<s>
The	O
NCEP/NCAR	B-Application
Reanalysis	I-Application
is	O
an	O
atmospheric	O
reanalysis	O
produced	O
by	O
the	O
National	O
Centers	O
for	O
Environmental	O
Prediction	O
(	O
NCEP	O
)	O
and	O
the	O
National	O
Center	O
for	O
Atmospheric	O
Research	O
(	O
NCAR	O
)	O
.	O
</s>
<s>
It	O
is	O
a	O
continually	O
updated	O
globally	O
gridded	O
data	O
set	O
that	O
represents	O
the	O
state	O
of	O
the	O
Earth	O
's	O
atmosphere	O
,	O
incorporating	O
observations	O
and	O
numerical	B-General_Concept
weather	I-General_Concept
prediction	I-General_Concept
(	O
NWP	O
)	O
model	O
output	O
from	O
1948	O
to	O
present	O
.	O
</s>
<s>
It	O
is	O
distributed	O
in	O
Netcdf	B-Application
and	O
GRIB	B-Application
files	O
,	O
for	O
which	O
a	O
number	O
of	O
tools	O
and	O
libraries	O
exist	O
.	O
</s>
<s>
It	O
is	O
available	O
for	O
download	O
through	O
the	O
NCAR	O
CISL	O
Research	O
Data	O
Archive	O
on	O
the	O
NCEP/NCAR	B-Application
Reanalysis	I-Application
main	O
data	O
page	O
.	O
</s>
<s>
The	O
former	O
focuses	O
in	O
fixing	O
existing	O
bugs	O
with	O
the	O
NCEP/NCAR	B-Application
Reanalysis	I-Application
system	O
–	O
most	O
notably	O
surface	O
energy	O
and	O
usage	O
of	O
observed	O
precipitation	O
forcing	O
to	O
the	O
land	O
surface	O
,	O
but	O
otherwise	O
uses	O
a	O
similar	O
numerical	B-General_Concept
model	I-General_Concept
and	O
data	O
assimilation	O
system	O
.	O
</s>
