1. Inter-annual Variation of Southwest Monsoon and ENSO in Thailand

2.  Ms. KornraweeSitthichivapak, Director, Climatology Center.  Mr. Charoon Laohalertchai, Director, Northern Meteorological Center, Chiangmai.  Ms. SugunyaneeYavinchan, Director, Numerical Weather Prediction. 

3.  To study impact of ENSO on SW Monsoon over Thailand  To study mechanism of SW Monsoon, linking to ENSO

4.  30 years (1971 – 2000) meteorological data  Parameters: MSLP, Wind at 850 and 200 hPa  Climatological data from TMD  Data Reanalysis from ECMWF

5.  Analyze monthly wind direction and its speed from July to September at 850 and 200 hPa  Compare monthly wind direction and its speed between ENSO year and neutral year

6.  Analyze pattern winds for starting and ending of the rainy season (account for topography)  Compare pattern winds for starting and ending of the rainy season between ENSO year and neutral year

7.  To know the variability of the wind patterns for starting and ending of the rainy season  To know the variability of the wind patterns during the SW monsoon in the ENSO year.

8.  Monsoon is the result of the shift of the Inter Tropical Convergence Zone (ITCZ) under the influence of the vertical sunInter Tropical Convergence Zonevertical sun  the South East Trade winds of the Southern Hemisphere have to cross the equator to reach the ITCZ  Coriolis effect in northern hemisphere to turn to its right are deflected eastwards in the Northern Hemisphere transforming into South West trades. Coriolis effectNorthern Hemisphere  orographic rain

9. MAY

10. JUNE

11. JULY

12. AUGUST

13. SEPTEMBER

14. OCTUBER

15. Surface wind upper wind Edward Linacre and Bart Geerts:1997

17. 1980 is a neutral year Southwest wind prevail Andaman sea, southern Thailand and upper Thailand 1997 is a El ni no year Westerly wind prevail Andaman sea and Thailand 1988 is Lanina year the active southwest monsoon prevail Andaman sea and Thailand

18. 1980 is a neutral year the active Easterly wind prevail south China sea, upper Thailand. The Southern Thailand is westerly wind. 1997 is Elnino year Easterly wind prevail South China Sea and Thailand. 1988 is a Lanina Year Northeast wind prevail Northeast Thailand For Southern Thailand is active westerly wind

19.  850 and 200 hPa mean wind JJAS in neutral year  850 and 200 hPa mean wind JJAS in strong El- Nino year  850 and 200 hPa mean wind JJAS in strong La- Nina year

29. 850 hPa Elnino Neutral Lanina

30. Elnino NeutralLanina 200 hPa

36. Criteria used by the Thai meteorological Department  Upper level, westerly wind is changed to easterly  Lower level, wind is changed to westerly or southwest wind  In any 5-day period, there must be at least 3continuous days with rain, or the total 5-day rain must be at least 25 mm with the minimum daily rain of 5 mm. ศูนย์ภูมิอากาศ กรม อุตุนิยมวิทยา The Meteorological Department (TMD) Climatological Center

37. Onset of rainy season in Thailand (1971-2000) May El ninoLaninaNeutral ศูนย์ภูมิอากาศ กรม อุตุนิยมวิทยา The Meteorological Department (TMD) Climatological Center

38.  Analysis data from 1971-2000 found that  Neutral year : the beginning of rainy season is mostly mid May  El nino year : the beginning of rainy season is late than neutral year  La nina year : the beginning of rainy season is earlier than neutral year  Analysis of monsoon pattern during May found that  La nina year : Southwest monsoon prevail over the Andaman sea, Thailand and the Gulf of Thailand is stronger and clearer than neutral year and El nino year.  El nino year : Mostly westerly wind prevail the Andaman sea Thailand and the Gulf of Thailand  For the end of rainy season is mostly mid October all condition.

39. El nino year : 850 hPa  Southwest monsoon prevail over upper Thailand and more active than normal 200 hPa  Easterly wind prevail over Thailand and active than normal La nina Year : 850 hPa  Southwest monsoon prevail over upper Thailand and weakly than normal 200 hPa  Easterly wind prevail over Thailand and weakly than normal

40. Thank You for your kind Attention