Colloquy: Waiting on Weather

November 27, 2013

Colloquy: Editor’s Column

A lot of time and money can be wasted waiting on weather. Down time is expensive. Wave height and period determine vessel motion and when they exceed operating limits, work slows or stops. Working in rough weather can lead to injuries and damage equipment.

Weather forecasts are particularly important for critical operations; metocean data is used to predict available weather windows.

Satellites carrying a new generation of equipment are providing increasingly better data and wider coverage.

The risks of inclement weather and related downtime can be managed. Downtime analysis tools incorporate statistical weather data to estimate the best time for operations. Typical records include wave height, wave period, wind speed, direction, currents, and spectral wave data. Typical output is the predictable number of WOW days/task, with results output at different levels of reliability (P50, P95, etc.).

Offshore simulators using weather models can be used to evaluate floating drilling rigs, anchor handling, installation, and pipelay vessels, as well as offshore tanker loading and other operations.

NOAA, NWS

The National Oceanic and Atmospheric Administration in the US is focused on the condition of the oceans and the atmosphere and its mission statement, in part, is “To understand and predict changes in climate, weather, oceans, and coasts [and to] share that knowledge and information with others.”

Although NOAA was formed in 1970, its roots stretch back to 1807, when the first scientific agency of the US federal government, the Survey of the Coast, was established.

The National Weather Service is the largest single entity within NOAA and it provides climate forecasts for the US, its territories, and adjacent waters. NWS operates 122 weather forecast offices, 13 river forecast centers, 9 national centers, and other offices, in which 4700 employees gather and analyze global data. The Service uses an array of satellites, including Geostationary Operational Environmental Satellites (GEOS) that orbit 22,300mi. above the Earth’s surface. NWS also gathers data from marine data buoys, surface observing systems, and instruments that monitor space weather and air quality.

JPSS

The Joint Polar Satellite System is the US’ next-generation polar-orbiting environmental satellite system. JPSS is a collaborative program between NOAA and NASA. The program includes three satellites (SNPP, JPSS-1, JPSS-2) and one experimental program (TCTE).

The Suomi National Polarorbiting Partnership (SNPP) was named in honor of Verner E. Suomi, University of Wisconsin meteorologist, widely recognized as the “Father of Satellite Meteorology.”

Suomi is the “first next generation” polar-orbiting satellite, launched in 2011 with a Delta-II mission launch vehicle from Vandenberg Air Force Base, California. It has a design life of five years and carries five instruments: VIIRS, CrIS, ATMS, OMPS, and CERES-FM6.

[The Delta II rocket is an expendable launch, mediumlift vehicle best known for launching Navstar global positioning system (GPS) satellites into orbit, but also used to launch civil and commercial payloads into low-earth, polar, geo-transfer and geosynchronous orbits. Delta II stands 125.9ft (37.8m) high, with different fairing diameters, 9.5ft or 10ft, to accommodate different payloads.]

Joint Polar Satellite System-1 will be the second of NOAA’s polar-orbiting satellites and will carry the same five instruments as Suomi. It has a longer design life, seven years, and is scheduled to launch in 2017 aboard a Delta-II mission launch vehicle.

JPSS-2 is the third satellite planned to provide continuity in the program. JPSS-2 will host VIIRS, CrIS, ATMS, and OMPS, but not CERES instruments.

The Total Solar Irradiance (TSI) Calibration Transfer Experiment (TCTE) is an instrument aboard Suomi that measures the sun’s energy output.

Instruments

The Cross-track Infrared Sounder (CrIS) provides detailed atmospheric temperature and moisture observations for weather and climate applications. It’s a highspectral resolution infrared instrument measures the three-dimensional structure of atmospheric temperatures, water vapor, and trace gases. The CrIS instrument was developed by ITT Exelis, Fort Wayne, Indiana.

The Ozone Mapping and Profiler Suite (OMPS) measures the concentration of ozone in the atmosphere, showing how ozone concentration varies with altitude. The OMPS instrument was developed by the Ball Aerospace & Technologies Corp., Boulder, Colorado.

The Visible Infrared Imager Radiometer Suite (VIIRS) features multi-band imaging capabilities to support the acquisition of high-resolution atmospheric imagery and produces accurate measurements of sea surface temperature. The VIIRS instrument was developed by Raytheon Company, El Segundo, California.

The Advanced Technology Microwave Sounder (ATMS) is a next-gen, cross-track microwave sounder, hosting 22 microwave channels, and operates in conjunction with the CrIS to profile atmospheric temperature and moisture. The ATMS instrument was developed by Northrop Grumman Corp., Azusa, California.

The Clouds and the Earth’s Radiant System (CERES-FM6) measurements help to improve weather forecast and climate model predictions, through understanding the effect of clouds on the Earth’s energy balance. The overall goal of the CERES project “is to provide a long-term record of radiation budget at the top-of-atmosphere, within the atmosphere, and at the surface with consistent cloud and aerosol properties.”

The CERES instrument (60x60x70cm) is reminiscent of a folded, paperboard oyster pail (Chinese-takeout box) wrapped in gold foil, with a horizontal cylinder at the base. It weighs 45kg.

Data

NOAA says the JPSS program “provides key products to the primary NOAA user community, including the National Weather Service, which requires data at low latency (not delayed) to ensure that weather forecasts and numerical simulations of weather patterns are supported in real time.”

The National Ocean Service uses polar-orbiting satellite data in real-time to monitor changing sea surface temperatures and coastal hazards. JPSS provides worldwide weather and oceanic data coverage. Global operations forecasting relies heavily on NOAA’s polar-orbiting satellite data. OE

Image Caption (top): Nina Rach

Image Caption (bottom): The Suomi National Polar-orbiting Partnership spacecraft lifted off on Oct. 28, 2011. Image: NASA/Bill Ingalls.