 |
|
|
|
|
|
|
|
|
|
|
|
 |
|
||||||||||
 |
 |
 |
|
||||||||
 |
|
||||||||||
 |
 |
 |
 |
 |
 |
|
|||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||||||||||
|
|
|
|
||||||||
|
|
||||||||||
|
|
|
|
|
|
|
|||||
The UMDCR (Albrecht et al., 1999) is a single antenna 94-GHz Doppler radar (W-band, Fig. 2). The UMDCR is lightweight (200 pounds, 4x4x4 ft radar container and 3-foot Cassegrain antenna) and often operates as a stand-alone instrument outside an environmental enclosure such as the Environmental Technology Laboratory (ETL)/University of Miami (UM) seatainer used during the RICO 2005 experiment. The seatainer during the RICO experiment was located on the rear deck of the R/V Seward Johnson (Fig. 1). With its small wavelength, the W-band radar can be used for detecting small cloud particles and non-precipitating clouds. With well-developed, precipitating clouds, this radar becomes saturated and radars with a longer wavelength can be used to see the cloud structure more accurately. The original plan was to use a stabilizing platform, which would compensate for the ship motion. The beam would shoot out horizontally onto a 45° inclined platform, which would always direct the beam vertically with respect to the earth coordinates. However, this did not work properly due to the excessive motion of the ship, so the radar was oriented to point vertically out of the container. The data now requires correction due to the motion of the ship.
The X-band radar points vertically and operates at a frequency of 9.4 GHz and a wavelength of 3.2 cm (Fig. 2). The X-band radar antenna was also located on the top of the ETL/UM seatainer located on the rear deck of the R/V Seaward Johnson (Fig. 1). The larger wavelength of the X-band is more suitable for viewing well-developed, precipitating clouds. Depending on the stage of development of the cloud, the X-band radar can be tuned for “high gain” or “low gain.” High gain can be used if the reflectivity is too low, for example, a cloud in its early development stage, where a higher strength of reflectivity may be needed. The graphical output from both the X-band radar and the W-band radar will show the reflectivity, spectral width, and the Doppler velocities, all plotted with height and over a time period of twenty minutes. These images can be used to see the cloud base, the development of the cloud over time through reflectivity, and the horizontal and vertical velocities associated with the cloud (RICO 2005 Data).
Radiosondes were launched approximately 4-6 times per day from the rear deck of the R/V Seaward Johnson (Fig 3). A sonde was sent up attached to a weather balloon filled with approximately 450 psi of helium. As the balloon rose, it recorded the pressure, height, temperature, relative humidity, lapse rate, ascent rate of the balloon, wind speed, and wind direction every two seconds. The sonde transmitted this data back to the ship continuously using the specified radio frequency. The data was then sent to NOAA ETL in Boulder, Colorado, using the satellite phone and was made available over the internet so the scientists based in Antigua could use it. When completed, the soundings were used to see the stability of each layer in the atmosphere, including the boundary layer, which was important to RICO.
Among other instruments onboard the R/V Seaward Johnson during the RICO 2005 experiment, there was a 915-MHz wind profiler mapping the wind field The NOAA K-Band was scanning a 60-100 km swath, linking individual clouds observed overhead to the mesoscale organization of precipitating and non-precipitating trade-wind cumuli. The S-POLKa radar system (S-band and K-band) was scanning from Barbuda, providing observations on the early development of precipitation within the clouds.
Three different state of art aircrafts were flying over
the zone at selected times. The NCAR C-130, University of Wyoming King
Air, and the BAE-146 flew at different heights (cloud top, above cloud
base, below the cloud base and near the surface). The data acquired
by these aircrafts were used to help evaluate the turbulence statistics
in the boundary layer.
Figure 1. The antennas for the X-band, and W-band radars mounted on top of the ETL/UM seatainer during the RICO 2005 experiment with graduate students Ieng Jo and Virendra Ghate pictured.
Figure 2. The University of Miami X-band and W-band Radars in the ETL/UM seatainer during the RICO 2005 experiment with Dr. Pavlos Kollias and graduate student Virendra Ghate pictured.
Figure 3. Radiosonde launch from the rear deck of the R/V Seaward Johnson during the RICO 2005 experiment with graduate student Efthymios Serpetzoglou pictured.