IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing,
Journal Year:
2024,
Volume and Issue:
17, P. 12969 - 12982
Published: Jan. 1, 2024
Gross
primary
production
(GPP)
measures
the
amount
of
carbon
fixed
by
plants
and,
thus,
plays
a
significant
role
in
terrestrial
cycle
and
global
food
security,
especially
context
climate
change
neutrality.
Currently,
all-sky
high-resolution
(<100
m)
GPP
is
increasingly
needed
for
better
understanding
food–carbon–water–energy
nexus.
However,
previous
studies
usually
used
optical
satellites
to
estimate
clear-sky
at
kilometer-scale
resolution.
Due
missing
estimates
under
cloudy-sky
conditions,
monitoring
spatio–temporal
changes
from
would
suffer
some
uncertainties.
Moreover,
one
issue
that
they
only
satellite
images
or
environmental
data
rather
than
jointly
integrating
them
biome
types.
To
address
these
challenges,
this
study
attempts
use
active
microwave
Sentinel-1
synthetic
aperture
radar
(SAR)
10
m
resolution
GPP.
measurements
across
nine
types
North
America
were
employed
develop
SAR-based
model.
Meanwhile,
an
optical-based
model
with
Landsat-8
was
also
proposed
comparison.
The
results
revealed
that,
first,
SAR
can
be
utilized
By
images,
data,
types,
optimal
showed
high
accuracy
estimating
daily
coefficient
determination
(R
2
)
=
0.764,
root-mean-square
error
(RMSE)
1.976
gC/m
/d,
mean
absolute
(MAE)
1.308
/d.
Second,
had
reasonable
validation
0.809,
RMSE
1.762
MAE
1.165
/d).
Third,
contributed
more
model,
while
contribution
higher
Fourth,
performance
GPP,
two
models
consistency
0.730
1.858
/d)
together.
Therefore,
demonstrated
provides
important
source
advancing
our
cycle,
change.
Remote Sensing,
Journal Year:
2024,
Volume and Issue:
16(20), P. 3787 - 3787
Published: Oct. 11, 2024
Drought
has
extensive,
far-reaching,
and
long-lasting
asymmetric
effects
on
vegetation
growth
worldwide
in
the
context
of
global
warming.
However,
to
date,
few
scholars
have
attempted
systematic
quantification
temporal
drought
across
various
types
diverse
climate
zones.
Addressing
this
gap,
we
quantitatively
investigated
under
scenarios,
considering
lagged
cumulative
as
well
combined
1982–2018
period.
Our
investigation
was
based
long-term
net
primary
productivity
(NPP)
two
multiple-timescale
indices:
standardised
precipitation
index
(SPI)
evapotranspiration
(SPEI).
main
findings
were
following:
(1)
SPI
SPEI
exhibited
52.08%
37.05%
vegetation,
leading
average
time
lags
2.48
months
1.76
months,
respectively.
The
observed
80.01%
72.16%
vegetated
areas,
respectively,
being
associated
with
relatively
longer
timescales
5.60
5.16
(2)
Compared
scenario
excluding
effects,
there
increases
explanatory
powers
for
variations
NPP
lagged,
cumulative,
drought:
increased
by
0.82%,
6.65%,
6.92%,
whereas
0.67%,
5.73%,
6.07%,
stronger
than
approximately
two-thirds
(64.95%
63.52%
SPEI,
respectively)
areas.
(3)
varied
according
zones
types.
Interestingly,
arid
most
sensitive
resilient
drought,
indicated
its
rapid
response
longest
timescales.
tropical
temperate
a
that
cold
polar
strongest
correlation
occurred
shrubland
followed
grassland,
cropland,
forest,
tundra
Moreover,
each
type,
correlations
between
differed
significantly
among
(4)
warming-induced
regions
displayed
higher
non-warming-induced
regions,
shorter
highlight
heterogeneity
types;
could
enhance
our
understanding
coupling
relationship
vegetation.