Draft Ocean Surface Winds (OSW) Pilot SOW.pdf

ATTACHMENT 1

NOAA Commercial Data Program GNSS Reflectometry for Ocean Surface Winds Pilot: 2023-2024

Statement of Work

I. INTRODUCTION

NOAA's scientific mission is to understand and predict changes in climate, weather, the ocean and coasts through the systematic study of the structure and behavior of related ecosystems. A key NOAA mission need is for accurate and comprehensive measurements of global sea-surface wind speed and direction. Wind speed measurements are important to meteorologists and oceanographers in the preparation of marine weather forecasts for hurricanes, winter storms, and high seas. Wind information is also used in forecasts of ocean currents, and in observing and understanding the global manifestation of phenomena like the El Niño Southern Oscillation. Winds are also related to key processes in the hydrological cycle of evaporation and precipitation, the energy cycle, and the CO2 budget.

Global Navigation Satellite System Reflectometry (GNSS-R) is a remote sensing technique that utilizes signals from positioning, navigation, and timing (PNT) service satellites, such as GPS and Galileo, to measure and study various properties of the Earth's surface. NOAA has performed significant scientific work on investigating the utility of GNSS-R for addressing mission needs including measuring ocean wind speeds, land surface freeze/thaw, sea ice, soil moisture, and flooding inundation.

Retrieving ocean surface winds is a promising application of GNSS-R. In GNSS-R reflectometry, GNSS signals emitted by satellites are reflected off the ocean surface, and the reflected signals are received by GNSS receivers on satellites, aircraft, or ground-based stations. By analyzing the characteristics of reflected signals, valuable information about the ocean surface can be derived, including wind speeds. The interaction between GNSS signals and the ocean surface causes changes in the signal's properties, such as amplitude, phase, and polarization. These changes are influenced by the roughness of the ocean surface, which is directly related to wind speed. By measuring and analyzing these changes, GNSS-R can provide estimates of ocean surface wind speed.

The use of GNSS-R for ocean surface wind speed retrievals has the potential to allow for regular monitoring of ocean surface winds at a relatively low cost. GNSS-R can complement existing observation systems and has the potential to improve forecast accuracy. By leveraging GNSS-R wind speed measurements, researchers and scientists can contribute to improving weather forecasting models and climate research.

A GNSS-R NASA Earth Venture mission was launched in 2016 to investigate measuring surface wind speeds in tropical cyclones to improve storm forecasting. This mission, the Cyclone Global Navigation Satellite System (CYGNSS), consisted of a constellation of eight micro-satellites equipped with Delay Doppler Mapping instruments receiving direct and reflected signals from GNSS satellites. In 2021, NOAA conducted an independent assessment of CYGNSS GNSS-R applicability for NOAA operations. In the assessment, NOAA worked with NASA and the CYGNSS scientific community to investigate the viability of GNSS-R and identify requirements for future GNSS-R constellations. The assessment identified limitations with the CYGNSS constellation and GNSS-R data processing that prevented data from meeting NOAA wind product requirements for user applications and analysis. As a part of this activity, NOAA developed a CYGNSS wind product in-house which addressed many of the issues with existing wind products. The NOAA wind product is now ready for testing in NOAA applications and a thorough experiment using the NOAA wind product within the NOAA Data Assimilation (DA) system on new GNSS-R system data represents the next step to fully assess the potential for NOAA operations. As such, a key recommendation of the study was for NOAA to assess the quality and impact of available commercial GNSS-R observations using in-house expertise to conduct further studies.

The NESDIS Commercial Weather Data Pilot (CWDP) Program pursues demonstration projects on behalf of NOAA and assesses the viability of assimilating commercially provided satellite data and products to diversify NOAA’s portfolio of data collection capabilities. Through the CWDP, NOAA intends to conduct a commercial data pilot study (Pilot Study) that may help NOAA meet its terrestrial weather mission objectives. For this Pilot Study, NOAA will assess the quality and impact of available commercial GNSS-R observations for the determination of ocean surface wind characteristics. NOAA will use Pilot Study data to conduct studies to improve upon derived wind speed products previously developed by NOAA, and will investigate the utility of derived wind speed products developed by commercial vendors. As an ancillary part of the Pilot Study, NOAA may assess the quality and impact of commercial GNSS-R observations for additional environmental measurements including but not limited to: land surface flooding inundation, freeze/thaw events, sea ice, and soil moisture.

II. DATA SPECIFICATIONS

The Contractor for this Pilot Study shall supply near-real-time GNSS-R observation data and derived products collected on-orbit from one or more satellites. The observation data will primarily be used for the evaluation of commercial GNSS-R data for ocean surface wind speed measurement. Observation data may also be used for the evaluation of commercial GNSS-R data for land surface flooding inundation, freeze/thaw event, sea ice, soil moisture, and altimetry measurements.

The requirements set forth below constitute the specific operational measurement requirements for the Pilot Study. Requirements are categorized as threshold values, representing minimum acceptable levels, and objective values, representing desired levels of performance with increased utility. Threshold and objective requirements specified in this document are not necessarily indicative of requirements that may be developed for future contracts or solicitations.

Due to the nature of this Pilot Study as an initial pilot for GNSS-R applications, it is understood that contractors may not be able to meet all objective requirements presented. Contractors proposing to deliver data not meeting a requirement during the Pilot Study data delivery period should indicate the nature of the deficiency, reason for not meeting the requirement, and the expected impact. Contractors should also provide a clear and detailed plan and schedule to meet objective requirements and capabilities.

III. DATA REQUIREMENTS

Data supplied for the Pilot Study are required to meet the following threshold requirements.

1. GNSS-R observations shall be delivered at the following levels:

a. Level 0 data including:

i. Raw in phase/quadrature (I/Q) samples before Delay Doppler Map (DDM) lag correlations are performed on-board

ii. Fully resolved DDMs

iii. Subsample DDMs (which Level 0 data type is downlinked depends on the mode of DDMI operation)

b. Level 1 products including:

i. Calibrated DDMs of received power (Watts), calibrated using on-board cal load measurements

ii. Calibrated DDMs of scattering cross section (m^2), calibrated using spacecraft and GNSS spacecraft altitude and location knowledge and Earth geoid model

iii. Specular reflection point location estimates.

c. Level 2 products including:

i. Wind speed in observatory coordinate system and serial time stamp with precision geolocation accompanied with all appropriate flags and ancillary data used in the retrieval process.

ii. Mean square slope (surface roughness) in observatory coordinate system and serial time stamp with precision geolocation.

iii. Any ancillary data used in the retrieval process.

d. Ancillary data provided to analysis team:

i. Quality flags generated in processing pertaining to provided level 0, 1, 2 data, and relevant documentation.

ii. All data used for calibration and product development.

iii. Data readers and format descriptions (i.e., reader software source, data dictionaries, etc.) necessary for processing and analysis.

iv. Algorithm Theoretical Basis Documents

v. Command Catalogs

2. Data delivered shall meet the following requirements:

a. The data delivery process shall follow standard NESDIS methods and protocols to be determined by NESDIS (i.e., OSGS NESDIS Common Cloud Framework (NCCF) secure ingest).

b. The data delivery process shall follow NOAA security requirements (see VIII.

SECURITY REQUIREMENTS)

Data supplied for the Pilot Study are preferred to meet the following objective requirements.

1. GNSS-R observations shall be delivered at the following levels:

a. Level 3 Products, including:

i. Gridded wind speed with precision geolocation

ii. Gridded ocean surface roughness with precision geolocation

iii. All necessary flags and ancillary data together with geolocation and time stamp

2. Data used for validation and quality control of GNSS-R observations:

a. Measurements of transmitted power of different GPS constellations

b. Acquisition data of more than 4 reflections per contact

IV. Observation requirements

Data supplied for the Pilot Study are required to meet the following objective requirements:

1. Continuous data collection with all recorded data provided. Greater than 500 daily GNSS-R observations, when averaged over any 30-day period.

2. Greater than 65% of GNSS-R observations shall have a specular point occurring over water surfaces.

3. The time of GNSS-R observations shall be nearly uniformly distributed in time of day such that the quantity delivered in any six-hour period of the day, when averaged over 30 consecutive days, shall vary by less than a factor of two from any other six-hour period.

4. GNSS-R observation capabilities of:

a. Spatial resolution of 25 km x 25 km or better.

b. Mean revisit time of less than 12 hours.

c. 100% duty cycle during the study period.

d. Operation in the presence of rain.

e. Wind speed dynamic range at 5 km x 5 km resolution of 3-70 m/s.

f. Retrieval uncertainty for winds of greater than 20 m/s is less than 10%.

g. Retrieval uncertainty for winds of less than 20 m/s is less than 2 m/s.

5. All GNSS-R observations purchased for the Pilot Study shall be unique and not provided to any U.S. Government agency or affiliate through any other contract. Contractors providing observations for the Pilot Study that are provided to any U.S. Government agency or affiliate through any other contract may include indirect costs applicable to the pilot study, including technical documentation, format specification, data ingest and processing development, data calibration, and engineering/technical support as needed for problem resolution and technical assistance.

V. General Measurement Requirements

1. Data shall be provided only from instruments on satellites with an assigned World Meteorological Organization (WMO) satellite identifier.

2. GNSS-R observations shall be from GPS, GLONASS, BeiDou, or Galileo systems on at least two frequencies. GNSS-R observations collected from other Signal of Opportunity (SoOP) sources are out of scope for the Pilot Study, but are acceptable as additional data for experimental purposes.

3. GNSS-R observations shall be provided with concurrent precise orbit determination

(POD) tracking data.

4. POD tracking data shall include dual-frequency pseudorange, carrier phase, and signal to noise ratio (SNR), as collected on-orbit in real time.

5. POD tracking data shall include dual-frequency measurements recorded at 1 Hz or greater rate from a minimum of four GNSS satellites simultaneously for 95% of the POD data collection period.

6. Every other orbit of each satellite from which data are provided shall be covered by POD tracking data at no less than 50% duty cycle with continuous arc length of at least 50 minutes per orbit.

7. POD tracking data shall be from GPS, GLONASS, or Galileo satellites.

8. Navigation solutions calculated onboard the spacecraft shall be provided, including receiver clock offsets and time-tagged Earth-Centered-Earth-Fixed position and velocity.

9. Navigation solution data shall be provided at intervals of 30 seconds or less.

10. Satellite attitude quaternions shall be collected concurrently with all data at intervals of 30 seconds or less.

11. Metadata shall include, at a minimum, for each satellite/instrument configuration:

a. Satellite mass, satellite coordinate system geometry, center of mass location, external dimensions including any protruding appendages (e.g., solar array, antennae) and, if appropriate, their variation with time (e.g. articulating solar panel).

b. Antenna reference point vectors relative to the center of mass and corresponding uncertainty estimates, antenna boresight vectors, and antenna fields of view.

c. Antenna phase center offset and phase center variation measurements and corresponding uncertainty estimates representing the as installed on-orbit configuration for all relevant frequencies, in ANTEX format (https://files.igs.org/pub/station/general/antex14.txt).

d. Antenna gain patterns representing the as installed on-orbit configuration for all relevant frequencies, and file format documentation.

e. Measurements of sensor bias and/or drift, if appropriate.

12. All satellite/instrument configuration changes shall be logged and notifications shall be sent to the Government point of contact.

VI. CONTRACTING OFFICER’S REPRESENTATIVE

In accordance with CAR Clause 1352.201-72, a Contracting Officer's Representative (COR) will be designated at award. The COR may provide technical direction and has the authority to accept delivery. The COR is not authorized to make any commitments or otherwise obligate the Government or authorize any changes which affect the contract price, terms, or conditions of the award. Any Contractor request for changes shall be referred to the Contracting Officer https://files.igs.org/pub/station/general/antex14.txt directly or through the COR. No such changes shall be made without the express written prior authorization of the Contracting Officer.

VII. PERFORMANCE SCHEDULE

The Pilot study will be conducted in three phases:

Phase 1: Preparation - 6 months In this initial phase, the Contractor shall supply the necessary technical documentation which may include format specifications, calibration data, and any other information that will be needed to ingest and process the data. Delivery mechanisms and data handling processes will be communicated to the Contractor. A delivery of 24-hours of sample data will be required during this phase and used to test and adjust the delivery and data flow process as needed.

Phase 2: Data Delivery - 6 months In this phase, the Contractor shall supply a series of data deliveries for a period of 6 months meeting the requirements of Section 3. The start and end date/time of this data delivery period will be coordinated with the CO and COR.

Phase 3: Evaluation - 6 months In this final phase, the Contractor will be available for limited reachback engineering/technical support as needed for problem resolution and technical assistance, as the Government evaluates the supplied dataset.

VIII. SECURITY REQUIREMENTS

The Contractor shall comply with CAR 1352.239-72, section (i). The Contractor may request COR approval of alternate security accreditation methodologies for compliance with section (i) including: information security assessment methodology promulgated by the U.S Federal Government (specifically, National Institute of Standards and Technology (NIST) Special Publication (SP) 800-37 and NIST SP 800- 53), or internationally recognized private industry information technology (IT) security frameworks (such as International Standards Organization (ISO)/International Electrotechnical Commission (IEC) 27033, 27001, 27006 and 27002, or Control Objectives for Information and Related Technology (COBIT)). The Contractor will provide an analysis for alternative methodologies compared to SP 800-53 high impact baseline identifying any gaps. The Contractor shall deliver files to NOAA ingest using either Hypertext Transfer Protocol Secure (HTTPS) (preferred) or Secure File Transfer Protocol (SFTP). The Contractor shall use a data integrity method compliant with the NCCF ICD and approved by

NOAA.

IX. DATA RIGHTS

NOAA will retain all data purchased under this contract for non-operational use, including, but not limited to, analysis related to research and modeling. The Contractor shall grant NOAA a Limited License, allowing it to provide free access to data upon delivery to NOAA, not for further dissemination for commercial purposes, to U.S. Government agencies, WMO-designated National Meteorological and Hydrological Services, regional specialized meteorological centers, university research centers, members of the Coordination Group for Meteorological Satellites, and others responsible for national meteorological, space weather, or hydrological services.