Attachment 1 - Statement of Work.pdf

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA)

NATIONAL WEATHER SERVICE (NWS)

TOTAL PRECIPITABLE WATER / ZENITH TOTAL DELAY DATA PURCHASE

STATEMENT OF WORK

JULY 9, 2021

SERVICED BY:

EASTERN ACQUISITION DIVISION (EAD)

THE NATIONAL WEATHER SERVICE ACQUISITION BRANCH

1.0.INTRODUCTION

It is the intent for the National Weather Service (NWS) to purchase Total Precipitable Water (TPW) and Zenith Total Delay (ZTD) data derived from surface based Global Positioning System (GPS) and Global Navigation Satellite System (GNSS) receivers. These data were originally developed and made available by the Global Systems Division (GSD) of the Earth Science Research Laboratory (ESRL) which is a component of the National Oceanic and Atmospheric Administration’s (NOAA’s) Office of Atmospheric Research (OAR). This ground-based water vapor observing system is known collectively as Global Positioning System Meteorology (GPS-Met). GSD has been operating GPS-Met Data Acquisition and Processing System (DAPS) in a pseudo-operational mode since 2002, and both NWS and NESDIS have been incorporating these data, operationally, into their systems since 2005 and 2009, respectively. By 2016, GSD, as a research organization, transitioned this project out of their facilities, and into the purview of private enterprise via Cooperative Research and Development Agreement (CRADA), and GSD ceased the production of the data.

In order to maintain continuity of these data to NWS meteorologists, modeling capabilities and to its partners, the NWS intends to enter into a contract for a long-term purchase of these data as was received from the GSD.

2.0.CRITICAL DATA USAGE

GPS-Met TPW data are used by NWS meteorologists to provide situational awareness during rapidly changing weather conditions to support the issuance of watches, warning and forecasts to the emergency managers, key technical partners and to the general public of the United States.

They are also assimilated by the operational Rapid Refresh (RAP) numerical weather prediction (NWP) models. GPS-Met TPW estimates are also used by the National Environmental Satellite, Data, and Information Service (NESDIS) Blended TPW product available on the NWS’ Advanced Weather Interactive Processing System (AWIPS).

3.0.BACKGROUND

Water vapor is one of the most significant constituents of the atmosphere because it is the means by which moisture and latent heat are transported to cause weather. Despite its importance to atmospheric processes over a wide range of spatial and temporal scales, water vapor is one of the least understood and poorly described components of the Earth’s atmosphere. This is because water vapor moves rapidly through the atmosphere, and can change abruptly over extremely short distances. Therefore, water vapor is often under observed in time and space, especially during severe weather.

GPS-Met is a ground-based remote sensing system that uses GPS and/or GNSS radio signal delay measurements to estimate Zenith Total Delay (ZTD) and then uses nearby surface meteorological observations to derive TPW. The technique of using GPS/GNSS TPW data works in real-time under all weather conditions, providing water vapor measurements regardless of cloud or precipitation conditions. Traditional methods of measuring atmospheric water vapor have various shortfalls. Balloon-borne instruments, launched every 12 hours, miss more rapid atmospheric changes. Surface measurements are frequent but give little information about upper-air moisture. Infrared measurements from satellites do not penetrate cloud layers, and satellite-borne microwave sounders can be used only over open bodies of water and have limited temporal resolution because of their near polar-orbits. Water vapor sensing systems on commercial and research aircraft acquire the vast majority of their data at flight level, above most of the “weather” and moisture in the atmosphere. Furthermore, aircraft tend to avoid severe weather conditions by flying around it and therefore critical observations of moisture in these regions are routinely missed. GPS/GNSS TPW fills these voids and compliments these other systems capable of measuring atmospheric moisture.

NOAA scientists have quantified the impact of these real-time moisture estimates when used in NWP models, which are the basis for most weather forecasts. Across the Continental United States (CONUS), it was determined that at least 200 GPS/GNSS sites are the minimum needed to have any positive impact on NWP models (Gutman and Benjamin, 2001). This accounts for about an average 200 kilometer grid spacing between sites. Results from the current network show GPS-Met TPW data improve forecasts of relative humidity, rainfall, atmospheric rivers (narrow corridor of highly concentrated moisture in the atmospheric), and severe convection, improve calibration for satellites and in situ observing systems, and reliably monitor water vapor for climate change applications.

4.0. SCOPE

This Statement of Work (SOW) describes NOAA’s requirement for the acquisition of GPS/GNSS TPW estimates and the methodology for its delivery to NOAA. Included are the base requirements for the data, distribution, and data quality and verification assessment.

5.0. OVERVIEW OF DATA AND SITES INVOLVED

The first and most mature use of GPS for atmospheric remote sensing is for the measurement of TPW directly above GPS continuously operating reference station (CORS) sites. NOAA’s National Geodetic Survey (https://ngs.noaa.gov/CORS) established a network of CORS sites across the U.S. to improve the National Spatial Reference System and facilitate high accuracy positioning and navigation throughout America. The reference CORS map can be found at Appendix 11.4 as well as https://www.ngs.noaa.gov/CORS_Map.

The data utilized by the NWS forecaster and the NWP models consists of TPW measurements from more than 330 locations across the Continental United States (CONUS), Alaska, Hawaii, Puerto Rico, the tropical Western Pacific, the Caribbean, Canada, Mexico, Central America, and Northern South America.

These data are available on a continuous basis, 24 hours per day, 365 days per year. These data are collected and processed every 30 minutes and delivered to the NWS through standard data communications lines at 20 minutes and 50 minutes after the hour, every hour.

It is the intent of the NWS to retain these capabilities by purchasing the data as a service to satisfy key stakeholder requirements and to support the NWS’ mission.

http://www.ngs.noaa.gov/CORS_Map

6.0. DATA AS A SERVICE (DAAS)

6.1.Base Data Requirement The NWS intends to purchase GPS/GNSS TPW data as a service in at least the same frequency of collection (every thirty (30) minutes), with the same delivery frequency (20 minutes and 50 minutes after the hour), 24 hours per day, 365 days per year with the same quality, availability and reliability as it is received today. Data users will include any Line Offices within NOAA including, but not limited to, National Weather Service (NWS), National Environmental Satellite, Data and Information Service (NESDIS), and the Office of Atmospheric Research (OAR). NWS will ensure that other NOAA Line Offices comply with the terms of use.

NWS requires data in the geographic region containing the CONUS, Alaska, Hawaii, Puerto Rico, the tropical Western Pacific, the Caribbean, Canada, Mexico, Central America, and Northern South America. A geographic depiction of this domain is shown in Appendix 11.

The prospective contractor shall have a network of continuously operating reference stations (CORS) of GNSS/GPS receivers in place, or have legal access to data from other CORS network owners or other organization’s networks of receivers with sufficient coverage to meet the base requirement of at least 330 sites out of reference sites listed in https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/GPSMETSt atio n.txt within the above stated geographic area, in a reasonably uniform distribution. The network may be owned, operated, and maintained by the prospective contractor or by other organizations.

If the prospective contractor supplies data from another organization’s network the prospective contractor must have legal rights to redistribute these data.

6.2.Additional Data Beyond Base Requirement

The prospective contractor may provide additional data above and beyond the base requirement that the NWS is requesting. This is separate and optional from the base data requirements listed above in section 6.1. The additional proposal may include, but will not be limited to, additional GPS/GNSS sites within or outside of the North American domain, a more frequent interrogation of the data, higher delivery frequency, etc. It will be at the discretion of the NWS to determine if they will exercise this option.

7.0.DATA DELIVERY REQUIREMENTS

Data should be available at the rate of 96% for all base stations. System outages per station that fall below 96% available constitute a deficiency and those data not available subject to possible remedy. In the event of critical weather events, this requirement will be waived as these stations are subject to the effects of harsh weather and may be unavailable through no fault of the Contractor.

The prospective contractor shall deliver GPS-Met products to NOAA using secure file transfer protocol (sFTP) connection to NOAA’s National Weather Service Telecommunications Gateway

(NWSTG).

NOAA requires the vendor GPS-Met system to be compliant with the World Meteorological http://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/GPSMETStatio

Organization (WMO) standard for Ground-based GNSS Delay and Water Vapor Data while continuing to provide data to MADIS (Meteorological Assimilation Data Ingest System).

Achieving this goal requires products be delivered in two distinct formats.

The first format, which shall be delivered to MADIS, will be a comma-delimited ASCII format.

Details for this format type are described at:

https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/gpsmet.desc https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/GPSMETStat io n.txt The vendor will also deliver the data as WMO compliant ISX*14 BUFR messages. The * is a letter algorithmically determined from the geographic distribution of sites within the BUFR message.

NWS reserves the right to request periodic data comparisons between Contractor provided TPW data values and NOAA radiosonde values from the Contractor at no added cost. These requests will occur at no greater frequency than once per month unless known anomalies are found in the data sets. NWS reserves the right to request additional data archives not to exceed two years before the award date for NOAA to perform any necessary re-calibration, regression testing, tuning, and optimization of modeling and assimilation processes.

8.0.DATA USAGE AND DISTRIBUTION

All TPW data received by the NWS will be shared freely with all NOAA users only. Streaming TPW data will not be distributed beyond NOAA. NOAA will be able to freely and openly distribute any NOAA-generated and value-added products integrating TPW data along with other types of data in order to generate a new service product.

NOAA reserves the right to archive these data at one or more of NOAA’s National Centers (such as the National Centers for Environmental Information) and request historical archives from the contractor as part of the base requirement. Archived data is considered any data that is more than 24 hours old. The prospective contractor shall state the length of time TPW data is retained in its archive in the contract proposal. The vendor archive shall consist of at least 30 days of TPW data.

This contract is generally not intended to provide non-NOAA Agencies and non-U.S.

government agencies with TPW data for their respective missions or commercial purposes.

However, NOAA reserves the right to provide this data to another Federal Agency when that agency is collaborating with NOAA under a written agreement for the purposes of advancing NOAA’s mission. Other non-NOAA Agencies that require TPW data for their own missions will not be able to obtain that data through this contract, unless agreed upon by the government and the contractor.

State and local government users cooperating with NOAA may need these TPW data to satisfy their agreement/contract obligations. These users may receive TPW data and products under this contract provided they have a documented agreement with NWS or another NOAA Line Offices.

NOAA reserves the right to provide these data and products to state and local government users working with NOAA under such agreements. State and local government users will adhere to the http://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/gpsmet.desc same agreement as NOAA with the prospective contractor.

Non-government organizations, companies, and institutes cooperating with NOAA may need these TPW data to satisfy their agreement/contract obligation. These include cooperating organizations and support contractors. Cooperating organizations are organizations with a cooperative working relationship with one or more NOAA agencies. Support contractors are organizations that have contracts with one or more NOAA Line Offices to perform a task(s) for NOAA. The tasks may involve operational use of TPW data, application development, or research. NOAA reserves the right to provide these TPW data to non-federal users who have a direct relationship under written agreement or contract. The non-federal agency receiving NOAA-provided TPW data will adhere to the same agreement as NOAA has with the prospective contractor under this SOW.

TPW data may only be distributed to organizations under the auspices of the WMO or to foreign governments with which NOAA has explicit agreements about the exchange of TPW data in foreign countries, with which international arrangements have been established with a partnering NOAA line office, and coordination with the prospective contractor.

Internet redistribution is allowed to participating agencies through secure Internet connections that deny access to unauthorized organizations or individuals. Non-real-time data/products may be included in scientific papers or journal articles with proper acknowledgement to the prospective contractor where applicable.

NOAA reserves the right to freely share the archived ZTD data which are at least 48 hours after data observed time with any domestic and international partners and research collaborators.

9.0.CONTRACT TERMS

Contract for TPW data should be for one (1) year, with an additional four (4) options at one (1) year each. Invoices should be monthly with a verification of those data obtained.

10.0. DATA QUALITY VERIFICATION

Table 10-1: Data Quality

Parameter Requirement

Data Reliability

TPW data must be provided to NWS every 30 minutes, at every 20 and 50 minutes after the hour. The prospective vendor shall provide time-stamped data (minimum of 48 hours of sample data) as part of Response to this Request For Proposal (RFP).

TPW Data Accuracy

TPW data, provided by the prospective vendor, data must be within (+/-) 1.5 millimeters when compared to the precipitable water value at a nearby NOAA Radiosonde station (Gutman and Benjamin, 2001). The maximum range of the nearest NOAA Radiosonde station should be 50 kilometers, but should be minimized when and if possible (Gutman et al., 2003). The time of the supplied TPW observation should be within +/- 30 minutes of the NOAA Radiosonde launch.

As part of the Response to the RFP, the prospective vendor shall supply at least a data comparison spreadsheet with at least columns specified in Table 10-2 below from at least 5 GPS/GNSS system sites, from within their chosen network of CORS sites, from at least each of the following NWS Service Regions: Western Region, Central Region, Southern Region, and Eastern Region. The geographic depiction of these regions is shown in appendix 12.3. The statistical comparison should cover a minimum of one year so as to include data statistics of the four astronomical seasons. In addition, the vendor can also provide other data accuracy and data quality reports with any other charts, plots, graphs, and spreadsheets.

NWS reserves the right to request periodic data comparisons between vendor provided TPW data values and NOAA radiosonde values from the vendor at no added cost. These requests will occur at no greater frequency than once per month unless known anomalies are found in the data sets.

Table 10-2: Minimum Data Comparison Columns

Column Name Column Description UA Site ID Upper Air Radiosonde Site ID to compare to UA Site Lat/Lon UA site latitude and longitude UA Site Height UA site height (m) CORS Site ID CORS site that is close to UA site (within 50km)

Region NWS Service Regions: Western Region, Central Region, Southern Region, Eastern Region, Alaska, and Hawaii, or Other

Horizontal Distance Horizontal distance from CORS site to UA site (km) Site Height Offset UA site height - CORS site height (m)

# of Samples Compared Total number of samples compared, minimally covers one year

Average TPW Delta Average of (UA-CORS) TPW delta (mm) Standard Deviation of the Delta Standard Deviation of the above Delta (Sigma) (mm)

# of Samples the Delta > 2*Sigma # of samples the positive delta is greater than 2 times the standard deviation of the delta

# of Samples the Delta < -2*Sigma # of samples the negative delta is greater than 2 times the standard deviation of the delta

Max Positive Delta Max positive delta (mm) Time and Date of Max Positive Delta Time and Date when max positive delta occurred Max Negative Delta Max negative delta (mm) Time and Date of Max Negative Delta Time and Date when max negative delta occurred

11.0. APPENDIX

11.0 Types of Data

This SOW addresses multiple types of data as defined in TABLE 11-1.

TABLE 11-1: TYPES OF DATA

TYPE DESCRIPTION

GNSS Carrier Phase Observations

The ‘raw’ data measured by GNSS receivers. These observations are counts of the number of carrier frequency waves, from each GPS/GNSS satellite, that were observed passing the antenna during a given time period.

Surface Meteorological (MET) Observations

Atmospheric temperature and pressure measurements that are representative at the location and elevation of the GPS/GNSS station. Surface meteorological (MET) measurements are required to derive TPW and they can be obtained preferably from in-situ instruments or if needed from nearby MET data sources.

Zenith Total Delay

(ZTD)

ZTD is an estimate of the GPS radio signal’s ‘excess path length’ and it is the difference between where a GPS/GNSS antenna is known to be located versus where the GPS/GNSS system estimate is currently located. ZTD is measured in meters and typical values range between 1.8 and 2.5 meters, depending on the amount of water vapor present in the air column above a GPS/GNSS station. No meteorological information is needed to derive ZTD from raw measurements.

Total Precipitable Water (TPW)

PWV is the amount of water vapor present in the air column above a GPS/GNSS antenna. TPW is the height of the column of liquid water that would be obtained if all the water vapor in the air column above a GPS/GNSS site were condensed. It is measured in units of millimeters with typical values ranging between 0 and 100. TPW products are derived from ZTD estimates and auxiliary meteorological information.

11.1 Base Requirement Domain

FIGURE 11-2: This figure is intended to show the geographic domain for the base requirement of TPW data.

11.2 NWS Service Regions

FIGURE 11-3: This figure shows a geographic depiction of each of the NWS service regions across the CONUS, including Alaska and Hawaii (including Guam and American Samoa). TPW data will be provided from these specific regions as part of the vendor response to determine data accuracy.

11.3 Current CORS network Map

FIGURE 11-4: Map indicating the current CORS network map (https://www.ngs.noaa.gov/CORS_Map) http://www.ngs.noaa.gov/CORS_Map)

11.4 Current GPS-Met Comma-Delimited ASCII Format Description

Reference:

https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/gpsmet.desc gpsmet.desc # Data Source | Missing | Data Provider # The Data Source must match one of the entries in the first field # of LDADinfo.txt in order for the data to be decoded and stored.

# Multiple "missing" strings may be separated by commas or whitespace.

# The Data Provider field will be used to identify the data in the # netCDF files.

gpsmet | -9999 -9.99 -99.9000 -99.90 -9.900 | GPSMET ---- Header Group ----dataSourceDescription | STRING | STRING | STRING observationTime | DATE_TIME | DATE_TIME_STRING | ABSTIME timeZone | STRING | STRING | STRING # Var Name data type input units stored units ---- Data Group ------providerId | STRING | STRING | STRING stationId | STRING | STRING | STRING observationTime | DATE_TIME | DATE_TIME_STRING | ABSTIME totalColumnPWV | FLOAT | cm | cm notInUse1 | FLOAT | mB | Pa notInUse2 | FLOAT | K | K notInUse3 | FLOAT | % | % totalSignalDelay | FLOAT | m | m wetSignalDelay | FLOAT | m | m drySignalDelay | FLOAT | m | m meanWeightedTemperature | FLOAT | m | m capPi | FLOAT | dimensionless | dimensionless formalError | FLOAT | cm | cm http://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/gpsmet.desc

11.5 Current GPS-Met Comma-Delimited ASCII Format Data Provider Metadata

# This file contains the data provider metadata for gpsmet data

# Record format:

Dummy|ProviderKey|ProviderName|Contact|Phone1|Phone2|Fax|Street|City|State|ZIP| e-mail # Dummy: This field is no longer used; just make it a space.

# ProviderKey: The provider of the data. This key is used in lda/ldd.conf.

# ProviderName: The full name of the provider organization # Contact: Point of contact in the organization # Phone1: Primary phone number # Phone2: Secondary phone number # Fax Fax number # Street: Street address # City: City # State: State # ZIP: ZIP Code # e-mail: e-mail Address |FSLDD|Earth System Research Laboratory|Kirk

Holub|3034976642|3037486390|3034976014|325 Broadway|Boulder|CO|80303-3328|gpsmetproc.gsd@noaa.gov mailto:gpsmetproc.gsd@noaa.gov

11.6 Current GPS-Met Comma-Delimited ASCII Station Table Format (truncated due to space limitations) Reference:

https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/GPSMETStatio n.txt

# Station Table format:

ProviderId|AFOS(HB5)Id|StationName|StationElevation|Latitude|Longitude|localTZ| StationLocation| # StationType|NumberOfInstruments|NumberOfLevels|Maint/CalibSchedules| # SiteDesc| # Provider Sta.Id - Data provider station id # AFOS(HB5)Id - The AFOS or Handbook 5 id (NWS assigned) # Name - Text name of station # Elevation - Elevation of station GPS antenna in meters # Latitude - Latitude of station # Longitude - Longitude of station # local TZ - local Timezone (i.e. MST7MDT) # Station Location - Location of Station (Text) # Station Type - Type of station (i.e. tower, surface, floating platform,etc.)

# Number of Instruments - The number of reporting instruments for the station # Number of Levels - Number of Reporting Levels for the data (Level # information should be provided in the instrument table.)

# Maintenance/Calibration Schedules - Frequency of Maintenance/Calibration # Site Description - A text description of the site surroundings # *Note* Do not use the '#' in any of the fields below. The '#' is a comment # line marker.

# DO NOT EDIT THIS FILE -- It is generated by cgi-bin/sie/update_tables.cgi # Last modified: Thu Jan 16 16:23:10 UTC 2014 1LSU | 1LSU |Baton Rouge, LA | 19.4168 | 30.4074 | -91.180 |GMT|||1|||| 1NSU | 1NSU |Natchitoches, LA | 54.0996 | 31.7508 | -93.098 |GMT|||1|||| 1ULM | 1ULM |Monroe, LA | 41.9252 | 32.5290 | -92.076 |GMT|||1||||

ABQ1 | ABQ1 |Kirtland AFB, NM |1741.2010 | 34.9574 |-106.494 |GMT|||4|||| ABQ5 | ABQ5 |Kirtland AFB, NM |1738.6298 | 34.9574 |-106.494 |GMT|||1||||

11.7 Current LDAD Entry for GPS-Met Data

Reference:

https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/LDADinfo.txt

# This file contains the LDADinfo.txt entry for the gpsmet data type

#data Station netCDF|plot LDAD storage preprocess #type .txt dataKey type directory script gpsmet |GPSMET |87 |86 |CVS_TYPE |mesonet |moveGPSMETproduct.pl| http://www.nco.ncep.noaa.gov/pmb/codes/nwprod/madis_dump.v1.1.0/fix/data/LDADinfo.txt

11.8 Formats for WMO Standard Messages

NOAA requires data in a format compliant with the World Meteorological Organization (WMO) standard for Ground-based GNSS Delay and Water Vapor Data. Two file formats are required to meet this requirement and are listed as follows:

1. ‘COST-Format’ ASCII files as documented at http://egvap.dmi.dk/support/formats/egvap_cost_v22a.pdf

2. WMO compliant ISX*14 BUFR messages

The ISX*14 BUFR messages are generated using the COST-format files and the GWV Support Package created by the UK Met Office [contact Dave Offiler <dave.offiler@metoffice.gov.uk>]. The * is a letter algorithmically determined from the geographic distribution of sites within the BUFR message.

To enable the transmission of BUFR messages on the Global Telecommunication System the prospective contractor must replace the first 10 bytes of the ISX*14 message with a 19-byte routing header described below:

Four (4) astericks, zero-padded 10 byte length of the message, four (4) astericks, Ascii line feed (0A)

Example: For a BUFR file that contains 54327 bytes, the GTS header would be ****0000054327****<lf>.

The following PERL code adds this GTS header on the wfobufrfile to create an nwsbufrfile my $filesize = -s wmofilename;

# skip over the 10 byte header written by cost2bufr and write the GTS routing header instead

$filesize = $filesize - 10;

open( OUT, “nwsfilename” );

header = '****' . sprintf( ‘%010d`, $filesize) . '****' . ‘\n’;

syswrite OUT, $header, 19;

my $data = `/bin/cat $wmofilename`;

$data = substr( $data, 10 );

syswrite OUT, $data, $size;

close OUT;

The prospective contractor must transmit GTS header enabled ISX*14 BUFR messages to NOAA each duty cycle. NOAA will provide the prospective contractor with an account and login credential to an SFTP server for the purpose of receiving these files.

http://egvap.dmi.dk/support/formats/egvap_cost_v22a.pdf mailto:dave.offiler@metoffice.gov.uk

12.0 References

Gutman, S. I, S. G. Benjamin, 2001: The Role of Ground-Based GPS Meteorological Observations in Numerical Weather Prediction, 2001: GPS Solutions, Vol. 4, No. 4, pp. 16-24.

Gutman, S. I., S. R. Sahm, J. Stewart, S. Benjamin, T. Smith, and B. Schwartz (2003), A new composite observing system strategy for ground-based GPS meteorology, paper presented at the 12th Symposium on Meteorological Observations and Instrumentation, Am. Meteorol. Soc., Boston, Mass.