Issue 10 Volume 41 May 16, 2003

for the large-scale intercontinental transport, but also produce the small-scale spatial and temporal variations that are adequate
for aircraft measurements planning.
Author
Aerosols; Asia; Atmospheric Models; Weather Forecasting
20030033017 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Global Gridded Data from the Goddard Earth Observing System Data Assimilation System (GEOS-DAS)
November 2001; 2 pp.; In English; Fall 2002 AGU Meeting, Fall 2002; Original contains black and white illustrations; No
Copyright; Avail: CASI; A01, Hardcopy
The Goddard Earth Observing System Data Assimilation System (GEOS-DAS) timeseries is a globally gridded
atmospheric data set for use in climate research. This near real-time data set is produced by the Data Assimilation Office
(DAO) at the NASA Goddard Space Flight Center in direct support of the operational EOS instrument product generation from
the Terra (12/1999 launch), Aqua (05/2002 launch) and Aura (01/2004 launch) spacecrafts. The data is archived in the EOS
Core System (ECS) at the Goddard Earth Sciences Data and Information Services Center/Distributed Active Archive Center
(GES DISC DAAC). The data is only a selection of the products available from the GEOS-DAS. The data is organized
chronologically in timeseries format to facilitate the computation of statistics. GEOS-DAS data will be available for the time
period January 1, 2000, through present.
Derived from text
Earth Observing System (Eos); Earth Sciences; Climatology; Data Acquisition; Information Systems
20030033115 Army Research Lab., White Sands Missile Range, NM, USA
Battlescale Forecast Model Sensitivity Study
Sauter, Barbara; Henmi, Teizi; Pedrego, Edgar; Jan. 2003; 23 pp.; In English; Original contains color illustrations
Report No.(s): AD-A410711; ARL-TR-2905; No Copyright; Avail: CASI; A03, Hardcopy
Expendable sensors might be used on the battlefield to report weather data not in conformance with normal weather sensor
placement and accuracy standards. The purpose of this study was to investigate the impact of errors in surface measurements
on a model forecast initialized with the inaccurate observations. Changes to the surface observations used in the Battlescale
Forecast Model initialization led to no significant changes in the resulting forecast values of temperature, relative humidity,
wind speed, or wind direction. Some information on the forecast accuracies using the original surface observations is also
provided.
DTIC
Meteorological Parameters; Weather Forecasting; Sensors; Military Operations; Sensitivity Analysis
20030033856 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Lightning Return-Stroke Current Waveforms Aloft, From Measured Field Change, Current, and Channel Geometry
Willett, J. C.; LeVine, D. M.; [2002]; 1 pp.; In English; AGU Meeting, 7-10 Dec. 2002, San Francisco, CA, USA; Copyright;
Avail: Other Sources; Abstract Only
Direct current measurements are available near the attachment point from both natural cloud-to-ground lightning and
rocket-triggered lightning, but little is known about the rise time and peak amplitude of return-stroke currents aloft. We
present, as functions of height, current amplitudes, rise times, and effective propagation velocities that have been estimated
with a novel remote-sensing technique from data on 24 subsequent return strokes in six different lightning flashes that were
triggering at the NASA Kennedy Space Center, FL, during 1987. The unique feature of this data set is the stereo pairs of still
photographs, from which three-dimensional channel geometries were determined previously. This has permitted us to calculate
the fine structure of the electric-field-change (E) waveforms produced by these strokes, using the current waveforms measured
at the channel base together with physically reasonable assumptions about the current distributions aloft. The computed
waveforms have been compared with observed E waveforms from the same strokes, and our assumptions have been adjusted
to maximize agreement. In spite of the non-uniqueness of solutions derived by this technique, several conclusions seem
inescapable: 1) The effective propagation speed of the current up the channel is usually significantly (but not unreasonably)
faster than the two-dimensional velocity measured by a streak camera for 14 of these strokes. 2) Given the deduced
propagation speed, the peak amplitude of the current waveform often must decrease dramatically with height to prevent the
electric field from being over-predicted. 3) The rise time of the current wave front must always increase rapidly with height
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