NOTES FOR HM01X_P COMPLETED ON 11/10/2007 ____________________________________________________________________________________________ All hourly observations between 2007091000:00 and 2007101123:59 Local standard time. ____________________________________________________________________________________________ DATA FILE DETAILS _____________________ Byte Location , Byte Size , Explanation ---------------------------------------- 1-2 ,2 , Record identifier - hm 4-9 ,6 , Bureau of Meteorology Station Number. 11-50 ,40 , Station Name. 52-67 ,16 , Year Month Day Hours Minutes in YYYY,MM,DD,HH24,MI format in Local standard time 69-74 ,6 , Precipitation since 9am local time in mm 76 ,1 , * Quality of precipitation since 9am local time 78-82 ,5 , Air Temperature in degrees C 84 ,1 , * Quality of Air Temperature 86-90 ,5 , Wet bulb temperature in degrees C 92 ,1 , * Quality of Wet Bulb Temperature 94-98 ,5 , Dew point temperature in degrees C 100 ,1 , * Quality of Dew point Temperature 102-104 ,3 , ** Relative humidity in percentage % 106 ,1 , * Quality of Relative humidity 108-113 ,6 , ** Vapour pressure in hPa 115 ,1 , * Quality of vapour pressure 117-122 ,6 , ** Saturated vapour pressure in hPa 124 ,1 , * Quality of saturated vapour pressure 126-130 ,5 , *-* Wind speed in m/s 132 ,1 , * Quality of Wind speed 134-136 ,3 , *-* Wind direction in degrees 138 ,1 , * Quality of Wind direction 140-144 ,5 , *-* Speed of maximum wind gust in last 10 minutes in m/s 146 ,1 , * Quality of speed of maximum wind gust in last 10 minutes 148 ,1 , --* Cloud amount(of first group) in eighths 150 ,1 , * Quality of first group of cloud amount 152-153 ,2 , --* Cloud type(of first group) in code 155 ,1 , * Quality of first group of cloud type. 157-161 ,5 , --* Cloud height (of first group) in feet 163 ,1 , * Quality of first group of cloud height 165 ,1 , --* Cloud amount(of second group) in eighths 167 ,1 , * Quality of second group of cloud amount 169-170 ,2 , --* Cloud type(of second group) in code 172 ,1 , * Quality of second group of cloud type. 174-178 ,5 , --* Cloud height (of second group) in feet 180 ,1 , * Quality of second group of cloud height 182 ,1 , --* Cloud amount(of third group) in eighths 184 ,1 , * Quality of third group of cloud amount 186-187 ,2 , --* Cloud type(of third group) in code 189 ,1 , * Quality of third group of cloud type. 191-195 ,5 , --* Cloud height (of third group) in feet 197 ,1 , * Quality of third group of cloud height 199 ,1 , --* Cloud amount(of fourth group) in eighths 201 ,1 , * Quality of fourth group of cloud amount 203-204 ,2 , --* Cloud type(of fourth group) in code 206 ,1 , * Quality of fourth group of cloud type 208-212 ,5 , --* Cloud height (of fourth group) in feet 214 ,1 , * Quality of fourth group of cloud height 216-218 ,3 , --- Ceilometer cloud amount(of first group) 220 ,1 , * Quality of first group of ceilometer cloud amount 222-226 ,5 , --- Ceilometer cloud height (of first group) in feet 228 ,1 , * Quality of first group of ceilometer cloud height 230-232 ,3 , --- Ceilometer cloud amount(of second group) 234 ,1 , * Quality of second group of ceilometer cloud amount 236-240 ,5 , --- Ceilometer cloud height (of second group) in feet 242 ,1 , * Quality of second group of ceilometer cloud height 244-246 ,3 , --- Ceilometer cloud amount(of third group) 248 ,1 , * Quality of third group of ceilometer cloud amount 250-254 ,5 , --- Ceilometer cloud height (of third group) in feet 256 ,1 , * Quality of third group of ceilometer cloud height 258 ,1 , *** Ceilometer sky clear flag 260-265 ,6 , -*- Horizontal visibility in km 267 ,1 , * Quality of visibility of horizontal 269-271 ,3 , Direction of minimum visibility in degrees 273 ,1 , * Quality of direction of minimum visibility 275-280 ,6 , -*- Automatic Weather Station visibility in km 282 ,1 , * Quality of Automatic Weather Station visibility 284-285 ,2 , **-- Present weather in code 287 ,1 , * Quality of present weather 289-294 ,6 , Mean sea level pressure in hPa 296 ,1 , * Quality of mean sea level pressure 298-303 ,6 , Station level pressure in hPa 305 ,1 , * Quality of station level pressure 307-312 ,6 , QNH pressure in hPa 314 ,1 , * Quality of QNH pressure 316-317 ,2 , **** Automatic Weather Station Flag 319 ,1 , # symbol, end of record indicator. Where an observation was missed, the nearest observation has been included within 10 minutes of the observation. * QUALITY FLAG DESCRIPTIONS ____________________________ Y: quality controlled and acceptable N: not quality controlled W: quality controlled and considered wrong S: quality controlled and considered suspect I: quality controlled and inconsistent with other known information -*- VISIBILITY ____________ Where visibility is given as 10km, this most likely means that visbility is 10km or more. ** MOISTURE EQUATIONS ______________________ The following formulas have been used: Vapour pressure = exp (1.8096 + (17.269425 * Dew_Point)/(237.3 + Dew_Point)) Saturated Vapour pressure = exp (1.8096 + (17.269425 * Air_Temperature)/(237.3 + Air_Temperature)) Relative Humidity = Vapour pressure / Saturated vapour pressure * 100 *-* WIND ________ Wind speed and direction are mostly an average over the 10 minutes prior to observation time. Where there is an observer present (AWS_FLAG=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 degrees 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'. Wind gusts reported are the highest 1 second value over the last 10 minutes. Wind direction can be output as either degrees or points of the compass (8 or 16). If degrees are output, then values are rounded to the nearest 10 degrees and directions ending in 5 are rounded up (eg 105 degrees rounds to 110 degrees). --* CLOUD __________ In the following list, the cloud type is associated with the preceding code number or the following 2 or 3 letter abbreviation, dependent on the output requested. 0: Cirris (Ci) 1: Cirrocumulus (Cc) 2: Cirrostratus (Cs) 3: Altocumulus (Ac) 4: Altostratus (As) 5: Nimbostratus (Ns) 6: Stratocumulus (Sc) 7: Stratus (St) 8: Cumulus (Cu) 9: Cumulonimbus (Cb) 32: Towering Cumulus (TCU) Note: Reports use the 1-3-5 rule for reporting cloud. This rule implies that the lowest cloud layer is reported first. The next highest cloud layer of at least 3/8 sky coverage is reported next. The next layer reported must be of at least 5/8 coverage of the sky. The exceptions to this rule is that significant convective cloud such as CB or TCU (see cloud list above) will always be reported. Different cloud types at the same level will be grouped as the most significant type. --- CEILOMETER DATA ___________________ The Ceilometer is an instrument which uses a vertical laser beam to estimate cloud amounts and heights. The instrument only samples the sky directly above it and so care should be taken when using these values for estimates of whole sky amounts. The ceilometer reports heights to 12,500 feet with amounts broken into the following subgroups; SCT: scattered BKN: broken OVC: overcast *** CEILOMETER SKY CLEAR FLAG _____________________________ For sites with a ceilometer: Y: sky clear below 12500 ft N: sky not clear below 12500 ft **-- PRESENT WEATHER _____________________ The code meanings are as follows: 0-3 Fine 4 Smoke 5 Haze 6-7 Dust 8 Dust whirls 9 Dust storm 10 Mist 11,41 Fog patches 12 Shallow fog 13 Lightning 14 Distant/nearby virga 15-16 Distant precipitation 17 Thunder 18 Squall 19 Funnel cloud 20 Recent drizzle 21 Recent rain 22,26 Recent snow 23 Recent rain and snow 24 Recent precipitation 25 Recent shower 27 Recent hail 28 Recent fog 29 Recent thunderstorm 30-32 Dust storm 33-35 Severe dust storm 36-37 Drifting snow 38-39 Blowing snow 40 Distant fog 42-49 Fog 50-55 Drizzle 56-57 Freezing drizzle 58-59 Drizzle 60-65 Rain 66-67 Freezing rain 68-69 Sleet 70-75 Snow 76 Ice prisms 77 Snow grains 78 Starlike crystals 79 Ice pellets 80-81 Shower 82 Violent shower 83-84 Sleet 85-86 Snow shower 87-88 Soft hail shower 89-90 Hail shower 91-95 Thunderstorm 96,99 Thunderstorm and hail 97 Heavy thunderstorm 98 Thunderstorm and dust ADDITIONAL NOTES ON WEATHER PHENOMENA _____________________________________ Care should be taken when doing climatologies as weathers have been reported in different ways over the years, and data has been merged from different sources. **** AWS (AUTOMATIC WEATHER STATION) FLAG ___________________________________________ AWS (Automatic Weather Station) flag 0 Manned 1 Automatic 2 Hybrid Indicates whether the observations are completely automatic or whether an observer is present, or a hybrid.In a couple of situations some differences occur due to the observation method. For example, Automatic Weather Station algorithms have had some difficulties in responding quickly to significant wind changes. Depending on the direction change the AWS may take several minutes to register the change and output a special weather report. 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 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. 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%.