Climate Sense

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bserving

, P

redicting

and

rojecting

limate

onditions

seasonal predictions ahead, and shorter term flow fore-

casting (up to four days ahead).

A meeting on the climate information needs of the

water planning and management community was

held at WMO in 2006. The objective was to provide

a platform for dialogue between water managers and

climatologists and consider a project concept to facili-

tate and expand the use of climate information in water

resources management. The meeting developed a set

of conclusions to guide interactions between water

management and climate information, including:

• Recognition that both water managers and climate

information providers benefit from addressing

common issues

• General consensus that climate information has high

potential value, but that there are still large uncer-

tainties with regard to the kinds of quantitative

information water managers traditionally use

• Most immediate opportunities exist at the scale of

seasonal climate outlooks, as this type of informa-

tion is easier for water managers to assimilate

• Opportunities should be based on temporal syner-

gies, that is, using climate information on different

relies upon routine communication between the Centre’s clima-

tologists and oceanographers (based at offices in Wellington and

Auckland) and hydrologists (Christchurch). Over ten years of

monthly operations, greater understanding has developed between

the two science areas, and an increased awareness of each disci-

pline’s terminology. At the same time an operational environmental

forecasting (up to six days ahead) capability is being developed

among the weather scientists, oceanographers and hydrologists.

In 2001, the Centre’s soil moisture and streamflow predictions

changed from simply above normal, normal or below normal

predictions for the time of year, to quantitative probabilistic

predictions – predicting probabilities of three-month soil mois-

ture levels and mean river flows being in the top, middle or bottom

third of their distributions.

The accuracy of streamflow predictions has been assessed.

The skill level is better than ‘climatology’ (the null prediction of

apportioning 33 per cent probabilities to each third). Biases in flow

predictions have been examined. Predictions of normal or below

normal flows predominated over above normal predictions. The

biases were associated with the difficulty of predicting the climate

for extreme weather events a season ahead. Reliable records of

river flows can be presented in near real-time. Knowledge of the

status of river flows now is useful as initial conditions for making

Lake Pukaki, South Island – New Zealand’s largest hydropower generation source

Image: Steve le Gal, NIWA