Kipp&Zonen BSRN Scientific Solar Monitoring System - Manual (Page 10)

VIII
List of Figures
Figure 1.1. Map of BSRN sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 3.1. Diagram indicating appropriate distances from an obstruction m eteorological instrum entation
(from AES Guidlines for Co-operative Clim atological Autostations, Version 2.0). . . . . . . 25
Figure 3.2. Sim ple post m ount in concrete base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 3.3. The support structure used to elevate instrum ents above the local horizon . . . . . . . . . . . . . . . 27
Figure 3.4 Generalized schem atic of the interface between radiation sensors (RF) and a data acquisition
unit showing lightning protection and cable grounding. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 4.1. Ventilator with m otor located beside the instrum ent as used by Deutscher W etterdienst. . . . . 32
Figure 4.2. Ventilator with the m otor located beneath the instrum ent. Note the extra ventilation holes
near the top of the housing used to reduce snow accum ulation (Davos, Switzerland).
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 4.3. An one-axis tracker used in shading a pyranom eter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 4.4. View of two Swiss oversize tracking disks. Note how the pyranom eter is physically separated
from the m otor and the shade device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 4.5. Australian active tracker used for both diffuse and direct beam m easurem ents . . . . . . . . . . . 36
Figure 4.6. Canadian com puter-controlled, friction-drive tracker used for m easuring direct beam , diffuse
and infrared radiation using a shaded pyrgeom eter. The pyrheliom eter m ounting block is
capable of holding three instrum ents, including an active cavity radiom eter. A second
m ounting place is m ounted on the opposite side of the tracker. . . . . . . . . . . . . . . . . . . . .
38
Figure 4.7. The contribution of the solar disk to the irradiance of pyrheliom etric sensors depending on the
pointing error. (A) Case of m ountain aerosol and 60° solar elevation. (B) Case of
continental aerosol and a 20° solar elevation. (Calculations and graph courtesy of G.
Major) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41
Figure 4.9. Brusag two-axis active tracker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 4.8. A single-axis synchronous m otor tracker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 8.1. Percentage change in infrared flux due to case therm istor errors . . . . . . . . . . . . . . . . . . . . . . . 69
Figure C 2.1. Penam bra functions of diffusom eters for 45 degrees solar elevation. . . . . . . . . . . . . . . . . . 117
Figure C 2.2. Com pared log m easured and calculated circum solar functions. Letters A, B, C, D, E, F
sym bolizes different aerosol m odels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Figure C 2.3. Measured sky functions and their approxim ations by ones calculated for m odel atm osphere
containing rural aerosol and haze particles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Figure C 2.5. Dependence of the HUNI/HUNIII on direct radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Figure C 4.1. Measured sky functions and their approxim ations by ones calculated for m odel atm osphere
containing rural aerosol and haze particles too (courtesy of Major, 2001). . . . . . . . . . . 129
Figure C 4.2. Relationship between the geom etry of pyrheliom eters and radiance (The relationship
applies for a diffusom eter when the sun is at zenith). . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Figure C 4.3a. Relationship between the shadow disc and the sensor of a pyranom eter. . . . . . . . . . . . . 131
Figure C 4.3b. Detail of the sensor projection on to the norm al plane parallel to the shadow disc. . . . . . 131