232
Depth resolution
Range
Measurement time per profile
Sensitivity / precision (10-)
15 m
3km
1 minute
3 ppb
C. Weitkamp
Table 10.4: ARGOS performance data (for S02 under conditions of:O:: 20 km visibility).
Care must therefore be taken to use only those pairs of wavelengths for which S02 cross
sections are minimum and equal. Of the 13 pairs of suitable wavelengths determined from
high-resolution S02 cross-section measurements (Weitkamp et aI., 1992) the optimum pair was
determined in an optimization procedure based on the analysis of Eq. (lO.16) and taking into
account parameters such as range, sensitivity, and systematic error due to aerosols and aerosol gradients (Goers 1994). The results shown in Fig. 10.ll clearly demonstrate that the
on/off-resonance pair of 280.91/282.72 nm is a good choice as for longer wavelengths the (negative) error increases, whereas shorter wavelengths (not seen from Fig. 10.ll) result in range
limitations as soon as medium or high 0 3 concentrations are encountered.
CONSOLE
'·COMPONEN'r
PHASED-ARRAY
SODAR
Figure 10.10: Block diagram of the ARGOS lidar system.
In several applications ARGOS proved to be an excellent system for the measurement of tropospheric ozone concentration distributions. Time series of concentration profiles from the
ground to the top of the mixing layer taken in a rural and a nearby urban environment during
a fair-weather summer smog episode occasionally showed 0 3 concentrations in excess of 250
J.lg/m 3 , both at the rural and the urban site. The maxima usually occurred between 600 and
800 m above ground. Surface concentrations did not exceed 150 J.lg/m 3 . An interesting feature
of the time series was a nocturnal maximum in addition to the early-afternoon maximum easily
explained by photochemical processes. The nocturnal maximum only appeared aloft, not at
ground level, and is attributed to the advection of high-ozone air masses that formed during
the day and contain too little oxidizable material (such as NO) to reduce the ozone. Sulfur
Depth resolution
Range
Measurement time per profile
Sensitivity / precision (10-)
15 m
3km
1 minute
3 ppb
C. Weitkamp
Table 10.4: ARGOS performance data (for S02 under conditions of:O:: 20 km visibility).
Care must therefore be taken to use only those pairs of wavelengths for which S02 cross
sections are minimum and equal. Of the 13 pairs of suitable wavelengths determined from
high-resolution S02 cross-section measurements (Weitkamp et aI., 1992) the optimum pair was
determined in an optimization procedure based on the analysis of Eq. (lO.16) and taking into
account parameters such as range, sensitivity, and systematic error due to aerosols and aerosol gradients (Goers 1994). The results shown in Fig. 10.ll clearly demonstrate that the
on/off-resonance pair of 280.91/282.72 nm is a good choice as for longer wavelengths the (negative) error increases, whereas shorter wavelengths (not seen from Fig. 10.ll) result in range
limitations as soon as medium or high 0 3 concentrations are encountered.
CONSOLE
'·COMPONEN'r
PHASED-ARRAY
SODAR
Figure 10.10: Block diagram of the ARGOS lidar system.
In several applications ARGOS proved to be an excellent system for the measurement of tropospheric ozone concentration distributions. Time series of concentration profiles from the
ground to the top of the mixing layer taken in a rural and a nearby urban environment during
a fair-weather summer smog episode occasionally showed 0 3 concentrations in excess of 250
J.lg/m 3 , both at the rural and the urban site. The maxima usually occurred between 600 and
800 m above ground. Surface concentrations did not exceed 150 J.lg/m 3 . An interesting feature
of the time series was a nocturnal maximum in addition to the early-afternoon maximum easily
explained by photochemical processes. The nocturnal maximum only appeared aloft, not at
ground level, and is attributed to the advection of high-ozone air masses that formed during
the day and contain too little oxidizable material (such as NO) to reduce the ozone. Sulfur