source: inundation/ga/storm_surge/validation/HC08D_Notes_99999999110678.txt @ 643

NOTES FOR HC08D_P COMPLETED ON 24/06/2004
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DATA FILE



Byte Location , Byte Size  , Explanation
--------------------------------------------------------------------------------------------


1-2           ,2           , Record identifier - hd
4-9           ,6           , Bureau of Meteorology Station Number.
11-26         ,16          , (Local time)Day/Month/Year in DD/MM/YYYY format,Hour24:Minutes in HH24:MI format in Local time
28            ,1           , Message type
30-34         ,5           , *Air Temperature in Celsius
36-38         ,3           , Wind speed in km/h
40-42         ,3           , Wind direction in degrees
44-49         ,6           , *QNH preasure in hPa
51            ,1           , # symbol, end of record indicator.




NOTE:- Any fields prefixed with '*' are derived from the 3 hourly table, and a different
       set of quality flags apply.




Message type
_________________________________________________________

m: METAR (routine aerodrome weather report), automatic
M: METAR (routine aerodrome weather report), manual
s: SPECI  (special aerodrome weather report -where weather below certain criteria
or there has been a significant change since last report), automatic
S: SPECI  (special aerodrome weather report - where weather below certain criteria
or there has been a significant change since last report), manual




Wind
________________________

Wind speed and direction are mostly an average over the 10
minutes prior to observation time.  Where there is an observer
recent (AWS= 0) and a marked discontinuity occurs then
only data after the discontinuity is used and therefore the
time period is less.  In this case a marked discontinuity is
a "sustained change in wind direction of 30° or more, with a
wind speed of 10 knots or more before or after the change.
or a change in wind speed of 10 knots or more, lasting at least
two minutes".




GAPS AND MISSING DATA
_____________________

Very few sites have a complete unbroken record of climate information. A site
may have been closed, reopened, upgraded to a full weather site or downgraded
to a rainfall only site during its existence causing breaks in the record for
some or all elements. Some gaps may be for one element due to a damaged
instrument, others may be for all elements due to the absence or illness of
an observer.




INSTUMENTS AND OBSERVATIONAL PRACTICES
______________________________________

Historically a nearby site (within about 1 mile in earlier days) may have used the same 
site number.  There may have been changes in instrumentation and/or observing practices
over the period included in a dataset, which may have an effect on the long-term record.
In recent years many sites have had observers replaced by Automatic Weather Stations,
either completely or at certain times of the day.  




TIME
____

For a part of the year some Australian States adopt Daylight Savings Time (DST), and
observers continue to take observations according to the local clock.  Times provided 
with this data are Local Time, unless otherwise noted. 

Care needs to be taken when comparing values from year to year or month to month, because for
some elements the effect of one hour can be marked, for example air temperature often rises 
sharply between 8am and 9am.

Daylight Savings has been used in many Australian states since 1973. The
changeovers occur almost always in October and March, but exact dates vary
from State to State and year to year. More information can be found at:
http://www.bom.gov.au/climate/averages/tables/daysavtm.shtml




ROUNDING
________

The primary way of sending current weather information around the world is via a coded message 
known as a SYNOP.  This message only allows some measurements to be sent as rounded values.  
Once manuscript records have been sent in many of these values are typed in with greater 
precision (normally to one decimal place). This usually occurs within a few months.

If consecutive values all have a zero in the decimal place, then it is almost certain that
rounding was used earlier.  A new type of message format is progressively being introduced to
overcome this situation.




COPYRIGHT
_________

The copyright for any data is held in the Commonwealth of Australia and the purchaser
shall give acknowledgement of the source in reference to the data.  Apart from dealings
under the copyright Act, 1968, the purchaser shall not reproduce, modify or supply (by
sale or otherwise) these data without written permission.  Enquiries should be made in
the first instance to the National Climate Centre, Bureau of Meteorology, 
PO Box 1289K, Melbourne 3001, marked to the attention of SRDS.




LIABILITY
_________

While every effort is made to supply the best data available this may not be possible
in all cases.  We do not give any warranty, nor accept any liability in relation
to the information given, except that liability (if any), that is required by law.





IF DATA IS NOT AS REQUESTED
___________________________

If the data provided are not as requested, the data will be repeated at no extra cost, 
provided that:
a) the Bureau is notified within 60 days.
b) the printout/disc/data file is returned to the Bureau for checking.
c) there has been a fault or error in providing the data.

Where there has been no fault or error of provision, the cost involved in
requested corrective action such as resending the data or providing alternative
sites will be charged for as necessary.




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SITE DETAILS FILE

This file contains the details for the current site or are those which applied when the site
was closed.  Many sites have been moved, downgraded, upgraded etc over the years.

Byte Location , Byte Size  , Explanation
--------------------------------------------------------------------------------------------


1-2           ,2           , Record identifier - st
4-9           ,6           , Bureau of Meteorology Station Number.
11-14         ,4           , Rainfall district code
16-55         ,40          , Station Name.
57-63         ,7           , Month/Year site opened. (MM/YYYY)
65-71         ,7           , Month/Year site closed. (MM/YYYY)
73-80         ,8           , Latitude to 4 decimal places, in decimal degrees.
82-90         ,9           , Longitude to 4 decimal places, in decimal degrees.
92-106        ,15          , Method by which latitude/longitude was derived.
108-110       ,3           , State.
112-117       ,6           , Height of station above mean sea level in metres.
119-124       ,6           , Height of barometer above mean sea level in metres.
126-130       ,5           , WMO (World Meteorological Organisation) Index Number.
132-135       ,4           , First year of data supplied in data file.
137-140       ,4           , Last year of data supplied in data file.
142-144       ,3           , Percentage complete between first and last records.
146-148       ,3           , Percentage of values with quality flag 'Y'.
150-152       ,3           , Percentage of values with quality flag 'N'.
154-156       ,3           , Percentage of values with quality flag 'W'.
158-160       ,3           , Percentage of values with quality flag 'S'.
162-164       ,3           , Percentage of values with quality flag 'I'.
166           ,1           , # symbol, end of record indicator.




LATITUDES AND LONGITUDES
________________________

Latitudes and longitudes are given to 4 decimal places, but in many cases will not be
accurate to 4 decimal places.  This is because in the early days the positions of stations
were estimated from maps. Gradually the network of open stations is being checked (and
if necessary corrected) using GPS (Global Positioning System). The method used is given
in the site details file.




WMO INDEX NUMBER
________________

This is the number assigned to a site that makes international weather reports every day.
The number is not actively used in the climate archive, and only a few hundred such 
numbers are assigned at any time.  These are not perpetual but may be reassigned 
where a site no longer makes the international reports (synops); thus a particular
number cannot be regarded as unique and exclusive to any particular site.




PERCENTAGE INFORMATION
______________________

In some cases the percentage completeness will be overestimated. This will occur if the
database has incomplete information about the element being selected. In cases where several
elements are selected, rows with a least one of the elements available are considered
complete. Where only a limited amount of data is available and the percentage completeness
is less than 0.5%, an "*" has been used.

An "*" is also used if the percentage of values with a particular quality flag is non zero
and less than 0.5%.