WVSS-II - Atmospheric Gas Analyzer

Prior to the advent of the SpectraSensors WVSS-II (Water Vapor Sensing System), weather forecasts for commercial and general aviation were often a compilation of data from weather satellites, weather balloons, pilots’ experience and sophisticated estimates of emerging patterns. But the most accurate weather models are updated in 12-hour intervals only at 70 national launch sites for radiosonde balloons and cannot respond to unforecasted atmospheric instability.

Brochure

Data Sheet

Aviation Industry on Climate Change with WVSS

Application Note

Why weather satellites and balloons are not enough

Accurate weather forecasting needs measurements of water vapor, wind, temperature and pressure at all levels of the atmosphere. Weather satellites provide broad coverage of atmospheric information for regional and international forecasting. But their data, whether derived from infrared or visual imaging, cannot reveal the detailed changes in water vapor in the vertical dimension. Traditional radiosonde weather balloons provide a vertical profile of observed data. But they are limited by the low number of locations that launch balloons at the required twelve hour intervals, and by the recurring cost of operations. By contrast a fleet of aircraft equipped with the Water Vapor Sensor System (WVSS-II) can provide thousands of times the number of vertical profiles accurately, automatically, and at a fraction of the operational cost.

2500 weather forecasting points vs. 70

Continuous, real time information captured and communicated by 2500 aircraft ascending to high altitudes and descending to their destinations can more reliably update weather observations and dramatically increase severe weather prediction capabilities. Data collected and transmitted by crisscrossing aircraft at various altitudes provide a more efficient tool for collecting the observations necessary for accurate weather modeling. Climate models also benefit by answering more questions about the role of water vapor in Climate Change research and Climate Services.

Everyone wins

The SpectraSensors Water Vapor Sensor System (WVSS-II) provides the formerly missing essential parameter needed for accurate weather modeling— laser fast and accurate measurement of water vapor in the upper atmosphere. Passengers and cargo can arrive more safely, Airlines can save money and conserve fuel, and Federal Government agencies can reap the benefits of more than two decades of research towards water vapor detection to continuously improve forecasting of weather and climate change. Additional technical and background information is available through the National Weather Service Office of Communications.

Improved weather modeling and optimal aircraft routing will have a number of benefits for the aviation industry. For example, eliminating just 60 seconds off each flight would reduce CO2 emissions by 5 tons per year and save the industry $3.8 billion in fuel costs on a worldwide basis.

Weather delays impact the global economy

Significant weather events can cause delays costing the airlines and flying public $4 billion annually. A fuel savings of more than 25% could be achieved through weather prediction improvements, if all aircraft were to measure the four essential parameters: wind, temperature, pressure and water vapor (via the WVSS-II).

On a day-to-day basis, shaving just one minute off of each commercial flight would save 5 millions tons of CO2 emissions and $3.8 billion in fuel costs each year
Passenger and airfreight companies can measure a rapid ROI while enhancing safety and comfort for passengers
Aircraft can be routed through calmer weather, saving up to 10% on fuel
The WVSS-II is fully compatible with the existing government and aviation industry’s global infrastructure for data logging and recording
The low maintenance requirements of WVSS-II allow service intervals to coincide with C - level aircraft maintenance, keeping the fleet in operation

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Data Sheet

Performance
Principle of Measurement	Tunable Diode Laser Absorption Spectroscopy
Response Time/Data Output	Internal Sample Rate: 4 Times/Sec Real Time Output Rate: Every 2 Seconds Water Vapor Concentration Pressure Temperature Engineering Data System Status Data Downlink rate determined by ACARS/ARINC
Range of Coverage	Surface to 45,000 ft (13.7km)
Minimum Detectable Signal	50 ppmv (0.0311 g/kg)
Maximum Detectable Signal	60,000 ppmv (37.32 g/kg)
Accuracy (% of signal)	±50 ppmv or ±5% of reading (whichever greater)
Minimum Absorbance Detected (resolution)	1 x10-4
Analyzer Optical Path Length	22.7cm (8.938 in)
Model Number	01023

Environmental Range (SEB = System Electronics Box)
Outside Air Temperature Range for Operation	-65º to +50ºC
SEB Inside Operating Temperature Range	-5º to +30ºC
SEB Storage Temperature Range	-40º to +85ºC
Sample Gas Pressure Range	Surface (1016mb) to 200 mb
SEB Operating Pressure Range	14.7 PSI ± 10 PSI

Power Requirements
Input Voltage	28 VDC standard aircraft power
Current	5 amp maximum @ 28 VDC
Minimum Operating Voltage (any temperature)	17 VDC
Drop Out Voltage (any temperature)	15.8 VDC
Maximum Operating Voltage (any temperature)	33 VDC

Physical Specifications - Internal System Electronics Box (SEB)
Size	254.00mm (10.00") long x 138.18mm (5.44") wide x 92.08mm (3.625") high. (Ref. Figures 2&3)
Weight	3.43kg (7.56lb)
Outputs (Standard Operating Mode)	ARINC 429 via ACARS
Outputs (Research and Test Modes)	RS-232 output direct to PC applications
Mounting (Ref. Figure 2)	6x10-32 Screws Thermal Isolation from the airframe required
Replacement interval	At the convenience of the air carrier

Physical Specifications - External Air Sampler
Replacement Internval	None Required unless visible evidence of damage - 20 years
Size	136.36mm (5.37") long x 80.89mm (3.185") wide x 19.98mm (0.787") high
Weight	0.20kg (44lb)
Mounting	Flush-mounted on the outside skin of the aircraft

Service Interface Module and Local Test Connector
Test Connector	High Density DB-26 Connector (Female)
Outputs	Display/Keypad I/O RS-232 on test connector (tx only)
Service Interface Module (Ref. Figure 3)	Available Option Access to operating modes of the system and system status

Certifications
WVSS-II Product
Compliant to all environmental conditions specified by FAA Document Number RTCA/DO-160E dated December 9, 2004 FAA Supplemental Type Certifications (STC) for: - B757-200PF - B737-300 (Models: 737-301, 737-317, 737-3A4, 737-3G7, 737-3H4, 737-3K2, 737-3L9, 737-3Q8, 737-3T0,737-3T5, 737-3Y0) FAA Supplemental Type Certifications (STC) in Process: - B737-700 (Planned completion Oct 2010)

SpectraSensors, Inc. Manufacturing and Engineering Facilities
ISO 9001: 2000 U.S. FAA Certified WVSS-II Repair Stations

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Committed to Climate Change

The Aviation community wants to do its part in reducing (CO2) emissions. With Climate Change becoming a serious issue facing mankind and fuel costs rising, SpectraSensors, Inc (SSI) has developed a means to provide atmospheric Water Vapor data needed by the worlds Meteorological and Hydrological Services to dramatically improve upper air weather observation and overall prediction. The results will be increased societal and economic benefits,including a reduction in CO2 emissions and a reduction in aviation fuel consumption and costs.

Atmospheric water vapor affects virtually every aspect of aviation weather. It has an important role in the stability of the atmosphere, leading to Severe Weather outbreaks. While winds and temperatures can readily be obtained from the aircraft, atmospheric water vapor is only available twice a day from weather balloons. The SpectraSensors WaterVapor Sensor System (WVSS) enablesup-to-date water vapor information to be collected from aircraft platforms in a compact, low weight configuration.

Improved weather modeling and optimal aircraft routing will have a number of benefits for the aviation industry. For example, eliminating just 60 seconds off of each flight would reduce CO2 emissions by 5.0 tons per year and save the industry $3.8 billion in fuel on a worldwide basis.

Contact SpectraSensors today to learn more about the WVSS system and its role in helping the aviation industry with improved safety, fuel savings and reduced CO2 emissions.

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WVSS-II Water Vapor Sensing System Version Two

This paper is designed to describe what the WVSS-II system is, how it works and how will the information be transmitted and used, also how it is important to the prediction of weather forecasting.

Before understanding what WVSS-II is and why it is so important to implement the system we will first describe weather data measurement and collection, who uses the weather data and how this system can help improve weather prediction.

Following will be a few descriptions of agencies, companies and systems that are used and responsible for the gathering of weather data from flying weather stations on commercial aircraft.

NOAA/National Weather Service
NOAA/NWS is a government agency reporting to the Commerce Department that is responsible for the gathering of weather data, assimilation of this data and making weather predictions. Today there are many inputs into the NWS and weather models used world wide, these inputs are from satellites, ground stations, weather balloons and flying weather stations on commercial aircraft.

ARINC – Aeronautical Radio, Inc.
This is the company located in Annapolis, MD contracted for the transmission of proprietary air to ground communications from commercial aircraft, there are seven participation domestic airlines.

ACARS – Aircraft Communications Addressing and Reporting System
This is the proprietary system run by ARINC to transmit a variety of information from aircraft to ground including meteorological data.

Meteorological Data Collection and Reporting System
This is a system operated by ARINC and jointly funded by the U.S. Government and the seven participating airlines that takes the weather data being reported by ACARS, it is then put into proper format and transmitted to the NWS as well as all seven airlines for weather prediction.

WVSS-II – Water Vapor Sensing System Version Two
The WVSS-II is a patented sensor developed by SpectraSensors, Inc. under sponsorship by the National Weather Service to measure water vapor in the atmosphere. This system utilizes Tunable Diode Laser technology to accurately measure the amount of water in the atmosphere and is designed to be mounted on commercial aircraft; to date 30 units have flown on UPS 757 aircraft as a test program and 30 more units will be deployed in 2009 on Southwest Airlines 737-300 aircraft.

UCAR – University Corporation for Atmospheric Research

Located in Boulder, CO developed the patented air scoop used with the WVSS-II system.

System Description

The WVSS-II system is designed to mount on board commercial aircraft of any size or manufacturer to measure the water vapor content in the atmosphere as a plane flies its daily routes, the aircraft must utilize a data transmission system such as ACARS that transmits this data to the MDCRS system for assimilation and transmission of this data to the NWS.

The measurement system itself is manufactured by SpectraSensors, Inc. headquartered in Houston, TX with actual manufacturing being done at their facility in Rancho Cucamonga, CA, the system consists of three main parts, the patented air scoop designed by UCAR is mounted on the outer skin of an aircraft and has an inlet port and outlet port, the sample then flows to and from the analyzer through two heated hoses, the analyzer itself uses a Tunable Diode Laser as a source, detector and electronics to actually measure the amount of water in the atmospheric sample taken by the air scoop.

This measurement is in parts per million of moisture and the measurement result is then outputted to the ACARS system mounted in the aircraft avionics systems and then on a regular interval is transmitted from the aircraft to ground stations and then sent on to ARINC in Annapolis, MD to be put into the MDCRS data system.

This formatted data is then transmitted to the NWS for input into their weather models for weather prediction. Along with water vapor content the ACARS and MDCRS system has other inputs reported by these aircraft such as wind speed and direction, as well as temperature. All of these inputs are needed as inputs to weather models used today and of course the more often you can have fresh data points the better weather can be predicted.

Today for all data except water vapor the NWS receives close to 140,000 measurement points a day for wind and temperature because there are over 2000 aircraft flying the ACARS/MDCRS systems which means weather models for these inputs can be updated at least every three hours. Water vapor models can only be updated every 12 hours through weather balloon launches at forty to seventy sites scattered throughout the USA, once WVSS-II is fully deployed the same the water vapor data input can also be updated 140,000 times from the same commercial aircraft transmitting the wind and temperature data.

Why is the Measurement of Water Vapor So Important

The measurement of water vapor in the atmosphere is very important as it is one of the main reasons severe weather is created in sudden, unpredicted storms that play havoc on our cities throughout the USA as well as causing unexpected delays with airline schedules and safety. Improved water vapor data from the USA and around the world as it will improve the forecast of thunderstorms, micro bursts, turbulence, and fog, ceiling visibility, rotating wakes from other aircraft, snow and ice storms.

The Federal Aviation Administration in 1997 suggested that these storms cost the aviation industry over a billion dollars a year, also water vapor is one of the greenhouse gases responsible for global warming. There is a greater amount of water vapor in the atmosphere than any other greenhouse gas, water vapor can be up to 2% of the atmosphere but this amount does vary place to place and over time. As a comparison carbon dioxide only comprises 0.37%(370 ppm) of the atmosphere.

Water vapor traps heat very effectively because it is a clear gas like other greenhouse gases, it allows radiation to pass through it relatively undiminished on its way to earth and once the Earths surface re-radiates that energy in the form of heat it is absorbed by the water vapor which in turn causes a warming effect. It is estimated that water vapor is responsible for two-thirds of nature’s greenhouse effect.

According to Dr. Rex Fleming who is a researcher retired from UCAR there is more water in the form of water vapor and clouds that flows over the dry state of Arizona than flows down the Mississippi River. With this amount of water in our atmosphere it is clear that a more robust collection of water vapor measurement like we have for wind and temperature will greatly improve weather forecasting for both civilian and aviation users, remember that today weather forecasts are updated every three hours by the NWS with current data for every required input except one of the most important which is water vapor, this data can be up to 12 hours old depending on when the last weather balloon launch took place.

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