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ESCAP/WMO Typhoon Committee 5th Integrated Workshop Macao, China, 6-10 September 2010 PowerPoint Presentation
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ESCAP/WMO Typhoon Committee 5th Integrated Workshop Macao, China, 6-10 September 2010

ESCAP/WMO Typhoon Committee 5th Integrated Workshop Macao, China, 6-10 September 2010

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ESCAP/WMO Typhoon Committee 5th Integrated Workshop Macao, China, 6-10 September 2010

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  1. ESCAP/WMO Typhoon Committee 5th Integrated WorkshopMacao, China, 6-10 September 2010 Benefits of Typhoon from a Hong Kong Perspective Hilda Lam, M.H. Kok and Karen Shum Hong Kong Observatory Hong Kong, China

  2. Contents • Experience from other places • Benefits of typhoons from a Hong Kong perspective • source of water • for relieving long and severe drought • Potential contribution to wind energy • cooling effect in summer

  3. Benefits of Tropical Cyclones Experience from other places

  4. Benefits of TCs in Hydrology Rainfall from TCs provides important water resources in many places: • In inland Australia, significant amount of total rainfall comes from TCs (Ryan, 1993). • In China, “Ranaim”, “Haitang” and “Matsa” in 2004 replenished reservoirs andincreased grain production and farmer’s income (Liu, 2006).

  5. In the United States, 9 major TCs in 1932-1963 terminated drought conditions over an area of 10,000 sq. miles or more (Sugg, 1968). Tracks of TCs that terminated drought in the US The estimated area where drought was terminated

  6. Benefits of TCs in Fisheries Surface Chrorophyll-a satellite image composite • TCs enhance the production of phytoplankton, the base of the ocean food chain • Vertical mixingbring the nutrient-rich water in deep layer to ocean surface • “Kai-Tak” in 2000 triggered an average 30-fold increase in surface chlorophyll-a concentration over the South China Sea • (Lin et al., 2003) Before the arrival of Kai-tak Enhancement of biological activities After the passage of Kai-tak

  7. Benefits of TCs in Fisheries Increases in the lobster population have been observed after rough sea and high tides generated by TCs (Sugg, 1968).

  8. Role of TCs in Regulating Climate • Induce upper-ocean mixing(Korty et al., 2008) • Stronger mixing of the tropical oceans can force the oceans’ meridianal heat flux to increase, which cools the tropical latitudes and warms the higher latitudes. • Redistribute heat polewards and drives the thermohaline circulation (Emanuel, 2001; Sriver et al., 2007; Jansen et al., 2009). Sea surface temperature after the passage of Hurricane Edouard in 1996 (Emanuel,2001) Average cyclone-induced surface cooling of the upper ocean (Sriver et al., 2007)

  9. Enhanced Wind Power Production by TCs • High winds associated with TCs could enhance production of wind energy, especially for the wind farms in the coastal areas. • Influence of TCs on the wind power generation in China • ~ 30% of landfalling TCs may cause damage to the wind farms • ~ 55% of landfalling TCs with winds of less than Force 10 to wind farms are beneficial to the efficiency of the wind power production • Song et al., 2006

  10. From a Hong Kong perspective

  11. Hong Kong • Size: ~1100 sq. km • Population: • 7 million ( 2009) • GDP (2009) • 1632 trillion • Services( 92%) • Industries( 8%) • Agriculture( 0.1%) • Modern city with good infrastructure

  12. TC casualties in HK Most devastating typhoons over HK • 1906 typhoon : 15 000 death • 1937 typhoon : 11 000 loss of lives

  13. Ocean-going vessels in trouble

  14. Small craft sunk or wrecked; damaged

  15. Damagecaused by TC in Hong Kong

  16. Benefits of typhoons from a Hong Kong perspective Source of water

  17. Climatologically, TCscontribute ~30% rainfall in Hong Kong 1987 8% 1964 60%

  18. Benefits of typhoons from a Hong Kong perspective for relieving long and severe drought

  19. Worst drought in Memory(Monthly rainfall 1962-1964)

  20. Downpour of Viola as relief of severe drought • 1962 was dry - 1741mm of rainfall (~ 20% below normal ) • 1963 even drier only 901 mm of rainfall (~ 60% below) • By 2 May 1963 - water supply down to 3 hours/ day • By 16 May - forced to restrict water supply to 4 hours every other day • By 1 June 1963 when reservoir storage dropped to 175 million gallon, ~1.7%of reservoir capacity, forced to restrict further to 4 hours of supply every 4 days • Not until 27 May 1964 when passage of Typhoon Viola brought torrential rain (300.6 mm in 5 days ), the persistent drought was relieved • Year long “4 hours every 4 days” measure terminated

  21. Track of Typhoon Viola in May 1964

  22. 1963: driest year; water supply:4 hours every 4 days- the long queuefor fresh water • Courtesy Hong Kong SARInformation Services Department

  23. 1963 Severe Water Rationing • Source: Water Supplies Department

  24. Benefits of typhoons from a Hong Kong perspective Enhancement of wind energy potential

  25. Wind energy Wind energy resource at a potential site is expressed in mean wind power density (WPD), is defined as: • watts per square meter (Wm-2) • average wind power available per unit area swept by a wind turbine blade over a certain period (Janardan & Nelson, 1994) • 10 min mean wind is used in the calculation of WPD below

  26. Wind power density in Hong Kong • ≥Class 3 utility-scale wind power applications, • ≥Class 4 large-scale wind farms • areas with potential for large-scale wind farms in Hong Kong  hilltops and offshore waters.

  27. Ratio of potential wind power density (WPD) during TC passage to the annual average • Hilltops & offshore sitesin HK selected with potential for large-scale wind farms * TC within 600 km of Hong Kong in 2007-2009: 69 days

  28. 1st Wind Turbine at Lamma Island, S of HK~5 yr effort by HK Electric, a local power co.policy & other constraints

  29. Benefits of typhoons from a Hong Kong perspective cooling effect in summer

  30. TCs in 2007-2009 studied(within 600 km of HK)

  31. r : 600km T1 x Hong Kong T1-2 T2 Passage of Tropical Cyclones near Hong Kong (T1,T2 T1-2 mark the day)

  32. Data and methodology • Use daily mean air temperature at the Observatory during the passage of TC (T1 to T2) • Calculate deviation from the mean temperature for that day and sum for all TC • Mean temp is the 5-day mean for 2000-2009 • Normally include + 2 days before entering 600km of HK to take account of possible subsidence ahead.

  33. T1 T1 T1 T1 T2 T2 T2 T2 Temperature -Fengshen in 2008(within 600 km on 23-26Jun)

  34. Fengshen

  35. Fengshen 00Z 25 June 2008

  36. T1-2 T1-2 T1-2 T1-2 T1-1 T1 T2 Hagupit 2008 warming in preceding 2 days (21-22 Sep)

  37. Air temperature anomaly of 21 Tropical cyclones in 2007 -2009 • T1-2 ~ T2 starts preceding 2 days & when TC within 600 km of Hong Kong or TC formation, whichever is later • Anomaly with reference to 5-day mean 2000-2009

  38. No. of TC with net cooling effect (T1-2~T2)

  39. r : 600km T1 T2+1 x Hong Kong T1-2 T2+2 T2+3 T2 Days of T1-2, T1, T2, T2+1, T2+2, T2+3

  40. Air temperature anomaly –extended to cover 3 days after T2r • T1-2 ~ T2 starts preceding 2 days & when TC within 600 km of Hong Kong or TC formation, whichever is later • 21 TCs within 600 km of HK in 2007-2009 spanning 93 days

  41. Calculate the temperature deviations using different means as reference 5-day mean 2000-2009 5-day mean 1971-2000 5-day mean 2007-2009

  42. T1 T1 T1 T1 T2 T2 T2 T2 Temperature -Fengshen in 2008(within 600 km on 23-26Jun)

  43. Air temperature anomaly of all TCsunder various references • In a changing climate, following 5 day mean compiled for inter-comparison • 1971-2000 of 30 years • 2000-2009 of 10 years • 2007-2009 of 3 years

  44. Increased annual impact of electricity consumption per degree rise of temperature Impact in Billion HK$ • Source :Fung (2004) deg

  45. Estimated economic saving in electricity consumption (HK$) *based on electricity consumption in 2002 (Fung 2004) ~HK$20m per year

  46. Some TC with net cooling effect (T1-2~T2, total anomaly non -ve) • +ve anomaly of Linfa and TD Jul in T1-2~T2 everyday

  47. Summary –Typhoon Benefits in Hong Kong • Source of water • Relieve prolonged • Cooling and moderating hot summertime • Potential wind energy

  48. ~ Thank you ~