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SILO Agro-Meteorological Datasets for Geo-Spatial Modellers.

Keith Moodie, Stephen Jeffrey and Alan R. Beswic

Queensland Centre for Climate Applications,
Department of Natural Resources and Mines
Queensland, Australia.
Phone (07) 3896 9850, Fax: (07) 3896 9843
Email: Keith.Moodie@dnr.qld.gov.au
http://www.dnr.qld.gov.au/silo

A comprehensive archive of Australian rainfall and climate data has been constructed from ground-based observational data provided by the Bureau of Meteorology.

A complete and accurate source of rainfall and climate data is a prerequisite for the efficient modelling of a wide variety of environmental processes. While the nature of the individual model may vary, most have the fundamental requirement of a dataset that is complete on a temporal and/or spatial basis. To date this problem has restricted the research efforts of many workers due to the fact that observational records are typically incomplete, making it difficult to construct a continuous climate record. In particular, such data may: (1) be recorded for discrete periods, not spanning the entire time period of interest; (2) contain short intermittent periods where data have not been recorded; and (3) contain either systematic or random errors. While these points focus on the incomplete temporal aspects of observational data, another inherent problem is the spatial distribution of recording stations. In many applications, the success or at least accuracy of simulations can be critically dependent upon the availability of observational data within an acceptable distance of the location under investigation. Ideally the nearest recording station would be situated such that its climatology was identical to that of the location of interest. However, due to the sparsity of observational networks, the distance to the nearest station can be of the order of several hundred kilometres. As a result, the only available data may not be representative of the climatology at the desired location.

A set of daily time step, spatial interpolations of rainfall and climate data has been constructed using various spatial interpolation algorithms to estimate the data across Australia. Datasets have been constructed for daily rainfall, maximum and minimum temperatures, evaporation, solar radiation and vapour pressure, commencing in 1889 for rainfall, 1970 for evaporation, and 1957 for the other climate variables. The interpolated surfaces have been computed on a regular 0.05 degree grid extending from latitude 10 degrees S to 44 degrees S and longitude 112 degrees E to 154 degrees E. A thin plate smoothing spline was used to interpolate daily climate variables, and kriging to interpolate daily and monthly rainfall. The characteristics of the interpolations have been described1. Temporal datasets for a single grid point from multiple interpolations are available through the Data Drill (discussed below).

Additionally, continuous, daily time step records for selected recording stations have been constructed using data from the spatial interpolations to estimate values missing from the observed data, again commencing in 1890 for rainfall, 1970 for evaporation, and 1957 for the other climate variables. Datasets are available for approximately 4600 recording stations across Australia and are referred to as the Patched Point Dataset (discussed below).

Prior to 1957, almost all of the observations of non-rainfall climate data remain uncomputerised. The interpolations, the Patched Point Dataset and the Data Drill address this problem by providing data from long term, daily average interpolations in data sets requiring an estimate of non-rainfall climate before 1957.

Availability of the data sets

Interpolated data surfaces

These are available from the Queensland Department of Natural Resources and Mines. They are available in a generic binary format covering Australia, as state-based subsets, or averaged or totalled over GIS catchment areas. Further information is available from silo@dnr.qld.gov.au.

Data Drill

The Data Drill provides a temporal dataset for a single grid point from the interpolated climate dataset. The required location is specified by latitude and longitude to an accuracy of 0.05 degrees.

The Data Drill can be accessed on the Internet at http://www.dnr.qld.gov.au/silo, and a free sample data set for any location across Australia can be obtained using the user name sample and password sample.

Patched Point Dataset

The Patched Point Dataset can be searched on http://www.dnr.qld.gov.au/silo and data is delivered by email. Some applications need to have all of the PPD files for a region readily available and up-to-date. For these applications, SILO offers a PPD mirror service with daily updates to ensure that the latest information is available.

Data Examples

Data Drill in Standard format

Date Day T.Max Smx T.Min Smn Rain Srn Evap Sev Radn Ssl VP Svp RHmaxT RHminT Date2

(yyyymmdd) () (oC) () (oC) () (mm) () (mm) () (MJ/m2) () (hPa) () (%) (%) (ddmmyyyy)

19691230 364 33.0 25 16.5 25 0.0 25 12.2 75 27.0 25 11.0 25 21.9 58.6 30/12/1969

19691231 365 31.0 25 14.0 25 0.0 25 12.6 75 29.0 25 10.0 25 22.3 62.6 31/12/1969

19700101 1 31.0 25 15.0 25 0.0 25 13.4 25 29.0 25 9.0 25 20.0 52.8 1/01/1970

19700102 2 33.5 25 18.0 25 0.0 25 12.4 25 29.0 25 10.0 25 19.3 48.5 2/01/1970

The data drill Standard format is designed for use with programs and popular spreadsheets. RhmaxT and RHminT are the calculated relative humidity at the daily maximum and minimum temperatures, T.max and T.min. The columns Smx, Smn, Srn, Sev, Ssl, Svp contain source codes for the column on their left

Patched Point Dataset in ASCII format

Statio|Year| M| D| Max| S| Min| S| Rain| S| Evap| S| Rad| S| VP| S

Patched data for station 53030

53030|1983|12|25| 36.5| 0| 21.7| 0| 0.0| 0| 10.8|25| 30.0|25|16.0|25

53030|1983|12|26| 37.3| 0| 22.0| 0| 0.0| 0| 10.4|25| 21.0|25|18.0|25

53030|1983|12|27| 32.8| 0| 19.5|25| 1.6| 0| 7.6|25| 24.0|25|20.0|25

53030|1983|12|28| 30.7| 0| 17.3| 0| 0.0| 0| 8.0|25| 26.0|25|15.0|25

53030|1983|12|29| 31.5| 0| 17.2| 0| 0.0| 0| 8.6|25| 27.0|25|15.0|25

53030|1983|12|30| 32.5| 0| 15.0| 0| 0.0| 0| 8.6|25| 25.0|25|17.0|25

The Patched Point Data format is compatible with popular spreadsheets. The ’S’ columns contain source codes for the column on their left.

Source codes

Code

Type of data

Included in Data Drill

Included in Patched Point Dataset

0

Observed Data

No

Yes

15

deaccumulated rainfall, e.g. a 3 day accumulation measured on Monday. The data is partitioned according to reports from nearby stations

No

Yes

23

Observed data from partner station (where the stations are flagged as a PPD composite station)

No

Yes

25

Data from a single grid cell of a daily interpolation

Yes

Yes

75

Data from a single grid cell of long term average daily interpolation

Yes

Yes

Other Formats

The output from the Data Drill and the Patched Point Dataset can be formatted for some popular models. Two examples are shown below and other data formats might be available upon request.

 

AussieGRASP

               
   

-30.00

120.00

evap

shifted,

rad

from

oktas

Sample

 

date

 

jday

tmax

tmin

rain

evap

rad

vp

 

19691230

364

33.0

16.5

0.0

12.2

27.0

11.0

 
 

19691231

365

31.0

14.0

0.0

12.6

29.0

10.0

 
 

19700101

 

1

31.0

15.0

0.0

13.4

29.0

9.0

 

19700102

 

2

33.5

18.0

0.0

13.4

29.0

10.0

                   
 

APSIM

               

Year

Day

Radn

MaxT

MinT

Rain

Evap

 

VP

Code

 

()

()

(mj/m2)

(oC)

(oC)

(mm)

(mm)

(hPa)

()

1969

364

27.0

33.0

16.5

0.0

12.2

11.0

222272

 

1969

365

29.0

31.0

14.0

0.0

12.6

10.0

222272

 

1970

1

29.0

31.0

15.0

0.0

13.4

9.0

222222

 

The code column contains abbreviated source codes for the 6 data columns.

These datasets can be accessed on the Internet at http://www.dnr.qld.gov.au/silo and more information is obtainable from silo@dnr.qld.gov.au.

Existing Applications

The data sets described are supporting a number of production systems. These systems are largely automated and where applicable have products on the internet.

1 Stephen J. Jeffrey, John O. Carter, Keith B. Moodie and Alan R. Beswick (2001) "Using spatial interpolation to construct a comprehensive archive of Australian climate data", Environmental Modelling and Software May 2001 Vol 16/4, 309-330.

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