RAINFALL FORECASTING AND ITS APPLICATIONS IN FLOOD EARLY WARNING SYSTEMS HE SHAN NATIONAL UNIVERSITY OF SINGAPORE 2011 RAINFALL FORECASTING AND ITS APPLICATIONS IN FLOOD EARLY WARNING SYSTEMS HE SHAN (B.Eng., Hohai University; M.Eng., Wuhan University) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CIVIL ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2011 ACKNOWLEDGEMENT I would like to express my sincere appreciation to my supervisor, Associate Professor Liong Shie-Yui, for his continuous encouragement and guidance given to me, and his patience throughout the whole Ph.D period I am also very grateful to my colleagues at Tropical Marine Science Institute (TMSI) for their assistance and warm-hearted help, in particular to Dr Srivatsan Vijayaraghavan for introducing and guiding me on Numerical Weather Prediction model, Weather Research and Forecasting (WRF); Dr Nguyen Ngoc Son and Dr Doan Chi Dung for their assistance in the weather nowcasting model, Translation Model (TM) Other colleagues at TMSI who have also been very helpful, one way or another, and for their camaraderie are Ms Liew San Chuin, Mr Vu Minh Tue, Mr Nguyen Tam Chinh, and Ms Cui Chun My thanks also go to SOBEK experts from Deltares especially Senior Specialist Adri Verwey, Janjaap Brinkman and Jaap Zeekant for introducing me to the SOBEK software; this led me to explore this model further I also wish to acknowledge my deepest appreciation to Tropical Marine Science Institute which has been the main financial supporter throughout the study period Other financial supporters, equally appreciated, are National University of Singapore (with its Research Scholarship) and Singapore-Delft Water Alliance (under ―MultipleObjective Multi-Reservoir Management‖ project) i ii TABLE OF CONTENTS ACKNOWLEDGEMENT I TABLE OF CONTENTS III SUMMARY VII LIST OF TABLES IX LIST OF FIGURES XI CHAPTER INTRODUCTION 1.1 Overview ·········································1 ········································· 1.2 Objectives and Scope ·································· ·································6 1.3 Contents of the Study ································· ································ 10 CHAPTER NUMERICAL WEATHER PREDICTION 12 2.1 Introduction ······································· ······································ 13 2.2 The early history of NWP Model·························· 16 ·························· 2.3 NWP formulation ··································· 17 ··································· 2.3.1 Model equations 18 2.3.2 Parameterization of physical process 22 2.4 Advantages and challenges ······························ ····························· 22 2.5 Forecasting review··································· ·································· 24 2.6 Weather Research and Forecasting Model ····················· ···················· 25 iii 2.6.1 Introduction 25 2.6.2 WRF Forecasting and Parameterizations Sensitivity Review 27 2.6.3 Data Source 31 2.6.4 Singapore Case Study 33 2.6.4.1 Model Parameterization sensitivity 35 2.6.4.2 Model domain design sensitivity 40 2.6.4.3 Model resolution sensitivity 41 2.6.4.4 Multiple Nesting Sensitivity 42 2.6.4.5 Time series comparison: WRF versus Station data 44 2.6.4.6 Long-term WRF Hindcast: North-East Monsoon Season 46 2.6.5 Conclusion 48 CHAPTER RAINFALL NOWCASTING MODEL: TRANSLATION MODEL 90 3.1 Introduction ······································· ······································ 90 3.2 Translation Model ··································· ·································· 93 3.2.1 Governing Equations 93 3.2.2 Identification of translation vector 94 3.2.3 Quadratic translation vector 96 3.2.4 Re-identifying translation vector in the filtered quarter 98 3.2.5 Quantitative Precipitation Forecast Indicator 99 3.3 Application of TM to Marina Catchment ···················· 101 ···················· 3.3.1 Comparison between various functions of translation vector 102 3.3.1.1 3.3.1.2 3.4 Areal Average Rainfall (AAR) comparison 102 At site comparison 103 Conclusion ······································ 104 ······································ CHAPTER COMBINED RAINFALL FORECASTING: COUPLING TM AND WRF 116 4.1 Introduction ······································116 ····································· iv 4.2 Approach ······································· 118 ······································· 4.3 Application, Results and Discussion ······················· 121 ······················· 4.3.1 Results and Discussion 121 4.3.1.1 Rainfall Event on 8th December 2008 121 4.3.1.2 Rainfall Event on 18th and 19th November 2009 125 4.4 Conclusions ······································127 ····································· CHAPTER RAINFALL-RUNOFF MODEL: SOBEK 169 5.1 Introduction ······································169 ····································· 5.2 Rainfall-Runoff Model ······························· 171 ······························· 5.2.1 SOBEK and Rainfall-Runoff Concept 171 5.2.2 Model Calibration Technique 172 5.2.3 Data collection and model setup 174 5.2.4 Calibration Results 174 5.3 Conclusions ······································176 ····································· CHAPTER CONCLUSIONS AND FUTURE WORK 180 6.1 Research work summary······························ 182 ······························ 6.2 Future works ····································· 183 ····································· REFERENCES 186 APPENDIX A PARAMETERIZATION OPTIONS 198 APPENDIX B PHYSICS TESTING 200 v APPENDIX C COMPARISON OF WRF RESULTS WITH OBSERVED RAINFALL 204 C-1 Tengah Station ······································205 ····································· C-2 Seletar Station ······································210 ····································· C-3 Paya Lebar Station ··································· 216 ··································· C-5 Simei Station ······································ 220 ······································ APPENDIX D COMPARISON OF COMBINED RAINFALL FORECASTING WITH OBSERVED RAINFALL 222 vi SUMMARY One of the important factors in reservoir management involves employment of a flood early warning system that predicts large surface runoff before their actual arrival in a holistic and integrated manner For urban scales, heavy precipitation events need to be forecast to be able to be prepared for a flash flood This becomes more important in a changing climate should more heavy rainfall events occur This is in turn linked to reservoir management The overall objective of this study is to improve the forecasting accuracy of the precipitation in the Singapore region by means of rainfall forecasting and nowcasting The Weather Research and Forecasting Model (WRF) was applied over Singapore and its neighboring region for rainfall forecasting Its performance was evaluated on various rainfall events to ensure its ability to provide credible forecasts A rainfall nowcasting method using a Translation Model (TM) was also applied, which incorporates the radar measurements Based on the results obtained from the TM and the WRF, a combined rainfall forecasting was constructed Weighting factors of 0.7 and 0.3 have been used and assigned to results from TM and WRF, respectively Results presented in this thesis consist of the individual results from WRF and TM and the results from the Combined Rainfall Forecasting The combined rainfall forecasting covered the fullspan of 24 hours forecasting by combining the WRF results and TM results to provide an improved rainfall forecasting Combined rainfall forecasting provides more vii accurate results than rainfall forecasts from a single combined member Finally, an urban rainfall-runoff model SOBEK was implemented to simulate the flood and a reasonably good performance shows this model can be used for flood forecasts viii WRF vs Obs AT PAYALEBAR STATION (a) WRF Forecast Station Obs 24- hr (b) Rainfall (mm) 20:00 22:00 2009-12-23 30 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 0:00 2:00 WRF Forecast Station Obs 20 24- hr 10 (c) TM Rainfall Nowcasting Rainfall (mm) 20:00 22:00 2009-12-23 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 3- hr Rainfall (mm) 20:00 22:00 2009-12-23 (d) 0:00 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 10 0:00 2:00 TM Forecast 3- hr 20:00 22:00 2009-12-23 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 0:00 2:00 (e) Rainfall (mm) TM Forecast 3- hr 20:00 22:00 2009-12-23 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 259 Figure D-29 Comparison between observed and simulated WRF and TM rainfall data on 24 th Dec 2009 at PayaLebar Station: (a) WRF started at 20:00 of 23th Dec; (b) WRF started at 2:00 of 24th Dec; (c) TM started at 8:00 of 24th Dec; (d) TM started at 9:00 of 24th Dec v; (e) TM started at 10:00 of 24th Dec Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall WRF Rainfall Forecasting Rainfall (mm) Ensemble rainfall Forecast vs Obs AT PAYALEBAR STATION 12- hr Ensemble rainfall Forecast Station Obs Rainfall (mm) 20:00 22:00 2009-12-24 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT PAYALEBAR STATION 12- hr Ensemble rainfall Forecast Station Obs (b) Rainfall (mm) Combined Rainfall Forecast 20:00 22:00 2009-12-24 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT PAYALEBAR STATION 12- hr (c) Rainfall (mm) Ensemble rainfall Forecast Station Obs 20:00 22:00 2009-12-24 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 260 Figure D-30 Comparison between observed and Combined rainfall data on 24th Dec 2009 at PayeLebar Station: (a) Combined rainfall started at 8:00 of 24th Dec; (b) Combined c rainfall started at 9:00 of 24th Dec; (c) Combined rainfall started at 10:00 of 24th Dec e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) WRF vs Obs AT SIMEI STATION (a) WRF Forecast Station Obs 24- hr 10 (b) Rainfall (mm) 20:00 22:00 2009-12-23 30 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT SIMEI STATION 16:00 18:00 20:00 22:00 0:00 2:00 WRF Forecast Station Obs 20 24- hr 10 (c) Rainfall (mm) 20:00 22:00 2009-12-23 0:00 2:00 4:00 6:00 8:00 10:00 12:00 TM AT SIMEI STATION 14:00 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 10 3- hr TM Rainfall Nowcasting (d) Rainfall (mm) 20:00 22:00 2009-12-23 0:00 2:00 4:00 6:00 8:00 10:00 12:00 TM AT SIMEI STATION 14:00 16:00 18:00 20:00 22:00 10 0:00 2:00 TM Forecast 3- hr 20:00 22:00 2009-12-23 0:00 2:00 4:00 6:00 8:00 10:00 12:00 TM AT SIMEI STATION 14:00 16:00 18:00 20:00 22:00 0:00 2:00 (e) Rainfall (mm) TM Forecast 3- hr 20:00 22:00 2009-12-23 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 261 Figure D-31 Comparison between observed and simulated WRF and TM rainfall data on 24 th Dec 2009 at Simei Station: (a) WRF started at 20:00 of 23th Dec; (b) WRF started at 2:00 of 24th Dec; (c) TM started at 8:00 of 24th Dec; (d) TM started at 9:00 of 24th Dec v; (e) TM started at 10:00 of 24th Dec Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall WRF Rainfall Forecasting Rainfall (mm) 15 Ensemble rainfall Forecast vs Obs AT SIMEI STATION Rainfall (mm) 10 20:00 22:00 2009-12-24 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT SIMEI STATION Combined Rainfall Forecast (b) Rainfall (mm) 15 Ensemble rainfall Forecast Station Obs 12- hr 10 20:00 22:00 2009-12-24 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT SIMEI STATION Rainfall (mm) (c) Ensemble rainfall Forecast Station Obs 12- hr 15 10 20:00 22:00 2009-12-24 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 262 Figure D-32 Comparison between observed and Combined rainfall data on 24th Dec 2009 at Simei Station: (a) Combined rainfall started at 8:00 of 24th Dec; (b) Combined rainfall started at 9:00 of 24th Dec; (c) Combined rainfall started at 10:00 of 24th Dec c e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Ensemble rainfall Forecast Station Obs 12- hr 15 WRF vs Obs AT CHANGI STATION WRF Rainfall Forecasting WRF Forecast Station Obs 24- hr 10 (b) Rainfall (mm) 20:00 22:00 2010-06-15 20 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT CHANGI STATION 16:00 18:00 20:00 22:00 0:00 2:00 WRF Forecast Station Obs 24- hr 10 (c) TM Rainfall Nowcasting Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT CHANGI STATION 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 10 3- hr 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT CHANGI STATION 16:00 18:00 20:00 22:00 0:00 2:00 (d) Rainfall (mm) 30 TM Forecast 10 Rainfall (mm) 20:00 22:00 2010-06-15 (e) 3- hr 20 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT CHANGI STATION 16:00 18:00 20:00 22:00 20 0:00 2:00 TM Forecast 3- hr 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 263 Figure D-33 Comparison between observed and simulated WRF and TM rainfall data on 16th Jun 2010 at Changi Station: (a) WRF started at 20:00 of 15th Jun; (b) WRF started at 2:00 of 16th Jun; (c) TM started at 9:00 of 16th Jun; (d) TM started at 10:00 of 16th Jun; (e) TM started at 11:00 of 16th Jun Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Rainfall (mm) 20 Ensemble rainfall Forecast vs Obs AT CHANGI STATION Rainfall (mm) 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT CHANGI STATION 12- hr Combined Rainfall Forecast Rainfall (mm) 20 (b) Ensemble rainfall Forecast Station Obs 15 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT CHANGI STATION Rainfall (mm) 20 Ensemble rainfall Forecast Station Obs 12- hr 15 10 (c) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 264 Figure D-34 Comparison between observed and Combined rainfall data on 16th Jun 2010 at Changi Station: (a) Combined rainfall started at 9:00 of 16th Jun 2010; (b) Combined rainfall started at 10:00 of 16th Jun 2010; (c) Combined rainfall started at 11:00 of 16th Jun 2010 c e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Ensemble rainfall Forecast Station Obs 12- hr 15 WRF Rainfall Forecasting WRF Forecast Station Obs 24- hr (b) Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT TENGAH STATION 16:00 18:00 20:00 22:00 0:00 2:00 WRF Forecast Station Obs 24- hr (c) TM Rainfall Nowcasting Rainfall (mm) 20:00 22:00 2010-06-15 4:00 6:00 8:00 10:00 12:00 14:00 TM AT TEGNAH STATION 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 3- hr Rainfall (mm) 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT TEGNAH STATION 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 15 3- hr 10 Rainfall (mm) 20:00 22:00 2010-06-15 (e) 2:00 10 20:00 22:00 2010-06-15 (d) 0:00 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT TEGNAH STATION 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 3- hr 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 265 Figure D-35 Comparison between observed and simulated WRF and TM rainfall data on 16 th Jun 2010 at Tengah Station: (a) WRF started at 20:00 of 15th Jun; (b) WRF started at 2:00 of 16 th Jun; (c) TM started at 9:00 of 16 th Jun; (d) TM started at 10:00 of 16 th Jun; (e) TM started at 11:00 of 16 th Jun Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Rainfall (mm) WRF vs Obs AT TENGAH STATION Ensemble rainfall Forecast vs Obs AT TENGAH STATION Ensemble rainfall Forecast Station Obs 12- hr 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT TENGAH STATION 12- hr 14 Ensemble rainfall Forecast Station Obs Combined Rainfall Forecast (b) Rainfall (mm) 12 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT TENGAH STATION 12 12- hr Ensemble rainfall Forecast Station Obs Rainfall (mm) 10 (c) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 266 Figure D-36 Comparison between observed and Combined rainfall data on 16th Jun 2010 at Tengah Station: (a) Combined rainfall started at 9:00 of 16th Jun 2010; (b) Combined rainfall started at 10:00 of 16th Jun 2010; (c) Combined rainfall started at 11:00 of 16th Jun 2010 c e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Rainfall (mm) WRF vs Obs AT SELETAR STATION (a) WRF Forecast Station Obs 24- hr 20 (b) Rainfall (mm) 20:00 22:00 2010-06-15 40 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT SELETAR STATION 16:00 18:00 20:00 22:00 2:00 WRF Forecast Station Obs 24- hr 20 0:00 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT SELETAR STATION 16:00 18:00 20:00 22:00 2:00 TM Forecast 3- hr 10 0:00 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT SELETAR STATION 16:00 18:00 20:00 22:00 60 (d) Rainfall (mm) TM Rainfall Nowcasting (c) Rainfall (mm) 20:00 22:00 2010-06-15 2:00 TM Forecast 3- hr 40 0:00 20 (e) Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT SELETAR STATION 16:00 18:00 20:00 22:00 3- hr 15 0:00 2:00 TM Forecast 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 267 Figure D-37 Comparison between observed and simulated WRF and TM rainfall data on 16th Jun 2010 at Seletar Station:(a) WRF started at 20:00 of 15th Jun; (b) WRF started at 2:00 of 16th Jun; (c) TM started at 9:00 of 16th Jun; (d) TM started at 10:00 of 16th Jun; (e) TM started at 11:00 of 16th Jun Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall WRF Rainfall Forecasting Rainfall (mm) 40 Ensemble rainfall Forecast vs Obs AT SELETAR STATION 40 30 Rainfall (mm) Ensemble rainfall Forecast Station Obs 12- hr 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT SELETAR STATION (b) Ensemble rainfall Forecast Station Obs 12- hr 40 Rainfall (mm) Combined Rainfall Forecast 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT SELETAR STATION 12- hr Rainfall (mm) 40 (c) Ensemble rainfall Forecast Station Obs 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 268 Figure D-38 Comparison between observed and Combined rainfall data on 16th Jun 2010 at Seletar Station: (a) Combined rainfall started at 9:00 of 16th Jun 2010; (b) Combined c rainfall started at 10:00 of 16th Jun 2010; (c) Combined rainfall started at 11:00 of 16th Jun 2010 e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) WRF vs Obs AT PAYALEBAR STATION WRF Rainfall Forecasting WRF Forecast Station Obs 24- hr 40 20 (b) Rainfall (mm) 20:00 22:00 2010-06-15 60 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 0:00 2:00 WRF Forecast Station Obs 40 24- hr 20 (c) TM Rainfall Nowcasting Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 3- hr (d) Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 40 0:00 2:00 TM Forecast 3- hr 20 (e) Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 TM AT PAYALEBAR STATION 16:00 18:00 20:00 22:00 2:00 TM Forecast 3- hr 10 0:00 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 269 Figure D-39 Comparison between observed and simulated WRF and TM rainfall data on 16th Jun 2010 at PayaLebar Station:(a) WRF started at 20:00 of 15th Jun; (b) WRF started at 2:00 of 16th Jun; (c) TM started at 9:00 of 16th Jun; (d) TM started at 10:00 of 16th Jun; (e) TM started at 11:00 of 16th Jun Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Rainfall (mm) 60 Ensemble rainfall Forecast vs Obs AT PAYALEBAR STATION 12- hr 50 Ensemble rainfall Forecast Station Obs Rainfall (mm) 40 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT PAYALEBAR STATION 50 12- hr Ensemble rainfall Forecast Station Obs 40 (b) Rainfall (mm) Combined Rainfall Forecast 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT PAYALEBAR STATION 50 12- hr Ensemble rainfall Forecast Station Obs Rainfall (mm) 40 (c) 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 270 Figure D-40 Comparison between observed and Combined rainfall data on 16th Jun 2010 at PayaLebar Station: (a) Combined rainfall started at 9:00 of 16th Jun 2010; (b) c Combined rainfall started at 10:00 of 16th Jun 2010; (c) Combined rainfall started at 11:00 of 16th Jun 2010 e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) WRF vs Obs AT SIMEI STATION WRF Rainfall Forecasting WRF Forecast Station Obs 24- hr 20 (b) Rainfall (mm) 20:00 22:00 2010-06-15 40 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 WRF vs Obs AT SIMEI STATION 16:00 18:00 20:00 22:00 0:00 2:00 WRF Forecast Station Obs 20 24- hr (c) Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 TM AT SIMEI STATION 14:00 16:00 18:00 20:00 22:00 0:00 2:00 TM Forecast 3- hr TM Rainfall Nowcasting 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 TM AT SIMEI STATION 14:00 16:00 18:00 20:00 22:00 0:00 2:00 (d) Rainfall (mm) 40 TM Forecast 3- hr 20 (e) Rainfall (mm) 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 TM AT SIMEI STATION 14:00 16:00 18:00 20:00 22:00 10 0:00 2:00 TM Forecast 3- hr 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 271 Figure D-41 Comparison between observed and simulated WRF and TM rainfall data on 16 th Jun 2010 at Simei Station: (a) WRF started at 20:00 of 15th Jun; (b) WRF started at 2:00 of 16th Jun; (c) TM started at 9:00 of 16th Jun; (d) TM started at 10:00 of 16th Jun; (e) TM started at 11:00 of 16th Jun Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Rainfall (mm) 40 Ensemble rainfall Forecast vs Obs AT SIMEI STATION 12- hr 40 Rainfall (mm) 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT SIMEI STATION 12- hr Combined Rainfall Forecast Rainfall (mm) 40 (b) Ensemble rainfall Forecast Station Obs 30 20 10 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 Ensemble rainfall Forecast vs Obs AT SIMEI STATION Rainfall (mm) 30 (c) Ensemble rainfall Forecast Station Obs 12- hr 40 10 20 20:00 22:00 2010-06-15 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 272 Figure D-42 Comparison between observed and Combined rainfall data on 16th Jun 2010 at Simei Station:(a) Combined rainfall started at 9:00 of 16th Jun 2010; (b) Combined rainfall started at 10:00 of 16th Jun 2010; (c) Combined rainfall started at 11:00 of 16th Jun 2010 c e Appendix D Comparison of Ensemble Rainfall Forecasting with Observed Rainfall (a) Ensemble rainfall Forecast Station Obs 273 ... by means of rainfall forecasting and nowcasting The Weather Research and Forecasting Model (WRF) was applied over Singapore and its neighboring region for rainfall forecasting Its performance... rainfall model resulting from NWP and from TM The combined rainfall forecasting covered the full-span of a 24-hour rainfall forecasting Introduce, conceptualize and calibrate a widely used rainfall-runoff... forecasting by combining the WRF results and TM results to provide an improved rainfall forecasting Combined rainfall forecasting provides more vii accurate results than rainfall forecasts from a single