Attachment B PORD.pdf

Effective Date: April 20, 2021 418-XO-GXSPORD-0031 Expiration Date: Five years from date of last signature Baseline Version 1.0 Responsible Organization: GeoXO Flight Project/Code 418

Check the GeoXO portal at https://goesportal.ndc.nasa.gov to verify correct version prior to use.

Geostationary Extended Observations (GeoXO) Sounder (GXS)

Performance and Operational Requirements Document (PORD)

Signature page

Prepared by:

Electronically approved 04/08/2021

Nicolaas Du Toit Date GeoXO Flight Project, Chief Staff Engineer NASA GSFC, Code 418

Reviewed by:

Electronically approved 04/16/2021

Alexander Krimchansky Date GeoXO Flight Project, Sys. Eng. Mgr.

NASA GSFC, Code 599

Approved by:

Electronically approved 04/20/2021

Jason H. Hair Date GeoXO Flight Project, Project Manager NASA GSFC, Code 418

/GeoXO Flight Project GXS Sounder

GXSPORD

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational Requirements Document (PORD)

Version: 1.0 Printed by: rkhoover Printed on: Friday, April 23, 2021

No filter applied.

No sort applied.

Generated from DOORS 9.6.1.11

Contents

1 1Scope

1.1 1Identification

1.2 1Mission Review

1.3 1Document Overview

1.4 2Terminology

1.5 2Definitions

2 5Documents

2.1 5Applicable Documents

2.2 5Reference Documents

3 6Sensor Requirements

3.1 6Sensor Definition

3.1.1 6GXS Modes

3.1.1.1 6Safe Mode

3.1.1.2 6Normal Operational Mode

3.1.1.3 6Instrument Diagnostic Mode

3.1.1.4 7Outgas Capability

3.1.2 7On orbit Operations

3.1.2.1 7Zones of Reduced Data Quality

3.1.2.1.1 7Operational Zone

3.1.2.1.2 7Restricted Zone / Zones of Reduced Data Quality (ZRDQ)

3.1.2.2 7Scanning Across the Sun

3.1.2.3 8Eclipse

3.1.2.4 8Operations after Maneuvers

3.1.2.4.1 8Yaw Flip

3.1.2.4.2 8Other Maneuvers

3.1.2.4.3 8Post Storage Activation

3.1.2.4.4 8Detector Set-Point Temperature

3.2 8Normal Operational Mode Sensor Requirements

3.2.1 8Spectral Requirements

3.2.1.1 9Spectral Resolution

3.2.1.2 9Spectral Response

3.2.1.2.1 9Reserved

3.2.1.3 9Spectral Purity

Project: GeoXO Flight Project GXS Sounder Module: GXSPORD Baseline Version: 1.0

Contents ii

3.2.1.4 10Spectral Knowledge, Uniformity, and Stability

3.2.1.5 10Spectral Region Breaks

3.2.2 10Scan Requirements

3.2.2.1 10Coverage Rate

3.2.2.2 11Scan/Step Direction

3.2.2.3 11Flexible and Selectable Scan Pattern

3.2.2.4 12Scan Efficiency and Simultaneities

3.2.2.5 12Data Latency

3.2.3 13Coverage Area Requirements (Reserved)

3.2.4 13Spatial Sampling Requirements

3.2.4.1 13Field of Regard

3.2.4.2 13Ground Sample Distance and Angle

3.2.4.3 13Reserved

3.2.4.4 13Detector Sample Ground Footprint

3.2.4.4.1 13Overshoot/Undershoot

3.2.4.4.2 13Detector / Optics Ensquared Energy

3.2.4.4.3 14Modulation Transfer Function

3.2.4.5 14Co-Registration

3.2.5 15Reserved

3.2.6 15Radiometric Performance Requirements

3.2.6.1 15Dynamic Range

3.2.6.2 15Measurement Precision (SNR, NEdN, and NEdT)

3.2.6.2.1 16Pixel Operability

3.2.6.2.2 17Reserved

3.2.6.2.3 17Reserved

3.2.6.3 17Radiometric Accuracy

3.2.6.3.1 17Absolute Accuracy

3.2.6.3.2 18Relative Accuracy

3.2.6.3.2.1 18Scan Position to Scan Position Relative Accuracy

3.2.6.3.2.2 19Pixel-to-Pixel Relative Accuracy

3.2.6.3.2.3 20Channel-to-Channel Relative Accuracy

3.2.6.3.2.4 21Calibration-to-Calibration

3.2.6.3.3 22Reserved

3.2.6.3.4 22On-Orbit Calibration

3.2.6.3.5 22Reserved

3.2.6.3.6 22Reserved

3.2.6.4 22Reserved

3.2.6.5 22Reserved

Contents iii

3.2.6.6 22Reserved

3.2.6.6.1 22Reserved

3.2.6.6.2 22Reserved

3.2.6.6.3 22Reserved

3.2.7 22Image Navigation and Registration

3.2.7.1 22INR Scope

3.2.7.2 22INR Function

3.2.7.2.1 23Star Sensing

3.2.7.2.2 23(Removed)

3.2.7.3 23INR Performance Requirements

3.2.7.3.1 23Navigation

3.2.7.3.2 23Frame-to-Frame Registration

3.2.7.3.3 24Within-Frame Registration

3.2.8 24Data Compression

3.3 24Design Requirements

3.3.1 24Reliability

3.3.2 25Mechanical Requirements (Reserved)

3.3.2.1 25Design Limit Loads (Reserved)

3.3.2.2 25Nonlinear Loads (Reserved)

3.3.2.3 25Yield Strength (Partially Reserved)

3.3.2.4 25Ultimate Strength

3.3.2.5 25Structural Stiffness (Reserved)

3.3.2.6 25Unit Stiffness

3.3.2.7 25Material Properties (Reserved)

3.3.2.8 25Critical Members Design Values

3.3.2.9 25Redundant Members Design Values

3.3.2.10 26Selective Design Values

3.3.2.11 26Structural Reliability (Reserved)

3.3.2.12 26Mechanisms

3.3.2.13 26Pressurized Units

3.3.2.14 27Alignment Reference

3.3.3 27Thermal Requirements

3.3.3.1 27Temperature Limits

3.3.3.2 27Non Operational Temperature

3.3.3.3 27Thermal Control Hardware

3.3.3.4 28Detector Cooling Margin

3.3.3.5 28Non-Detector Radiator Margin

3.3.3.6 28Heat Pipe Capacity Margin

Contents iv

3.3.4 28Onboard Processors Requirements

3.3.4.1 28Flight Load Non-Volatile Memory

3.3.4.2 28Commandable Reinitialization

3.3.4.3 29Deterministic Power-on Configuration

3.3.4.4 29Fail-safe Recovery Mode

3.3.5 29Flight Software Requirements

3.3.5.1 29Language and Methodology

3.3.5.2 29Flight Software Upload

3.3.5.3 29Flexibility and Ease of Software Modification

3.3.5.4 29Version Identifiers

3.3.5.5 29Flight Processor Resource Sizing

3.3.6 30Software Event Logging

3.3.6.1 30Warm Restart

3.3.6.2 30Memory Tests

3.3.6.3 30Memory Dump

3.3.6.4 31Telemetry

3.3.7 31Power Requirements

3.3.7.1 31Power Regulators and Supplies

3.3.7.2 31Fuses

3.3.7.3 31Test Connectors

3.3.8 31Magnetic Properties

3.3.9 31Spacecraft Level Ground Testing

3.3.10 31Ground Support Equipment and Development Facilities

3.3.10.1 31Electrical System Test Equipment

3.3.10.2 32Flight Software Development Environment

3.3.10.3 32Shipping Container

3.3.10.4 33GXS Emulator

4 34Acronyms

5 36Design Verification Requirements

5.1 36Performance Operating Time and Trouble-Free Performance Testing

5.2 36Structural and Mechanical Verification Requirements

5.2.1 36Mechanical Test Factors and Duration

5.2.2 36Minimum Workmanship

5.2.3 36Testing in Flight Configuration

5.2.4 36Structural Proof Testing

5.2.5 36Modal Survey Characterization

5.2.6 37Structural Qualification

Contents v

5.2.7 37Deployment and Articulation Verification

5.2.8 38Life Test

5.2.9 38Mechanical Clearance Verification

5.3 38Electromagnetic Compatibility Requirements

5.3.1 38General

5.3.2 38Electrostatic Arc-Discharge Susceptibility

5.3.2.1 38External Surface-to-Surface direct discharge

5.3.2.2 38Deep Dielectric Charging

5.3.2.3 38ESD Characteristics

5.4 39Magnetic Properties

5.4.1 39General

5.5 39Thermal Requirements

5.5.1 39General

5.5.1.1 39Test Chronology

5.5.1.2 40Thermal Test Chronology

5.5.1.3 40Pressure

5.5.2 40Thermal Vacuum

5.5.2.1 40Transition Rates

5.5.2.2 40Corona Operation

5.5.2.3 40Hot and Cold Start Demonstrations

5.5.2.4 40Heater Verification

5.5.2.5 41Flight Temperature Sensor Verification

5.5.3 41Thermal Cycling

5.5.3.1 41Spacecraft Level TV Test

5.5.3.2 41Cumulative Cycles

5.5.3.3 41Instrument Level TV Cycling

5.5.3.4 41Ambient Pressure Thermal Cycling Substitution

5.5.3.5 42Test Temperatures

5.5.3.5.1 42Mission Allowable Temperatures

5.5.3.5.2 42Qualification, Protoflight and Acceptance Temperatures

5.5.3.5.3 42Non-operating Temperatures

5.5.3.6 43Temperature test tolerances

5.5.3.7 43Plateau Criteria

5.5.4 43Thermal Balance (TB)

5.5.4.1 43TB Applicability

5.5.4.2 43Balance Points

5.5.4.3 43TB-Instrument Configuration

5.5.4.4 43TB Accuracy and Knowledge

Contents vi

5.5.4.5 44TB Steady State Criteria

5.6 44Test Condition Tolerances

5.6.1 44General

6 47Appendix

6.1 47Reserved

6.1.1 47Reserved

6.1.1.1 47Reserved

6.1.1.2 47Reserved

6.1.1.3 47Eclipse

6.2 47Normal Operational Mode Sensor Requirements

6.2.1 47Spectral Requirements

6.2.1.1 47Spectral Resolution

6.2.1.2 48Reserved

6.2.1.3 48Reserved

6.2.1.4 48Reserved

6.2.1.5 48Spectral Region Breaks

6.2.2 48Reserved

6.2.3 48Reserved

6.2.4 48Spatial Sampling Requirements

6.2.4.1 48Reserved

6.2.4.2 48Ground Sample Distance and Angle

6.2.4.3 48Reserved

6.2.4.4 48Reserved

6.2.4.4.1 48Reserved

6.2.4.4.2 48Reserved

6.2.4.4.3 49Modulation Transfer Function

6.2.4.5 49Reserved

6.2.5 49Reserved

6.2.6 49Radiometric Performance Requirements

6.2.6.1 49Dynamic Range

6.2.6.2 49Measurement Precision (SNR, NEdN, and NEdT)

6.2.6.2.1 50Pixel Operability

6.2.6.3 50Radiometric Accuracy

6.2.6.3.1 50Absolute Accuracy

6.2.6.3.2 50Relative Accuracy

6.2.6.3.2.1 50Scan Position to Scan Position Relative Accuracy

6.2.6.3.2.2 50Pixel-to-Pixel Relative Accuracy

Contents vii

6.2.7 51Image Navigation and Registration

6.2.7.1 51Reserved

6.2.7.2 51Reserved

6.2.7.3 51Reserved

6.2.7.3.1 51Navigation

6.2.7.3.2 51Frame-to-Frame Registration

6.2.7.3.3 51Within-Frame Registration

7 53Appendix

7.1 53GXS Scan Requirements

Contents viii

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418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

1 Scope

1.1 Identification

This Performance and Operational Requirements Document (PORD) sets forth the performance requirements for the National Oceanic and Atmospheric Administration (NOAA) next generation Geostationary (GEO) – eXtended Observations (GeoXO) hyperspectral radiometric Sounder (GXS). Note that the GXS may incorporate additional capabilities described in the Appendix.

1.2 Mission Review

The GXS is a hyperspectral infrared passive radiometric sounder used to collect environmental data as part of a 3-axis stabilized geostationary (GEO) weather satellite system of the GEO-eXtended Observations (GeoXO) program. The GXS will collect radiance observations of the earth’s atmosphere with both spectral and horizontal resolution that will yield vertical temperature and moisture information.

Winds can also be derived from rapid mesoscale observations. GXS will provide hyperspectral geostationary operational observations for soundings of the western hemisphere for the first time. GXS data will enhance convective storm nowcasting as well as improve numerical weather production (NWP) in short range weather forecasting and longer range weather prediction.

The GXS mission objectives are to:

1. Provide radiance data that will be used by NOAA and other public and private agencies to produce routine meteorological analyses and forecasts of temperature, moisture, and winds.

2. Provide radiance data to expand knowledge of mesoscale and synoptic scale storm development and improve forecasting of severe weather events.

3. Provide radiance data for the measurement and trending of longer term climate change.

The GXS instrument, designated as GXS in this document, provides data to the GeoXO Ground System via the spacecraft communication system. The GeoXO Ground System takes the GXS data, spacecraft telemetry data, orbit determination data and other required information and autonomously generates radiometrically calibrated and navigated data (level 1b) that will be used by NOAA to generate end-products for users. The GeoXO Ground System will implement algorithms developed by the GXS contractor to satisfy GXS performance requirements.

1.3 Document Overview

This document contains all performance requirements for the GXS instrument and Ground Support Equipment (GSE). This document, the General Interface Requirements Document (GIRD), and the GXS Unique Instrument Interface Document (UIID) define all instrument to spacecraft interfaces for the GXS instrument.

The main body of the document contains specifications for a sounder processing emissive radiances in the LWIR and MWIR bands. Section 6 contains specifications relative to an optional enhancement for additional coverage of a Day-Night Band (DNB). Section 7 contains other optional enhancements.

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Object Number

1.4

1.4.0-1

1.4.0-2

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1.4.0-5

1.4.0-6

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1.5

1.5.0-1

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1.5.0-3

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1.5.0-6

1.5.0-7

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Requirements Document (PORD)

1.4 Terminology

The use of “shall” designates a requirement that must be met.

The use of “should” designates good practice.

The use of “will” is a statement of fact.

The use of “may” designates permission by the Government.

The term “(TBS)”, which means “to be specified”, means that the contractor will supply the missing information in the course of the contract. These serve as a placeholder for future requirements. The contractor is not liable for compliance with these “placeholder” requirements, as insufficient information is provided on which to base a design.

The term “(TBR)”, which means “to be refined/reviewed”, means that the requirement is subject to review for appropriateness and subject to revision. The contractor is liable for compliance with the requirement as if the “TBR” notation did not exist. The “TBR” merely provides an indication that the value is more likely to change in a future modification than requirements not accompanied by a “TBR”.

The term “(TBD)” means “to be determined” and is used when no value is available, and subsequent vendor study will be needed to obtain it.

1.5 Definitions

Throughout this document, the following definitions apply:

Accuracy: Refers to the error in a measurement, which is the difference between the measurement result and the object to be measured (the measured or true value). It includes both systematic and random errors. Systematic errors must be estimated from an analysis of the experimental conditions and techniques. Random errors can be determined, and reduced, through repeated measurements under identical conditions.

Albedo: Refers to the fraction of the input spectrum that is reflected by the Earth at the top of the atmosphere assuming a Lambertian surface with the radiances for a 110% albedo scene as specified in 418-XO-RPT-001.

All requirements/all performance requirements/all operational requirements: Refers to any performance characteristic or requirement in the GXS PORD, GXS UIID, and the GIRD.

Band: A set of channels.

Channel: A measurement that is an aggregate of one or more spectral samples that meets or exceeds GXS requirements.

Derived Noise Equivalent Delta Radiance (NEdN): Refers to the NEdN required to meet the Noise Equivalent Delta Temperature (NEdT) specification, the NEdN specification, or the Signal-to-Noise Ratio (SNR) specification.

Detector sample or element: Digitized output from a single detector element.

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Object Number

1.5.0-9

1.5.0-10

1.5.0-11

1.5.0-12

1.5.0-13

1.5.0-14

1.5.0-15

1.5.0-16

1.5.0-17

1.5.0-18

1.5.0-19

1.5.0-20

1.5.0-21

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Eclipse: Defined as when the solar disk is completely occulted by the Earth or Moon, as viewed from the GeoXO satellite.

Frame: Collection of pixels from a contiguous region as commanded by a minimum bounding rectangle or one of the predefined regions such as Superregional, 62 degree LZA Disk, etc.

Fourier Transform Spectrometer (FTS) System: One approach to spectroscopy that, in contrast to a Grating System, relies on time-domain interference measurements that are converted into spectral data using a Fourier Transform.

Full Disk: Defined as a 17.4 degree diameter circle centered at nadir.

Fully Functional Configuration: Being able to perform the following functions: scene radiance measurement; radiometric calibration; star sensing; on-orbit monitoring of calibration sources and instrument response changes; acquisition of sensor health and status data; generation of the following data streams: sensor, calibration, monitoring, health and status; and reception and execution of command and control data.

Grating System: One approach to spectroscopy that, in contrast to an FTS System, relies on spectral dispersion by means of an optical grating.

Launch: The time between lift off and the separation of the GeoXO satellite from the launch vehicle.

Mesoscale: Defined as the equivalent of a 1.6043 x 1.6043 degree, 1000 km (TBS) x 1000 km (TBS) nadir-viewed area.

Navigation: Refers to the determination of the location of each pixel relative to a fixed reference, namely for the GXS, the GRS80 geoid viewed from the idealized geostationary position.

Pixel: All spectral channels associated with a given spatial resolution element after processing, including calibration and navigation.

Precision: Refers to the standard deviation of a statistically meaningful number of samples of a measurement.

Registration: Refers to maintaining the spatial relationship between pixels within frames, between frames, and between channels.

Sounding Disk (SD): Defined as a collection of spatial resolution elements viewing the earth where the local zenith angle (LZA) to a GOES satellite is less than 62 degrees and the local zenith angle is less than or equal to the local zenith angle to the neighboring GOES satellite.

Spectral Sample: A measurement within a channel that may or may not be aggregated for transmission to the ground.

Superregional: Defined as a equivalent to a nadir-viewed rectangle 8.0215 (TBR) x

4.8129 (TBR) degrees, 5000 (TBR) East/West x 3000 (TBR) North/South kilometers.

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Swath: Refers to any set of detector samples that are collected during a continuous scan or stepping of the detectors over the scene, in a horizontal fashion, which covers the entire horizontal extent of the scene.

Task: Repeating data collection pattern providing coverage of one or more observing regions.

Threshold Channel: A channel with the GXS required spectral resolution element width.

Unit: A functional subdivision of a subsystem and generally a self-contained combination of items performing a function necessary for the subsystem's operation.

Examples are electronics unit and sensor unit.

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2 Documents

2.1 Applicable Documents

A New Distortion Measure for Video Coding Blocking Artifacts. Wu, H. R., Proceedings from the 1996 International Conference on Communication Technology.

Volume 2, May 5-7, 1996, Beijing, China. pp 658-651.

CCSDS Recommendation for Space Data System Standards, Image Data Compression, CCSDS 122.0-B-2, September 2017.

General Environmental Verification Specification for STS and ELV Payloads, Subsystems and Components, Document Number GSFC GEVS-SE, June1, 1996.

General Specification for Assemblies, Moving Mechanical, for Space and Launch Vehicles, Document Number MIL-A-83577B, February 1, 1988.

Geostationary and eXtended Observations (GeoXO) Flight Project Instrument Mission Assurance Requirements (IMAR), 418-XO-IMAR-0026, February 03, 2021.

Geostationary Extended Observations (GeoXO) Sounding Radiances Upwelling, 418-

XO-RPT-0093.

Geostationary Extended Observations (GeoXO) hyperspectral radiometric Sounder (GXS) Unique Instrument Interface Document (UIID), 418-XO-GXSUIID-0030.

NASA-STD-8719.24 NASA Expendable Launch Vehicle Payload Safety Requirements (Base + Annex), June 2018.

Space Mechanisms Handbook, Document Number NASA TP-1999-206988.

Structural Design and Test Factors of Safety for Spaceflight Hardware, NASA, Document Number NASA-STD-5001B, August 6, 2014.

2.2 Reference Documents

Geostationary Extended Observations (GeoXO) General Interface Requirements Document (GIRD), 418-XO-GIRD-0041.

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3.1

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3.1.1.1

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Requirements Document (PORD)

3 Sensor Requirements

3.1 Sensor Definition

3.1.1 GXS Modes

The GXS shall execute commands to individually enable and disable each autonomous function.

The GXS shall initiate all commanded mode transitions in no more than 20 seconds after receipt of command.

The GXS shall make limits and triggers of autonomous functions changeable by command.

The GXS shall indicate the mode of the instrument in housekeeping telemetry.

The GXS shall provide command and housekeeping telemetry functions in all powered modes.

3.1.1.1 Safe Mode

The GXS shall implement a Safe Mode.

The GXS shall be in a thermally and optically safe configuration for an indefinite period of time while in Safe Mode.

The GXS shall enter Safe Mode upon detection of internal faults capable of causing permanent damage to the instrument.

3.1.1.2 Normal Operational Mode

The GXS shall be in a fully functional configuration while in Normal Operational Mode.

3.1.1.3 Instrument Diagnostic Mode

The GXS shall implement an Instrument Diagnostic Mode.

The GXS shall be in a fully functional configuration while in Instrument Diagnostic Mode.

The GXS shall by command send selected channels while in Instrument Diagnostic Mode.

The GXS shall by command send the individual measurement in those cases where TDI data is digitally processed off the focal plane while in Instrument Diagnostic Mode.

The GXS shall by command send data from all detectors while in Instrument Diagnostic Mode.

The GXS shall by command send all bits from the A to D converter while in Instrument Diagnostic Mode.

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3.1.1.3.0-7

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3.1.1.4

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3.1.2

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3.1.2.1.1

3.1.2.1.1.0-1

3.1.2.1.2

3.1.2.1.2.0-1

3.1.2.1.2.0-2

3.1.2.1.2.0-3

3.1.2.2

3.1.2.2.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

The GXS shall by command perform electronic in-flight calibration while in Instrument Diagnostic Mode.

The GXS shall by command send dwell data (increased samples per second of a particular telemetry measurand) while in Diagnostic Mode.

3.1.1.4 Outgas Capability

The post-launch outgas period shall be no longer than 30 days (TBR).

3.1.2 On orbit Operations

3.1.2.1 Zones of Reduced Data Quality

3.1.2.1.1 Operational Zone

The GXS shall meet all operational sounding requirements for all pixels that are greater than 10 (TBR) degrees in angular distance from the center of the uneclipsed sun.

Rationale: Measurement Precision, on-orbit calibration, and accuracy are met outside of the Zones of Reduced Data Quality.

3.1.2.1.2 Restricted Zone / Zones of Reduced Data Quality (ZRDQ)

The GXS shall meet all sounding requirements, except the measurement precision and On-Orbit calibration and accuracy sections, for all pixels between 10 degrees (TBR) and 3 degrees (TBR) in angular distance from the center of the uneclipsed Sun.

Rationale: Measurement Precision, on-orbit calibration, and accuracy are relaxed near the sun in the Zones of Reduced Data Quality.

For all pixels between 10 degrees (TBR) and 3 degrees (TBR) in angular distance from the center of the uneclipsed sun, the GXS shall meet the sounding requirements in the measurement precision section relaxed by a factor of two.

Rationale: Specifically the measurement precision is relaxed by a factor of 2 in the Zones of Reduced Data Quality near the sun.

For all pixels between 10 degrees and 3 degrees in angular distance from the center of the uneclipsed sun, the GXS shall have an absolute calibration accuracy of either less than 2.0 K or less than the derived NEdT, whichever is greater.

Rationale: Specifically the calibration accuracy is relaxed to 2.0 K in the Zones of Reduced Data Quality near the sun.

3.1.2.2 Scanning Across the Sun

The GXS shall survive an unintentional command to image the sun without sustaining any permanent degradation in performance.

Rationale: Unintended imaging of the sun or unexpected loss of pointing control that accidently points at the sun must not results in damage to the instrument.

Page 8 of 53 Printed Friday, April 23, 2021

ID

GXSPORD94

GXSPORD95

GXSPORD96

GXSPORD97

GXSPORD98

GXSPORD99

GXSPORD100

GXSPORD101

GXSPORD102

GXSPORD103

GXSPORD104

GXSPORD105

GXSPORD106

GXSPORD107

Object Number

3.1.2.3

3.1.2.3.0-1

3.1.2.4

3.1.2.4.1

3.1.2.4.1.0-1

3.1.2.4.2

3.1.2.4.2.0-1

3.1.2.4.3

3.1.2.4.3.0-1

3.1.2.4.4

3.1.2.4.4.0-1

3.1.2.4.4.0-2

3.2

3.2.1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

3.1.2.3 Eclipse

During eclipse periods, for all emissive channels (sounding channels other than the DNB), the GXS shall meet all requirements, except the four-hour phased relaxation specified in the INR section.

Rationale: Any loss of power from the solar arrays and conversion to battery power for the Spacecraft shall not adversely impact the instrument performance.

3.1.2.4 Operations after Maneuvers

3.1.2.4.1 Yaw Flip

The GXS shall meet all requirements within 30 (TBR) minutes after the spacecraft interface has returned to being within specification following a yaw flip.

Rationale: If the spacecraft executes a yaw flip, the instrument recovery will occur in this duration after the interface is restored to nominal conditions.

3.1.2.4.2 Other Maneuvers

With the exception of a yaw flip, the GXS shall meet all requirements within 2 (TBR) minute after the spacecraft meets GXS interface requirements.

Rationale: If the spacecraft executes a different maneuver than a yaw flip, the instrument recovery will occur in this short duration after the interface is restored to nominal conditions.

3.1.2.4.3 Post Storage Activation

The GXS shall meet all requirements within 5 days of GXS turn-on after post storage activation for a GXS with passively cooled detectors and 3 days for a GXS with actively cooled detectors.

Rationale: After activation, GXS will cool for operations in this time listed here.

3.1.2.4.4 Detector Set-Point Temperature

The GXS detector set-point temperature shall be selectable by command near the nominal temperature to ensure radiometric performance during degradation and at end of life.

Rationale: This provides for set point temperature adjustments that may be needed due to aging or troubleshooting.

Knowledge of the GXS detector temperature shall be less than +/- 0.05 K (TBR).

Rationale: GXS will be thermally sensitive due to its detectors and thermal telemetry will provide information for potential corrections and troubleshooting.

3.2 Normal Operational Mode Sensor Requirements

3.2.1 Spectral Requirements

Page 9 of 53 Printed Friday, April 23, 2021

ID

GXSPORD108

GXSPORD109

GXSPORD110

GXSPORD111

GXSPORD112

GXSPORD113

Object Number

3.2.1.0-1

3.2.1.1

3.2.1.1.0-1

3.2.1.2

3.2.1.2.1

3.2.1.3

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

GXS shall provide the spectral range as specified in the wavelength or wavenumber column in the Sounding Spectral Range Table for a grating or FTS system, respectively, listed in the Sounding Spectral Range Table below.

Sounding Spectral Range Table

Band Wavenumber (cm‐1 ) Wavelength (μm)

LWIR region (temperature, LWIR window, ozone, NH3, isoprene, HNO3, low level moisture)

680‐ 1095 14.7 – 9.13

MWIR region (vertical moisture, window and temperature, N20 and

CO)

1689 – 2250 5.92 – 4.44μm

Rationale: Spectral ranges for GXS provide data for temperature and moisture profiles of the earth’s atmosphere. These bands overlap with the European MTG-IRS instrument that will provide valuable test data to NOAA for future algorithm validation.

3.2.1.1 Spectral Resolution

The achieved spectral resolution element is defined as the full-width-half-maximum (FWHM) of the instrument line-shape function (ILS) for filter or grating implementations, or one-half the distance between the first minima of the unapodized line-shape function (ideally a Sinc function) for an FTS implementation.

The GXS sounding channels shall have a maximum width for a given spectral region as specified in the wavelength or wavenumber column in the Maximum Width for Sounding Channels table for a grating or FTS system, respectively.

Maximum Width for Sounding Channels Table

Spectral Range Wavenumber (cm‐1) (FTS) Wavelength (μm) (Grating)

680‐ 1095 (cm‐1)

14.7 – 9.13 (μm )

0.625 0.0052

1689 – 2250 (cm‐1)

5.92 – 4.44 (μm )

0.625 0.0012

Rationale: Spectral resolution reflects that of the CO2 features that provide vertical temperature information. Water vapor band resolution matches that of the European MTG-IRS instrument that will provide valuable test data to NOAA for future algorithm validation.

3.2.1.2 Spectral Response

3.2.1.2.1 Reserved

3.2.1.3 Spectral Purity

Page 10 of 53 Printed Friday, April 23, 2021

ID

GXSPORD114

GXSPORD115

GXSPORD116

GXSPORD117

GXSPORD118

GXSPORD119

GXSPORD120

GXSPORD121

Object Number

3.2.1.3.0-1

3.2.1.4

3.2.1.4.0-1

3.2.1.5

3.2.1.5.0-1

3.2.2

3.2.2.1

3.2.2.1.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

For the sounding tasks, the integrated absolute value of the spectral response from outside the channel of interest shall be less than 35% (TBR) of the total spectral response in the channel for a uniformly illuminated aperture.

Rationale: Spectral purity is important for retrieving temperature and moisture vertical profiles.

3.2.1.4 Spectral Knowledge, Uniformity, and Stability

With channel center knowledge provided by the GeoXO System of at least one channel in the 11.20 μm to 14.7 μm spectral region and one channel in either the

8.26 μm to 5.92 μm spectral region, 5.92 to 4.65 μm spectral region, or the 4.65 to 4.166 μm spectral region, for 50% of the detector IFOV’s in the sensor, and with updates occurring at the minimum of once per hour, the GXS channel center stability shall be within 5 ppm (TBR) of channel wavelength over any 24 hour period.

Rationale: Reflects likely spectral calibration method provided by ground processing in order to achieve GXS channel center stability.

3.2.1.5 Spectral Region Breaks

With the exception of permissible inoperable channels, the GXS spectral coverage shall be continuous for the required spectral range except for one allowable missing span per region less than the “maximum size of break” column and not contained in the “excluded region for region break” column in the following table.

Spectral Region Breaks

Region Excluded span for region break (μm )

Maximum size of break (μm )

680‐ 1095 (cm‐1)

14.7 – 11.20 (μm )

13.4 – 13.95 0.12

1689 – 2150 (cm‐1)

5.92 – 4.65 (μm )

None 0.05

2150 – 2250 (cm‐1)

4.65 – 4.44 (μm )

4.65 – 4.44 0.050

Note that these regions intentionally do not correspond exactly with the spectral bands defined above.

Rationale: Spectral band breaks are not permitted in key spectral regions.

3.2.2 Scan Requirements

3.2.2.1 Coverage Rate

Note that these coverage requirements define a capability and not a definitive operational scenario. Rather, NOAA anticipates operating GXS in an asynchronous manner that uses information from other instruments and models to identify potential regions for scanning/stepping by GXS. To perform its tasks, commanding of GXS for these targeted observations will be based on priorities and availability.

Page 11 of 53 Printed Friday, April 23, 2021

ID

GXSPORD122

GXSPORD123

GXSPORD124

GXSPORD125

GXSPORD126

GXSPORD127

GXSPORD128

GXSPORD129

Object Number

3.2.2.1.0-2

3.2.2.1.0-3

3.2.2.2

3.2.2.2.0-1

3.2.2.2.0-2

3.2.2.2.0-3

3.2.2.2.0-4

3.2.2.3

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

In Disk Sounding task, the GXS shall acquire each SD and perform all necessary housekeeping and calibration functions in less than 30 minutes.

Rationale: When covering the 62-degree LZA region, the coverage including all calibrations will take 30 minutes or less to ensure a timely coverage rate for the instrument that may be used to cover either smaller areas in proportionally smaller times or larger areas in proportionally longer times.

The GXS shall be commandable into custom tasks with regions interspersed in any order, including within other acquisitions, in order to collect individual sounding coverage areas (e.g. super-regional, mesoscale, or any other shape). An example of potential operations is shown in the table below. This capability should reflect the coverage rate above, based on area-per-time calculation.

Example of Potential Operations (For Reference Only)

Example of a potential multi‐regional sounding task for operations

Region Revisit Time

SD 60 min

Super‐regional (3000 km x 5000 km) 15 min

Mesoscale (1000 km x 1000 km) 5 min

Rationale: The GXS must be commandable to cover regions of interest. Regions will be covered with the same instrument coverage rate as SD in 30 minutes. Adding multiple regions will reduce refresh for the SD and coverage times for Full Disk, Superregional, mesoscale, or other areas will essentially scale with coverage area for these other regions.

3.2.2.2 Scan/Step Direction

The dominant direction of instrument data collection shall be in the West-East directions.

Rationale: Weather moves from West to East in CONUS.

To accommodate a possible seasonal yaw flip, data collection shall be possible in West to East, and East to West directions.

Rationale: Weather moves from West to East so need to address this after yaw flip as well.

To accommodate a possible seasonal yaw flip, stepping shall be possible in North to South, and South to North directions.

Rationale: After yaw flip, North and South flip relative to instrument axes.

Ground sample data acquisition should begin with the northernmost coordinate and proceed south.

Rationale: This reflects current observations and conventions.

3.2.2.3 Flexible and Selectable Scan Pattern

Page 12 of 53 Printed Friday, April 23, 2021

ID

GXSPORD130

GXSPORD131

GXSPORD132

GXSPORD133

GXSPORD134

GXSPORD135

GXSPORD136

GXSPORD137

GXSPORD138

Object Number

3.2.2.3.0-1

3.2.2.3.0-2

3.2.2.3.0-3

3.2.2.4

3.2.2.4.0-1

3.2.2.4.0-2

3.2.2.4.0-3

3.2.2.5

3.2.2.5.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

The GXS sensor shall scan an area of arbitrary size anywhere within the field of regard when commanded, including Superregional and Mesoscale regions.

Rationale: Permits flexible tasking of GXS to regions of interest, likely including Superregional and Mesoscale.

The scan area and geographic location shall be selectable from one frame to the next.

Rationale: Permits flexible tasking of GXS to regions of interest, likely including Superregional and Mesoscale.

The GXS shall be designed such that the Earth-scanning patterns are fully programmable on-orbit.

Rationale: Permits flexible tasking of GXS to regions of interest, likely including Superregional and Mesoscale.

3.2.2.4 Scan Efficiency and Simultaneities

For the sounding tasks, data for all the channels obtained from any specific point on the Earth shall be coincident within 10 seconds.

Rationale: Spectrally simultaneous observations provide observations of the same features in the atmosphere and avoid artifacts in resulting data.

The time between collection of adjacent pixels within a single GXS data frame shall be less than or equal 10 minutes.

Rationale: This limits shearing in an image composed of multiple individual observations.

The data shall be time identified so that the time any detector sample in the data was acquired can be determined to within 0.1 milliseconds relative to the spacecraft provided clock information. The spacecraft clock is synchronized to Universal Time (UT) to an accuracy defined in the GIRD.

Rationale: Temporal telemetry is needed to facilitate data processing.

3.2.2.5 Data Latency

For sounding products, the GXS shall contribute to the total data latency for the Level 1b product of no more than 180 (TBR) seconds for calibrated, navigated radiances.

Data latency is measured from the time the instrument collects all samples for an earth scene (or frame) to the time the data is available for dissemination on the ground as level 1b data. The GXS contribution to data latency includes delay of delivery of data to the spacecraft and delay due to ground algorithm processing (i.e., any resampling and INR).

Rationale: Latency between the last observation of the input data to the level 1b processing and the availability of the data for further processing should be as short as practical.

Page 13 of 53 Printed Friday, April 23, 2021

ID

GXSPORD139

GXSPORD140

GXSPORD141

GXSPORD142

GXSPORD143

GXSPORD144

GXSPORD145

GXSPORD146

GXSPORD147

GXSPORD148

GXSPORD149

Object Number

3.2.3

3.2.4

3.2.4.1

3.2.4.1.0-1

3.2.4.2

3.2.4.2.0-1

3.2.4.3

3.2.4.4

3.2.4.4.1

3.2.4.4.2

3.2.4.4.2.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

3.2.3 Coverage Area Requirements (Reserved)

3.2.4 Spatial Sampling Requirements

3.2.4.1 Field of Regard

The unvignetted Field of Regard (FOR) of the instrument shall include a circle of at least 20 degrees in diameter with its center at the sub-satellite point and accounting for alignment errors as described in the GIRD.

Rationale: A boresighted, clear FOR of 20 degrees affords sufficient star coverage in the annulus around the edge of the earth and the edge of the FOV to permit acceptable navigation, and also supports observations of the moon which is an important calibration reference sources.

3.2.4.2 Ground Sample Distance and Angle

The centroid-to-centroid distance between adjacent spatial samples on the Earth’s surface, as measured at the Sub-Satellite Point, defines the ground sample distance (GSD). The ground sample angle (GSA) is the associated angle. A two-dimensional pixel is defined by the GSD in the East/West and North/South dimensions.

The GXS shall have a GSA no larger than 112 microradians (4 km at nadir) for emissive channels.

Rationale: GSA defines the spatial sampling for the Level 1b output of GXS.

3.2.4.3 Reserved

3.2.4.4 Detector Sample Ground Footprint

3.2.4.4.1 Overshoot/Undershoot

3.2.4.4.2 Detector / Optics Ensquared Energy

The detector/optics ensquared energy (DOEE) is a unitless figure of merit, which is the ratio of the energy measured by a detector from its corresponding ground sample area (defined by the Threshold GSD (TGSD), not the detector active-area projection on the ground) to the energy measured by the detector from the entire large and uniform scene. The DOEE can be understood in terms of the scene-spread function (SSF), which is the convolution of the polychromatic system point-spread function (PSF) with the detector spatial response function (SRF); however, the detector spatial response function must be measured in order to fully characterize all of the optical and electrical cross-talking.

Page 14 of 53 Printed Friday, April 23, 2021

ID

GXSPORD149

GXSPORD150

GXSPORD151

GXSPORD152

GXSPORD153

Object Number

3.2.4.4.2.0-1

3.2.4.4.3

3.2.4.4.3.0-1

3.2.4.5

3.2.4.5.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

DOEE Equation

Graphical Representation of DOEE Equation

As a standard, the DOEE is always referenced to the TGSD. The DOEE requirements are presented by band. The requirement applies to all channels within each specified band.

The GXS DOEE shall be greater than or equal 70% (TBR) for the aggregate of the channels within each band as defined in the Sounding Spectral Range Table.

Rationale: DOEE places a limit on the limit on the light not coming from the region of interest when observing the region of interest.

3.2.4.4.3 Modulation Transfer Function

Reserved.

3.2.4.5 Co-Registration

Between emissive channels, the channel-to-channel registration, or co-registration, is defined as the following correlation equation:

Page 15 of 53 Printed Friday, April 23, 2021

ID

GXSPORD153

GXSPORD154

GXSPORD155

GXSPORD156

GXSPORD157

GXSPORD158

GXSPORD161

GXSPORD162

Object Number

3.2.4.5.0-1

3.2.4.5.0-2

3.2.5

3.2.6

3.2.6.1

3.2.6.1.0-1

3.2.6.2

3.2.6.2.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

The co-registration between emissive channels within the same band (LWIR or MWIR) shall be greater than 95% (TBR).

Rationale: Co-registration needs to be very high to ensure that the same phenomena are being observed for all bands.

The co-registration between emissive channels from different bands shall be greater than 80% (TBR).

3.2.5 Reserved

3.2.6 Radiometric Performance Requirements

3.2.6.1 Dynamic Range

The sounding spectral regions shall have sufficient dynamic range to measure cold space and the peak temperature for any one channel (as specified in the Dynamic Range and Precision Table) and the integrated flux for the band (as specified in the Dynamic Range and Precision Table).

Rationale: Both cold space and the earth scene need to be observed, along with a reference blackbody in order to provide sufficiently calibrated data.

3.2.6.2 Measurement Precision (SNR, NEdN, and NEdT)

For the corresponding black body scene and for linear interpolation in the corresponding dimensions for regions with multiple points specified, the GXS sounder shall have a maximum Noise Equivalent Delta Temperature or Noise Equivalent Delta Radiance as specified in the Dynamic Range and Precision Table for individual channel observations and for Fourier transformed channel observations, respectively. Note that per industry standard, the noise equivalent temperature error is reported as the error if viewing a 250K scene; however, the actual scene is not necessarily a 250K scene. Also note that for data acquired at more than one sample per channel, the noise performance for terms that are uncorrelated between channels can be reduced by a factor of the inverse of the square root of the oversampling.

Page 16 of 53 Printed Friday, April 23, 2021

ID

GXSPORD162

GXSPORD163

GXSPORD164

Object Number

3.2.6.2.0-1

3.2.6.2.1

3.2.6.2.1.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

Dynamic Range and Precision Table

Spectral Range Max BB Temp for any one channel

Max BB Temp for integrated flux in range

NEdN mW/m2 sr cm‐1 for Fourier transformed channel observations

NEdT (in K) with dN/dT evaluated at 250 K for individual channel observations

680‐718 cm‐1

13.9‐14.7 μm 306 K 287 K 2.5 (TBR) at

680 cm‐1 and

0.352 at 718 cm‐1 for 224K scene and interpolated in wavenumber

2.0 (TBR) at 14.7 μm and

0.3 at 13.9μm for 224K scene and interpolated in wavelength

718‐800 cm‐1 12.5‐13.9 μm

306 K 287 K 0.352 for 224K scene

0.3 for 224K scene

800‐881 cm‐1

11.34‐12.5 μm

306 K 304.5 K 0.2 (TBR)

for 234 K scene

0.2 (TBR)

for 234K scene

881‐1095 cm‐1

9.13‐11.34 μm 306 K 297 K 0.2 (TBR) for

218 K scene

0.2 (TBR)

for 234K scene

1689‐2150 cm‐1

4.65‐5.92 μm

306 K 270 K 0.022 (TBR)

for 234 K scene

0.25 (TBR)

for 234K scene

2150 ‐ 2250 cm‐1

4.44‐4.65 μm

304 K 273 K 0.016 (TBR)

for 228 K scene

0.92 (TBR) at 4.44 μm

0.6 (TBR) at 4.65 μm interpolated in wavelength for 228K scene

3.2.6.2.1 Pixel Operability

Neglecting missing spectral channels resulting from permissible band breaks, the number of channels meeting the noise requirements associated with the Dynamic Range and Precision Table shall be 50% (TBR) for grating systems with the distribution of failing channels being less than the percentages in the “Inoperability per Region” column in the following table and with contiguous failing channels being less than the “Maximum Cluster Length” column in the 1x Channel Inoperability for Grating Table below.

Page 17 of 53 Printed Friday, April 23, 2021

ID

GXSPORD164

GXSPORD165

GXSPORD166

GXSPORD167

GXSPORD168

GXSPORD170

GXSPORD171

GXSPORD172

GXSPORD173

Object Number

3.2.6.2.1.0-1

3.2.6.2.1.0-2

3.2.6.2.1.0-3

3.2.6.2.1.0-4

3.2.6.2.1.0-5

3.2.6.2.2

3.2.6.2.3

3.2.6.3

3.2.6.3.1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

1x Channel Inoperability for Grating Table

Spectral Range Maximum Cluster Length Inoperability per Region (TBR)

12.5‐14.7 μm 5 50%

11.34‐12.5 μm 5 50%

9.13‐11.34 μm 5 (TBR) 50%

4.65‐5.92 μm 5 50%

4.44‐4.65 μm 5 50%

Neglecting missing spectral channels resulting from permissible band breaks, the number of channels meeting 2x the noise requirements associated with the Dynamic Range and Precision Table shall be 84% (TBR) for grating systems with the distribution of failing channels being less than the percentages in the “Inoperability per Region” column in the following table and with contiguous failing channels being less than the “Maximum Cluster Length” column in the 2x Channel Inoperability for Grating Table below.

Rationale: For grating systems, individual pixel outage are permitted to avoid driving detector quality.

2x Channel Inoperability for Grating Table

Spectral Range Maximum Cluster Length Inoperability per Region (TBR)

12.5‐14.7 μm 5 16%

11.34‐12.5 μm 5 16%

9.13‐11.34 μm 5 (TBR) 16%

4.65‐5.92 μm 5 16%

4.44‐4.65 μm 5 16%

The number of pixels compliant with the 1x noise in the Dynamic Range and Precision Table above shall be 50% (TBR) for an FTS system.

The number of pixels compliant with the 2x noise in the Dynamic Range and Precision Table shall be 84% (TBR) for an FTS system.

For pixels failing a 2x noise requirement or inoperability per region requirement, no more than 50% (TBR) of the failing pixels shall have a neighbor, including diagonal neighbors, which is also a failing pixel.

Rationale: For grating systems, individual pixel outage are permitted to avoid driving detector quality.

3.2.6.2.2 Reserved

3.2.6.2.3 Reserved

3.2.6.3 Radiometric Accuracy

3.2.6.3.1 Absolute Accuracy

Page 18 of 53 Printed Friday, April 23, 2021

ID

GXSPORD174

GXSPORD175

GXSPORD176

GXSPORD177

GXSPORD178

GXSPORD179

Object Number

3.2.6.3.1.0-1

3.2.6.3.1.0-2

3.2.6.3.2

3.2.6.3.2.0-1

3.2.6.3.2.1

3.2.6.3.2.1.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

The GXS absolute radiometric accuracy is the unknown bias error in the measured radiance in each spectral channel, root-mean-squared with any random precision or repeatability component in a specific measurement period. It is specified in terms of a brightness temperature error at 300 K for emissive bands.

For all emissive channels, the GXS absolute accuracy shall be less than or equal to 1K or the derived NEdT, whichever is greater.

Rationale: Using the definition above, the GXS absolute accuracy is constrained to be less than 1 K or the noise level to avoid limiting impact to higher level products.

All calibration shall be traceable to National Institute of Standards and Technology (NIST) standards.

Rationale: Calibrations shall follow NIST methodologies to ensure unbreakable chain for traceability.

3.2.6.3.2 Relative Accuracy

The relative radiometric accuracy is defined as the unknown bias error between two arbitrary radiance measurements, root-mean-squared with any random precision or repeatability component in a specific measurement period. The relative accuracy error is defined as the RMS variation in signal level, for all measurements in a large ensemble (e.g. all the pixels in a frame such that the residual temporal variation does not dominate the calculation,) illuminated by constant scene radiance and over expected geostationary environmental conditions and calibration frequency.

All relative accuracy values presented are 1-sigma.

3.2.6.3.2.1 Scan Position to Scan Position Relative Accuracy

The difference in calibrated radiance between scan positions (where scan position refers to location of a target within a swath) for the emissive channels shall be less than or equal to the derived NEdN evaluated using the scan position to scan position equation below.

Scan Position to Scan Position Equation

Page 19 of 53 Printed Friday, April 23, 2021

ID

GXSPORD179

GXSPORD180

GXSPORD181

Object Number

3.2.6.3.2.1.0-1

3.2.6.3.2.2

3.2.6.3.2.2.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

Illustration of Scan Position to Scan Position Evaluation

Rationale: Scan position to scan position relative accuracy limits detection errors as a function of scan position.

3.2.6.3.2.2 Pixel-to-Pixel Relative Accuracy

For each and every 3x10 region on the SD, the difference in radiance between calibrated detector samples for each emissive channel shall be less than or equal to the derived NEdN evaluated using the pixel-to-pixel equation below.

Pixel-to-Pixel Equation

Page 20 of 53 Printed Friday, April 23, 2021

ID

GXSPORD181

GXSPORD182

GXSPORD183

Object Number

3.2.6.3.2.2.0-1

3.2.6.3.2.3

3.2.6.3.2.3.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

Illustration of Pixel-to-Pixel Evaluation

Rationale: Pixel-to-pixel relative accuracy limits detection errors in nearby observing regions.

3.2.6.3.2.3 Channel-to-Channel Relative Accuracy

The difference in calibrated radiance between emissive channels shall be less than or equal to the derived NEdT evaluated using the channel-to-channel equation below.

Channel-to-Channel Equation

Page 21 of 53 Printed Friday, April 23, 2021

ID

GXSPORD183

GXSPORD184

GXSPORD185

Object Number

3.2.6.3.2.3.0-1

3.2.6.3.2.4

3.2.6.3.2.4.0-1

418-XO-GXSPORD-0031, RM Version, GeoXO hyperspectral radiometric Sounder (GXS) Performance and Operational

Requirements Document (PORD)

Illustration of Channel-to-Channel…