Laserfiche WebLink
<br />radiation, this is a measurement of the direct component of sunlight plus the diffuse component of <br />skylight received together on a horizontal surface. The output signal is proportional to the light <br />intensity across the selected bandwidth. Through signal conditioning, the output voltage is directly <br />proportional to watts per square meter, as given in Table 2. <br /> <br />Specificatio~ <br />Range: 400 to 1100 run <br />Sensitivity: Typ. 80 /-lA per 1000 W m-2 <br /> <br />Calibration <br />No calibration is performed in the field. Calibration was performed by the manufacturer <br />against an Eppley Precision Pyranometer. The calibration was performed under full-sun <br />conditions at midday 25 April 1983 . A more recent calibration was accomplished December <br />of 1991 with reference to the NOAA reference standard, a TMl model MKVI serial number <br />67502 active cavity radiometer. <br /> <br />Operational procedures <br />The sensor was mounted upward on top of the cabin and connected to the data acquisition <br />system before the field study. No other preparation was necessary as this instrument required <br />no power. <br /> <br />4.6 Optical Array Probe <br /> <br />A Particle Measuring Systems (PMS) Model OAP-2D2-C, two-dimensional cloud particle <br />imaging instrument, was installed outboard and below the right wing of the research aircraft. A linear <br />array of32 active silicon photodiodes (elements) form the sensor that is illuminated by a laser beam <br />via suitable beam forming optics and mirrors. The transit of each particle through the sample area <br />shadows various array elements depending on its size and orientation during transit. The signals from <br />these elements are processed in a high speed data storage register as a series of32-bit image slices, <br />at a rate of up to 4 million per second, which develop a true two-dimensional image of each particle. <br /> <br />Specifications <br />Size range (nominal resolution): 25-800 Jim <br />Particle Size Resolution (Bits): 32 x 1024 (width x length) <br />Maximum count rate: 4,000,000 slices S.l <br /> <br />Calibrations <br />Droplet Measurements Technology: October 1990 <br />Laboratory: Prior to the field experiment, the probe was calibrated in the laboratory using <br />calibrated spheres and a Droplet Measurements Technologies (DMT) spinning optical <br />disk etched with particle images of graduated sizes. <br />Onsite: During the field experiment we checked the probe with the DMT spinning disk on a <br />mission by mission basis. <br /> <br />12 <br />