GLObal. Backscatter. Experiment. (GLOBE)Pacific. Sur_vJy Missio- _. David. A. Bowdle,. University of Alabama in Huntsville. Jeffry. Rothermel,. NASA/Marshall.
N 9 1 " 25= 5 2 GLObal
Title: Authors:
David Jeffry James Steven
Backscatter
Experiment
(GLOBE)Pacific
Sur_vJy
A. Bowdle, University of Alabama in Huntsville Rothermel, NASA/Marshall Space Flight Center E. Arnold, NASA/Marshall Space Flight Center F. Williams, University of Alabama in Huntsville
Missio- _
../C4_l
Discipline: Atmosphere
_
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The National Aeronautics and Space Administration (NAS_A) conducted the GLObal Backscatter Experiment (GLOBE) Survey Missions on a NASA DC-8 aircraft over the near-coastal and remote Pacific Ocean during November 6 - 30, 1989 (GLOBE I) and May 13 - June 5, 1990 (GLOBE II). These missions w_re designed to study the optical, physical, and chemical properties of atmospheric aerosols. Particular variability of aerosol (9-11 #m) wavelengths, these aerosol properties Survey measurements
instruments at the
global-scale model any of
emphasis was given to the m_gn_tude and spatial backscatter coefficients {_] m'_sr" ) at mid-infrared and to the remote middle and upper troposphere, where are poorly understood. f-T-able i) were key wavelengths,
aerosol climatologies, the above quantities.-
selected to provide either direct= empirical links with long_term or
or aerosol microphysics data The core instruments included
required to three lidar
systems, a pulsed coherent CO 2 lidar, a pulsed incoherent Nd:YAG lidar, and two focused continuous-wave (CW) CO 2 Doppler lidars. The pulsed lidars provided _ profiles above and belo_ the aircraft, while the CW lidars provided complementary flight-level _ measurements. The lidar instruments were supported by flight-level instruments for aerosol microphysical and optical properties. Some of the suppQ_ting instruments were mounted on aerodynamic pylons below the wingtips, to characterize aerosol concentrations and size distributions as nearly in situ as possible, with minimal interference from the aircraft boundary layer. Other sensors were mounted in the DC-8 cabin, where they sampled isokinetically from nozzles mounted on the aircraft fuselage, to provide detailed information on aerosol chemical, morphological, and visible-wavelength optical properties. Supporting meteorological data on the Survey aircraft were obtained from a microwave moisture sounder, video camera cloud monitors, and standard meteorological sensors. In addition, satellite imagery, rawinsonde soundings, weather analyses, and calculated airmass trajectories were obtained to augment Survey aerosol data analyses. The Survey deployment included both long-distance 6-8 hour transit flights and detailed 4-6 hour local flights (Fig. I). Transit flight altitudes were usually near 8 km, except when higher altitudes were required to avoid extensive cloud fields. Overall, the transit flights provided relatively rapid and nearly pole-to-pole coverage, along with important seasonal, hemispheric, and airmass contrasts. Local flights usually involved multiple passes over the same test area at varying altitudes. These flights were conducted before and after deployment for engineering check-out and measurement validation, and during deployment for additional validation and for empirical links with key aerosol climatologies. Overall, approximately two-thirds of mission flight
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were
used
aerosol
for
transit,
climatology
and
the
remainder
for
validation
experiments
intercomparlsons. l
m Several
general
analyses.
Validation
usually
better
hibited
a
in
highly
and
when
water
subtle
and
upper with
CO 2 _
size
changes
to
_Three
quantify
major
fairly
layer;
(2)
Frequent from
were
correlated not
with
acco_-panied
CO 2
_
values
statistical
layer;
by
and
and
within
aerosol
were case
cloud
visually
w
composition,
changes
also
m
variable
clouds
deep
i
moderate
latitudinally
troposphere.
were
exuniform
"cloud-pumped"
lidar
Detailed
these
and
and
returns
data
agreement,
high
overlying
seasonally
good
frequently
boundary
deeper
distribution.
concentration.
shown
Survey
aerosols (i)
marine a
values
have
with:
but
often
chemical
or
vapor
underway
middle
preliminary
Atmospheric
structure,
in
from
results
two.
uniform,
shields.
observed
cloud-capped
observed,
concentration
of
backscatter
the
were cirrus
even
shallow
regionally in
residues
been
intercomparison
factor vertical
the
low,
backscatter
opaque
a
variable
(3)
have
and
than
three-layer
backscatter and
features
in
aerosol
correlated
study
W
with
analyses
are
observations.
uncertainties
u
remain
in
the
characterization
of
the
global
%
aer@sol The-_
system
first
that
concerns
the
backscatter
validity of
Survey
data
Sions
--
-rection
is
Survey
by
data at
will
MSFC.
NASA
the
late
lldar-based gets
for
Special
on
Facility
systems
that
measurements
of
from
NAS8-37585;
two
of
this
into in
turn,
use
is
due
to
the Dr.
Earth
is
(DAB
and
gratefully
SFW)
be
which
AL.
This
in
from
overall
and
model simulated
(LAWS),
the
one
System design
passive
E
the GLOBE
backscatter design
of
under-
base,
results
Observing
useful
the
conduct Ramesh
as
Sounder
as
portion
best
of
scattering
of
I
(EOS) other tar-
variables.
acknowledge in
the
small
The
for
Wind
aerosols
atmospheric
well
used
be
important
data
aerosol
assistance
of Kakar,
the Mission Management at NASA Ames Research
authors
support
for
J
cor-
"background"
Huntsville,
programs.
being
also
atmospheric
authors
and to aircraft the
will
GLOBE
as
Atmospheric
planned
results
a can
Center,
global-scale
are
Laser
of
comprehensive
field
a
mis-
and
provide
results
climatologies,
both
system.
snapshots
Flight
GLOBE-related
groups
acknowledgment
aerosol
comprehen-
from
of
I
con-
concept.
biases,
will
second
third
the
estimates
analyses
Survey
more
aerosol
primary
The research
isolated
Space
Instruments GLOBE
and
two
the
MSFC's
1990's.
NASA Headquarters, sonnel for the DC-8 tions
key
results,
Acknowledgments dividuals
with
smaller
studies
global
Marshall
incorporated
model
the
of
g
including
model
data
sampling
robust
these
Consequently,
NASA
and
The
performance
in
represent
them
being
of
The
The
analyses
validation
Ocean. physical
regimes,
aerosol
sensitivities,
of
the
variability.
detailed
develop
Pacific
conditions.
backscatter
extensive
to
dynamics
include
is
require
sensor
the of
"background"
results
system.
at
Missions base
several
The
Missions
compiled
low
latitudinal
the
ultimately
the
aerosol
base
Survey
and
backscatter
the /
will
quantify
synthesizing
being
data
seasonal
over
quantification
low
of
including
to
troposphere and
observed
issues
base,
into
global
upper
quasi-steady-state
properties.
insights
stood
a
these
factors,
The
and of
initially
-backscatter
--
the
magnitude
the
and
identification
produced
Sive
the
middle
representativeness
Exploratlon
°new
the
concerns
mechanisms
ce_rns
for
were
the
GLOBE
GLOBE
of
numerous
Survey Program
in-
Missions. Manager
at
and Mission Operations perCenter. Research contribusupported
under
NASA
contract
acknowledged. U
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