urn:nasa:pds:grail_gravity_derived:data_shadr:gggrx_1200l_sha
1.1
GRAIL Gravity ASCII Spherical Harmonic Model: GRGM1200L
1.18.0.0
Product_Observational
2023-02-01
1.1
Updated a description in the SHADR Coefficients Table
2022-08-12
1.0
Initial version
2012-03-01Z
2012-12-14Z
Gravity Recovery and Interior Laboratory
Mission
urn:nasa:pds:context:investigation:mission.gravity_recovery_and_interior_laboratory
data_to_investigation
Gravity Recovery and Interior Laboratory A
Host
urn:nasa:pds:context:instrument_host:spacecraft.grail-a
is_instrument_host
Gravity Recovery and Interior Laboratory B
Host
urn:nasa:pds:context:instrument_host:spacecraft.grail-b
is_instrument_host
Lunar Gravity Ranging System A for GRAIL-A
Instrument
urn:nasa:pds:context:instrument:grail-a.lgrs-a
is_instrument
Lunar Gravity Ranging System B for GRAIL-B
Instrument
urn:nasa:pds:context:instrument:grail-b.lgrs-b
is_instrument
Moon
Satellite
urn:nasa:pds:context:target:satellite.earth.moon
data_to_target
gggrx_1200l_sha.tab
2021-03-16
This file contains coefficients and related data for the GSFC Lunar gravity
field model GRGM1200L. This project was funded by grant NNX15AJ65G.
This is a degree and order 1199 Spherical Harmonic Model. This product was
derived from a local analysis of GRAIL data. The Moon was divided into 14
regions, and for each region, a separate solution was determined, using
GRAIL inter-satellite Ka-band range-rate data only. Gravity was represented
as gridded gravity anomalies, and a global background gravity model in
spherical harmonics was also used. This background model was the GRGM1200A
model. Neighbor smoothing was used as a constraint. The details of the method
can be found in an earlier publication, GOOSSENSETAL2014, and this new model
is described in detail in GOOSSENSETAL2021.
The separate solutions were patched together, and the final global map was
transformed into spherical harmonics. Because of the latter, the maximum
degree for this model is 1199 instead of 1200, but since it is based on the
GRGM1200A model, it is counted among the GRGM1200 series.
Because this model is the result of a spherical harmonic transform of a map,
there are no uncertainties given on the coefficients, or on GM (the latter is
the same as for the GRGM1200A model). All uncertainty values are therefore
set to zero.
The maximum degree of this model is 1199, because the grid spacing to do the
spherical harmonic transforms uses 'Lmax+1', and so in order to use a 0.15
degrees by 0.15 degrees grid, we use Lmax=1199.
This file is a pair of ASCII tables: a header table and a table of
1439996 coefficients. Definitions of the tables follow.
0
1
The SHADR header includes
descriptive information about the spherical harmonic
coefficients which follow in SHADR_COEFFICIENTS_TABLE.
The header consists of a single record of eight (delimited)
data columns requiring 137 bytes, a pad of 105 unspecified
ASCII characters, an ASCII carriage-return, and an ASCII
line-feed.
Carriage-Return Line-Feed
9
0
244
Reference_Raduis
1
1
ASCII_Real
23
Km
The assumed reference radius of the spherical planet.
Constant
2
25
ASCII_Real
23
For a gravity field model the assumed gravitational
constant GM in kilometers cubed per seconds squared for the
planet. For a topography model, set to 1.
Uncertainty_in_Constant
3
49
ASCII_Real
23
For a gravity field model the uncertainty in the gravitational
constant GM in kilometers cubed per seconds squared for the
planet. For a topography model, set to 1.
Degree_of_Field
4
73
ASCII_Integer
5
The degree of model field.
Order_of_Field
5
79
ASCII_Integer
5
The order of the model field.
Normalization_State
6
85
ASCII_Integer
5
The normalization indicator. For gravity field:
0 coefficients are unnormalized
1 coefficients are normalized
2 other.
Reference_Longitude
7
91
ASCII_Real
23
Degree
The reference longitude for
the spherical harmonic expansion; normally 0.
Reference_Latitude
8
115
ASCII_Real
23
Degree
The reference latitude for
the spherical harmonic expansion; normally 0.
Fill
9
138
ASCII_String
105
SHADR Coefficients Table
244
720599
The SHADR coefficients table
contains the coefficients for the Spherical Harmonic Model.
Each row in the table contains the degree index m, the
order index n, the coefficients Cmn and Smn, and the
uncertainties in Cmn and Smn. The (delimited) data
require 107 ASCII characters; these are followed by a pad
of 13 unspecified ASCII characters, an ASCII carriage-
return, and an ASCII line-feed.
Carriage-Return Line-Feed
7
0
122
COEFFICIENT DEGREE
1
1
ASCII_Integer
5
The degree index m of the C and S coefficients
in this record.
COEFFICIENT ORDER
2
7
ASCII_Integer
5
The order index n of the C and S coefficients
in this record.
C
3
13
ASCII_Real
23
The coefficient Cmn for this spherical harmonic
model.
S
4
37
ASCII_Real
23
The coefficient Smn for this spherical harmonic
model.
C_Uncertainty
5
61
ASCII_Real
23
The uncertainty in the
coefficient Cmn for this Spherical Harmonic Model.
S_Uncertainty
6
85
ASCII_Real
23
The uncertainty in the
coefficient Smn for this Spherical Harmonic Model.
Fill
7
108
ASCII_String
13
A pad of 13 unspecified ASCII characters.
gggrx_1200l_sha.lbl
0
PDS3
Original PDS3 label
Carriage-Return Line-Feed