This Visualisation allows you to view each wet and dry period map as a 'carousel', moving along with a mouse click and a switch between rainfall and pasture mode.
As the carousel moves along, the contributing rainfall or pasture growth annual maps will match that particular sequence to offer the best interpretation of the period.
Note: the wet and dry periods are relative to Queensland (April-March)
Our variable rainfall and pasture growth posters provide a useful way of looking at how annual rainfall, pasture growth and tropical cyclones have compared with the past years. The Queensland's extended wet/dry period poster provides a history of beneficial rainfall and drought sequences relative to Queensland over the last ~130 years.
The combination of these maps merged into the Rainfall and Pasture Growth Visualisation allows viewing of each wet and dry period map as a 'carousel', moving along with a mouse click and switching between rainfall/pasture growth maps.
As the carousel moves along, the contributing rainfall or pasture growth annual maps will match that particular sequence and provide the best interpretation of the period.
The Southern Oscillation Index (SOI) / Interdecadal Pacific Oscillation (IPO) timeseries from the posters are also displayed and will match the displayed wet or dry sequence.
Social and economic implications of the wet and dry periods on the grazing industry in Queensland are described in the adjacent text next to the maps.
Definitions for climate terms can be found below.
Years are classified, according to colour, based on whether they are either 'El Niño' years (red text year title), 'La Niña' years (blue text) or 'ENSO Neutral' years (dark grey text). For this visualisation: El Niño and La Niña year classification is based on values of the Southern Oscillation Index (SOI)* between June and March. An original classification proposed by Dr Rob Allan (UK Met office) has been modified to allow for late-forming El Niño or La Niña events. Threshold values of the SOI have been adjusted such that the frequency of El Niño and La Niña years from 1950–51 to 2009–10 is similar to that obtained by the 'WMO RA IV Consensus Index and Definitions of El Niño and La Niña'**.
Originally referred specifically to a warming of the sea surface off the coast of Peru, now more generally refers to the warming of the central and eastern equatorial Pacific Ocean, strongly associated with persistently negative values of the Southern Oscillation Index (SOI). Generally associated with extended drier periods - when sea surface temperatures in the central and eastern tropical Pacific Ocean become substantially warmer than average.
For this visualisation: An 'El Niño year' is indicated if the six-month average value of the SOI, ending in any month between November and March, was below a threshold value of negative 6.0.
Now used to refer to the opposite of El Niño, or events associated with persistently positive values of the SOI. Generally associated with extended wetter periods – associated with cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean.
For this visualisation: A 'La Niña year' is indicated if the six-month average value of the SOI, ending in any month between November and March, was above a threshold value of positive 6.0.
ENSO refers to the El Niño–Southern Oscillation which fluctuates between El Niño or La Niña (above). 'ENSO Neutral' refers to neither El Niño or La Niña. Often the equatorial Pacific Ocean temperatures are near the long-term average. Neutral years should NOT be interpreted as being "average" rainfall. Neutral years may also contain droughts and wet periods.
For this visualisation: 'ENSO Neutral' are all years which do not fall in either El Niño or La Niña categories (above).
Maps for each year show rainfall ranked against historical records from 1890 to the current year. The ranking is expressed as a percentile. For example, a percentile rank of 0–10 indicates that rainfall over the year ranks within the lowest ten per cent of rainfall values recorded for all annual periods, at that location, whereas a percentile rank above 90 would be the wettest 10% of years.
Rainfall maps are constructed using SILO (https://silo.longpaddock.qld.gov.au/) datasets from point location observational records provided by the Bureau of Meteorology. SILO interpolates the raw data to derive map datasets which are both spatially and temporally complete. However, the low density of observing stations in some regions and changes in the observation network over time may, at times, lead to lower quality mapping.
Pasture growth maps are constructed using the AussieGRASS model (https://www.longpaddock.qld.gov.au/aussiegrass/about/). AussieGRASS (Carter et al. 2000), is an advanced spatial water balance and plant growth model, producing output on a daily time-step across Australia that should be accurate at regional scales.
The accuracy of climate data used to drive the AussieGRASS model may limit accuracy of the pasture growth results in some circumstances. However, as the maps are relative (0-100 percentile scale), the influence of these systematic errors are reduced.
The Rainfall and Pasture Growth Visualisation is a product resulting from a collaboration between the Department of Environment and Science and the University of Queensland's DECO3800/DECO3801 Studio 3 courses (2017).
We acknowledge the invaluable contribution from the groups involved, including: Team Weather (Semester one): Matthew Lord, Coleen Mckay, Kirstyn Jozefowski, Jesse Head, Melissa Nguyen, Abicantya Sophie; and Team Coderush (Semester two): Jianghua Hui, Steven Law Kai, Yuen Xiaotong Li, Linxuan Sheng, Ziheng Liu, Yau Matthew Wing-Heng.