CSRP Facilities

Aircraft operational facilities were located at the Archerfield Airport (Figure 1). Archerfield is about 17.5 km at 051° from CP2.

Figure 1. Map of Southeast Queensland water catchments (red) and location of primary radars used during the CSRP (green). The CP2 radar site near Redbank Plains was used as the Operations Center for the field efforts. (click to enlarge)

There were two aircraft used during the 2007–2008 season of this project (see Figures 2–3). The first aircraft (ZS–JRA; call sign SEEDA1) served a dual purpose: 1) primarily as a research aircraft to perform trace gas, aerosol, and microphysical measurements in the area and during the treatment of clouds; and 2) as a secondary seeding aircraft when conditions are ideal for multiple seeding aircraft. The second aircraft (N747RE; call sign WXMOD) was the primary seeding aircraft and carried instrumentation necessary for monitoring seeding operations (state parameters, GPS position, and flare events). SEEDA1 was equipped with a trace gas, aerosol, and cloud physics instrumentation package (see Table 1) to measure conditions that affect cloud properties and to document hypothesized microphysical responses in seeded clouds in support of the scientific physical basis for the experiment. Both aircraft were equipped with an instrumentation system that includes a telemetry link to the operations centre as well as a data acquisition system. Digital cameras were used to record flight conditions. SEEDA1 (WXMOD) were capable of carrying twenty (24) hygroscopic flares – two racks of 10 (12) flares each – or twenty (24) "end burning" silver iodide flares (interchangeable on the two racks). In addition, WXMOD was capable of carrying 306 ejectable silver iodide flares. The WXMOD base instrumentation included GPS position, temperature, pressure, and dewpoint sensors.

Figure 2: Photos of the Aerocommander (SEEDA1) aircraft and its instrumentation. (click to enlarge)

Figure 3: Photos of the Piper Cheyenne II (WXMOD) aircraft. (click to enlarge)

During the 2008–2009 season, there is one aircraft (ZS–JRA; call sign SEEDA1) that serves as the research and seeding aircraft. The instrumentation onboard SEEDA1 will be nearly identical to that in the previous season (see Table 1), and it's seeding equipment capabilities are also the same as described above.

Table 1.  List of instrumentation that will be used on SEEDA1 (SAWS, NCAR). (click to enlarge)

The CP2 dual–wavelength (S– and X–band) polarimetric radar, located at Redbank Plains near Brisbane (Figures 1, 4), was the primary research radar for the project. Operations were therefore focused within CP2's observational domain (i.e. within a radius of 140 km from CP2). In addition, coordination with the Mt Stapylton Doppler weather radar yielded an additional priority area within the dual–Doppler lobes (Figure 1).

Figure 1. Map of Southeast Queensland water catchments (red) and location of primary radars used during the CSRP (green). The CP2 radar site near Redbank Plains was used as the Operations Center for the field efforts. (click to enlarge)

Clouds occurring in the dual–Doppler lobes provided a unique opportunity to substantially increase our understanding of potential cloud seeding effects on the dynamic evolution of convective clouds. Access to other BOM weather radars in the vicinity, brought together in a merged display, also provided information for nowcasting and aircraft operations. The BOM radars operated in a surveillance scanning mode, while the CP2 radar operated in varying scanning modes, depending on the mission and weather conditions.

Figure 4:  Photo of the CP2 radar at the Redbank Plains site.
(click to enlarge)

Drop size distribution (DSD) measurements were made at the ground with a 2D video disdrometer provided by NCAR (Figure 5a) in season one, and by the BOM in season two. Two additional disdrometers were deployed in season two (Figure 5b): an impact disdrometer (from BOM) and a NASA Particle Video Imager (PVI; from NCAR). The disdrometer(s) was (were) sited near the CP2 radar (roughly at a range of 17 km and an azimuth of 61°; at 27.5999° S, 153.0087° E, and 15 m MSL elevation) in order to provide supplemental calibration information for the radar power measurements (radar reflectivity and differential reflectivity) and for the development and verification of techniques for estimating drop size distributions in precipitation using polarimetric radar measurements.

Figure 5a: Photo of the NCAR video disdrometer. (click to enlarge)

The disdrometer observations were processed in 1–min intervals at the close of the field program. Computed parameters include radar reflectivity, differential reflectivity, and specific differential phase. Other DSD attributes will include the governing parameters of truncated and untruncated exponential and gamma drop size distributions, the drop medium volume diameter, and the maximum drop diameter.

Figure 5b: NASA PVI and impact disdrometer (on the ground in the field of view of the PVI) at the disdrometer site in Queensland. (click to enlarge)