Central California Ozone Study (CCOS) - Desert Research Institute

CCOS Field Operations Plan Version 2: 5/31/00
Table 4.5-1. Summary of Meteorolgy Audit Methods and Criteria.
Measurement
Variable
Audit Criteria
Procedure
Reference
General Procedure
Horizontal
Speed
Wind
Accuracy ±(0.2 m/s + 5% of
observed)
Equivalent wind speed
starting torque to meet the
wind speed starting thresholds
for the respective sensors.
EPA-454/R-99-005-013
with 3/15/99 updates
EPA/600/R-94-038d
Three wind speeds within the expected range of operation. If any points are
outside of criteria then corrective action is necessary.
Horizontal
Direction
Wind
Accuracy ±3 degrees for
linearity, ±2 degrees for
alignment to known direction.
Equivalent wind speed
starting torque to meet the
wind speed starting thresholds
for the respective sensors.
EPA-454/R-99-005-013
with 3/15/99 updates
EPA/600/R-94-038d
Depending on the mechanical sensor type from 4 to 36 points equally spaced
around the compass will be compared. If any points are outside of criteria
then corrective action is necessary. Torque measurements will be made to
determine the mechanical sensor starting threshold. Sensor alignment will be
verified using solar methods.
Temperature ±0.5°C EPA-454/R-99-005-013
with 3/15/99 updates
Three temperatures within the expected range of temperatures (0 to 40°C). If
any points are outside of criteria then corrective action is necessary.
EPA/600/R-94-038d
Solar Radiation ± 5% of observed EPA-454/R-99-005-013
with 3/15/99 updates
EPA/600/R-94-038d
Barometric Pressure ±3 mb EPA-454/R-99-005-013
with 3/15/99 updates
Five measurements within the range of operations on a given audit day will
be made. If any points are outside of criteria then corrective action is
necessary.
Three pressures over the period of the audit will be compared. If any points
are outside of criteria then corrective action is necessary.
EPA/600/R-94-038d
Relative Humidity ± 1.5°C equivalent dew point EPA-454/R-99-005-013
with 3/15/99 updates
EPA/600/R-94-038d
Three comparisons are made of the station sensor to an aspirated
psychrometer. If any points are outside of criteria then corrective action is
necessary. An alternate method is to use LiCl salt solutions for a direct
evaluation of the response at know relative humidities. This method is
preferred for the high accuracy systems since solutions can be selected at the
Chapter 4: QUALITY ASSURANCE 4-24