<s>
The	O
MM5	B-Application
(	O
short	O
for	O
Fifth-Generation	O
Penn	O
State/NCAR	O
Mesoscale	O
Model	B-General_Concept
)	O
is	O
a	O
regional	O
mesoscale	O
model	B-General_Concept
used	O
for	O
creating	O
weather	O
forecasts	O
and	O
climate	O
projections	O
.	O
</s>
<s>
It	O
is	O
a	O
community	O
model	B-General_Concept
maintained	O
by	O
Penn	O
State	O
University	O
and	O
the	O
National	O
Center	O
for	O
Atmospheric	O
Research	O
.	O
</s>
<s>
The	O
MM5	B-Application
is	O
a	O
limited-area	O
,	O
terrain-following	O
sigma	B-Application
coordinate	O
model	B-General_Concept
that	O
is	O
used	O
to	O
replicate	O
or	O
forecast	O
mesoscale	O
and	O
regional	O
scale	O
atmospheric	O
circulation	O
.	O
</s>
<s>
Active	O
development	O
on	O
the	O
model	B-General_Concept
ended	O
with	O
version	O
3.7.2	O
in	O
2005	O
,	O
and	O
it	O
has	O
been	O
largely	O
superseded	O
by	O
the	O
Weather	B-Application
Research	I-Application
and	I-Application
Forecasting	I-Application
(	O
WRF	O
)	O
model	B-General_Concept
.	O
</s>
<s>
MM5	B-Application
is	O
globally	O
relocatable	O
,	O
which	O
helps	O
support	O
different	O
latitudes	O
,	O
terrain	O
types	O
,	O
elevations	O
,	O
soil	O
types	O
,	O
etc	O
.	O
</s>
<s>
The	O
model	B-General_Concept
can	O
be	O
either	O
hydrostatic	O
or	O
non-hydrostatic	O
,	O
depending	O
on	O
the	O
desired	O
outcome	O
.	O
</s>
<s>
The	O
fact	O
that	O
the	O
model	B-General_Concept
is	O
regional	O
implies	O
that	O
it	O
requires	O
initial	O
conditions	O
and	O
lateral	O
boundary	O
conditions	O
.	O
</s>
<s>
This	O
model	B-General_Concept
takes	O
and	O
then	O
analyzes	O
its	O
data	O
based	O
on	O
pressure	O
surfaces	O
.	O
</s>
<s>
This	O
vertical	O
coordinate	O
,	O
sigma	B-Application
,	O
is	O
computed	O
and	O
then	O
used	O
throughout	O
the	O
program	O
.	O
</s>
<s>
Where	O
p	O
is	O
pressure	O
,	O
ps	O
is	O
surface	O
pressure	O
,	O
and	O
pt	O
is	O
the	O
pressure	O
at	O
the	O
top	O
of	O
the	O
model	B-General_Concept
.	O
</s>
<s>
MM5	B-Application
features	O
inputs	O
from	O
actual	O
data	O
,	O
which	O
is	O
helpful	O
because	O
routine	O
observations	O
can	O
be	O
used	O
.	O
</s>
<s>
MM5	B-Application
also	O
features	O
terrain-following	O
vertical	O
coordinates	O
and	O
four-dimensional	O
data	O
assimilation	O
(	O
FDDA	O
)	O
.	O
</s>
<s>
Most	O
importantly	O
,	O
MM5	B-Application
is	O
well	O
documented	O
and	O
has	O
many	O
places	O
for	O
user	O
support	O
.	O
</s>
<s>
There	O
are	O
many	O
pieces	O
of	O
the	O
MM5	B-Application
modeling	O
system	O
,	O
each	O
with	O
different	O
functions	O
.	O
</s>
<s>
In	O
the	O
basic	O
sense	O
,	O
the	O
model	B-General_Concept
begins	O
by	O
taking	O
the	O
information	O
and	O
then	O
makes	O
a	O
model	B-General_Concept
of	O
the	O
land	O
.	O
</s>
<s>
Then	O
,	O
the	O
model	B-General_Concept
guesses	O
the	O
different	O
pressures	O
that	O
exist	O
in	O
the	O
atmosphere	O
throughout	O
this	O
plot	O
of	O
land	O
,	O
which	O
is	O
done	O
through	O
REGRID	O
.	O
</s>
<s>
Then	O
,	O
the	O
model	B-General_Concept
takes	O
these	O
guesses	O
,	O
and	O
with	O
the	O
help	O
of	O
some	O
surface	O
observations	O
,	O
can	O
create	O
an	O
objective	O
analysis	O
,	O
using	O
LITTLE_R	O
.	O
</s>
<s>
Then	O
INTERPF	O
takes	O
that	O
data	O
from	O
RAWINS/LITTLE_R	O
and	O
REGRID	O
to	O
interpolate	O
that	O
data	O
to	O
the	O
sigma	B-Application
coordinate	O
explained	O
above	O
.	O
</s>
<s>
MM5	B-Application
itself	O
computes	O
the	O
time	O
combination	O
.	O
</s>
<s>
The	O
NESTDOWN	O
function	O
has	O
the	O
ability	O
to	O
change	O
the	O
vertical	O
sigma	B-Application
levels	O
.	O
</s>
<s>
RIP	O
stands	O
for	O
Read/Interpolate/Plot	O
,	O
and	O
it	O
uses	O
NCAR	O
Graphics	O
to	O
help	O
envisage	O
the	O
output	O
from	O
the	O
MM5	B-Application
.	O
</s>
<s>
MM5	B-Application
is	O
written	O
in	O
FORTRAN	B-Application
.	O
</s>
<s>
These	O
FORTRAN	B-Application
programs	O
must	O
be	O
compiled	O
on	O
a	O
local	O
computer	O
,	O
and	O
some	O
need	O
to	O
be	O
recompiled	O
each	O
time	O
a	O
model	B-General_Concept
configuration	O
is	O
changed	O
.	O
</s>
<s>
MM5	B-Application
can	O
also	O
perform	O
multiple	O
tasks	O
at	O
once	O
.	O
</s>
<s>
Specifically	O
,	O
two	O
different	O
tasks	O
can	O
be	O
executed	O
on	O
different	O
processors	O
simultaneously	O
and	O
MM5	B-Application
uses	O
this	O
as	O
much	O
as	O
possible	O
.	O
</s>
<s>
This	O
multi-tasking	O
also	O
uses	O
nesting	O
,	O
and	O
MM5	B-Application
allows	O
up	O
to	O
nine	O
domains	B-Architecture
(	O
processes	O
)	O
running	O
at	O
the	O
same	O
time	O
and	O
they	O
interact	O
throughout	O
the	O
whole	O
process	O
.	O
</s>
<s>
The	O
model	B-General_Concept
utilizes	O
two-way	O
nesting	O
,	O
which	O
occurs	O
when	O
the	O
input	O
from	O
one	O
nest	O
's	O
coarse	O
mesh	O
,	O
which	O
is	O
a	O
high	O
density	O
of	O
cells	O
in	O
one	O
area	O
,	O
comes	O
from	O
one	O
of	O
the	O
four	O
boundaries	O
,	O
but	O
the	O
feedback	O
to	O
the	O
coarser	O
mesh	O
happens	O
through	O
the	O
nest	O
interior	O
.	O
</s>
<s>
MM5	B-Application
can	O
be	O
run	O
in	O
many	O
different	O
ways	O
,	O
depending	O
on	O
the	O
computer	O
.	O
</s>
<s>
The	O
model	B-General_Concept
can	O
be	O
run	O
on	O
a	O
single	O
processor	O
computer	O
,	O
shared	B-Operating_System
memory	I-Operating_System
architecture	I-Operating_System
or	O
distributed	O
memory	O
architecture	O
.	O
</s>
<s>
It	O
can	O
be	O
run	O
on	O
many	O
different	O
platforms	O
as	O
well	O
such	O
as	O
IBM	O
,	O
SGI	O
origin	O
200/2000	O
,	O
CRAYs	O
(	O
J90	O
,	O
C90	O
,	O
T3E	O
)	O
,	O
DEC	O
Alphas	B-Language
,	O
Alphas	B-Language
running	O
Linux	O
,	O
Sun	O
,	O
and	O
more	O
.	O
</s>
<s>
The	O
computer	O
it	O
is	O
run	O
on	O
must	O
have	O
a	O
Fortran	B-Application
90	O
and	O
77	O
compilers	O
and	O
a	O
C	O
compiler	O
.	O
</s>
<s>
Additionally	O
,	O
it	O
can	O
have	O
NCAR	O
graphics	O
and	O
MPI	O
tools	O
for	O
running	O
the	O
MPI	O
MM5	B-Application
model	B-General_Concept
.	O
</s>
<s>
The	O
MM5	B-Application
model	B-General_Concept
takes	O
up	O
at	O
least	O
half	O
a	O
gigabyte	O
of	O
memory	O
and	O
a	O
few	O
gigabytes	O
of	O
disk	B-General_Concept
space	I-General_Concept
.	O
</s>
<s>
The	O
MM5	B-Application
code	O
itself	O
has	O
over	O
220	O
subroutines	O
,	O
with	O
more	O
than	O
55,000	O
lines	O
of	O
code	O
.	O
</s>
<s>
It	O
uses	O
Standard	O
Fortran	B-Application
77	O
with	O
“	O
Cray	O
”	O
pointers	O
.	O
</s>
<s>
A	O
list	O
of	O
the	O
subroutines	O
of	O
all	O
of	O
the	O
functions	O
within	O
the	O
MM5	B-Application
,	O
with	O
a	O
short	O
description	O
and	O
the	O
routines	O
that	O
are	O
called	O
within	O
it	O
can	O
be	O
found	O
here	O
.	O
</s>
<s>
The	O
MM5	B-Application
had	O
been	O
adapted	O
for	O
use	O
in	O
many	O
different	O
types	O
of	O
atmospheric	O
simulations	O
:	O
</s>
<s>
This	O
new	O
update	O
also	O
allows	O
for	O
a	O
better	O
quality	O
terrain	O
image	O
that	O
can	O
be	O
used	O
in	O
MM5	B-Application
.	O
</s>
