As well as being the place where weather systems are born,
travel, and die, the atmosphere is a dynamic system that forms
a protective shell around the planet. Without this protective
layer, life on the planet would not be possible. There would
be no air to breathe, we would have to protection from the
Sun’s powerful radiative energy, temperatures would
skyrocket during the day and plummet at night, and we’d
have no protection from debris moving through the solar system.
Without the atmosphere, the Earth would be much like the Moon
– barren and inhospitable to life. The importance of
our atmosphere to life on Earth cannot be understated, which
is why so much effort is made to understand it and why, for
example, the “hole” in the ozone layer over Antarctica
receives so much public attention.
In order to help scientists study and gain an understanding
of earth’s protective layer of gasses, MODIS scientists
have developed the MOD 07 Atmospheric Profile product, which
describes the atmosphere in four ways: total-column ozone,
atmospheric stability, atmospheric temperature- and moisture-sounding,
and total-column precipitable water. These profiles are based
on MODIS' sequential observations of the columns of atmosphere
between the satellite and the Earth's surface as the satellite
The total-column ozone product provides data for monitoring
ozone levels – and thereby helps to evaluate potential
harm via anthropogenic (human) sources. It also helps weather
forecasters to predict the position and intensity of jet streams
(wind currents 10-15 miles up in the atmosphere moving at
very high speeds, often exceeding 250 mph) and to identify
turbulent regions of the atmosphere for airplanes to avoid.
The total-column precipitable-water (i.e., water vapor) is
an estimate of how much precipitation could be produced by
the moisture contained in a column of the atmosphere. This
product can be used to track regional and global climate phenomena,
like monsoons. The presence of water vapor in the atmosphere
influences heat and energy budgets (water vapor is the most
powerful greenhouse gas) and cloud formation, and of course,
plays a major role in the hydrological cycle.
Both the ozone and total precipitable water products are
needed to develop and refine atmospheric correction algorithms.
Corrections are needed for MODIS' observations of surface
features, since those observations may be influenced by the
conditions in the atmosphere at the time of the observation.
The correction algorithms that MODIS scientists develop must
be extremely accurate so that the data products that they
help to produce, such as vegetation amount and health, surface
reflectance, and ocean color, are of the highest possible
The atmospheric stability observations provide key indications
of how likely a portion of the atmosphere is to produce thunderstorms,
resulting in precipitation on a large scale. For example,
having very dense air resting on top of less dense air is
unstable because within a confined volume (like a column of
atmosphere) the denser air will be heavier and will want to
sink, while the less dense air is more buoyant, and will want
to rise. To interpret how the environment affects thunderstorm
potential and severity, meteorologists have invented several
stability indices that characterize the stability of the atmosphere
in a single number. MODIS provides stability indices at a
high spatial resolution, which helps forecasters identify
local regions with chances of severe thunderstorms.
The atmospheric temperature and moisture profiles provide
temperature and moisture readings at twenty different levels
between the surface of the earth and the top of the atmosphere
under cloud-free conditions. These profiles provide basic
information about how the atmosphere itself is constructed.
This basic understanding of the atmosphere, or baseline, is
necessary for both fundamental studies of climate and the
When these four portions are pulled together into the Atmospheric
Profile product, the result is a data set that will have many
powerful and far-reaching applications and will enhance our
understanding the atmosphere. Further, understanding how our
atmosphere works is an important step in understanding how
our planet functions as a whole – from life to land
to ocean to atmosphere.