FINO1 Research Platform in the North Sea

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1 1 FINO1 Research Platform in the North Sea Anthony J. Kettle Dec. 27/2013 Situated over 40km offshore in the North Sea and instrumented with a large suite of the meteorological and oceanographic instruments, the FINO1 research platform offers insight into the physics of the boundary layers of the upper ocean and lower atmosphere that has not previously been possible. This contribution reviews some of the data from FINO1 research platform and presents background information about the project from the published and unpublished sources. 1. Government Policy Basis and Background The FINO1 platform originated in a German federal government policy in 2000 to double the amount of electricity produced by renewables by 2010 to 12.5%, with a long-term goal to produce 50% of the country s electricity by renewables by 2050 (Rakebrandt-Grassner and Neumanm, 2003). It was recognized that wind energy would be an important element in implementing the new policy, and that in particular offshore wind farms would be important in the German Bight and the Baltic Sea. The new wind farms being envisioned for the North Sea were larger and further offshore compared with existing projects, in particular the wind farms that had been set up in Denmark. The Danish Horns Rev wind farm, in operation from 2001, was the largest offshore wind farm in the world at the time that the FINO program was being established. The stated priorities underlying the background research into the development of offshore wind energy were to understand the met-ocean loading on the masts, turbines, and other structures constructed in the far offshore environment, and also to investigate the potential impact on marine life (Rakebrandt-Grassner and Neumann, 2003; Fischer, 2006). The offshore research project was to be developed gradually to ensure the protection of the sea and to follow the principle of precaution (Rakebrandt-Grassner and Neumann, 2003). The German Federal Ministry of Economics and Labour commissioned Germanischer Lloyd WindEnergie GmbH (GL Wind) with the construction, erection, and commissioning of research platforms in the North Sea (Neumann et al., 2003; Rakebrandt- Grassner and Neumann, 2003). The FINO project started in 2001, and the platform design was initiated in autumn, An EU-tendering process for the construction of the platform was resolved in June, 2002, and the construction of the components of the platform started at different sites in Germany in the summer of 2002 (Fischer, 2006). The structure was constructed from its prefabricated elements ~45km north of Borkum in June-July, 2003 with final construction details and instrument installation performed in August, 2003 (Neumann et al., 2003). 2. The Designed Platform Structure The physical structure of FINO1 was designed to meet certain measurement goals in a demanding environment with high wind and wave conditions, subject to financial constraints (Rakebrand-Grassner and Neumann, 2003). The primary goal of the FINO program was the erection of a 100m meteorological mast that could operate reliably and without maintenance for extended time intervals. The height of 100m was identified in 2001 as the design hub height that offshore turbines could attain in the near future. The area of the main platform deck was constrained by containers that supported the measurement program and infrastructure equipment, plus a helicopter landing pad for access. FINO1 was initially planned with four containers for 1. computers and scientific equipment, 2. radar equipment, 3. generators and batteries, and 4. emergency accommodation (Rakebrandt-Grassner and Neumann, 2003). In the process of construction and actualizing the measurement program a fifth container was added (Fischer, 2006). The main platform was constructed at a height of 20m above chart datum, and this was

2 2 determined by consideration of the design wave of 17m plus a safety gap (Rakebrandt-Grassner and Neumann, 2003; Fischer, 2006). There is ambiguity in the literature about the expected extreme geophysical conditions at the FINO1 site. Fischer (2006) shows an excerpt from the design basis of the FINO1 structure, and clarifies that 17m is the maximum wave height that is expected with a repeat period of 100 years. However, the design basis also specifies a design sea level as 5.7m over an average chart datum (CD) sea level of 28m (Fischer, 2006). The design sea level accounts for abnormally high tides during storms, which may be uncorrelated with the design wave. There is no background information about the origin of the expected met-ocean conditions in the design basis from Fischer (2006), but it may have been drawn from similar maps of offshore temperature, winds, and waves conditions (average and extreme) for the design and certification of Norwegian North Sea petroleum structures (Norsok Standard, 2007). requests have been sent to GL-Wind for a full copy of the design basis for FINO1, but there has been no response. Budget constraints are not explained in detail in the background literature for FINO1, but Rakebrandt- Grassner and Neumann (2003) specify that the choice of the lattice-type jacket for the FINO1 substructure was based on a balance between financial considerations and also acceptable levels of the physical vibrations in response to the expected wind and wave loading. Canadillas et al. (2011) state that the jacket construction provides a very stable platform that avoids data contamination by motion of the sensors. The choice of the jacket structure was also partly governed by the expected interactions between the structure and the underlying soil. As part of the background preparations for the design of the research mast, a seabed study was carried out at the Borkum Riff site in October, 2001 (Rakebrandt- Grassner and Neumann, 2003; Fischer, 2006). This included a drilled core to understand the structure of the underlying soil matrix (see Appendix A, downloaded from before Nov. 1, 2013). An outline of the final structure of the FINO1 are described on the Internet at with structural diagrams and further explanation appearing in different publications (Neumann et al., 2003, Rakebrandt-Grassner and Neumann, 2003; Fischer, 2004, 2006) and conference presentations (Neumann and Beeken, 2009). Structural diagrams of the platform are reproduced in Appendix A. The platform consists of 3 main sections: jacket foundation, platform, and mast. The jacket foundation has base dimensions of 26 26m on the seabed and has a height of 48m. It is attached to four piles driven into the seabed that are 38m length. The piles are characterized by high rigidity and low weight with a mass of 37 tons each (Fischer, 2006). The platform deck on the jacket has dimensions 16 16m, and the helicopter pad is offset and above the main deck of the platform with dimensions 15 15m. The meteorological mast on the main deck of the platform has a height of 100m above chart datum. The structure was partly preassembled on land with the jacket forming one unit, and the platform, helicopter pad, and lower mast forming a second unit. The mast was erected as three pre-assembled units. 3. Instrument Array, Data Logging, and Communication The instrumentation array on FINO1 was mainly established during the initial design of the physical structure (Neumann et al., 2003; Rakebrandt-Grassner and Neumann, 2003). The configuration of the current system is outlined on the BSH Internet resource and with further information obtained by personal communication from technical staff at DEWI and BSH (Appendix B). The sensor suite includes instrument packages to monitor the meteorological and oceanographic conditions, as well as sensors for monitoring structure accelerations and loads. There is some description in the published and Internet literature about the sensor types and their calibration (e.g., Argyriadis et al., 2005, 2006; Nolopp and Neumann, 2006; Tautz et al., 2004), but little background information about how the instruments were

3 3 selected on the basis of previous offshore measurement experience from other areas of northwest Europe (Andersen and Lovseth, 1993; Wills and Cole, 1990) Meteorological Instrumentation Key scientific goals that were recognized from the start were to understand the vertical wind speed profile at heights up to the 100m and also turbulence. This was met by a vertical array of the 8 cup anemometers spaced at approximately 10m intervals and extending out from the mast on horizontal booms toward the southeast. There is also a set of three sonic anemometers spaced at approximately 20m intervals (at 40, 60, 80m height) on the other side of the mast on booms facing northwest. A set of four wind vanes were placed on booms between the sonic anemometers on the northwest side of the mast at 30, 50, 70, and 90m. The measurement of the vertical atmospheric static stability was recognized as an important component of the goal to understand the wind speed profile (Nolopp and Neumann, 2006), this was met by a set of unventilated Thiess temperature (40, 70m) and combined temperature/humidity sensors (30, 50, 100m) located on booms set out from the mast. Because the expected vertical temperature gradients in the lowest 100m of the atmosphere were expected to be small, it was important that the temperature measurements be accurate to 0.1K to evaluate atmospheric stability. The temperature instruments were therefore modified and the PT100 sensors components were the individually recalibrated at the DEWI laboratory. The instruments were sent back the manufacturer for a cross-check before installation on FINO1 (Nolopp and Neumann, 2006). Nolopp and Neumann (2006) report on an additional check of the temperature sensor calibration with an independent mobile system moved around to different locations on the mast. F. Kinder (personal communication, 2013) verified that this was carried out on two occasions in 2004 and A slight sensor drift was noted in the second in situ calibration, but sensor accuracy was still good to K. The PT100 sensors are among the most precise, accurate, and stable temperature measurement devices available (Nolopp and Neumann, 2006, Jelacic, 1970), and they have a potential accuracy that is much better than the 0.1K reported in the BSH database (Jelacic, 1970). However, their calibrations are known to drift with time so that periodic calibration checks are necessary to achieve the full potential of the instrument (Jelacic, 1970). The meteorological instrumentation system is completed by sensors for atmospheric pressure, insolation, UV-radiation, and rain amount. Early schematic designs before 2004 differ in the details of the configuration and identity of these sensors, compared with the configurations in a more recent design plan at DEWI (F. Kinder, personal communication, Feb. 11, 2011) and website resource created by BSH in ( Neumann et al. (2003) and Rakebrandt-Grassner and Neumann (2003) indicate that there is one atmospheric pressure sensor at ~85m, but this shifted down to the 20m deck level in the modern plans, and F. Kinder indicates it is next to the measurement container (personal communication, Oct. 16, 2013). The BSH online database indicates a second atmospheric pressure operating for approximately one year between the early part of The pre-construction design drawings of Neumann et al. (2003) and Rakebrandt-Grassner and Neumann (2003) indicate an insolation sensor at platform level. In the DEWI design plan, this was shifted up to 30m, and additional insolation and UV-radiation sensors were added at 90m. The current BSH Internet resource ( confirms this instrument configuration with a lower insolation instrument at 34m LAT (lowest astronomical tide) and separate insolation and UV sensors mounted in tandem on a boom at 91.5m LAT. For rain, the preconstruction plans of Neumann et al. (2003) and Rakebrandt-Grassner and Neumann (2003) indicate sensors at ~35m and 85m. Rain sensors are indicated at 20m and 90m in the DEWI design plans. Initially, these were rain monitoring

4 4 sensors (i.e., presence/absence of precipitation), but in 2008 the deck level monitoring sensor was exchanged for a quantitative sensor. However, the quantitative information was modified to give a presence/absence binary signal to make it compatible with the information with the precipitation monitoring sensor higher on the mast (F. Kinder, personal communication, Sept. 16, 2013). The current online BSH database includes the binary rain data from two heights on the FINO1 mast. FINO1 was also designed with a lightning detector to count lightning strikes (Rakebrandt-Grassner and Neumann, 2003). This information is held at DEWI, but it is without date/time stamps, in an uncertain archival format, and not available for general research (F. Kinder, personal communication, Oct. 17, 2013). The slow profiling meteorological data is available as 10 minute average values on the BSH website by registering and sending a request to the BSH administrators. The sonic anemometer data is not available from BSH and requests must be directed toward DEWI. For this review report, sonic data from the 2005 has been made available by DEWI for research analysis Wave and Oceanographic Instrumentation The suite of BSH oceanographic instrumentation was recognized as important to understand the physical forces acting on the platform (Herklotz, 2007). The instrumentation suite includes multiple packages to understand the surface wave field, along with a mooring array for the water column properties. Three separate instrument systems monitor the wave field. A WaMoS radar system was installed on FINO1 in From radar scans of the ocean surface, this provides statistical information about the significant wave height, period and direction (Hessner and Reichert, 2007). A Datawell wave buoy, moored m from the platform (Neumann et al., 2004), was identified as the most important device for understanding wave loads on the FINO1 structure and is especially important as it can record individual extreme waves (Herklotz, 2007). The instrument has a set of sensitive accelerometers that detect how the buoy is moving in the wave field, so that surface wave height and direction data can be reconstructed from a double integration of the recorded accelerations (Datawell Bv, 2000). A Datawell WAVEC buoy was initially placed at the FINO1 site from 2003, but this was replaced with a Datawell MkIII buoy on Apr. 21, 2006 (O. Outzen, personal communication Oct. 17, 2013), and this is the instrument currently described on the BSH Internet resource ( BSH conducts a maintenance visit of the FINO1 platform approximately every 6 months, and the batteries of the Datawell buoy are changed at this time (O. Outzen, personal communication, Oct. 24, 2013). An upward-looking ADCP instrument (Nortek AWAC, is placed on the seabed ~150m from the FINO1 platform to which it is connected by a cable for power supply and data communication. This device uses multiple beam sonar technology to infer the three dimensional motion of water column, sea level, and surface wave properties. The instrument has the potential to deliver high resolution wave information comparable with a performance of the Datawell buoy. Currently, the BSH online database includes current speed and direction at 2m intervals in the water column, and statistical summaries of the significant wave height, wave period, and wave direction. The instrument cleaned by divers once per year. There have been long-term operational difficulties for this instrument associated with power outages, computer failures, and in particular cable/plug problems in the strong tidal currents at the FINO1 site. The instrument was exchanged once in 2009, and the cable was changed twice (O. Outzen, personal communication, Oct. 28, 2013). Comparatively little data has been gathered from the instrument since the start of the FINO1 program in The oceanographic instrumentation is completed by a fixed hydrographic mooring on a chain down through the centre of the foundation jacket with permanent sensors to monitor seawater conditions. The

5 5 preconstruction instrument plan (Rakebrandt-Grassner and Neumann, 2003) indicated mooring array of 6 CTD sondes that could measure temperature, salinity, and oxygen. This was modified to two SBE37 CTD sondes (6, 25m) in the actual measurement program and four Sea & Sun T40 temperature sensors (3, 10, 15, 20m). The BSH Internet resource indicates two Anderaa Optode 4175 sensors at 6 and 25m to measure dissolved oxygen. In the first winter in December 2003 there were reports of storm damage to the measurement chain (Fischer, 2004). The preconstruction instrument plan (Rakebrandt-Grassner and Neumann, 2003; Fischer, 2006) specified a tide gauge to measure water level. Underwater pressure gauges are not documented in the BSH website documentation for FINO1. However, O. Outzen (personal communication, Dec. 2, 2013) has indicated that there is pressure sensor in the central measuring chain, but that the data are poor quality because of chain movement, and its presence is not indicated in the BSH Internet resource. O. Outzen (personal communication, Dec. 12, 2012) has also indicated that each Seabird SBE37 CTD has a pressure sensor but that it is only used to indicate the depth of the temperature and salinity data. Although not listed in the BSH Internet resource, the SBE37 pressure data are available as 10-minute average values on request from BSH. Information about water depth is also available from the ADCP based on the travel time measurements of sound. However, data retrieval from the instrument has been poor, and the water depth measurements are biased on longer time scales due instrument subsidence into the bottom sediments. O. Outzen (personal communication, Oct. 24, 2013) indicated that an Anderaa RCM 7 current meter was installed at the FINO1 platform until 2006 but was removed because it gave undeliverable results. A downward looking radar has recently been installed on platform to additional information on the sea level Instrumentation Associated with Structural Loading The foundation jacket, platform and tower has been instrumented with acceleration sensors and strain gauges (Rakebrandt-Grassner and Neumann, 2003; Neumann et al., 2003; Fischer, 2006; Schaumann and Boker, 2007). The 64 sensors are deployed at nodes in the lattice jacket structure and collect data at 10Hz. The data is archived DEWI and not available on BSH the data server. The analysis of the structural data has not been normally integrated with analyses of the meteorological data. Schaumann and Boker (2007) have used measured wave data to investigate the characteristics of possible fatigue damage to one of the diagonal bracing struts of the jacket Data Logging and Communication The information from the met-ocean instrumentation is recorded on different platform logging systems in addition to being transmitted by radio uplink. The instrumentation is divided into meteorological and oceanographic systems, which are the separate responsibilities of DEWI and BSH, respectively. For the meteorological instrumentation, there is a further division between sonic anemometers and the other conventional instrument types that are sampled at a slower rate. According to the initial design plan (Neumann et al., 2003; Neumann et al., 2004), the data from the sonic anemometers is collected at 10Hz sampling frequency on a dedicated computer that requires an uninterrupted power supply. The data from slow meteorological the instrumentation on the mast is collected at 1Hz sampling frequency. This is archived as 10 minute averages on an Ammonit data logger (Neumann et al., 2003; Nolopp and Neumann, 2006), but possibly also as a raw data file on the FINO1 platform computer systems. Neumann et al. (2003) specify that the data logging system is set up to prevent data loss even if the platform cannot be accessed for several months, and the slow-logging system should function for 14 days in the event of a power failure (Neumann et al., 2004; Nolopp and Neumann, 2006). The data are telemetered via radio uplink through Borkum to a computer at DEWI (Neumann et al., 2004), and are displayed in almost real time on the BSH computer systems.

6 6 For the oceanographic measurement systems, there is less information available about the logging system. Most of the oceanographic data are recorded and processed within their own sensor units (e.g., Wamos wave radar, Datawell Wave Rider, Seabird SBE 37 CTD; AWAC) and logged at various time intervals from 3 30 minutes. O. Outzen (personal communication, 2013) sent information that most of the oceanographic data are logged on one platform computer with a second dedicated computer for the WaMoS wave radar system. In addition to the data transmission by radio uplink, representatives of both DEWI and BSH make site visits to FINO1 platform at 5-8 week intervals (or sometimes longer if there are poor weather conditions in winter), and hard disk backups are made at this time of their respective computer systems (O. Outzen, personal communication, 2013). As originally designed, it was intended that the computer systems of FINO1 could be externally controlled and programmed, and not act only as passive data recording devices as is normal geophysical practice. The rationale was to introduce flexibility in the preparation of measurement campaigns and data scanning. There are a number of organizations involved in the FINO program, and Fischer (2006) specifies that there are 20 clients linked into the FINO1 computer systems. The complete list of partner organizations is not clear, but a number have been identified by Rakebrandt- Grassner and Neumann (2003) as well as the website of current operator FUE GmbH ( A number of different public and private organizations have used FINO1 in different projects, and appear to have separate archives of the platform data (see Section 5 below). 4. Recognized Problems in the FINO Data Set The FINO1 platform was initiated and designed to gain knowledge about atmospheric and oceanic boundary layers in a region far offshore that had previously not been the well investigated. The platform incorporated state-of-art features to enable a continuous series of met-ocean measurements, and meteorological data are regarded as having higher quality than information from offshore oil rigs, which are known to have flow distortion effects (Berge et al. 2009). On the other hand, the FINO1 dataset is not without problems, and these are revealed in a careful survey of the literature and also from information from the data providers. Part of the data problems were introduced with the initial experimental design of platform, but other problems developed during the course of the extended measurement series and the way that instrument system is maintained Mast Flow Distortion and Wind Speed For the wind energy applications, the biggest problem is distortion of flow associated with the large selfsupporting mast at FINO1 and its impact on wind-measurement instruments. This was recognized from the start of experiment design, and is a feature of all high meteorological measurement masts. For FINO1, the vertical arrays of cup and sonic anemometers are on opposite sides of the mast. The cup anemometers on the southeast side of the mast are affected by flow distortion for incoming winds from the northwest quadrant. The sonic anemometers, facing toward the northwest, are the similarly affected when the winds from the southeast. Westerhellweg et al. (2011) state that wind speed reductions can be up to 40% in the immediate wake of the mast. However, comparison of wind speeds from the sonic and cup anemometers reveal that wind speeds are affected to a small extent in all directions due to lateral distortion effects, although the greatest anemometer effects are when the wind passes directly across the mast. Because the mast tapers upward and the orientation of the instrument supporting booms is not identical for all sensors, the flow distortions changes by a small amount according to the instrument height. The largest difference is associated with the top-mounted 100m cup anemometer, which does not show a directional mast distortion effect but does show speed-up effects of flow passing over the structure, in addition to distortion effects associated with a lightning cage (Beeken and Neumann, 2008). The turbulence field evaluated as the standard deviation of high frequency wind speed measurements

7 7 shows greater distortion effects (in comparison with wind speed) from the mast and lightning cage. No computational fluid dynamics model or scale analog model has been investigated to evaluate the wind flow distortion effects FINO1 (Riedel et al., 2005), in a similar to what has been performed for earlier measurement masts (Wills, 1982). Instead, different correction strategies have been formulated to mitigate the distortion effects. For example, the distortion effect of the lightning cage on the important 100m cup anemometer was evaluated by temporarily mounting an extra unprotected anemometer above the fixed instrument and comparing the instruments (Beeken and Neumann, 2008). The mast flow distortion of the vertical array of cup anemometers was evaluated by comparison with the sonic anemometers for certain wind directions in unstable atmospheric conditions (Westerhellweg et al., 2011). Also, there have been several LIDAR deployments on FINO1 to the compare with mast anemometer instruments (Westerhellweg et al., 2011). The FINO1 wind data is provided by BSH without the correction algorithms applied, and many the investigations using FINO1 choose to exclude data from the mast impacted sectors Wind Direction The wind direction vanes on the northwest side of the mast also have points of the concern for data interpretation. These sensors would also have mast distortion effects, but in a different way from cup anemometers on the opposite side of the mast. The most serious problem is that the wind vanes at 30m and 90m are logged differently from the two middle wind vanes at 50m and 70m. While the data records for the 30m and 90m instruments are complete, there are large gaps in the 50m and 70m records in the northern sector where direction values cross from 0 to 360 degrees (F. Kinder, personal communication, 2013). The BSH website presents information for additional wind direction at 40, 60, and 80m. These have been calculated as 10-minute averages from the fast sonic anemometers, and calibrated against the good wind vane data. The 30m and 90m wind direction records appear to give the best and most independent information, and most investigations use the 90m data for wind direction Flagging Bad Data For the air temperature data, there are problems with the quality identification flags. For some sensors on the mast, there is a problem with the way that data are recorded at the start of each month so that 0 C are registered in the data record instead of a no-data flag. For other time periods, the air temperature data records appear to register values that are physically too high or low to be realistic. These mostly occur on very limited time intervals, and can be identified from a first difference time series and eliminated using a simple threshold filter. The air temperature sensors are unventilated (Nolopp and Neumann, 2006), and they might therefore be susceptible to solar heating effects in the daytime, but at least for the 2005 investigation period of this report, it was not an obvious problem Anomalies in the Logging Systems for the Slow and Fast Meteorological Data In the initial instrument setup of the meteorological mast, there were deviations in the way that the data from the slow profiling instruments were logged. It was originally intended for all the slow-profiling instruments to be logged on a single P414 Ammonit data logger (Neumann et al., 2003; Nolopp and Neumann, 2006). Most of the instruments are recorded on a single logger, but the combined temperature/relative humidity sensor at 50m and the air temperature sensors at 100m and 33m are logged on the fast recording system intended for the sonic anemometer. The reasons for this anomalous set-up are the not clear, but Nolopp and Neumann (2006) indicate that the FINO1 measurement system was set up in a short period of 1-2 weeks near the end of the platform construction period in August, It is not clear if the deviation in the logging system introduces errors to the datasets, but plots of the vertical

8 8 temperature profiles do not anomalies in the 100m air temperature in comparison with the rest of the air temperature array Data Gaps from Instrument Malfunction, Power Loss, and Computer Failure There are gaps of varying lengths in the FINO1 time series for most parameters, and no period when complete met-ocean data is available. Figure 1 shows timelines of approximate data availability for selection of some of the instruments from FINO1, estimated from the BSH online plotting function. The graph is meant to illustrate general trends, and data gaps less than a month are not shown. Mostly, the data gaps appear together, indicating a general computer failure or power loss (O. Outzen, personal communication, 2013). Sometimes, the data gaps occur as specific instruments malfunction, and for 2005 the cup anemometer at 33m failed in October, creating a one month gap in the time series. The number of gaps tends to be smaller near the start of the measurement campaign, and show large gaps in the meteorology records. Generally, the BSH oceanographic component has fewer long-term data gaps than the DEWI atmospheric component. Some instruments have been shown to be more susceptible to damage in the extreme environment in comparison with others. For example, during the first winter deployment, there was damage to the central chain with the vertical array of oceanographic instruments during a storm in December, The ADCP, a bottom-mounted upward-looking sonar device to record ocean currents and surface properties, has experienced long periods of downtime as the result of damage to the power and communications cable from the platform to the instrument location on the sea floor (see Section 3.2). Fully functional, this instrument has the capability to deliver the most comprehensive view of the ocean and wave conditions at the FINO1 platform. The patterns of extended data gaps in the FINO1 record due to instrument failure may not be totally consistent with the expected instrument reliability rate on oceanographic research vessels. For an oceanographic research vessel of the type maintained by the Alfred Wegener Institute (AWI, one of the project partners), a meteorological recording system is not expected to be down for more than a few hours. On the other hand, the first UK unmanned offshore measurement tower at West Sole in the North Sea showed similar data-continuity problems as FINO1 (Wills and Cole, 1990), and this illustrates the challenges of the keeping an automated measuring facility in operation. The early onshore measurement tower at Froya in Norway (Andersen and Lovseth, 1995) also showed operational problems in the extreme meteorological conditions that it was targeting, but these could be repaired rapidly because the facility was technically onshore. The FINO1 data retrieval rate issue highlights an important operational problem in offshore wind energy operations that the difficulty of access to remote sites makes routine repairs difficult (Breton and Moe, 2009). At least for the FINO1 measurement platform, a premium might be placed on self-logging systems and mechanisms compartmentalize of expected damage. Most of the FINO1 met-ocean instruments have analogs on the oceanographic research vessels for which AWI has responsibility in Germany. Data-continuity from the FINO1 platform might be improved by applying a comparable AWI standard as for research vessels and taking advantage of the platform s onsite accommodation Data Post-Processing, Archival, and Statistics There have been issues with the way that the data are processed and archived. Currently, data from the slow profiling met-ocean instruments (i.e., all except the sonic anemometers) is archived as 10minute average quantities. Wind speed is an exception to the other instruments, and standard deviation, minimum, and maximum values over 10 minute time intervals are also archive. The absence of basic statistics in the met-ocean data makes it difficult to evaluate data quality in the case of poorly functioning

9 9 instruments. The air temperature record is an important example, where average data from an instrument acting erratically is difficult to quality control without other statistical information: median, minimum, maximum. In other cases like the Datawell wave rider buoy, there is important information in the original high frequency data recording that is lost in the longer time-averaged statistics. Unfortunately, archives of the original high-frequency (1Hz) data recordings from the slow-profiling instruments at FINO1 have been lost for the period before Summary of Research Using FINO1 Data A number of studies have been undertaken with the data collected on the FINO1 platform. Most of these have focused on meteorological information, but studies have been carried out with the oceanographic parameters, and there have also been investigations of the ecology around the platform as well as bed scouring effects and structural loading. Tables D1 and D2 in Appendix D show information extracted from the publications related to FINO1. Table D1 focuses on the data that has been used in the investigations together with processing notes. A careful reading of the literature reveals most of the data problems described in section 4. Table D2 is focused more on the concepts that have originated from the FINO1 publications. The earlier publications describe policy framework, planning, and intended measurement programs for the FINO1 platform (Neumann et al., 2003; Rakebrandt-Grassner and Neumann, 2003; Fischer, 2004). Subsequent publications show information about the data characteristics including the properties of the wind field and the expected the wind power generation of the Alpha Ventus wind farm. A few of the earlier publications (Argyriadis et al., 2005, 2006) focus more on extreme wind and wave events that are important for the loading of the offshore the turbines. The flow distortion effect of the mast is a problem that recurs in the published work, and many of the publications from the DEWI organization describe the methods used to quantify and correct for the problem, including LIDAR deployment. More recent investigations have synthesized FINO1 information into larger scale themes, such as quantification of wake effects within wind turbine array with high resolution satellite SAR data (Li and Lehner, 2013), evaluation of the WRF mesoscale model over the ocean (Berge et al., 2009; Munoz-Esparza et al., 2012; Nunalee and Basu, 2013), and assessment of shallow internal boundary layers near the coast (Lange, 2004, 2007). The literature has revealed some unexpected data surprises that have not yet been resolved. The platform experienced some damage on Nov. 1, 2006 on an access gangway below the main deck as the result of anomalously high waves (Herklotz, 2007; Emeis and Turk, 2009). Wave damage at other times is shown on the website of the platform operator ( The full information about the details of Nov.1, 2006 event is not known, partly because the high frequency 1Hz data was the lost from the official BSH FINO1 archives after On the other hand, high resolution 2s records from the Datawell buoy have appeared in a couple of recent publications (Hessner and Reichert, 2007; Pleskachevsky et al., 2012) that document the approximate characteristics of the rogue waves that hit the FINO1 platform on Nov. 1, The information is incomplete because waves were so high (i.e., so slowly accelerating) that they exceeded the measuring capacity of the Datawell buoy at individual troughs and crests. However, the information available indicates that they travelled in short trains of 3-4 large waves, and this was repeated 4 times in a time span of 8 hours (Hessner and Reichert, 2007). Very little information about rogue waves is known, and Pleskachevksy et al. (2012) has used the information from FINO1 to suggest a resonance coupling between the surface wave field and a storm moving across the North Sea from the northwest. The rogue waves are interesting because they are so rare and so little is understood about the dynamics or statistics. Research on the phenomena is constructed the around careful analysis of a limited number of single events (Dysthe et al., 2008).

10 10 Waterspouts are another extreme event that has potential implications for the integrity of offshore measurement masts and turbines. Several of these were photographed passing the FINO1 platform during a site visit on Aug. 25, 2005 (Dotzek et al., 2005). Although these waterspouts did not strike the FINO1 platform on this occasion, Dotzek et al. (2012) calculated a high probability of a waterspout encounter with some element offshore wind energy infrastructure in the Germany as it is expected to develop in the future. One waterspout is expected to occur within the boundary of a future German offshore wind farm every two years, and it is not clear how a wind farm wake may affect the path of a waterspout. Although the FINO1 data archive of wind speed at 10Hz has been used in a bottom-up approach to estimate the recurrence period of extreme wind speeds, the simple analysis of the Dotzek et al. (2005) may provide the most robust prediction of the maximum wind speed that an offshore turbine may encounter during a year operation lifetime. Although offshore turbines are designed to withstand hurricane force winds, the possible effect of unusual shear conditions in a waterspout is not clear, and there is a precedent for substantial infrastructure damage to coastal wind farms from unexpected wind conditions in other parts of the world (Winther-Jensen and Jorgensen, 1999). References: Andersen, O.J. and J. Lovseth, Gale force maritime wind. The Froya data base. Part I: Sites and instrumentation. Review of the data base, Journal of Wind Engineering and Industrial Aerodynamics, 57, , Argyriadis, K., G. Fischer, P. Frohbose, D. Kindler, and F. Reher, Forschungsplattform FINO1 einige Messergebnisse, Tagungsband der 4. Tagung Offshore-Windenergie am 14/15 Juni, 2005 Hamburg, Germanischer Lloyd Windenergie GmbH, Hamburg, Argyriadis, K., G. Fischer, P. Frohbose, D. Kindler, and F. Reher, Research Platform FINO1 some measurement results, EWEC 2006 Athens, Beeken, A. and T. Neumann, Five years of offshore measurements of the FINO1 platform in the German Bight, DEWI Magazin, 33, pp. 6-11, Aug Berge, E., O. Byrkjedal, Y. Ydersbond, and D. Kindler, Modelling of offshore wind resources. Comparison of a mesoscale model and measurements from FINO1 and North Sea oil rigs, EWEC 2009 Marseille, Parc Chanot, Marseille, France, March 16-19, Breton, S.P. and G. Moe, Status, plans and technologies for offshore wind turbines in Europe and North America, Renewable Energy, 34, , Canadillas, B., D. Munoz-Esparza, and T. Neumann, Fluxes estimation and the derivation of the atmospheric stability at the offshore mast FINO1, EWEA Offshore 2011, Nov.28-Dec.1, 2011, Amsterdam, Netherlands, Datawell bv, Manual for the WAVEC buoy, Datawell bv Laboratory for Instrumentation, Zomerluststraat 4, 2012 LM Haarlem, The Netherlands, Dotzek, N., S. Emeis, C. Lefevre, and J. Gerpott, Waterspouts over the North and Baltic Seas: Observations and climatology, prediction and reporting, Meteorologische Zeitschrift, 19, , Dysthe, K., H.E. Krogstad, and P. Muller, Oceanic rogue waves, Annu. Rev. Fluid Mech., 40, , Emeis, S. and M. Turk, Wind-driven heights in the German Bight, Ocean Dynamics, 59, , Fischer, G., Die BMU-Forschungsplattform FINO 1 Erfahrungen beim Bau und Messbetrieb, Fischer, G., 15. Installation and operation of the research platform FINO1 in the North Sea, in J. Koller, J. Koppel, and W. Peters (ed.), Offshore Wind Energy, Springer-Verlag, Berlin, Herklotz, K., Oceanographic results of two years operation of the first offshore wind research platform in the German Bight FINO1, DEWI Magazin No. 30, 47 51, 2007.

11 Hessner, K. and K. Reichert, Sea surface elevation maps obtained with a nautical x-band radar examples from WaMoS II stations, 10 th International Workshop on Wave Hindcasting and Forecasting and Coastal Hazard Symposium, North Shore, Oahu, Hawaii, Nov , Jelacic, A.J., Physical limnology of Green and Round Lakes, Fayetteville, New York, Ph.D. Thesis, University of Rochester, New York, Lange, B., Comparison of wind conditions of offshore wind farm sites in the Baltic and North Sea, Proceedings of the German Wind Energy Conference DEWEK 2004, Wilhelmshaven, Germany, Lange, B., Offshore wind power meteorology, in Proceedings of the Euromech Colloquium, ed. by J. Peinke, P. Schaumann, and S. Barth, Springer, Munoz-Esparza, D. and B. Canaillas, Forecasting the diabatic offshore wind profile at FINO1 with the WRF mesoscale model, DEWI Magazin No. 40, February, Neumann, T., K. Nolopp, M. Strack, H. Mellinghoff, H. Soker, E. Mittelstaedt, W.J. Gerasch, and G. Fischer, Errichtung der ersten deutschen Offshore Wind Messplattform in der Nordsee, DEWI Magazin, No. 23, August, Neumann, T. and A. Beeken, Erkenntnisse aus 6 Jahren Windmessungen auf FINO 1, conference pdf presentation downloaded from Neumann, T., E. Mittelstaedt, W.J. Gerasch, and G. Fischer, Erection of German Offshore Measuring Platform in the North Sea, DEWI Magazin No. 23, August Neumann, T., K. Nolopp, and K. Herklotz, Erste Betriebserfahrungen met der FINO1- Forschungsplattform in der Nordsee, DEWI Magazin, Nr. 24, Feb Nolopp, K. and T. Neumann, Temperature measurement on the FINO1 platform, DEWI Magazin No. 28, 54-59, Februar NORSOK Standard N-003, Actions and action effects, Edition 2, September, Nunalee, C. and S. Basu, Mesoscale modeling of low-level jets over the North Sea, in Wind Energy: Proceedings of the Euromech Colloquium, ed. by J. Peinke et al., Pleskachevsky, A.L., S. Lehner, and W. Rosenthal, Storm observations by remote sensing and influences of gustiness on ocean waves and on generation of rogue waves, Ocean Dynamics, 62, , Rakebrandt-Grassner, P. and T. Neumann, The German research platform in the North Sea, OWEMES 2003, Proceedings of a conference held in Naples, Apr , Riedel, V., F. Durante, T. Neumann, and M. Strack, The first year of measurements on the FINO1 Platform in the North Sea Evaluation and analysis of the wind profile and assessment of the statistical long-term mean value, DEWI Magazin Nr. 26, Februar Schaumann, P. and C. Boker, Influence of wave spreading in short-term sea states on the fatigue of offshore support structures at the example of the FINO1-research platform, DEWI Magazin, Nr. 30, 51 57, Tautz, S., B. Lange, and D. Heinemann, Correction of the heat and momentum flux measurements with the ultrasonic anemometers at the FINO1 offshore meteorological mast for the flow distortion and mounting effects, Proceedings, DEWEK Westerhellweg, A., V. Riedel, and T. Neumann, Comparison of Lidar- and UAM-based offshore mast effect corrections, EWEA 2011, Brussels, 2011 Wills, J.A.B., Report on the West Sole wind structure project 1982, National Maritime Institution (NMI) Report R145, OT-R-8240, Wills, J.A.B. and L.R. Cole, Wind measurement at West Sole Final Report, Contractor Report, ETSU WIN 5081, Department of Energy, Winther-Jensen, M. and E.R. Jorgensen, When real life wind speed exceeds design wind assumptions, 1999 European Wind Energy Conference, Mar. 1-5, 1999, Nice, France, pp ,

12 12 Figure 1. Approximate timelines of data availability from the FINO1 platform constructed from the BSH online data plotting function. Data gaps that are less than approximately month are not shown. Some of trends are unexpected, and the gaps in the original data should be verified. The BSH indicates that the rainfall data may only be available for one year, but this may actually be longer. Some of the parameters are generated in combination with other parameters from the same instrument (e.g., current direction and speed from AWAC or temperature, salinity and pressure data from the CTD), and it is not clear why the different data timelines would not be identical. Appendix A. Diagrams of FINO1 structure and seabed core profile during seabed study at Borkum Riff.

13 13

14 14 Figure A1. Scale figure of FINO1 structure with mast, jacket, and seabed piles (Rakebrandt-Grassner and Neumann, 2003; see also Neumann et al., 2003). Figure A2. Plan diagram of main deck with location of mast, containers and helicopter pad (Rakebrandt- Grassner and Neumann, 2003; see also Neumann et al., 2003).

15 15

16 16 Figure A.3. Borehole profile from seabed investigation at Borkum Riff, Oct (downloaded from the FINO1 website) Appendix B. Record of correspondence associated with FINO1 data Table B1. Information provided by F. Kinder Date Information 10/11/2011 -The FINO1 wind measurements are affected by the mast, and this is described by Westerhellweg et al., Comparison of LIDAR- and UAM-based offshore mast effect corrections, EWEA2011, Brussels, /11/2011 -The UAM method is a correction to the measured wind speed from based on the Windcube LIDAR; the accuracy of the correction decreases further away from the top of the mast; correction to the 30m level had not yet been published. 23/11/2011 -The 10min text files of sonic data do not include data from the anemometer cups or wind vanes: the horizontal velocity and direction are derived from u and v. -The sonic anemometers have significant offsets from north, and instrument corrections have to be applied according to when and to whom the data set was released. -The corrections that should be applied to the current sonic data are: 80m: 320 or -40degrees; 60m: 59.5degrees; 40m: 53.5degrees -Another year of data can be released on request (2004 was requested). 24/11/2011 -The sonic anemometer data files for 2005 were made accessible on an ftp site for download. 19/01/2012 -There was a query on the offsets to apply to the sonic anemometer data. 24/01/2012 -The directional offset of the wind vanes was determined with a compass. The wind direction from the sonic anemometers was compared with the wind vane measurements to derive the sonic anemometer direction corrections. The directions of sonic anemometers should agree with the wind vanes exactly (since they do represent independent direction information). 24/01/2012 -There is ambiguity in the wind direction record in the BSH FINO1 website. There are wind vanes only at 30,50,70, and 90m; the sonic anemometers are at 40,60, and 80m 07/02/2013 -F. Kinder at DEWI also sees a few air temperature outliers every month -The reason for outliers not certain but assumption of defect in logging system; sets error flag -The problem in the air temperature record was not known in Hz meteorological data only exists since There is 1 minute data available at DEWI for 2005 but this has outliers like the 10min record -The leap over north is considered when averaging wind conditions 08/02/2013 -There is a datasheet attachment with information on sensors & placement on FINO1: sensor_readme_new_ pdf -The 10min means are based on 1Hz measurements -There are no available 1Hz measurements before /02/2013 -There is confusion on the Thies website about thermohygro transmitter; there is a scanned picture of the thermohygro instrument. -1Hz data not held by T. Neumann, O. Outzen or DEWI -The 1s gust reference in Neumann & Nolopp is the 1s maximum wind that is logged in the 1 minute record along with mean, minimum, and standard deviation. 22/02/2013 -A photograph of air temperature/relative humidity housing was attached. -The heights in FINO database are given as general mast level or initial intended installation height -The official height reference was changed from Seekartennull (SKN) to LAN -Tidal variations mean that instruments heights changing all the time -Air temperature outliers likely due sudden electrical changes; best to remove them 18/04/2013 -Two photographs of cup anemometers taken on Mar 17, 2011 & Aug. 6, /08/2013 -The cup anemometers were exchanged in Aug The cup anemometers are exchanged every year -A malfunctioning cup anemometer at 34m was exchanged in Oct The wind vanes at 51m & 71m have excluded sectors near north 09/08/2013 -The FINO1 cup anemometers were exchanged on Aug. 2, 2005, with an associated data gap between UTC. -The calibrations between the old and new sets of anemometers already applied to the dataset. -The signal around the north mark of the 51m & 71m wind vanes cannot be recorded completely -Wind vanes are not pointing north, but have an offset already considered in the data -The height designation LAT is lowest astronomical tide 21/08/2013 -Wind direction at 50m and 70m were sampled and logged differently compared with 30m 90m. During post-processing significant amounts of data were removed from the 50m and 70m datasets, making the entire data difficult to interpret. The sampling logging differences at different heights were implemented intentionally as part of a test. -The 50m relative humidity data is not part of the standard data suite released by BSH. The instrument does not function as well as the instrument 33m and 100m and will be removed in the future. -The 33m temperature data was recorded on the different data logger (i.e., same at the 50m relative humidity) compared with the other air temperature measurement. -The wind vanes record the direction of an internal compass. The mounting direction information is supplementary information. 25/09/2013 -The qualitative precipitation sensor at deck level was exchanged for a quantitative device on Oct. 9, To maintain continuity of the 0-1 record the amount of precipitation is not in the database; only the presence/absence of precipitation.