16-2: There is a temperature
limit to the occurrence/survival of life. In the magmas/lavas
of an active volcano, life will be absent. BACK
16-3: The list is long.
Here are some samples: Introduction of noxious gases
into the atmosphere; Increase in atmospheric carbon
dioxide; Alteration of the natural ozone layer in
the upper atmosphere; Possible acceleration of ice
sheet melting, causing sea level rise; Deforestation;
Destruction of range and grazing lands; Pollution
of Streams; Extinction of biotic species. BACK
16-4: Pinatubo lies at
about 17° N latitude, well within the "horse latitudes"
dominated by the trade winds. This sub-equatorial
wind circulation systems kept the ash confined to
these low latitudes. BACK
16-5: In the right center
is a long, narrow black pattern; there are several
other such patterns around the volcano. These are
all "lahars" - mudflows of volcanic ash caused by
heavy rains sweeping this material into streams. The
one that enlarged to double its size results from
rain wash that brought the ash to lower elevations
and redeposited it. The red at the bottom is not ash.
BACK
16-6: The introduction
of carbon dioxide is seasonal in magnitude. Much less
is added during the northern hemisphere winters, so
there is a downturn in the plot, making this a cyclic
phenomenon. All three curves steadily increase, roughly
in accord with increasing human population and also
further industrialization. It is difficult to explain
these increases by known natural factors, so by default
the environmentalists who voice dire warnings about
Man's degradation of the global natural state have
rather convincing evidence. BACK
16-7: There is not a steady
decrease in ozone from 1979 to 1992. In fact, there
are somewhat non-systematic variations from year to
year. Two major minima occur in 1986 and 1992. But
there are rises after years of decreased ozone content.
This tends to blunt the arguments of those who portend
catastrophe in the protective ozone layer. Other,
natural factors may be partly responsible for the
fluctuations. Obviously, a longer period of observations
is necessary to verify any general downward trend.
BACK
16-8: About threefold or
300% in the five year period between 1982 and 1987.
BACK
16-9: Physical Geography
and, to a lesser extent, Environmental Science or
Ecology. BACK
16-10: Right now, those
in the seconds to minutes time scale and those whose
changes take centuries or longer. But, that can change.
In principle, geostationary satellites, particularly
if equipped with improved telescopes, can monitor
very short term changes. And, looking well ahead into
the future, the satellite-based data now being archived
will someday become greatly relevant to those evaluating
long-term trends in the Earth's environment. BACK
16-11: Energy, climate,
biogeochemistry, and Man's activities. BACK
16-12: This published
diagram perhaps is overgeneralized to keep it simple.
The arrow from the CO2 box goes to the
ocean but seems to be directed at zooplankton when,
in fact, phytoplankton are the principal intakers
of that gas. A bit misleading; the draftsman intended
it to simply enter the ocean. The SO3 and
NO3 box seems to end in the atmosphere
but these two gases can be returned to Earth by reaction
with water to make sulphuric and nitric acids (acid
rain). There are several other shortcomings. BACK
16-13: The principal source
is the burning of hydrocarbons (extracted mainly as
petroleum and natural gas); the main sink is the deep
ocean. Not shown is carbon already locked up in sedimentary
carbonates (mostly limestones) in the Earth's crust;
this is a minor source since most is buried and not
actively contributing to the cycle except where it
is being weathered at the surface. BACK
16-14: That player perhaps
should reader "payer", namely, Congress which appropriates
the funds. To a lesser extent the executive branch
plays an important role also, in deciding on what
programs to sponsor and push through. Each year around
budget time, the agencies must do a "hard sell" on
their continuing participation in the programs that
involve the U.S. in environmental monitoring from
space and particularly the Mission to Planet Earth.
Budget cuts in recent years have somewhat tapered
the original plans for this venture. BACK
16-15: The "culprit" is
the Global Data and Information System (referred to
later as EOSDIS). The problem is simply that never
before has so much data (more than three terabytes
or 3 x 1012 or three trillion bytes of
computer-compatible data) been received on a daily
basis and the computer power to handle this through-put
must be both grandiose and efficient beyond any experience
to date. The data come from the multiple numbers of
sensors that will be on several satellites that eventually
will be in orbit simultaneously. Difficulties in getting
that facility ready have slowed the launch dates of
the primary satellites supporting MTPE. BACK
16-16: Most of the data
will be connected to quantities needed for environmental
assessment. Thus, the sensors should be able to image
the surface of land and sea and identify land cover
classes; determine plant types, biomass, and stress
state; measure a range of atmospheric properties such
as temperature, pressure, wind direction, water content,
chemical composition; gather data on sea surface temperature,
chlorophyll content, wave and current movements; monitor
water distribution (inventory), and the like. Thus,
EOS really is an amalgamation of sensors that each
are somewhat specialized and have flown before on
their own satellites but are now to operate in consort
together so that disparate data are now collected
simultaneously over the same target while orbiting
to provide global coverage. BACK
16-17: In case you missed
their identification at the bottom of the table, SNR
stands for Signal to Noise Ratio (appropriate to reflectance
measurements) and NE deltaT stands for Noise-Equivalent
Temperature difference (pertinent to thermal measurements).
Each is a measure of quality of output or, more technically,
the sensitivity of the instrument detectors. There
is always some noise in the system due to a variety
of causes that contributes to the minimal value of
the signal. These two measures specify the minimum
values above the background noise that the instrument
detectors can discriminate as the signal coming from
the target of interest. BACK
16-18: MODIS is primarily
a meteorological and oceanographic satellite.BACK
16-19: Those who are interested
principally in land phenomena. BACK
16-20: Spread the load
out even further - to other receiving and processing
centers. This is the gist of the Regional Applications
Center (RAC) concept developed in the Applied Information
Sciences Branch and described in Section 20 of this
Tutorial. Each regional center will have its own antenna
dish and will be able to process data received right
at its own site. If enough of these are established
and funded, the EOSDIS will have notably reduced daily
demands. BACK
16-21: The partitioning
of solar energy among the physical, chemical, and
biological entities that make up the Earth's ecosystems.
BACK
Collaborators: Code
935 NASA GSFC, GST,
USAF Academy,
Webmaster: Bill Dickinson Jr.
Primary Author: Nicholas M. Short, Sr.
email: nmshort@epix.net
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Last Updated: July '99
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