SLIDE 1
Sixteenth Session of the Forum on Regional Climate Monitoring, Assessment and Prediction for Asia (FOCRAII), May 7, 2020
Outlook of Summer Rainfall Anomaly in Asia with
( ), y ,
Outlook of Summer Rainfall Anomaly in Asia with SMART-based Seasonal Prediction System (SMART-SPS)
Xiu-Qun Yang xqyang@nju.edu.cn
CMA-NJU Joint Laboratory for Climate Prediction Studies (LCPS/CMA-NJU) S h l f At h i S i N ji U i it N ji Chi School of Atmospheric Sciences, Nanjing University, Nanjing, China
SLIDE 2 Brief introduction to SMART-SPS
SMART-based Seasonal Prediction System
(SVD Mode and Anomalous Rainfall Tendency based Seasonal Prediction System) (SVD Mode and Anomalous Rainfall Tendency-based Seasonal Prediction System)
Predict the rainfall anomaly by predicting its interannual tendency ( ) Let interannual tendency: (Fan et al., 2007)
( 1) ( 1) ( ) R t R t R t
then:
( 1) ( ) ( 1) R t R t R t
Rainfall Anom Rainfall Anom Difference between
( 1) ( ) ( 1)
fcst
fcst
R t R t R t
this summer last summer two summers
SLIDE 3 Brief introduction to SMART-SPS
SMART-based Seasonal Prediction System
(SVD Mode and Anomalous Rainfall Tendency based Seasonal Prediction System)
Two strategies to predict the Anomalous Rainfall Tendency (ART) (Yang Sun Wang et al 2011; 2019)
(SVD Mode and Anomalous Rainfall Tendency-based Seasonal Prediction System)
SMART-based Physical-Statistical Model (SMART-PSM)
D i di ( JFM) h i SVD M d i h JJA ART
(Yang, Sun, Wang, et al., 2011; 2019)
- Determine preceding (say, JFM) atmospheric SVD Modes with JJA ART
- Build MRM for JJA ART using those preceding SVD Modes
- Predict JJA ART with the MRM using observed preceding SVD Modes
SMART-based Dynamical-Statistical combined Model (SMART-DSM)
- Determine simultaneous atmospheric SVD Modes with JJA ART
- Determine simultaneous atmospheric SVD Modes with JJA ART
- Predict those SVD modes with BCC-CSM1.1m’s ensemble predictions
- Reconstruct ART with MRM in terms of those predicted SVD Modes
SLIDE 4 Prediction of JJA Rainfall Anomaly Percentage (RAP) with SMART-PSM
ACC：tendency ACC：anomaly Independent validation for SVD mode selection
for SVD mode selection from recent 5 years
modes fo 6 6 f SVD m
RMSD：anomaly PS：anomaly Nolr=6 Nz500=6
6 6 mber of Num
GPCP data
6 6
2020/5/7 4
Number of SVD modes for Z500 6 6
SLIDE 5 Prediction of JJA Rainfall Anomaly Percentage (RAP) with SMART-PSM
Observed JJA RAP in 2019
( 1) ( ) ( 1)
fcst
fcst
R t R t R t
Predicted JJA RAP in 2020 Predicted JJA ART percentage in 2020 with preceding JFM SVD Modes
5 2020/5/7
SLIDE 6 Reasons for the prediction – tropical signals
JFM SSTA in 2019 JFM SSTA in 2920 Interannual Tendency of SSTA
- Similar SSTA distribution except TIO
h h l h where there is a slight warming
- Without significant ENSO signature
2019 2020
SLIDE 7
Reasons for the prediction – tropical signals
2019 JFM OLR Anomaly 2020 JFM OLR Anomaly 2020 minus 2019 JFM OLR Tendency Enhanced convection in western IO western IO
SLIDE 8
SVD mode 6: interannual tendency of JFM OLR & JJA Rainfall Reasons for the prediction – tropical signals SVD mode-6: interannual tendency of JFM OLR & JJA Rainfall
Predicted 2020 JJA rainfall tendency
Observed 2020 JFM OLR tendency
SLIDE 9
Reasons for the prediction – extratropical signals
2020 minus 2019 2019 2020 2020 minus 2019 JFM Z500 Tendency JFM Z500 Anomaly JFM Z500 Anomaly Shifted AO- like pattern
SLIDE 10
Reasons for the prediction – extratropical signals SVD mode 2: interannual tendency of JFM Z500 & JJA Rainfall
Predicted 2020 JJA rainfall tendency
SVD mode-2: interannual tendency of JFM Z500 & JJA Rainfall
Observed 2020 JFM Z500 tendency
SLIDE 11
SVD mode 6: interannual tendency of JFM Z500 & JJA Rainfall Reasons for the prediction – extratropical signals SVD mode-6: interannual tendency of JFM Z500 & JJA Rainfall
Predicted 2020 JJA rainfall tendency
Observed 2020 JFM Z500 tendency
SLIDE 12 （ ）
Reasons for the prediction – decadal background
PDO index （from JMA）
Positive PDO phase
Annual mean 5-yr running mean
p
AMO index （Enfield et al. 2001）
2014->2020
P iti Positive AMO phase
2020/5/7
Zhang, Sun, Yang (2018)@JC
SLIDE 13 Recent 5-yr（2015-2019）averaged JJA Predicted JJA ART
Reasons for the prediction – decadal background
Recent 5-yr（2015-2019）averaged JJA rainfall anomaly Predicted JJA ART
Decadal background Interannual anomaly
Predicted JJA total rainfall anomaly
Combined impact of interannual and interannual and decadal anomalies
2020/5/7
SLIDE 14 Associated predictions of JJA atmospheric circulation anomalies with SMART-PSM
Predicted: 2020 JJA Observed: 2019 JJA Predicted: 2020 JJA JJ tendency JJ anomaly JJ anomaly A A C A A A C C A A A C A A A
2020/5/7
A A A
SLIDE 15 Prediction of JJA Rainfall Anomaly Percentage (RAP) with SMART-DSM
Observed summer RAP in 2019 (GPCP data) Predicted summer ART percentage in 2020 with preceding JFM signatures
+
Predicted summer RAP in 2020
2020/5/7
SLIDE 16
Predictions of JJA Rainfall Anomaly Percentage (RAP)
SMART-PSM SMART-DSM versus
Predicted summer RAP in 2020 Predicted summer RAP in 2020
C t t D Xi Q Y @ j d Contact: Dr. Xiu-Qun Yang, xqyang@nju.edu.cn http://lcps.nju.edu.cn
