| Requirement type: Systematic Error (Radiometric Accuracy) |
|---|
| Req ID | Parent | Requirement Title | Requirement Statement | Rationale | Verification Report | Published References |
| OCI-82 | MRD-1982
MRD-1993
MRD-2005 | Pre Launch Absolute Gain Accuracy, K1 | The pre-launch accuracy of the OCI absolute gain factor (1-sigma), K1 (see figure 2) shall be:
2.0% for bands between 340nm - 585nm
2.0% for bands between 615nm - 890nm
5.0% for bands 940nm, 1038nm, 1250nm, 1615nm, 2130nm, 2260nm
8.0% for band 1378nm
over the entire operating temperature range, traceable to NIST standards, and shall be established at Ltyp for unpolarized light during prelaunch measurements. | The reason for requiring a better accuracy in this instrument is the expectation that the additional efforts spent on a more accurate prelaunch characterization will translate into a better understanding of the instrument. Note that the on-orbit calibration accuracy after vicarious calibration needs to be 0.2%, therefore it would raise serious concerns if the instrument cannot be calibrated to 2.0% prelaunch. The accuracy of the OCI absolute gain factor, K1 (see figure 3.4.1-1) is 2% threshold (one sigma) for all bands in Table 3.5-1 below 1000nm, and 4% threshold for bands above 1000nm, over the entire operating temperature range, traceable to NIST standards, and shall be established at Ltyp for unpolarized light during prelaunch measurements. | OCI spectral requirements (CAL-1) report
OCI-SCI-RPT-0488 | |
| OCI-83 | MRD-2007 | On-Orbit Absolute Gain Accuracy, K1 at Time = 0 | The accuracy of the OCI absolute gain factor at time = 0 via on-orbit solar calibration (1-sigma), K1 (see figure 2), shall be better than 1.6% for all bands. | Solar calibration absolute gain is the reference gain at t=0. K2 tracks the change in gain over time. This requirement is part of a mission allocation to the OCI solar calibration assembly | OCI Pointing Report (OCI-SYS-RPT-0459), Absolute calibration verification (OCI-SCI-RPT-0491) | |
| OCI-84 | MRD-2005
MRD-2006
MRD-2008 | On-Orbit Stability, K2
(EOL) | OCI system gain shall vary by less than or equal to +/- 0.1% for multispectral bands over 24 hours. This independent of temperature and linearity corrections.
Exception: for 1378nm, compliance is a goal. | On-Orbit Radiometric Response Trending.
15% is the allowable degradation in gain at EOL | OCI-SCI-RPT-0464: OCI Flight Cal-2, 24 hour stability Requirement Verification | |
| OCI-85 | MRD-2008 | Relative On-Orbit Gain Correction, K2 at Time = n (Solar and Lunar Calibration) | The OCI on-orbit relative radiometric response (System Gain Degradation) at Lbright shall be correctable after 3 years with an accuracy of:
0.12% for bands between 340nm - 400nm
0.12% for all bands between 400nm - 890nm
0.12% for bands above 940nm
For a single solar calibration measurement, the uncertainty in radiometric response shall be less than: 0.26% for bands between 340nm - 865nm
0.29% for bands above 940nm | On-Orbit Radiometric Response Trending | Relative on-orbit Gain Correction
OCI-SCI-RPT-0481 | |
| OCI-86 | MRD-367
MRD-368
MRD-369Lunar Calibration | OCI shall be capable of viewing the Moon through its Earth-view port and not saturate with a lunar radiance, Llunar, defined in table 1 | Lunar calibration is used to track the K2 gain degradation overtime | Model results of saturation margin are found here:
OCI-SYS-REQ-0150
OCI-SYS-REQ-0136
Lunar Calibration ConOps: PACE-SYS-TN-0047, Slide 37, ""Selected Lunar Cal Scan Angle"" agrees with OCI Flight Data Collection Control Tables: OCI-SYS-DESC-0114, #5 Lunar Sweep Cal
Test Results Here:
OCI-SCI-RPT-0469 | | |
| OCI-87 | MRD-117
MRD-373
MRD-374Daily Bright Target Solar Calibration | OCI shall perform a daily bright target solar calibration via on on-board solar diffuser at one point in the orbit and not saturate during calibration activites | The main purpose of the primary solar diffuser is to detect short term (less than 6 months) radiometric gain sensitivity variations. It can also be used to determine SNR on-orbit. Longer term variations are to be detected with lunar measurements. The radiometric gain degradation measured by the combination of the two solar diffusers shall validate the lunar measurements. | Model results of saturation margin are found here:
OCI-SYS-REQ-0150
OCI-SYS-REQ-0136
Test Results Here:
OCI-SCI-RPT-0468 | | |
| OCI-88 | MRD-117
MRD-373
MRD-374Monthly Bright Target Solar Calibration | OCI shall perform a monthly bright target solar calibration via on on-board solar diffuser at one point in the orbit and not saturate during calibration activites | The main purpose of the primary solar diffuser is to detect short term (less than 6 months) radiometric gain sensitivity variations. It can also be used to determine SNR on-orbit. Longer term variations are to be detected with lunar measurements. The radiometric gain degradation measured by the combination of the two solar diffusers shall validate the lunar measurements. | Model results of saturation margin are found here:
OCI-SYS-REQ-0150
OCI-SYS-REQ-0136
Test Results Here:
OCI-SCI-RPT-0468 | | |
| OCI-89 | MRD-1993
MRD-2005
MRD-2006 | Monthly Dim Target Solar Calibration | OCI shall perform a monthly dim target solar calibration via on on-board solar diffuser at one point in the orbit and not saturate during calibration activities | To track instrument response curve changes between Llow and Lbright | Model results of saturation margin are found here:
OCI-SYS-REQ-0150
OCI-SYS-REQ-0136
Test Results Here:
OCI-SCI-RPT-0468 | |
| OCI-90 | MRD-1993
MRD-2005
MRD-2006 | Allowable Radiometric Temperature Sensitivity, K3 | For a constant radiance source, the variation of dn with temperature over the entire on on-orbit thermal environment shall be less than 2% from Lbright to Lmax | To understand and characterize the radiometric response of the instrument over full expected temperature range on orbit. These characterizations will be used in the final calibration of the data product | Requirement verification for OCI-90 and OCI-91 CCD Bands (OCI-SCI-RPT-0512), Requirement verification for OCI-90 and OCI-91, SWIR bands only (OCI-SCI-RPT-0513) | |
| OCI-91 | MRD-1993
MRD-2005
MRD-2006 | Radiometric Temperature Sensitivity Correction, K3 | Pre-Launch, OCI temperature sensitivity of the multispectra bands, defined as change in dn with temperature, shall be characterized and correctable to:
340nm - 400nm: 0.15%
400nm - 585nm: 0.12%
615nm - 890nm: 0.13%
>940nm: 0.19% | Knowledge of temperature sensitivity makes up part of the artifact budget (square summation limit) | Requirement verification for OCI-90 and OCI-91 CCD Bands (OCI-SCI-RPT-0512), Requirement verification for OCI-90 and OCI-91, SWIR bands only (OCI-SCI-RPT-0513) | |
| OCI-92 | MRD-1993
MRD-2005
MRD-2006 | Allowable Response vs. Scan Angle, K4 | For bands between 340nm – 585nm & 615nm – 2260nm the response of OCI to a constant radiance source shall vary with scan angle by less than:
7.0% for the whole scan angle range.
0.5% for scan angles that differ by less than 1degree. | To understand the change in radiometric performance of the telescope as a function on scan angle | OCI-92 and OCI-93: RVS requirements
OCI-SCI-RPT-0489 rev A | |
| OCI-93 | MRD-1993
MRD-2005
MRD-2006 | Response vs. Scan Angle Correction, K4 | The OCI response vs scan angle shall be characterized and correctable with an accuracy of:
0.17% for bands between 340nm - 400nm
0.11% for all bands between 400nm - 585nm
0.11% for all bands between 615nm - 885nm
0.16% for all bands between 940nm – 1378nm
1.00% for all bands between 1615nm -2260nm
for all scan angles within the earth view range. | Knowledge of response vs scan angle makes up part of the artifact budget (square summation limit) | OCI-92 and OCI-93: RVS requirements
OCI-SCI-RPT-0489 rev A | |
| OCI-94 | MRD-1993
MRD-2005
MRD-2006 | Instrument Response Curve Shape, K5
(Linearity) | The OCI response curve for dn versus radiance shall be monotonic from Llow to Lmax (or Lclip, whichever is smaller), and, the OCI response (dn) shall not fall below its value at Lmax (or Lclip, whichever is smaller) for radiances from Lmax (or Lclip, whichever is smaller) to 1.3 times Lmax. | To understand the linearity and associated uncertainty of the radiometric response due to radiance levels that span Ltyp - Lmax | Linearity Requirements verification: OCI-94, OCI-95,OCI-96 Report (OCI-SCI-RPT-0511) | |
| OCI-95 | MRD-1993
MRD-2005
MRD- | Allowable Instrument Response Curve Shape, K5
(Linearity) | The OCI response curve deviation (Max Non-Linearity) shall be less than 6% (K5) from Lmin to Lmax or all multispectral bands. | To understand the linearity and associated uncertainty of the radiometric response due to radiance levels that span Lmin/Ltyp - Lmax | Linearity Requirements verification: OCI-94, OCI-95,OCI-96 Report (OCI-SCI-RPT-0511) | |
| OCI-96 | MRD-1993
MRD-2005
MRD-2006 | Instrument Response Curve Correction, K5
(Linearity) | Pre-launch, the OCI response curve shall be characterized and correctable over the instrument temperature range during pre-launch calibration to:
Multispectral Bands Between 350nm - 748nm
0.3% from Llow to Lhigh
0.4% from Lhigh to Lbright
2.0% from Lbright to Lmax
Multispectral Bands 820nm and 865nm
0.5% from Llow to Lbright
2.0% from Lbright to Lmax
Bands Between 940nm - 1378nm
0.25% from Llow to Lbright
2.0% from Lbright to Lmax
Bands Between 1615nm - 2260nm
2.0% from Llow to Lmax
The Lbright-Lmax specification in OCI-96 shall only apply to bands that do not saturate below Lmax. | Knowledge of linearity makes up part of the artifact budget (square summation limit) | Linearity Requirements verification: OCI-94, OCI-95,OCI-96 Report (OCI-SCI-RPT-0511) | |
| OCI-97 | MRD-1993
MRD-2005
MRD-2006 | Instrument Response Curve Stability, K5
(Linearity) (EOL) | EOL On-Orbit, uncertainty due to the shape of the response curve from linear shall be less than (this does not include fixed gain and offset):
Multispectral Bands Between 350nm - 748nm
0.3% from Llow to Lhigh
0.4% from Lhigh to Lbright
3.0% from Lbright to Lmax
Multispectral Bands 820nm and 865nm
0.5% from Llow to Lbright
3.0% from Lbright to Lmax | End of life instrument response curve | Radiation test report (OCI-DET-RPT-0285), Evaluation of radiation impact to FEE (OCI-ELEC-TN-0184), ADC radiation test report (OCI-ELEC-RPT-0016) | |
| OCI-98 | MRD-1993
MRD-2005
MRD-2006 | Allowable Polarization, P | The radiometric response of OCI shall vary by less than 1% for wavelengths between 345nm - 890nm and 2% for wavelengths above 900nm for all linear polarization angles and view angles of a radiance source between Ltyp and Lmax for all science bands except for the spectrograph transition region. (P)
Spectrograph Transition Region: 590.5nm - 609.5nm | To understand the radiometric response due to different light polarization | Verification Test Report OCI-SCI-RPT-0474 | |
| OCI-99 | MRD-1993
MRD-2005
MRD-2006 | Polarization Correction, P | OCI linear polarization sensitivity shall be characterized and correctable to:
0.17% for bands between 340nm - 400nm
0.11% for all bands between 400nm - 890nm
Bands above 940nm will be characterized pre-launch but are not correctable. | Knowledge of polarization makes up part of the artifact budget | Verification Test Report OCI-SCI-RPT-0474 | |
| OCI-100 | MRD-1993
MRD-2005
MRD-2006 | High Contrast & Spatial Crosstalk (Straylight Requirement) | For a global top-of-atmosphere radiances based on measured MODIS radiances, the global average residual contamination shall be less than 0.4% for 350nm, 360nm, 385nm, 555nm, 583nm, 820nm and 865nm and less than 0.20% for all other multispectral bands. For OCI pre-launch verification, the goal PSF is shown in Figure 3.
See OCI-SCI-TN-0120 for detailed explanation | Accurate resolution of high contrast in TOA radiance images is important to estimate stray light contamination due to clouds, and for studying small scale features like ocean fronts and for working in coastal and estuarine areas where the scales are 1km. This occurs in all wavelengths in the spatial direction. Knowledge of high contrast resolution makes up part of the artifact budget.
The PSF provided by OCI PDR Design meets the requirement as do any PSFs with smaller values. Even multiplying the PSF by a factor 4 (except for the central (receiver) value) meets the above specification. | OCI-100: OCI Stray Light, Science Impact Evaluation
OCI-SCI-RPT-0497 | |
| OCI-105 | MRD-1993
MRD-2005
MRD-2006 | Uniform Scene Artifacts Correction, U
(Striping) | There shall be no discontinuities greater than 0.1% after correction in the measured radiance in one band as a function of scan angle or in track direction. (Striping) | Knowledge of striping makes up part of the artifact budget | Striping Verification Report (OCI-SCI-RPT-0519) | |
| OCI-106 | MRD-1993
MRD-2005
MRD-2006 | Offset, DNo
(Dark Scan, Gain Offset Calibration) | OCI shall perform a dark calibration once per scan | To bias out dark noise of the instrument radiometric response | Offset Accuracy
OCI-SCI-RPT-0493 | |
| OCI-107 | MRD-1993
MRD-2005
MRD-2006 | Offset, DNo
Gain Offset Correction | OCI system offset contribution to radiometric uncertainty at Ltyp shall be known to:
0.15% Relative to Ltyp, Pre-Launch | Required number of samples to remove bias | Offset Accuracy
OCI-SCI-RPT-0493 | |
| OCI-108 | MRD-1993
MRD-2005
MRD-2006 | Fiber Optics, SWIR, K6 | EOL Radiometric uncertainty of bands >940nm due to fiber optics implementation shall be less than 0.25% | SWIR fiber optics implementation adds radiometric uncertainty to the SWIR bands | Flight:
WOA-OCI-OPT-2028
OCI-OPT-RPT-0374
Flight Spare:
WOA-OCI-OPT-2029
OCI-OPT-RPT-0374 | |
