NASA/Goddard Space Flight Center, Code 219, Greenbelt, MD 20771

59 -- RD-69 DISTROMET DISDROMETER SOL 473-73070-0000-901 DUE 051100 POC Marolyn S. Cross, Contract Specialist, Phone 301-614-5608, Fax 301-614-5619, Email mscross@pop500.gsfc.nasa.gov WEB: Click here for the latest information about this notice, http://nais.msfc.nasa.gov/cgi-bin/EPS/bizops.cgi?gr=D&pin=51#473-7 3070-0000-901. E-MAIL: Marolyn S. Cross, mscross@pop500.gsfc.nasa.gov. NASA/GSFC plans to issue a Request for Quotation (RFQ) for the purchase of two (2) impact-type disdrometers known specifically as an RD-69 Distromet disdrometer (also known as a Joss-Waldvogel disdrometer). This procurement is being conducted under the Simplified Acquisition Procedures (SAP). NASA/GSFC intends to purchase the items from Distromet LTD, P. O. Box 209, Basel, CH-4020, Switzerland. The cost involved in purchasing this instrument cannot be compared and justified by any existing comparable instrument, and the Joss-Waldvogel distrometer is unique, based on its specifications and is built in response to customer orders. Because the proposed effort involves basic research, there are no criteria or guidelines for developing specifications for the final product or a detailed and definitive statement of work. Thus, it is not possible to submit this kind of activity to open competition. The Joss-Waldvogel disdrometer is being purchased to continue basic research on improving methods and algorithms for ground validation of the Tropical Rainfall Measuring Mission (TRMM). The object of the proposed effort is to assess microphysical processes, such as evaporation, coalescence, and the evolution of drop-size distribution. The disdrometer will also continue to improve, develop, simulate, and evaluate algorithms for the measurement of rainfall from space and for the calibration and validation of the measurements by the ground truth. The proposed effort will support NASA's TRMM studies as well as the long-term goals of NASA/Goddard Space Flight Center (GSFC) participation in climate research. The TRMM project plans to operate the proposed instrument to validate data, which are specifically designed for the validation of TRMM spaceborne rainfall estimation. The Joss-Waldvogel RD-69 disdrometer is unique because of its capability in measuring rainfall parameters. The disdrometer was specifically developed 30 years ago to measure drop-size distribution for the purpose of calculating radar reflectivities. It is operated unattended and is a very reliable instrument. It is considered to be a standard instrument for the drop-size distribution measurements. The Joss-Waldvogel disdrometer is designed using state-of-the-art technology. The sensor head consists of a thin aluminum surface that covers a body of styrofoam. The disdrometer transmits the mechanical impulse of an impacting rain drop to a set of two moving coil systems. Voltage is induced in the sensing coil, by the drop, and it is amplified. The amplitude of the amplified voltage is compressed by signal processing electronics, which provides a voltage that is compressed that can be expressed, using a function of raindrop size. A pulse height analyzer sorts the peak amplitudes in 20 channels of diameter drops in the range of 0.3 to ~ 5.5 mm. The disdrometer has a 50 cm^2 sampling area. Refer to Joss and Waldvogel, 1969; Kinnel, 1976; Sheppard, 1990; for literature on the technical description, calibration, and operation of the RD-69. It can be operated in warm, moist tropical weather, which is an essential requirement for TRMM's use. Research was conducted that included information from references in scientific journals and research on the use of Joss-Waldvogel disdrometers. An extensive review on the measurements of drop size distribution was done. The pertinent literature from the research revealed that the Distromet LTD disdrometer is the only one which can operate unattended and continuously. The Government intends to acquire a commercial item using FAR Part 12. Interested organizations may submit their capabilities and qualifications to perform the effort in writing to the identified point of contact not later than 4:30 p.m. local time on May 1, 2000. Such capabilities/qualifications will be evaluated solely for the purpose of determining whether or not to conduct this procurement on a competitive basis. A determination by the Government not to compete this proposed effort on a full and open competition basis, based upon responses to this notice is solely within the discretion of the government. Oral communications are not acceptable in response to this notice. All responsible sources may submit an offer which shall be considered by the agency. OMBUDSMAN STATEMENT REQUIRED] An Ombudsman has been appointed. See Internet Note "B". Any referenced notes can be viewed at the following URL: http://genesis.gsfc.nasa.gov/nasanote.html Posted 04/11/00 (D-SN443620). (0102)

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