Making Decisions for the Next Season

Ian Foster Miles DracupWA Dept of Agriculture Water Corporation

Examples of Agricultural Forecasting Applications

Is there skill beyond climatology?

Climate Risk Management

•The importance of climate risk management to many sectors is a given

•Seasonal forecasts potentially have a major role

BUT (for example):

•95% of farmers find seasonal forecasts ‘interesting’

•25% of farmers find seasonal forecasts ‘useful’

Weeks (2005) Liebe Group Workshop, Wubin

The Nature of Decisions

-

• A schedule of decisions• Strategic vs Tactical decisions• Negotiability of decisions (some may be

locked in anyway)• Capacity to respond to a forecast• Information needs vary (eg, timeliness,

means of delivery)

Season Types - Eastern Wheatbelt

-0.1 0 0.1 0.2 0.3 0.4 0.5

m id so w in g , lo w su m m e r ra in [21% ye a rs]

m id so w in g , h ig h su m m e r ra in [18% ye a rs]

e a rly so w ing , lo w sum m e r ra in [20% ye a rs]

e a rly so w ing , h ig h sum m e r ra in [17% ye a rs]

la te so w ing , lo w su m m e r ra in [24% ye a rs]

Condensed from 11 MUDAS season types (R Kingwell, DAWA)

Proportion of long-term profit

‘Extra’ from climate knowledge

Changes in Season Types - Merredin

MUDAS Season Types

0

5

10

15

20

25

30

35

VH H A L VL

Yield Category

Oc

cu

rre

nc

e (

%)

1925-75

1976-2002

Schedule of Cropping Decisions

Forecast developed Forecast consolidated Season tracking

First cut at budget

Advance purchases

Grain carryover

Summer weed control

Nominate needs PurchasesInputs

Budget confirmed

Sowing Decide decisions to sow ?

Tactical Cutdecisions inputs?

When to harvest?

Wheat price locked in

Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Critical decision windows

Predictability barrier

A Targetted Forecast

A forecast that was aimed at strategic agricultural decisions in WA would look like:

• Long-lead (6 months)• Likelihood of seasonal extremes (eg Tercile

1 vs Tercile 3)• Available in summer/autumn• Is communicated well

Are we dreaming?

Current Seasonal Outlooks

• Operational outlooks – 0-1 month lead-time– Driven by ENSO– Autumn ‘predictability barrier’– Statistical (issues of stationarity wrt climate trends)– Expressed as probabilities

• Experimental outlooks – To 6 months lead-time– Rely on ENSO as a driver for seasonal memory– Autumn ‘predictability barrier’– Potential to adapt to climate trends– Expressed as probabilities

Analysis of Risk - Methods

• Historical climate data (BoM, DAWA, farmers’ own records)

• Historical production data• Analysis tools (Rainman, Climate Calculator …)• Soil moisture (PYCAL, DAWA, APSIM)• Crop Yield Estimates (STIN, APSIM, PYCAL …)• Combine season-to-date conditions with

climatology and derived products • Used more for tactical decisions within-season• Need facilitated access (eg develop

partnerships for delivery)

Analysis of Risk - Rainfall

0

30

60

90

120

150

180

210

240

270

300

330

360

1 Apr 21 Apr 11 May 31 May 20 Jun 10 Jul 30 Jul 19 Aug 8 Sep 28 Sep 18 Oct

Rai

nfa

ll (

mm

)

Perenjori rainfall to 1 August and possible finishPerenjori rainfall to 1 August and possible finish

Date

2005 Observed to date

Future

Analysis of Risk - Crop Yields

P o te n t ia l Y ie ld C a lc u la to r (P Y C A L )

0

10

20

30

40

50

60

70

80

90

100

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Yield (kg/ha)

Expe

ctan

cy (%

)

15 kg/ha/mm

20 kg/ha/mm

Yield Prophet (APSIM)

Source: Horses for Courses Bulletin Aug 2005. Site at West Morawa. Based on actual rain to 27 July 05, and historical finishes to the season.

The Search for Predictability - 1

Correlation of May-Oct rain with SOI indices over Feb-Apr.

EPI derived in Nov of previous year

Source: Telcik (2005)

The Search for Predictability - 2

Correlation of May-Oct rain with SOI indices over Mar-May.

EPI derived in Nov of previous year

Source: Telcik (2005)

Correlations with SSTs

Correlation of MJJ rain with MJJ de-trended SST

Source: Telcik (2005)

Correlation of MJJ rain with JFM de-trended SST

Location at 32.5 S 177 E

SST Anomalies in Neutral Years

Source: Telcik (2005)

Dry Av

Wet

May-Jul rainfall

Summary

• Climate risk management is important to many sectors. Seasonal climate forecasts form a part this.

• Current seasonal climate outlooks are not well matched to strategic decision making needs.

• Use of current conditions, climatology and derived products has practical application to tactical decisions.

• The search for predictability continues via enhancements to ENSO-based approaches and phenomena especially relevant to WA.