbers, the
ones for which the L2 retrieval processing has been applied, successfully or not. Thus, the DAP will contain exactly
the same number of DGG nodes as its L1c product input.
The content of this product can be divided in two parts:
• A descriptor (numerical) data part that records relevant temporary values, used and/or created by the
*
algorithms e.g. vector of residuals TBM
m
− TBF( α
m
, pi
L)
, weighting fraction list …. This variable-size
record is described in Table 32. Further efforts have been invested to complement the content of Table 32
with more information that should be relevant to analyse the SML2PP during the commissioning phase.
• A status (flags) part, which records all the events that occurred in the processing. This status traces the L2
processing behaviour in generating parameters, as well as in rejecting the L1c nodes. This could be a fixed-size
packed bit-field that describes branching conditions, operations, exceptions, flags … This fixed size record is
described in Table 33.
DAP records the whole PSD and PCD outputs, excluding the parts recorded in UDP.
Each node present in the L1c input product is associated with the record described in the following table:
Table 32: DAP descriptors
Name Origin Description Bytes
GNID L1c Input Data DGG node identifier (field #01) 4
Iterative
M_AVA x 2 (or 4)
VRES
Vector of Residuals TBM
retrieval
m -TBF m
floats
Mean cover fractions for each decision tree class (from
C_FM0
Pre-process
10 x 2 bytes
MEAN_ WEF and FM 0 list))
C_FM process Mean cover fractions (from MEAN_ WEF and FM list) 10 x 2 bytes
Cover fractions for each incidence angle (from WEFs M_AVA x 10 x 2
C_FV
process
and FV) 9 bytes
X_SWATH Pre-process Abscissa of dwell line (+ - km) 2
N_TB_RANGE L2 testing TB against range; count of deleted views 1
N_RFI_H RFI detected in L2 test H pol; count of deleted views (b) 1
N_RFI_V RFI detected in L2 test V pol; count of deleted views (b) 1
9 Note: if strip adaptative option is used, this is a vector since all AFP are the same.
.
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