Assessing Predictability of Seasonal Precipitation for May-June-July in Kazakhstan
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Assessing Predictability of Seasonal Precipitation for May-June-July
in Kazakhstan
Tony Barnston, IRI, New York, US
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Possible sources of seasonal climate predictability:
1. Tropical sea surface temperature (SST) anomalies such as El Nino and La Nina, or tropical Atlantic or Indian Ocean SST anomalies
2. Land surface anomalies (up to 1-2 months influence)
3. Persistent extratropical atmospheric circulation anomalies, such as the Arctic Oscillation
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El Nino
ENSO-based Teleconnections: May-Jun-Jul El Nino
Probability of above normal precipitation
(uses CRU precipitation)
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La Nina
ENSO-based Teleconnections: May-Jun-Jul La Nina
Probability of above normal precipitation
(uses CRU precipitation)
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Seasonal precipitation forecastsfor May-June-July
for northern Kazakhstan
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Using field of 500 hPa height as predictorof Kazakhstan rainfall in May-Jun-Jul
Lagged in time:
March-April 500 hPa is used to predict
May-Jun-Jul rainfall
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x Distribution of Skill using Mar-Apr 500 hPa ht
Correlation of precip atpoint X with predictor 500 hPa ht
Using earlier (Mar-Apr) 500 hPa height as predictor for MJJ rain
Cross-validation: 5 years held out, middle one predicted
skill
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Using observed tropical SST field as predictorof Kazakhstan rainfall in May-Jun-Jul
Lagged in time:
March-April SST is used to predict
May-Jun-Jul rainfall
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Using earlier March SST as predictor
March SST Time Series MJJ Kaz precip
March SST Time Series MJJ Kaz precip
Mode 1 Mode 1
Mode 2 Mode 2
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x Distribution of skill using March tropical SST
Cross-validation: 5 years held out, middle one predicted
skillMay-Jun-Jul
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Current dynamical model climate predictionsfor May-June-July 2014
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North American national multi-model ensemble forecastFor May-Jun-Jul 2014 rainfall
x
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North American National Multi-model Ensemble Anomaly CorrelationPrecipitation May-June-July
x
skill
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European national multi-model ensemble forecastFor May-Jun-Jul 2014 rainfall
x
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North American national multi-model ensemble forecastFor May-Jun-Jul 2014 temperature
x
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North American Multi-model Ensemble Anomaly CorrelationTemperature May-June-July
x
skill
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European national multi-model ensemble forecastFor May-Jun-Jul 2014 temperature
x
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Precipitation Skill IRI Forecasts 1998-2013 May-June-July 0.5-month lead
Heidke hit skill score
x
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Using autocorrelations of precipitation
In the 3 states in northern part of Kazakhstan,autocorrelations for precipitation are generallyweak. However, autocorrelations of
July Augustare at least 0.3, and >0.4 at some stations.
Lag correlations of temperature precipitationare very weak during the growing season.
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Global warming trend gives opportunity for some skill in seasonal temperature predictions:
With base period in the past, positive temperature anomalies are often a correct forecast.
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Time series of monthly anomaly of maximum temperature at station 28698 (Omsk, Russia)
warming?
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Warming trend is evident near Northern Kazakhstan
Time series of annual anomaly of maximum temperature at station 28698 (Omsk, Russia)
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ConclusionsTropical SST anomalies during months earlier thanMay-June-July have almost no relationship with rainfallor temperature in northern Kazakhstan in May-June-July.
Upper air geopotential height (500 hPa) in preceding months is related only weakly to Kazakhstan precipitation and temperature in May-June-July. A connection with the Arctic Oscillation is weak.
Autocorrelation statistics for precipitation in northernKazakhstan show some July-to-August anomaly persistence.
Dynamical model predictions for Kazakstan show very slight skill for May-June-July precipitation. Fortemperature, skill is present due to warming trends. Anupward temperature trend exists in observations fornorthern Kazakhstan for the May-June-July season.