This list describes many of the basic measurements made on the NSF/NCAR G-V aircraft, also know as State Parameters. State Parameters give the scientist a measurement of the current state of a particular parameter.
This list describes many of the basic measurements made on the NSF/NCAR G-V aircraft, also know as State Parameters. State Parameters give the scientist a measurement of the current state of a particular parameter.
These measurements are used by the scientists to have a better understanding of the physical measurements that their instruments are collecting. The State Parameters are used in conjunction with the data collected by the researchers to provide the most accurate data set possible. Measurements of altitude, latitude, longitude for example, give an exact location in space (and time) of the specific measure of a trace gas. The scientists can then infer on the physical, chemical and spatial characteristics of the measurement. The rest of the variables are used also by the scientists to make corrections or adjust their data sets depending on the conditions that the airplane experienced.
The Microwave Temperature Profiler (MTP) is a passive remote sensing system that provides researchers with atmospheric temperature structure above and below the aircraft. Basic components of the MTP are a receiver which measures emission by oxygen molecules at three microwave frequencies and a scanning mirror which views the emission at 10 elevation angles. The three microwave frequencies have different penetration depths so the sensor is able to “see” to different distances from the aircraft with each channel (the plastic window covering the sensor shown in the attached photo is transparent at microwave frequencies). Different effective viewing distances are also achieved by scanning in elevation. With three frequencies and 10 elevations angles, 30 separate measurements of brightness temperature are acquired with each 18 second scan. Calibration is performed as the scanning mirror views an internal target during each scan. A statistical retrieval algorithm is applied to convert the brightness temperature observables into temperature as a function of altitude.
The MTP is fixed to the under-side of the right wing of the aircraft, next to the Forward Looking Camera and the Ultra-High Sensitivity Aerosol Spectrometer (UHSAS).
Honeywell YG1854 Laseref SM Inertial Reference System (IRS) is used to obtain aircraft position, velocity, acceleration and attitude information.
GPS variables aboard RAF aircraft are gathered by a Trimble TANS-III GPS receiver. It has the ability to track up to 6 satellites at a time but needs only 4 to provide 3-dimensional position and velocity data (3 satellites for 2-dimensions). The accuracy of the position measurements is stated to be 25 meters (horizontal) and 35 meters (vertical) under "steady-state conditions." Likewise, velocity measurements are within 0.2 M/s for all axes.
Meteorological and aircraft state measurements are made at various locations on an aircraft. The present radome measurements all have pressure sensors located in the nose area of the aircraft connected to the radome by semi-rigid tubing.