Ka-band
Radar SystemS-Pol has seen some major modifications during FY04 and has been deployed on two major field projects: Winter Icing Storms Project 2004 (WISP04) and North American Monsoon Experiment (NAME). A dual-wavelength S and Ka-band radar system with matched resolution volume and sensitivity was built to remotely detect supercooled liquid droplets. The modified radar system was first deployed during WISP 04 near Boulder, Colorado to detect and estimate liquid water content.
One of the main design objectives of the S-PolKa radar was to match the Ka-band antenna with the S-Pol beamwidth, point the beams at the same direction and record the observation simultaneously. In addition to ensuring matched beams, i.e., common radar sampling volume, a simpler scanning procedure for a dual-wavelength measurement and simultaneous measurement in time, it was imperative that both S and Ka-band systems should have similar sensitivity.
The design and development of Ka-band was a major challenge because it was the first millimeter wave radar built by ATD. New millimeter wave test equipment was acquired to diagnose the performance of the system. In order to meet the required measurement sensitivity, ATD decided to mount the system on the existing S-Pol antenna pedestal. Since no radome is used to protect the S-Pol antenna from changing weather conditions and precipitation, the Ka-band system required complete weatherproofing. In spite of the many changes to the original design plan, the system was completed in time for the project. However, the weatherproofing was inadequate and it affected the performance of the transmitter and receiver during wet snow and rain periods.
This year, RTF deployed new S-Pol Radar Data Acquisition (RDA) software.
The RDA provides the following capabilities:
1. Synchronizes the data streams from the Ka-Band and S-Band radars.
2. Archives the radar data to disk
3. Saves the disk archive files to tape
4. Generates DORADE sweepfiles for the scientist's radar displays
The RDA was written using modern software engineering techniques and runs on Linux workstations which provide high performance at low cost. The RDA has a monitoring and control graphical user interface, which simplifies system operation and aids the operators in verifying the RDA is running properly.
The radar refractivity retrieval technique was initiated by Frederic Fabry as an ASP/ATD postdoc in 1996. He first incorporated it onto the McGill radar (Fabry et al. 1997) and ATD has since added it to S-Pol operations. This technique utilizes stationary ground targets to deduce the surface-layer refractivity field within ~50 km from S-Pol. The atmospheric refractivity is related to temperature, pressure and moisture changes between the radar and the ground targets. Thus with some surface station anchor point measurements, a low-level moisture field can be inferred. Please see the section on Water Cycle and USWRP research to learn more about refractivity-related research by ATD scientists.
The HIQ PC processor card is completed and working. This card is meant to provide an economical solution for obtaining research quality radar data from existing commercial radars, particularly those in foreign countries. This summer the HIQ was operated successfully as part of the NAME project on two SMN Mexican radars located at Guasave and Cabo San Lucas. The HIQ also operated successfully on the Al Ain radar in the UAE. All of these systems included a connection from the HIQ to the RAP developed TITAN display and the Internet.