John M. Holt, MIT/Haystack Observatory, jmh@haystack.mit.edu
NIST 1107, 1:00-3:00 PM
Friday, June 30, 2000
The Millstone Hill Observatory, located in Westford, Massachusetts, is a broad-based atmospheric sciences research facility owned and operated by the Massachusetts Institute of Technology. The Atmospheric Sciences Group, which staffs and manages the observatory, is a part of MIT.'s Haystack Observatory, a basic research organization whose focus is radio wave and radar science, instrumentation and techniques. For more information, see http://www.haystack.edu/homepage.html.
In this workshop, a series of short presentations will cover recent scientific results and current topics of interest to past, present and future users of Millstone Hill data.
Radar Engineering Developments and New Techniques at Millstone Hill
-Frank Lind
We have recently begun a program to upgrade the Millstone Hill radar in
order to modernize the hardware and software used to make radar
observations. As the focus of this upgrade we are implementing the
MIDAS-W "software radar" where much of the radio reception and all of
the signal processing is performed in software using general purpose
computers. I will give an overview of our upgrade plans, the
technologies that are involved, and the expected benefits of these new
developments. In particular I will focus on how the upgrades will
improve our scientific capabilities. These improvements include an
incoherent scatter plasma line mode, significantly increased receiver
dynamic range, a passive radar capability, and the ability to change
operating modes on a pulse to pulse basis.
http://www.haystack.mit.edu/midas_w/
Ionospheric Modeling at Millstone Hill
-Bob Sitar
Ionospheric data collected by the Millstone Hill incoherent scatter
radar are being used to model both basic scalar parameters (Te, Ti, Ne)
and ion drift velocities. These models can then be used to derive
other parameters such as netural winds, electric fields, conductivities
and Joule heating. This talk will briefly describe the basic
framework, current state of development, and future plans for these
models.
Java Enabled Madrigal
-Steve Cariglia
The goal of this presentation is to introduce a Java API for the
Madrigal database by focusing on a task relevant to the Atmospheric
Science community. Topics include usage of the API integrated into a
Madrigal Database and usage independent of the Madrigal Database.
http://www.haystack.edu/madrigal/DataCenter/MadrigalData.html
The MIT Firepond Lidar for Atmospheric Research
-Tom Duck
A new lidar (laser radar) for atmospheric research is now operational
at MIT Haystack Observatory. The instrument currently measures
temperatures between 25 - 95 km in altitude at night, and up to 65 km
during the day. The installation of a new liquid-crystal etalon is
expected to allow daytime measurements to higher altitudes, and provide
spectroscopic measurements of winds. Of particular interest to our
studies are observations of mesospheric temperature inversions
throughout the diurnal cycle and gravity wave dynamics.
http://www.haystack.mit.edu/~tomduck/mitlidar/
Derived parameters in the Madrigal database
-Larisa Goncharenko
A large set of derived parameter datasets based on Millstone Hill I.S.
radar data from 1984 to 1999 have been added recently to the Madrigal
database and are available for public access. Examples of derived
parameters include electric fields, neutral winds, ion drifts,
exospheric temperatures etc. Currently available datasets as well as
future plans will be presented and discussed. See example at:
http://www.haystack.edu/cgi-bin/madtoc/1997/mlh/06jan97
Ionospheric Density Gradients observed at mid latitudes by the Millstone
Hill radar
-Hien B. Vo
The subauroral ionosphere is subject to severe F-region ionospheric
density changes which are due to strong imposed magnetospheric
electric fields. We have investigated the latitude and local time
variation of total electron content (TEC) as functions of disturbance
level (Kp index) and solar cycle using the Millstone Hill incoherent
scatter radar database which goes back to 1983. The database consists
of radar elevation scans which cover a span of 20 deg latitude with
better than 1 deg latitude resolution and 35 km altitude resolution.
We find that TEC gradients of 5 TEC/deg latitude charactize the
equatorward edge of the ionospheric trough in the post-noon sector at
solar maximum.
Recent Coherent Backscatter Experiments at Millstone Hill
-Phil Erickson
When directed towards the north, Millstone Hill is sensitive not only
to weak incoherent scatter returns from the ambient ionosphere but also
to intense coherent echoes from 34 cm irregularities at aspect angles
near perpendicular to the geomagnetic field. The experimental geometry
most favorable to reception of these echoes occurs when low elevation
angles (4 - 10 degrees) are used, creating near-zero aspect magnetic
angles approximately 5 to 8 degrees poleward of Millstone's sub-auroral
location (288.5 E geodetic longitude, 42.6 N geodetic latitude, 55 deg
invariant). Recent experiments in this area during disturbed
conditions (i.e. the Kp=9 event of April 6-7, 2000) have extended our
ability to map the electric field structure in the vicinity of the
polarization jet using data with high time and spatial resolution. We
will describe our recent work, and show examples of dramatic
variability in SAID/polarization jet electric field evolution, scale
size, and latitudinal gradients as revealed through modeling of the
coherent backscattered signal.
http://www.haystack.mit.edu/coherent