Kipp&Zonen BSRN Scientific Solar Monitoring System - Manual (Page 43)

31
(iv) the directional responsivity of the instrum ent (cosine and azim uthal response of the
instrum ent) for pyranom eters
(v) the deviation of the tem perature com pensation circuit of the instrum ent over the
tem perature range (-10° to +40° of range) or if not com pensated, the required tem perature
correction of the instrum ent. In clim ates where the tem perature range is greater than
that specified, instrum entation should be selected to m eet the tem perature regim e.
For the m ost accurate m easurem ents, the tem perature of the therm opile should be
m onitored and the signal corrected for tem perature variations. A num ber of instrum ents
using non-therm opile sensors m ay be considered if they m eet all other criteria.
(vi) the instrum ent has been radiom etrically levelled. That is, the therm opile is horizontal
when the bubble level indicates such (the bubble level should have an accuracy of
±0.1°).
(2) Checks should be m ade of all wiring to ensure that there are no nicks in the sheathing nor
stress on the connections. The wire should be of a variety that will withstand the clim atic regim e
of the area in which the instrum ent is to be installed.
(3) All O-rings should be lubricated lightly with a very fine grease (e.g. Dow Corning Model 55
O-ring lubricant or Fischer Scientific Cello-Seal C-601).
(4) All threaded parts should be lubricated in a m anner sim ilar to the O-rings.
(5) The therm opile (or the signal transducer) should be visually inspected to ensure that the surface
is uniform in colour and texture.
(6) The BSRN accuracy guide indicates that the case tem perature of the instrum ent should be
m onitored. If the instrum ent is fitted with a therm al m easuring device, the wiring should be
checked and the reduction algorithm tested at known tem peratures. In the case of pyrgeom eters,
all therm istors should be tested.
(7) The inner and outer dom es should be checked for scratches or nicks. If found, the dom es
should be replaced. In the case of pyrgeom eters a sim ilar check should be m ade of the silicon
dom e. However, if the dom e requires replacem ent due to dam age, the instrum ent m ust be
re-calibrated.
(8) The im pedance of the instrum ent should be checked against the m anufacturer’s values.
(9) The desiccant should be fully activated. It is recom m ended that the desiccating m aterial be
of the bead type (e.g. Trockenperlen, Kali-chem ie AG) and not one which easily powders
(e.g. Drierite, Ham m ond Drierite)
(10) All connectors m ust be waterproof and should be appropriate for the clim atic conditions in
which the sensor will be deployed. For exam ple, in m arine environm ents care m ust be taken
against using connectors that are prone to corrode. It is recom m ended that keyed connectors
be used for greater safety in m aintaining instrum ent polarity.
4.2.2 Mechanical Installation
(1) The instrum ent should be m ounted with the direction of the connector facing poleward for
fixed platform s and away from the solar disk when m ounted on solar tracking devices.
(2) The instrum ent m ust be fastened to the platform (or ventilating device (see below)) so that
it will not m ove in inclem ent weather. The bolts used should be lubricated before assem bly
for ease of disassem bly. Initially, these bolts (norm ally two or three depending upon the
instrum ent) should be not be tightened until the instrum ent is levelled according to its bubble
level.