BAMOS November 2025
18 Article
The COtL Mesonet of South Australia
Dr Warwick Grace, COtL( wg @ graceresearch. com)
The COtL Mesonet is a mesoscale meteorological network of 112 high-quality weather stations in South Australia( Figure 1).
Primarily funded by the state government, with contributions from station site owners, COtL Mesonet captures both microand mesoscale features and stands out for its high-quality data, underpinned by rigorous procedures.
The combination of high-quality data and spatial coverage makes this network invaluable for meteorological research and analysis.
Why the network exists
The primary purpose of the COtL Mesonet is to reduce offtarget spray drift of agricultural pesticides. These spray drifts can result from stable conditions associated with inversions and extend over tens of kilometres( Yates et al., 1974).
In 2019, the Mesonet was the first in Australia to provide routine monitoring of inversion strength as measured by Vertical Temperature Difference( VTD) and other micrometeorological stability parameters, including the Richardson number, the Obukhov length, the Oklahoma Dispersion Index( Carlson and Arndt, 2008) and the Brunt-Vaisala frequency. Under licence from Grains Research & Development Corporation— albeit currently in negotiation— the vertical wind variance( Grace and Tepper, 2021) and its nowcast( Grace and Grace, 2023) are also provided.
Besides information relating to spray operations, the network also provides a range of observations and indices of broader relevance, with some key data such as wind and temperature freely available online in the form of maps, time series, and tables. Network density is designed such that all agriculturalists within the COtL mesonet’ s footprint can access useful information.
Figure 1: left: map of COtL Mesonet and BOM weather stations. A = Alawoona, C = Cadell, CJ = Cape Jaffa, HB = Hamley Bridge, MB = Mount Bryan, S = Saddleworth. Right: image of a typical station. Credit: Warwick Grace
Yates, W. E., Akesson, N. B. and Cowden, R. E. 1974. Criteria for minimizing drift residues on crops downwind from aerial applications. Transactions of the ASAE, 17( 4), 627 – 632.