James P. Avery - US grants

To understand the transport of energy throughout the middle atmosphere requires observations around the globe. Many observational programs are currently in place providing such information at middle and high latitudes. This project is to continue studies of the equatorial mesosphere using meteor echo returns on VHF profilers on Christmas Island. These data will be analyzed for mean wind and tidal climatologies as well as the structure and evolution of large-scale wave motions and how they relate to the mesospheric semiannual oscillation and tropospheric wave patterns. Additional meteor echo detection and collection systems will be built and installed on VHF radars located in Pohnpei, Indonesia and Peru. These additional stations will allow study of mesospheric dynamics in four different tropospheric climatic regions. ***

Studies are being conducted which if successful will demonstrate the feasibility of universities fabricating in a few hours their own low- cost prototype multichip modules (MCM). MCMs represent a state-of-the- art microsystems packaging technique, improving speed and power by factors of three or more. Current industrial MCM fabrication costs are prohibitive in prototype quantities to universities. The cost reduction and short turnaround time offered by this novel concept along with other fast prototyping methodologies have the potential to revolutionize microsystems design. The concept is to have standard pattern substrates mass produced by industry at low cost. Each substrate would have buried patterns of power and ground wiring, plus a buried level of signal wiring. All buried wiring would have strategically placed paths called vias to a surface layer. This surface layer would be a pattern of wiring including connections to the vias which could be cut by the universities to customize for a particular design. Pretested bare chips with solder bumps would be bonded to the customized substrate to form the customized module. The concept is being demonstrated by 1) designing, fabricating and testing the substrates and two types of memory MCMs, 2) functional design only of two other complex modules.

This research will focus on several issues critical to the development of the proposed quick prototyping system for multichip modules (MCMs). These issues are: 1) the detailed design of the workcenter; 2) the experimental demonstration of the accuracy and repeatability of two critical units in the workcenter--the photoplotter and the pick-and-place robot; 3) the evaluation of the solder joint's electrical resistance; 4) the complete description of the user-interface of the workcenter; (5) the electroless plating for single-chip solder bumping; and 6) the explicit comparison to MCC's QTAI and GE's High-Density Interconnect (HDI) alternative methods. Although the system is proposed for quick prototyping, the manufacturing requirements in these issues are being addressed. The requirements for manufacturing are more demanding than those for prototyping.

This proposal seeks funds for meteor radar studies of the mesosphere and lower thermosphere using a meteor echo detection and collection system (MEDAC). The objectives of the work are to provide an understanding of the long period wave motions, including the migrating and non-migrating tides, and their interaction with the large scale wind circulation. The studies will use data collected from the equatorial Pacific wind profiler network , which has been augmented with MEDAC systems that allow the determination of the winds in the mesosphere and lower thermosphere. In order to generate the long data sets necessary for this work, an upgrade of the MEDAC sites is required. Because the MEDAC requires the use of a wind profiler that is often not optimized for meteor echo detection, the PIs propose to design a new portable meteor radar system that would stand alone. This new system, as well as the current system, will be augmented with new data analysis techniques utilizing genetic algorithms. A final aspect of the proposed work is to establish a cooperative research program with the University of Adelaide allowing experiments to be done on the Buckland Park radars.

This grant develops the Platteville Atmospheric Observatory, located in Platteville, Colorado. The observatory currently has VHF, UHF, and boundary layer wind profilers for lower atmospheric measurements of winds, waves and stability. The PI plans to establish a medium frequency radar and all-sky meteor radar, providing measurements of upper atmosphere winds. She will also upgrade the VHF wind profiler and UHF boundary layer profiler to provide greater sensitivity for atmospheric coupling and precipitation studies. In sum, these acquisitions, developments and upgrades will implement research of large scale wave motions and their influence on circulation, wave-wave interactions, coupling of energy and momentum between regions of the atmosphere via gravity waves, boundary layer evolution, and land-atmosphere hydrological processes.

ATM0000957abs

The investigators will study the dynamics of the mesosphere and lower thermosphere over Antarctica using measurements from the TIMED instruments and a meteor radar to be installed at South Pole station. Specific science objectives include: the space-time decomposition of wave motions; delineation of the spatial climatology over Antarctica with emphasis on the structure of the polar vortex; dynamical response to energetic events; and interannual variability. The proposed meteor radar is a VHF system that will be able to measure the spatial structure and temporal evolution of the horizontal wind field over the South Pole. The investigators will also make use of existing ground-based radars at Davis, Syowa, Rothera, and Scott Base in the determination of the spatial climatology. Wind and temperature measurements to be made by NASA's TIMED satellite during orbits over the South Pole will provide opportunities for combined ground-based and space-based experiments and validation activities.

This proposal is for the study of electric field effects on meteor trails in the equatorial region. Additionally, the PIs seek to understand any deviation of the radar scattering properties of a meteor trail from traditional specular reflection processes.

These scientific goals require the upgrade and continued operation of an existing meteor radar at Piura, Peru (5S, 81W). The upgrade at this site consists of installing a complete all-sky meteor radar system, so that the angle-of-arrival of meteoric backscatter can be unambiguously determined. In addition, archive data from Christmas Island will be analyzed for meteor winds as well. As a byproduct of this work routine mean wind, tidal amplitudes and phases, and meteor decay statistics will be available to the scientific community via a web server.

The investigators will observe, model and study the spatial-temporal structure and variability of the semidiurnal tide in the middle atmosphere. The focus will be on the Arctic and Antarctic mesosphere and lower thermosphere horizontal wind and temperature fields. The mesosphere and lower thermosphere, at an altitude between 80 and 120km above the surface of the earth, is a highly dynamic region that couples the lower atmosphere (troposphere/stratosphere) with the upper atmosphere thermosphere/ionosphere). Of particular importance in this region are both the upward propagating thermally forced atmospheric tides and global scale planetary waves. Both of these phenomena transport heat and momentum from the lower atmosphere into the upper atmosphere. Studies in recent years have indicated that the high latitude (Arctic and Antarctic) mesosphere and lower thermosphere possess a rich spectrum of planetary waves that had previously gone undiscovered. These planetary waves can interact with the sun-synchronous migrating semidiurnal tide modifying its spatial and temporal structure while giving rise to the nonmigrating semidiurnal tide. Understanding the structure and variability of the semidiurnal tide is an important step to understanding the global heat and energy balance of the mesosphere and lower thermosphere. The data used for this project will include horizontal wind measurements from a global network of 30 ground-based meteor and medium frequency radars. Additionally, wind and temperature measurements from the NASA TIMED satellite will be combined with the radar data. It is expected, from previous observations, that planetary waves will play a significant role in the variability of the semidiurnal tide. For this reason the structure of the semidiurnal tide and the structure of the planetary waves will be estimated simultaneously. These estimates will be analyzed in conjunction with both linear mechanistic and global circulation models to aid in the interpretation of the observations and increase knowledge about the semidiurnal tide. As part of this effort a web based tool to ingest the radar data from the global network will be employed. Data submitted to the database will be processed and then disseminated via a website, the TIMED database and the CEDAR database. Such a database is required for this and future efforts that propose to make use of the global network of mesosphere and lower-thermosphere radar wind measurements.

The mesosphere and lower thermosphere (MLT), at an altitude between 80 and 120 km above the Earth's surface, is a highly dynamic region that couples the lower terrestrial atmosphere (troposphere and stratosphere) with the upper atmosphere near-Earth space environment (thermosphere and ionosphere). Of particular importance in this region are both the upward propagating thermally forced atmospheric tides and global scale planetary waves. Both of these phenomena transport heat and momentum from the lower atmosphere into the upper atmosphere. Studies in recent years have indicated that the Arctic and Antarctic MLT possess a rich spectrum waves and may be more sensitive to global change than the lower atmosphere. The primary goal of this research is to observe, quantify, model, and further understand the spatial-temporal structure and variability of the MLT circulation above Antarctica and its commonalities with the Arctic. A secondary goal is to quantify and understand the deposition of mass into the upper atmosphere through the ablation of meteors and the resulting effect on local and regional aeronomic processes. This includes the effect of meteor flux, temperature and dynamics on the seasonal distribution of sodium over the South Pole. Meteor radar was installed at the South Pole Amundsen-Scott station and has been running continuously since January 2002. A new sodium nightglow imager will be installed at the South Pole to infer the sodium abundance in the MLT. Observations from this instrument will be combined with the South Pole Fabry-Perot interferometer temperature measurements and the meteor radar wind and meteor flux measurements to improve our understanding of the sodium chemistry and dynamics. These observations will be interpreted using sophisticated numerical models and interpreted in conjunction with Arctic measurements along with current linear and nonlinear atmospheric models to advance the current understanding of processes important to the MLT region. This research also contributes to the training and education of the graduate and undergraduate students, a postdoc and early career tenure track faculty.