Table of Contents
Advertisement
01:
4
02:
4
03:
2
04:
4
05:
2
PAR. DATA
NO.
TYPE
DESCRIPTION
Number of values
to
move
1st
source location
Step of source
1
st
destination location
Step of destination
*** 55
sTH ORDER
POLYNOMIAL **i
FUNCTION
Evaluate a Slh order
polynomialof the form.
F(X)=9919
1
X+C2X2+C3X3a94X449515
where C0
SECTION
10,
PROCESSING INSTRUCTIONS'
Computation of Saturation
Vapor Pressure.
J.
Appl. Meteor. 16, 100-103.
Saturation
vapor pressure over ice (SVPI)
in
kilopascals for a
OoC
to -50oC range can
be
obtained using Instruction 55 and
the
relationship
SVPI=
-.00486
+ .85471X+ .2441X2
where
X
is
the SVPW derived by lnstruction
56.
This relationship
was
derived by.Campbell
Scientific
from the equations for the SVPW and
the SVPI given in Lowe's paper.
PAR. DATA
NO- TYPE
DESCRIPT1ON
01: 4
Input location of air
temperature
oC
IEMP.]
02: 4
Dest. input location for saturated
vapor pressure
IVP or
Zl
Input locations
altered:
1
*** 57
VAPOR PRESSURE
FROM
***
-
WET./DRY.BU
LB TEMPERATU RES
FUNCTION
This instruction calculates vapor pressure
in
kilopascals from
wet- and dry-bulb
temperatures
in
oC. The algorithm
is of
the type
used
by
the National Weather Service:
VPW
=
VPW
-
A(1 + B*TWXTA
-
TW)
P
ambient
vapor pressure
in
kilopascals
saturation
vapor pressure
at
the wet-
bulb
temperature in kilopascals
wet-bulb
temperature, deg.
C
ambient air
temperature, deg.
C
air pressure in kilopascals
0.000660
0.00115
Although
the algorithm requires an air pressure
entry, the daily fluctuations are small enough
that
for most applications
a
fixed entry
of
the
standard pressure
at
the site elevation will
suffice.
lf a pressure
sensor
is
employed,
the
current pressure can be used.
argument
X
power,
+99999 to
coefficients
C0
coefficient
C1
coetficient
C2
coefficient
C3
coefficient
C4
coetficient
C5
coefficient
Input locations altered:
1* Reps
C5 are the coefficients for
the
to
the zero through filth
.
The magnitude of the user
is limited
to a range of
Polynomials with
this range can be modified
lc0l
tcll
tc2l
lcal
tc4l
tc5l
by
the
X
value by an appropriate
the coefficients within
the entry
factor
to
range.
Pre-$caling can also
be used to modify
coefficients
phich
are very close
to 0
in
order
to
increase
the number of significant digits.
PAR. DATA
NO. TYPE
DESCRIPTION
Repetitions
IREPS]
Starting input location for
X
txl
Dest. input location
for F(X)
[F(X) or
z]
VP=
VP=
01:
2
02:
4
03:
4
04:
FP
05:
FP
06:
FP
07:
FP
08:
FP
09:
FP
TW=
TA=
P=
A=
B=
*** 56 SATRAT|ON
VAPOR PRESSURE ***
FUNCTION
Calculate sdturation
vapor pressure over water
(SVPW)
in
kilopascals from
the air temperature
(oC)
and plape it in
an input location. The
algorithm
fof obtaining SVPW from air
temperature
(oC) is
taken
from:
Lowe, Paul
R.,
1
976:
An
Approximating Polynomial for
10-5
Advertisement
Table of Contents
