Equipment　　

Prologue

In the new atmospheric observation project, two observation equipment were developed.

1.　Automatic Air Sampling Equipment (ASE) 

The ASE collects air samples in twelve flasks at predetermined locations over the flight route. It performs sampling after takeoff at any locations during the flight. After removal upon arrival at the destination such as Narita, it is transported to NIES at Tsukuba where detailed measurements and analysis of collected air are conducted . The ASE has similar hardware structure to equipment previously installed in the classic 747. It has, however, several improvements and enhanced capability to collect sample air at any precise locations. It can also retrieve required parameters, such as latitude, longitude and altitude etc., from the data bus which is connected to the aircraft systems. The ASE is installed in two 747-400s and the observations are conducted twice a month. * ARINC 429 data bus : One of the serial data bus specifications for exchanging information such as flight data among the airborne equipment.

2.　Continuous CO₂ Measuring Equipment (CME)

The CME is the equipment which measures CO2 concentration in the atmosphere continuously. The data measured is stored in the CME internal memory. The CME is removed from the aircraft at regular aircraft maintenance visit which occurs at approximately one to two month interval. The removed CME is transported to JAMCO at Narita for data downloading and then conveyed to NIES. The CME acquires aircraft flight information such as latitude, longitude and altitude like the ASE which are used for CME internal control and stored in the memory with measured CO2 concentration for further data analysis. The CME is installed in two 747-400s, three 777s and the beechcraft 65 which JAXA owns.

　

ASE (Automatic Air Sampling Equipment)

　

The ASE is composed of the following subsystems.

1. Flask container which reserves sampled air. (Total 12ea for ASE-1 and ASE-2)

2. The system which distributes the sampled air to each flask.

3. The control devices for overall equipment operation.

4. Interface to obtain aircraft flight information for the equipment.

An external pump is installed at the upper stream of the ASE to pressurize the sampled air(aircraft air conditioning air.)

Principle of Operation

The ASE-1 and ASE-2 have six flasks each and control the airflow routing by manipulating the 33 solenoid valves. In the ASE-1, pressure sensors to measure the inner pressure of the plumbing and ambient cabin pressure sensors are installed.

The ASE-1 also equips a processor to control the solenoids and the pump. The computer processor enables the data such as latitude, longitude, altitude, etc. to be retrieved. It also allows for the sampling of air at any locations into predetermined flasks by setting the conditions such as specific flight and location to collect samples.

　

ASE Plumbing

Function

Special surface treatment is provided for the internal surface of the flask to avoid unwanted contamination of the sampled air. The flask has a capacity of 1.7liters and is pressurized by approximately 2.7 atm., maximum for sampled air.

It is possible to start/stop the pump and fill the flask by responding to latitude, longitude or altitude. When each flask is filled up, date, time, latitude, longitude, pressure altitude, radio altitude, ambient temperatures, ASE internal temperature, cabin pressure and fill up pressure are recorded. Those records are used during the analysis of the sampled air as important references. In case of abnormal temperature, abnormal pressure or unusual electric power supply, the ASE is coded to terminate its operation.

After installing the ASE into the aircraft, it is possible to modify the sampling flight counter and the location of sampling through the RS-232C port of the ASE-1 connecting with a PC.

　

Dimension

CME (Continuous CO₂ Measuring Equipment)

　

The CME is composed of the following subsystems.
　

1. Measuring device of CO₂ concentration (NDIR : Non-Dispersive Infrared analyzer)

2. Two standard gas bottles with high/low concentration to ensure accurate measurements.

3. A system to provide the air to the measuring device which can switch between the sampled air, high concentration standard gas and lower concentration gas sequentially.

4. Pressure and flow controller to retain the pressure and flow of the measuring device, regardless of the ambient pressure.

5. Controller of the overall equipment operation, and a memory device to store the data of measured CO₂ concentration and aircraft parameters.

6. Interface to retrieve the aircraft information.

Principle of Operation

The CME consists of a measuring device of CO₂ concentration(NDIR), mass flow controller to retain the flow, pressure controller to stabilize the pressure, two types of standard gases to compensate the measured value to get further accuracy, data logger to control the CME, storage module to store the measured data and ARINC receiver to extract the aircraft position data.

External air to be measured from the inlet is dehumidified by the dryer before pressurized by the pump because water vapor(H₂O) has a similar IR absorption spectra to CO₂. The air enters into the mass flow controller via the solenoid valve and then constant flow of measured air is sent to the NDIR. At the exit side of the NDIR, a pressure controller is installed to retain the CME internal pressure constantly. The air measured after passing the pressure controller is released into the equipment.

The CME utilizes two kinds of standard gases, which have a known concentration value, to ensure accurate measurement of the CO₂ concentration. Measurement of the concentration for external air and two standard gases are alternately conducted.

The NDIR which measures CO₂ concentration uses the infrared absorption characteristics of CO₂.

CME Plumbing

Function

The measured CO₂ concentration is retained in the storage module along with the date, time, CME flow and pressure, cabin pressure, latitude, longitude, wind direction, wind speed, pressure altitude and static air temperature. It is possible to obtain highly accurate CO₂ concentrations by compensating the measured air with alternately injected standard gas concentrations. The stored data can be downloaded through the RS232C port connecting with a PC.

The CME is controlled by using the retrieved data from the ARINC 429 data buses such as ground speed(GS), radio altitude, pressure altitude etc. and continuously conduct the measurement above the predetermined altitude from takeoff to landing. This continues for a couple of months until removal occurs during regular aircraft maintenance.

Dimension

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