1.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 0 Deep-Water Oceanographic Buoys: Deployments, Measurements, Outcomes Wind Sea and Swells Characteristics Derived from the Deep-Water Buoy at Western North Pacific Ching-Jer Huang Coastal Ocean Monitoring Center Department of Hydraulic and Ocean Engineering National Cheng Kung University Tainan, Taiwan May 5-6, 2014

2.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 1 Contents: I.Backgrounds II.Ocean Monitoring System in Taiwan III.Applications of the Ocean Monitoring System IV.Deep-Water Buoy V.Characteristics of Wind Sea and Swells VI.Conclusions

3.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 2 I. Backgrounds Weather, Oceans, and Tides around Taiwan Fig. 2 Tidal system around Taiwan. Fig. 1 Weather system around Taiwan.

4.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 3 Length of coastline Main island: 1139 km incl. small islands: 1600 km Eastern waters: Pacific Ocean ( d > 5000 m) Seabed slope max. 1/10 rocky shoreline, cliff, beach Tidal diff. ~1.5 m. max. Hs~20 m Western waters: Taiwan Strait ( d < 200 m) Seabed slope min. 1/1000 sandy beaches, dune, wetland Tidal diff. ~4.0 m. max. Hs ~10 m 400 km 150 km

5.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 4 II. Ocean Monitoring System in Taiwan COMC focuses on developing automated meteo- oceanographic measurement systems, supported mainly by Water Resources Agency (WRA) and Central Weather Bureau (CWB). Coastal Ocean Monitoring Center (COMC), National Cheng Kung University (NCKU)

6.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 5 觀測項目 1997 年取得第一型資料浮標專利 Data Buoys Data Buoy Type I (patented in 1997) 1. 於淺水及深水區蒐集海氣象資料。 2. 作為近海水文觀測之基礎。 1. To collect marine & meteorological data in any water depth. 2. To be the basis of ocean monitoring. Measurable items: -Wave -Current -Water temperature -Barometric pressure -Wind -Air temperature -Others, such as water quality 波浪  海流  水溫  氣壓  風  氣溫  其他 ( 水質 …)

7.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 6 觀測項目 Permanent Ocean & Coast Observing Systems 海岸氣象站 Coastal weather station 潮位站 Tide station 海上觀測樁 Ocean observation pile 波浪  潮汐  海流  水溫 氣壓  風  氣溫  雨量  溼 度  日照  其他 Measurable items ： -Wave, tide, and current -Water temperature -Barometric pressure -Wind and air temperature -Rain, humidity, and sunshine duration -Others 作為近海水文觀測之基礎 To be the basis of ocean monitoring

8.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 7 Radar Images during Typhoon Nockten (Oct 24 22:00, 2004) Measurable items: -Wave height -Wave period -Wave direction -Wave spectrum -Surface current 岸基雷達 Land based radar Remote Sensing Systems for Sea-State 移動式 Vehicle based radar 船用雷達 Vessel based radar 波浪  表面流 觀測項目 以非接觸之方式，蒐集表面 區域的海象資料 To collect marine data from an area of the sea surface by a more convenient way. 2004 年那克坦颱風期間海面之雷達影像

9.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 8 00:00 01:00 02:00. 23:00 00:30 01:30 02:30. 23:30 RadioSignal GSM / GPRS / Satellite (Sites ) 現場 (Sites ) 資料品管 (Data QC) 使用者 ( Clients) Relaystation ADSL Internet Real-Time Data Transmission 於觀測結束約半小時後，使用者 可取得通過品管檢測之資料。 Half an hour after observation, users can access QC-d data. 資料傳輸流程圖 (data transmission) ADSL Internet 分鐘 ( min) 10 observationanalysis Data transmission 13 20 Data QC Data transmission 25 30 觀測 分析 資料傳輸 資料品管 資料傳輸

10.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 9 III. Applications of the Ocean Monitoring System During the typhoon period, COMC provides every 6 hours the following information to the government: (i)Forecasting water level at main river mouths (ii) Forecasting of high water levels and arrival times around Taiwan in 3 days (iii) Present sea states around Taiwan (based on the data obtained from buoys) (iv) Wave height of swells around the coastal area of Taiwan (v) Run-up and overtopping around some selected seawalls (with high disaster potential)

11.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 10 http://www.jma.go.jp/jma/index.html Tsunami warning on March 11, 2011 (Tohoku earthquake)

12.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 11 (astronomical) Tsunami Detection after the Japan Earthquake Occurred

13.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 12 Tracks of typhoons approaching Taiwan from 1997 to 2006. IV. Deep-Water Buoys

14.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 13  Where should we deploy the deep-water buoys?  21 o 18’ N., 124 o 03’ E. IV. Deep-Water Buoy

15.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 14 近十年有超過 67% 於侵台之前通過台 灣東方之海域 CWB 300 公里

16.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 15 台東外洋資料浮標 台東東南邊約 300 公里 水深達 5610 公尺 東經 123 度 59 分 54 秒 北緯 21 度 43 分 36 秒 風速、風向 波高、週期、波向 氣壓、氣溫、水溫 流速、流向

17.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 16 25 mm nylon rope, 3000 m Data buoy 19 mm iron chain, 70 m 38 mm nylon rope, 100 m 12 mm PE rope, 3000m Water depth 5600 m Sea bed Anchors Scope (mooring length/water depth) =1.25 3 glass floats 32 mm iron chain, 27.5 m 19 mm iron chain, 5 m 26 mm iron chain, 27.5 m 6 glass floats

18.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 17 Instruments Installed on the Data Buoy

19.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 18 Typhoon JELAWAT (Sep.27 ～ 28, 2012)

20.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 19 Significant wave heights and mean wave periods monitored by the Pacific buoy

21.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 20 Wind speed and direction

22.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 21 Air pressure and temperature

23.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 22 Sea surface current

24.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 23 V. Characteristics of Wind Sea and Swells 5.1 Selection of wave data 5.2 Separation of wind sea and swells 5.3 Propagation of swells 5.4 Generation and disappearance of swells 5.5 Characteristics of wind sea and swells

25.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 24 5.1 Selection of Wave Data Fig. 5.1 Temporal variations in the wind speed at 10 m high from 2010/09/26/12:00 to 2010/09/30/23:00 (Taiwan Time). Wind Speed and Direction

26.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 25 5.1 Selection of Wave Data Wind Speed and Direction Fig. 5.2 Temporal variations in the wind direction at 3 m high from 2010/09/26/12:00 to 2010/09/30/23:00 (Taiwan Time).

27.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 26 A wind wave system which is directly generated and affected by local winds is called a wind sea. A swell consists of wind-generated waves that are not generated by the local wind at that time. They have been generated elsewhere some time ago. 5.2 Separation of Wind Sea and Swells

28.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 27 Separation of Wind Sea and Swell is based on the wave age (A g ), which is defined as : phase velocity of the peak-frequency wave : wind speed at an elevation of 10 m : Wind waves (wind sea) : Swell Fully-developed Swells: Mitsuyasu (1981), Donelan et al. (1993), 5.2 Separation of Wind Sea and Swells

29.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 28 5.2 Separation of Wind Sea and Swells Wave age, significant wave height, and mean wave period Fig. 5.3 Temporal variation in the wave age for the waves measured by the deep-water buoy from 2010/09/26/12:00 to 2010/09/30/23:00 (Taiwan Time).

30.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 29 5.2 Separation of Wind Sea and Swells Wave age, significant wave height, and mean wave period Fig. 5.4 Temporal variation in the significant wave height.

31.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 30 5.2 Separation of Wind Sea and Swells Wave age, significant wave height, and mean wave period Fig. 5.5 Temporal variation in the mean wave period.

32.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 31 5.2 Separation of Wind Sea and Swells Based on the values of wave age, the waves appear at various times can be categorized into three Time Zones: Time Zone I : 2010/09/26/12:00 - 2010/09/27/20:00 (32 hours) wave age: 2.5 - 3.8, =1.70 - 2.39 m, = 8.0 - 9.3 s (Swells dominate) Time Zone II : 2010/09/27/20:00 - 2010/09/28/20:00 (24 hours) wave age: 1.7 - 2.5, =1.30 - 1.80 m, = 6.1 - 8.0 s (Swells decrease and wind sea increases) Time Zone III : 2010/09/28/20:00 - 2010/09/30/23:00 (51 hours) wave age: 1.3 - 2.2, =1.20 - 1.46 m, = 5.0 - 6.2 s (Wind sea dominates)

33.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 32 5.3 Propagation of Swells Dispersion relationship for linear water waves: g : gravitational acceleration, k : wave number, h : water depth Shallow-water waves ( ): Deep-water waves ( ): c : phase velocity of waves, T : wave period Group velocity In shallow water : In deep water :

34.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 33 5.3 Propagation of Swells Swells produced by Malakas Typhoon Fig. 5.6 Track of Malakas Typhoon (2010/09/21 - 2010/9/26).

35.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 34 Fig. 5.7 Weather map around the deep-water buoy deployed at Western North Pacific on 2010/09/24/14:00 (Taiwan Time). Taiwan Time - 8 hours = UTC time. 5.3 Propagation of Swells

36.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 35 5.3 Propagation of Swells Fig. 5.8 Directional wave spectrum obtained from the deep-water buoy deployed at Western North Pacific on 2010/09/26/20:00 (Taiwan Time).

37.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 36 5.3 Propagation of Swells Fig. 5.9 Weather map around the deep-water buoy deployed at Western North Pacific on 2010/09/25/18:00 (UTC Time), 2010/09/26/02:00 (Taiwan Time).

38.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 37 Generation and detection of swells: From Fig. 5.7, the distance,, from the Malakas Typhoon to the deep-water buoy is approximately 1165 km. From Fig. 5.5, the mean wave period in Time Zone I is The produced swell will take about 46 hours to reach the deep-water buoy. 2010/9/24/14:00 (Taiwan Time, Fig. 5.7) + 46 Hrs = 2010/09/26/12:00 (Taiwan Time) Consistent with the results shown in Fig. 5.3. 5.4 Generation and Disappearance of Swells

39.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 38 5.4 Generation and Disappearance of Swells Disappearance of swells: The weather map (Fig. 5.9) shows that the Malakas Typhoon landed Japan on 2010/09/26/02 (Taiwan Time). The distance,, from the Malakas Typhoon to the deep-water buoy is approximately 1800 km. From Fig. 5.5, the mean wave period in Time Zone III is This effect will be detected by the deep-water buoy 80 hours later. 2010/09/26/02:00 (Taiwan Time, Fig. 5.9) + ８０ Hrs = 2010/ ２９／１０：００ (Taiwan Time). Consistent with the results shown in Fig. 5.3.

40.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 39 5.5 Characteristics of Wind Sea and Swells Fully-developed Wind Sea (1/4) Fig. 5.10 Variations in the wave spectrum measured by the deep-water buoy deployed at the Western North pacific from 2010/09/27/06:00 to 2010/09/30/22:00 Taiwan Time).

41.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 40 5.5 Characteristics of Wind Sea and Swells Fully-developed Wind Sea (2/4) Fig. 5.11 Comparison of the measured wave spectrum at 2010/09/27/06:00 with the PM spectrum (First Time Zone). Fig. 5.12 Comparison of the measured wave spectrum at 2010/09/28/08:00 with the PM spectrum (Second Time Zone).

42.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 41 5.5 Characteristics of Wind Sea and Swells Fully-developed Wind Sea (3/4) Fig. 5.13 Comparison of the measured wave spectrum at 2010/09/30/14:00 with the PM spectrum (Third Time Zone, Part I). Fig. 5.14 Comparison of the measured wave spectrum at 2010/09/30/21:00 with the PM spectrum (Third Time Zone, Part II).

43.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 42 5.5 Characteristics of Wind Sea and Swells Fully-developed Wind Sea (4/4) Fig. 5.15 Comparison of the measured wave spectrum at 2010/09/30/22:00 with the PM spectrum (Third Time Zone, Part III).

44.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 43 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (1/11) Swells produced by Ma-On Typhoon (July 12-20, 2011) Fig. 5.16 Track of Ma-On Typhoon (July 12-31, 2011)

45.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 44 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (2/11) Fig. 5.17 Weather map around eastern water of Taiwan on July14, 2011 (14:00, Taiwan Time).

46.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 45 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (3/11) Fig. 5.18 Weather map around eastern water of Taiwan on July19, 2011 (20:00, Taiwan Time).

47.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 46 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (4/11) Fig. 5.19 Evolution of peak period of the swell and wind speed measured by the deep-water buoy from July 16, 00:00, 2011 to July 19, 00:00 (Taiwan Time). Apparent swell appears from 2011/7/16/16:00 (16th Hour) to 2011/7/18/12:00 (60th Hour).

48.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 47 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (5/11) Fig. 5.20 Directional wave spectrum obtained from the deep-water buoy deployed at Western North Pacific on 2011/07/16/23:00 (Taiwan Time).

49.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 48 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (6/11) Fig. 5.21 Temporal evolution of the wave spectra during the period of Ma-On Typhoon from 2011/07/15/00:00 to 2011/07/19/ 23:00 (Taiwan Time). Three Time Zones: Zone I : 2011/07/15/00:00 - 2011/07/16/15:00 Zone II : 2011/07/16/00:00 - 2011/07/18/12:00 Zone III: 2011/07/18/13:00 - 2011/07/19/23:00

50.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 49 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (7/11) Fig. 5.22 Temporal evolution of the wave spectra during the period of Ma-On Typhoon at Time Zone I (from 2011/07/15/00:00 to 2011/07/19/23:00, Taiwan Time). Fig. 5.23 Temporal evolution of the wave spectra during the period of Ma-On Typhoon at Time Zone II (from 2011/07/16/00:00 to 2011/07/18/12:00, Taiwan Time).

51.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 50 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (8/11) Fig. 5.24 Temporal evolution of the wave spectra during the period of Ma-On Typhoon at Time Zone II (from 2011/07/18/13:00 to 2011/07/19/23:00, Taiwan Time). Fig. 5.25 Representative wave spectra obtained by the deep-water buoy deployed at Western North Pacific during the period of Ma-On Typhoon from 2011/07/15/00:00 to 2011/07/17/ 23:00 (Taiwan Time).

52.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 51 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (9/11) Pierson-Moskowitz (P-M) Spectrum (1964) Modified JONSWAP Spectrum (Goda, 1999) : frequency, : peak frequency, : significant wave height : spectral width parameter, T: mean wave period, and : peak enhancement factor

53.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 52 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (10/11) Modified Wallops Spectrum (Huang et al., 1981; Goda, 1999) : frequency, : peak frequency, : significant wave height : mean wave period, and : peak enhancement factor

54.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 53 5.5 Characteristics of Wind Sea and Swells Characteristics of Swells (11/11) Fig. 5.26 Comparison of measured wave spectrum at Time Zone II with the modified Wallop Spectrum. Fig. 5.27 Comparison of measured wave spectrum at Time Zone II with the modified JONSWAP Spectrum. Comparison of measured wave spectrum at Time Zone II with the modified Wallop Spectrum and the modified JONSWAP spectrum.

55.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 54 VI. Conclusions 1.Data buoys are very important platforms for installing various sensors to monitor the sea states, such as wind speed, wind direction, wave height, wave direction, currents, etc. 2.The real-time information obtained from the buoys is important for rapid and effective responses to possible disasters. 3.The deployment of deep-water buoys is a hard task, but the obtained data provide much earlier precious information for handling possible disasters.

56.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 55 VI. Conclusions 1.Data buoys are very important platforms for installing various sensors to monitor the sea states, such as wind speed, wind direction, wave height, wave direction, currents, etc. 2.The real-time information obtained from the buoys is important for rapid and effective responses to possible disasters. 3.The deployment of deep-water buoys is a hard task, but the obtained data provide much earlier precious information for handling possible disasters.

57.  Copyright 2009 Coastal Ocean Monitoring Center. All right reserved. http://www.comc.ncku.edu.tw 56 Thank you! Comments are mostly welcome.