posted on Jun, 16 2004 @ 07:41 PM
WEATHER
AS A FORCE MULTIPLIER: OWNING THE WEATHER IN 2025
MILITARY APPLICATIONS OF WEATHER MODIFICATION
Appendix
A - Why is the ionosphere important?
The ionosphere is the part of the earth's atmosphere beginning
at an altitude of about 30 miles and extending outward 1,200 miles
or more. This region consists of layers of free electrically charged
particles that transmit, refract, and reflect radio waves, allowing
those waves to be transmitted great distances around the earth.
The interaction of the ionosphere on impinging electromagnetic
radiation depends on the properties of the ionospheric layer,
the geometry of transmission, and the frequency of the radiation.
For any given signal path through the atmosphere, a range of workable
frequency bands exists. This range, between the maximum usable
frequency (MUF) and the lowest usable frequency (LUF), is where
radio waves are reflected and refracted by the ionosphere much
as a partial mirror may reflect or refract visible light. The
reflective and refractive properties of the ionosphere provide
a means to transmit radio signals beyond direct "line-of-sight"
transmission between a transmitter and receiver. Ionospheric reflection
and refraction has therefore been used almost exclusively for
long-range HF (from 3 to 30 MHz) communications. Radio waves with
frequencies ranging from above 30 MHz to 300 GHz are usually used
for communications requiring line-of-sight transmissions, such
as satellite communications. At these higher frequencies, radio
waves propagate through the ionosphere with only a small fraction
of the wave scattering back in a pattern analogous to a sky wave.
Communicators receive significant benefit from using these frequencies
since they provide considerably greater bandwidths and thus have
greater data-carrying capacity; they are also less prone to natural
interference (noise).
Although the ionosphere acts as a natural "mirror" for HF radio
waves, it is in a constant state of flux, and thus, its "mirror
property" can be limited at times. Like terrestrial weather, ionospheric
properties change from year to year, from day to day, and even
from hour to hour. This ionospheric variability, called space
weather, can cause unreliability in ground- and space-based communications
that depend on ionospheric reflection or transmission. Space weather
variability affects how the ionosphere attenuates, absorbs, reflects,
refracts, and changes the propagation, phase, and amplitude characteristics
of radio waves. These weather dependent changes may arise from
certain space weather conditions such as: (1) variability of solar
radiation entering the upper atmosphere; (2) the solar plasma
entering the earth's magnetic field; (3) the gravitational atmospheric
tides produced by the sun and moon; and (4) the vertical swelling
of the atmosphere due to daytime heating of the sun. Space weather
is also significantly affected by solar flare activity, the tilt
of the earth's geomagnetic field, and abrupt ionospheric changes
resulting from events such as geomagnetic storms.
In summary, the ionosphere's inherent reflectivity is a natural
gift that humans have used to create long-range communications
connecting distant points on the globe. However, natural variability
in the ionosphere reduces the reliability of our communication
systems that depend on ionospheric reflection and refraction (primarily
HF). For the most part, higher frequency communications such as
UHF, SHF, and EHF bands are transmitted through the ionosphere
without distortion. However, these bands are also subject to degradation
caused by ionospheric scintillation, a phenomenon induced by abrupt
variations in electron density along the signal path, resulting
in signal fade caused by rapid signal path variations and defocusing
of the signal's amplitude and/or phase.
Understanding and predicting ionospheric variability and its influence
on the transmission and reflection of electromagnetic radiation
has been a much studied field of scientific inquiry. Improving
our ability to observe, model, and forecast space weather will
substantially improve our communication systems, both ground and
space-based. Considerable work is being conducted, both within
the DOD and the commercial sector, on improving observation, modeling,
and forecasting of space weather. While considerable technical
challenges remain, we assume for the purposes of this study that
dramatic improvements will occur in these areas over the next
several decades.
Appendix
B - Research to Better Understand and Predict Ionospheric Effects
According to a SPACECAST 2020 study titled, "Space Weather Support
for Communications," the major factors limiting our ability to
observe and accurately forecast space weather are (1) current
ionospheric sensing capability; (2) density and frequency of ionospheric
observations; (3) sophistication and accuracy of ionospheric models;
and (4) current scientific understanding of the physics of ionosphere-thermosphere-magnetosphere
coupling mechanisms. The report recommends that improvements be
realized in our ability to measure the ionosphere vertically and
spatially; to this end an architecture for ionospheric mapping
was proposed. Such a system would consist of ionospheric sounders
and other sensing devices installed on DoD and commercial satellite
constellations (taking advantage in particular of the proposed
IRIDIUM system and replenishment of the GPS) and an expanded ground-based
network of ionospheric vertical sounders in the US and other nations.
Understanding and predicting ionospheric scintillation would also
require launching of an equatorial remote sensing satellite in
addition to the currently planned or deployed DOD and commercial
constellations.
The payoff of such a system is an improvement in ionospheric forecasting
accuracy from the current range of 40-60 percent to an anticipated
80-100 percent accuracy. Daily worldwide ionospheric mapping would
provide the data required to accurately forecast diurnal, worldwide
terrestrial propagation characteristics of electromagnetic energy
from 3-300 MHz. This improved forecasting would assist satellite
operators and users, resulting in enhanced operational efficiency
of space systems. It would also provide an order of magnitude
improvement in locating the sources of tactical radio communications,
allowing for location and tracking of enemy and friendly platforms.59
Improved capability to forecast ionospheric scintillation would
provide a means to improve communications reliability by the use
of alternate ray paths or relay to undisturbed regions. It would
also enable operational users to ascertain whether outages were
due to naturally occurring ionospheric variability as opposed
to enemy action or hardware problems.
These advances in ionospheric observation, modeling, and prediction
would enhance the reliability and robustness of our military communications
network. In addition to their significant benefits for our existing
communications network, such advances are also requisite to further
exploitation of the ionosphere via active modification.
Appendix
C - Acronyms and Definitions
AOC
Air Operations Center
AOR
Area of Responsibility
ATO
Air Tasking Order
EHF
Extra High Frequency
GWN
Global Weather Network
HF
High Frequency
IR
Infra-red
LF
Low Frequency
LUF
Lowest Usable Frequency
Mesoscale
Less than 200 KM²
MUF
Maximum Usable Frequency
MW
Microwave
OTH
Over-the-horizon
PGM
Precision-guided-munitions
RF
Radio Frequency
SAR
Synthetic Aperture Radar
SARSAT
Search and Rescue Satellite-aided
Tracking
SHF
Super High Frequency
SPOT
Satellite Positioning and Tracking
UAV
Unmanned Aerial Vehicle
UV
Ultra-violet
VHF
Very High Frequency
WFS
Weather Force Specialist
WFSE
Weather Force Support Element
WX
Weather
Background
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