Geology Reference
In-Depth Information
The amount of data collected by ASTER is truly enormous, and analysis
and verification is a continuing process.
1.3.3 Procedures
All surveys require adherence to some form of procedure, and the field crew
should ensure that this is agreed with the geophysicist before commencing
fieldwork. Common aspects include, but are not limited to: daily checks
on equipment functionality and sensitivity (sometimes with target seeding,
depending on the target); survey station layout (to a specified accuracy); sur-
vey grid referencing (to previously agreed mapped features); frequency and
nature of data quality and repeatability checks; frequency of data archiving;
maintenance and format of decipherable field logbooks; and recording of all
client communications. Assumption is the mother of all miscommunication
between the office and the field, and a formal record of the agreed procedures
is worth its weight in gold.
1.3.4 Metadata
Automation in geophysical work proceeds apace, and is giving increased
importance to a distinction that, while always present, was sometimes not
even recognised when all information was stored in field notebooks. These
notebooks contained not only the numerical values displayed on whatever
instruments were being used, but also positional and logistical data and other
vital information, such as the observer's name. The term
metadata
is now
widely used for this largely non-numeric information. Modern data loggers
vary widely in the extent to which metadata can be entered into them,
but none, so far, have reached a level of sophistication that would allow
notebooks to be dispensed with altogether.
1.4 Geophysical Fieldwork
Geophysical instruments vary greatly in size and complexity but all are
used to make physical measurements, of the sort commonly made in
laboratories, at temporary sites under sometimes hostile conditions. They
should be economical in power use, portable, rugged, reliable and simple.
These criteria are satisfied to variable extents by the commercial equipment
currently available.
1.4.1 Choosing geophysical instruments
It seems that few instrument designers have ever tried to use their own
products for long periods in the field, since operator comfort seldom seems
to have been considered. Moreover, although many real improvements have
been made in the last 50 years, design features have been introduced during
the same period, for no obvious reasons, that have actually made fieldwork
