SCIAMACHY LoS Mispointing Modelling M. Gottwald & E. Krieg – DLR-IMF - DLR/IFE IUP-IFE, Bremen, 30...
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Transcript of SCIAMACHY LoS Mispointing Modelling M. Gottwald & E. Krieg – DLR-IMF - DLR/IFE IUP-IFE, Bremen, 30...
SCIAMACHYLoS MispointingModelling
M. Gottwald & E. Krieg – DLR-IMF
- DLR/IFE S S T
IUP-IFE, Bremen, 30 November 2006
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 2
Known LoS Anomalies
several measurements display small LoS anomalies auf (known since Commissioning Phase)
all of them, except BIAS in limb tangent height, are classified as ‘uncritical’
approach to use LoS anomalies to understand limb BIAS
what can cause LoS anomalies?
- extra instrument misalignment (pitch, roll, yaw)
- platform attitude misalignment
- FOCC planning and scheduling s/w (CFI, SCIACAL)
- scanner control s/w
- Sun Follower
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 3
LoS Anomalies – Measured Jumps
Jump-history Sun-states (LoS)
-0,07
-0,05
-0,03
-0,01
0,01
0,03
0,05
0,07
0,09
0,11
9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000
Orbit
jum
p [
deg
- L
oS
an
gle
]
ASM_jump (ID49) ESM-Jump (ID47) ESM_subsolar (ID53) ASM_jump (ID47)SCIA-OFF SCIA_Idle-OCM decontamination SCIA_Idle-MPS
Jump-history Sun-states (LoS)
-0,07
-0,05
-0,03
-0,01
0,01
0,03
0,05
0,07
0,09
0,11
9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000
Orbit
jum
p [
deg
- L
oS
an
gle
]
ASM_jump (ID49) ESM-Jump (ID47) ESM_subsolar (ID53) ASM_jump (ID47)SCIA-OFF SCIA_Idle-OCM decontamination SCIA_Idle-MPS
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 4
Coordinate Systems
+Y
-X
+Z
ESM:in X-Z plane-X (Z = 0): 0°+X (Z = 0): 180°
ASM:in Y-X plane+X (Y = 0): 0°-X (Y = 0): 180°
+X
+Y
-X
+ZElevationfrom X-Y plane+Z: -90°-Z: +90°
Azimut+ in X-Y plane-Y: 0°+Y: 180°
+X
Scanner CFI
-Y
Target
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 5
Observed Anomalies (LoS angle)
- limb: elevation = -0.016 deg1
‘SCIAMACHY is pointing too low tangent heights are too large’1 possibly larger
- solar occultation: azimuth = 0.1 deg2 elevation = -0.04 deg3
jumps of the ASM and ESM readings when switching to Sun Follower(State 47)
2 at 17.2 km3 at 100 km
- subsolar: azimuth = 0.05 deg4 elevation = -0.02 deg
jump of the ESM readings when switching to Sun Follower and temporal shift of maximum signal (State 53)
4 derived from temporal shift of maximum signal of about 5 BCPS
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 6
‘Modelling the Jumps’ (1)
assumption
- jumps, temporal shift in subsolar signal and limb BIAS are caused by extra misalignment
(known misalignment LoS: pitch = 0.00065°, roll = 0.00167°,
yaw = -0.22746°)
- azimuth jump in occultation may be a special case (acquisition at 17.2 km = well within the atmosphere)
misalignment budget- pitch: pt = pi + pp + pe (t = total misalignment, i = instrument, p = platform, e = extra)
- roll: rt = ri + rp + re
- yaw: yt = yi + yp + ye
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 7
‘Modelling the Jumps’ (2)
Modelling
- derive solar azimuth and elevation for occultation and subsolar viewing using the ENVISAT CFIs
- option 1: CFI without any misalignment = reference for subsolar azimuth
- option 2: CFI with instrument misalignment = reference for subsolar elevation and occultation elevation
- option 3: CFI with instrument misalignment, platform misalignment and variable extra misalignment
- combination of option 1/2 and option 3 = simulation of Sun Follower acquisition
determine ‘best fit’ extra misalignment which produces measured jump or time shift
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 8
‘Modelling the Jumps’ (3)
option 1 and 2 = scanner control with FOCC prediction
option 3 = scanner control with Sun Follower
absolute values of azimuth/elevation from SOST-CFIs and FOCC-CFIs are not fully identical (additional corrections at FOCC)
difference in absolute values about several 0.01°
jumps are relative changes jumps can be modelled with SOST-CFIs
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 9
Which Jump results from which Misalignment?
subsolar elevation roll
subsolar azimuth = time of maximum signal yaw and pitch
Sun occultation azimuth: not analysed
Sun occultation elevation pitch and roll
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 10
Modelling
20 orbits with state 53 (subsolar)
24 orbits with state 47 (occultation)
platform attitude information from AUX_FRA
pitch, roll and yaw extra misalignment variations around expected values (limits defined by maximum observed anomalies)
search for best fit extra misalignment in pitch, roll and yaw
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 11
Example: Subsolar Azimuth – Yaw
Azimuth Sun (at subsolar az = 270.0°); extra misalignment: p = - 0.016; r = - 0.020; y = variable
269,20
269,40
269,60
269,80
270,00
270,20
270,40
270,60
270,80
271,00
-100 -75 -50 -25 0 25 50 75 100
Sun_Max Elapsed Time (BCPS)
Azi
mu
th (
°)
y = instrument misalignment+platform y =-0,04 y =-0,08y =-0,12 y =-0,16 y =-0,20y =-0,24 y =-0,28 y =-0,32y =-0,36 y =-0,40 instrument misalignmentsignal maximum 270,0 deg reference = no mislignment
Azimuth Sun (at subsolar az = 270.0°); extra misalignment: p = - 0.016; r = - 0.020; y = variable
269,20
269,40
269,60
269,80
270,00
270,20
270,40
270,60
270,80
271,00
-100 -75 -50 -25 0 25 50 75 100
Sun_Max Elapsed Time (BCPS)
Azi
mu
th (
°)
y = instrument misalignment+platform y =-0,04 y =-0,08y =-0,12 y =-0,16 y =-0,20y =-0,24 y =-0,28 y =-0,32y =-0,36 y =-0,40 instrument misalignmentsignal maximum 270,0 deg reference = no mislignment
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 12
Example: Subsolar Azimuth – Pitch
Azimuth Sun (at subsolar az = 270,0°); misalignment: p = variable; r = -0.020; y = 0.000
269,20
269,40
269,60
269,80
270,00
270,20
270,40
270,60
270,80
271,00
-100 -75 -50 -25 0 25 50 75 100
Sun_Max Elapsed Time (BCPS)
Azi
mu
th (
°)
pitch = instrument misalignment + platform pitch -0,004 pitch -0,008pitch -0,012 pitch -0,016 pitch -0,02pitch -0,024 pitch -0,028 pitch -0,032
pitch -0,036 pitch -0,04 signal maximum270,0 deg reference = no misalignment instrument misalignment
Azimuth Sun (at subsolar az = 270,0°); misalignment: p = variable; r = -0.020; y = 0.000
269,20
269,40
269,60
269,80
270,00
270,20
270,40
270,60
270,80
271,00
-100 -75 -50 -25 0 25 50 75 100
Sun_Max Elapsed Time (BCPS)
Azi
mu
th (
°)
pitch = instrument misalignment + platform pitch -0,004 pitch -0,008pitch -0,012 pitch -0,016 pitch -0,02pitch -0,024 pitch -0,028 pitch -0,032
pitch -0,036 pitch -0,04 signal maximum270,0 deg reference = no misalignment instrument misalignment
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 13
Example: Subsolar Elevation – Roll
Elevation Sun (at subsolar az = 270.0°); extra misalignment: p = -0.016; r = variable; y = 0.000
-60,35
-60,30
-60,25
-60,20
-60,15
-60,10
-60,05
-400 -300 -200 -100 0 100 200 300 400 500
Sunpass Elapsed Time (BCPS)
Ele
va
tio
n (
°)
roll reference roll -0,004 roll -0,008 roll -0,012 roll -0,016
roll -0,020 roll -0,024 roll -0,028 roll -0,032 roll -0,036
roll -0,04 ESM_scan ESM-corr_scan
Elevation Sun (at subsolar az = 270.0°); extra misalignment: p = -0.016; r = variable; y = 0.000
-60,35
-60,30
-60,25
-60,20
-60,15
-60,10
-60,05
-400 -300 -200 -100 0 100 200 300 400 500
Sunpass Elapsed Time (BCPS)
Ele
va
tio
n (
°)
roll reference roll -0,004 roll -0,008 roll -0,012 roll -0,016
roll -0,020 roll -0,024 roll -0,028 roll -0,032 roll -0,036
roll -0,04 ESM_scan ESM-corr_scan
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 14
Solar Occultation Elevation – Assymetric Signal
PMD 4 LG State 47 (orbit 19822)
-10
10
30
50
70
90
110
130
150
0 200 400 600 800 1000
BCPS
PM
D_
4 s
ign
al
PMD_4 Read-Out
PMD 4 LG State 47 (orbit 19822)
-10
10
30
50
70
90
110
130
150
0 200 400 600 800 1000
BCPS
PM
D_
4 s
ign
al
PMD_4 Read-Out
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 15
Example: Solar Occultation Elevation – Pitch
Elevation Sun (at ESM acquisition); extra misalignment: p = variable ;r = - 0.020; y = 0.000
25,15
25,20
25,25
25,30
25,35
25,40
25,45
440 450 460 470 480 490 500 510 520 530 540 550
ASM-acquisition Elapsed Time (BCPS)
Ele
vati
on
(°)
no misalignment instrument misalignment only p = -0,004 p = -0,008
p = -0,012 p = -0,016 p = -0,020 p = -0,024
p = -0,028 p = -0,032 p = -0,036 p = -0,040
ESM_scan ESM_scan-center
Elevation Sun (at ESM acquisition); extra misalignment: p = variable ;r = - 0.020; y = 0.000
25,15
25,20
25,25
25,30
25,35
25,40
25,45
440 450 460 470 480 490 500 510 520 530 540 550
ASM-acquisition Elapsed Time (BCPS)
Ele
vati
on
(°)
no misalignment instrument misalignment only p = -0,004 p = -0,008
p = -0,012 p = -0,016 p = -0,020 p = -0,024
p = -0,028 p = -0,032 p = -0,036 p = -0,040
ESM_scan ESM_scan-center
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 16
Example: Solar Occultation Elevation – Roll
Elevation Sun (at ESM acquisition); misalignment: p = - 0.016; r = variable; y = 0.000
25,20
25,25
25,30
25,35
25,40
25,45
25,50
440 450 460 470 480 490 500 510 520 530 540 550
ASM-acquisition Elapsed Time (BCPS)
Ele
vati
on
(°)
no misalignment inst-mis-only r = -0,004 r = -0,008 r = -0,012
r = -0,016 r = -0,020 r = -0,024 r = -0,028 r = -0,032
r = -0,036 r = -0,040 ESM_scan ESM_scan-center
Elevation Sun (at ESM acquisition); misalignment: p = - 0.016; r = variable; y = 0.000
25,20
25,25
25,30
25,35
25,40
25,45
25,50
440 450 460 470 480 490 500 510 520 530 540 550
ASM-acquisition Elapsed Time (BCPS)
Ele
vati
on
(°)
no misalignment inst-mis-only r = -0,004 r = -0,008 r = -0,012
r = -0,016 r = -0,020 r = -0,024 r = -0,028 r = -0,032
r = -0,036 r = -0,040 ESM_scan ESM_scan-center
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 17
Example: Solar Occultation Elevation – Yaw
Elevation Sun (at ESM acquisition); misalignment: p = - 0.016; r = - 0.020; y = variable
25,15
25,20
25,25
25,30
25,35
25,40
25,45
440 450 460 470 480 490 500 510 520 530 540 550
ASM-acquisition Elapsed Time (BCPS)
Ele
vati
on
(°)
no misalignment instrument misalignment only y = -0,04 y = -0,08
y = -0,12 y = -0,16 y = -0,20 y = -0,24
y = -0,28 y = -0,32 y = -0,36 y = -0,40
ESM_scan ESM_scan-center
Elevation Sun (at ESM acquisition); misalignment: p = - 0.016; r = - 0.020; y = variable
25,15
25,20
25,25
25,30
25,35
25,40
25,45
440 450 460 470 480 490 500 510 520 530 540 550
ASM-acquisition Elapsed Time (BCPS)
Ele
vati
on
(°)
no misalignment instrument misalignment only y = -0,04 y = -0,08
y = -0,12 y = -0,16 y = -0,20 y = -0,24
y = -0,28 y = -0,32 y = -0,36 y = -0,40
ESM_scan ESM_scan-center
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 18
Example: Best Fit Roll – Subsolar Elevation (State 53)
Roll Variation vs Elevation
0,000
0,005
0,010
0,015
0,020
0,025
-0,040 -0,032 -0,024 -0,016 -0,008 0,000
Roll steps (°)
Sim
ula
ted
E
lev
ati
on
(°)
19822
19407
18978
18563
18148
17733
17303
15600
15170
14626
14326
13911
13481
13066
12651
12222
11806
11391
10962
10532
Roll Variation vs Elevation
0,000
0,005
0,010
0,015
0,020
0,025
-0,040 -0,032 -0,024 -0,016 -0,008 0,000
Roll steps (°)
Sim
ula
ted
E
lev
ati
on
(°)
19822
19407
18978
18563
18148
17733
17303
15600
15170
14626
14326
13911
13481
13066
12651
12222
11806
11391
10962
10532
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 19
Subsolar - Results
best fit extra misalignments
- pitch pe = -0.019° ± 0.004°
- roll re = -0.020° ± 0.004°
- yaw ye = 0.000° ± 0.000°
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 20
Solar Occultation – Results
best fit extra misalignments
- pitch pe = -0.027° ± 0.002°
- roll re = not sensitive
- yaw ye = not sensitive
SCIAMACHY Operations Support
M. Gottwald & E. Krieg – DLR-IMF, 30 November 2006 page 21
Summary
observed LoS anomalies (except azimuth jump in solar occultation) can be explained by extra misalignment:
pitch pe = -0.023°, roll re = -0.020°, yaw ye = 0.000°
estimated uncertainties ± 0.002° - 0.003° (equivalent to about 200 m at limb distance)
further simulations with smaller pe, re, ye steps required