Kipp & Zonen BREWER MK IV, Инструкция по эксплуатации

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MKIV OPERATOR'S MANUAL 100
Inter-Comparison Calibration
The Instrument Inter-Comparison Calibration determines the absorption coefficients and
extraterrestrial constants for the measurement of O
3
and SO
2
. These constants are instrument
dependent and must be determined for all instruments prior to O
3
or SO
2
measurements.
The uncalibrated instrument is compared to a certified Brewer reference by the analysis of a large
number of time-coincident direct-sun O
3
observations made by the two instruments.
Method:
The method by which direct-sun O
3
and SO
2
values are derived from the raw photon counts at the
five operational wavelengths is outlined in Appendix G. After corrections for dark count, deadtime,
Rayleigh scattering, and instrument temperature have been applied, the O
3
and SO
2
(MS(11) and
MS(10)), values are calculated using the following formulae:
2 1
1 ) 9 (
) 11 (
M A
B MS
MS
⋅
−
←






−
⋅
−
⋅ ←
) 11 (
2 3
2 ) 8 (
2
1
) 10 ( MS
M A
B MS
A
MS
where
MS(8) is the weighted double-ratio for SO
2
MS(9) is the weighted double-ratio for O
3
A1 is the differential O
3
absorption coefficient for the O
3
ratio
B1 is the extraterrestrial constant for the O
3
ratio
A2 is the relative SO
2
to O
3
absorption for the SO
2
ratio = (2.44)
A3 is the differential O
3
absorption coefficient for the SO
2
ratio
B2 is the extraterrestrial constant for the SO
2
ratio
M2 is the airmass, also referred to as MU.
The method to determine the four instrument-dependent values (A1, B1, A3, B2) for a particular
instrument via the Inter-Comparison Calibration procedure is outlined below.
Many simultaneous direct-sun measurements (at least 40) are made with both the instrument to be
calibrated and a reference instrument. Measurements should be taken over a wide range of
airmass values (1.0 < mu < 3.0) for at least one full day of good observing conditions. The O
3
and
SO
2
values (MS(11) and MS(10)) are determined from the measurements made with the reference
instrument. These values, together with the values of MS(8), MS(9), and M2 valid for the
instrument being calibrated are substituted into the above two equations which are rewritten as
follows:
MS(11) M2 A1 B1 MS(9)
⋅ ⋅ + ←
MS(11)] M2 MS(10) A2 [M2 A3 B2 MS(8)
⋅ + ⋅ ⋅ ⋅ + ←
Two least-squares linear regression fits are applied to these equations and the resulting two pairs of
regression coefficients (B1, A1; B2, A3) are the four instrument-dependent coefficients.
As for all previous tests, consult AES or KIPP & ZONEN prior to altering any of the constants in the
instrument Constants File.
RS: Slitmask Motor Run/Stop Test
The RS test verifies that the slitmask motor (slitmask motor) is operating correctly.
In the normal, or "dynamic" mode of operation the slitmask is cycled rapidly, permitting individual
measurements to be made at intervals of 131 milliseconds. To ensure that the light intensities are
being properly measured in this dynamic mode, the RS test also measures intensities in a "static"
mode. Light passing through each slit is measured for a longer period of time during which the
slitmask motor is stationary.