Fig. 2.10 Example of an urban monitoring station; meteorological sensors: wind (1), temperature
(2), global solar radiation (3), precipitation (4), air quality (5 – gas and aerosol samplers)
Variable
Range
Reported
resolu-tion
Mode of
meas./o
bs.
Required measurement uncertainty
Sensor
time constant
Output
avera-ging
time
Achievable measurement
uncertainty
Remarks
7. Radiation
7.1 Sunshine duration (daily)
7.2 Net radiation, radiant exposure (daily)
0-24 h
Not specified
60s
1 J m -2
T
T
0.1 h
0.4 MJ m -2
for≤ 8 MJ m -2
5% for >8 MJ m -2
20s
20s
n/a
n/a
The larger of 0.1 h
or 2%
0.4 MJ m -2
for≤ 8 MJ m -2
5% for >8 MJ m -2
Radiant exposure expressed as daily sums
(amount) of (net) radiation.
8. Visibility
8.1 Meteorological Optical
Range (MOR)
10 m-100 km
1 m
I
50 m
for ≤ 600 m
10%for > 600 m≤1500
20%for > 1500 m
<30s
1 and 10
min
The larger of 20 m
or 20%
Achievable measurement uncertainty may
depend on the cause of obscuration.
Quantity to be averaged: extinction coefficient (see WMO Guide 2008, Part III,
Chapter 2, section 2.6). Preference for averaging logarithmic values.
9. Evaporation
9.1 Amount of pan evaporation
0-100 mm
0.1 mm
T
0.1 mm for ≤ 5 mm
2%
for > 5 mm
n/a
Source: WMO Guide (2008)
Table 2.2 (continued)