Tide Gauge Records, Macquarie Island

Tides are recorded at Macquarie Island using two sensors, one an acoustic height measuring system and the other a pressure measuring system. The raw records are stored at AADC.\n The records are processed by The National Tidal Centre to produce tidal records, predictions and residuals.\n \n Documentation dated 2001-06-12\n The Macquarie Island Tide Gauge System\n \n The Macquarie Island Tide Gauge was first commissioned in November 1993. Since then every year attempts have been made to improve the performance of the system.\n The next improvement involves the installation of radio modems to effect a network link to the tide gauge dataloggers. Other improvements planned are include using the wave guide temperatures to correct the water heights for variations in the velocity of sound in air due to temperature gradients in the waveguide. \n The system consists of two separate sensors contained in separate housings on a rock shelf on the northern side of Garden Cove. One of the sensors is an Aquatrack acoustic type and the other is a Druck pressure transducer. Both housings contain a Platypus Engineering data logger and a battery. The housings consist each of an Admiralty Bronze ring bolted down to a concrete plinth and a glass fibre reinforced cover held down by a single central bolt and nut. \n Primary power for both installations comes from a solar panel array mounted on the northern side of the rock ridge behind the rock shelf. The solar panels are attached to an aluminium frame which is bolted to a galvanized steel frame cemented into holes in the rock face. The bolts are made of nylon with nylon washers so that the aluminium frame is not in contact with the galvanized frame.\n Mounted below the panels is a sealed plastic box with a hinged door. A multicore data cable runs from this box to the tide gauge housings. This cable is run inside a length of plastic conduit along with the power cable. The conduit is concealed in the vegetation and at the lower level is cemented into slots cut into the rock\n The batteries in the housing are kept charged by the solar panels but are isolated via power diodes, one in each housing. Either or both of the housing batteries or only the solar panel battery may be removed without interruption to data logging. The voltage of either housing battery may be found by interrogation of the appropriate data logger.\n \n Tide Gauge Bore Holes.\n \n Both gauges obtain access to the ocean via an inclined hole about 12 metres long inclined at approximately 34 and 39 degrees to the horizontal. Both holes are lined with a plastic pipe which is normally not removable. In the Aquatrack sensor hole a 50mm ABS pressure pipe runs down inside the liner and is fitted with a brass strainer and orifice at the lower end. This strainer protrudes into the ocean somewhat clear of the sea floor (see figure). Inside the 50mm pipe runs a 15mm diameter plastic pipe. The bottom end of this is fitted with a 600mm length of red brass tubing and stops about 100mm from the orifice at the bottom of the pipe. The 15mm pipe is held central in the 50mm pipe by three armed spiders placed about every metre down the pipe. The top end of both pipes is secured by a flange with two O rings and stainless steel screws. On top of the 15mm pipe is mounted the Aquatrack acoustic sensor the 15mm pipe acting as a waveguide for sound pulses from the sensor (see figure ). The Aquatrack sensor measures the distance of the water surface from a reference point on the sensor. About one metre down the wave guide is a small hole. This has two functions. One is to act as vent to allow water to rise and fall in the wave guide and the other is to provide an acoustic reflection at a known distance down the wave guide. This allows compensation for velocity of sound changes due to temperature changes.\n The Aquatrak wave guide has a series of thermistors placed along its length. The bottom one is always submerged and is used to measure the seawater temperature..The top one is placed just below the Sensor and the others evenly spaced along the length of the waveguide. The temperature readings from these can be used to compensate for the change in the velocity of sound due to density changes. This feature has not yet been used.\n The Druck Sensor has a single thermistor placed beside it which measures seawater temperature.\n \n System Components. \n \n The Aquatrak Installation houses four main components.\n 1. The Aquatrack Sensor and Waveguide Assembly. The sensor itself is in a waterproof plastic tube with a cable with a waterproof connector which plugs into the Bartek controller.\n 2. The Bartek Controller, housed in a waterproof diecast box with waterproof connectors. This lies in the centre of the installation housing.\n 3. The Platypus Engineering Datalogger \n 4. The Battery, a 15 Ah, 12 volt sealed gel cell lead acid battery. It is charged from the solar a diode. The battery lies in the main housing opposite the Datalogger .\n \n The Druck Installation houses four main components\n 1. The Druck Pressure Sensor, fitted to the end of a 13 metre cable, submerged in seawater about 10 metres down the borehole.\n The cable has five conductors and an air vent enclosed within it.\n 2. The Pressure Sensor Amplifier housed in a waterproof diecast box. This box has a vent leading to a vented bottle filled with silica gel to keep the transducer air vent dry.\n 3. A Datalogger As above.\n 4. A battery as above \n \n The Solar Panel Installation has three main parts.\n 1. Three Photo Voltaic Solar Panels, two 60 Watt and one 30 Watt. These are mounted on an aluminium frame attached to a hotdip galvanised steel frame with insulating bolts. \n 2. A sealed plastic box mounted below the panels containing a12V 24 Ah Battery and a regulator and the radio modem equipment. (The modems are not currently fitted.)\n 3. Antennae and cables protected with flexible conduit.\n Data Retrieval\n \n Data have been retrieved at approximately 30 day intervals from the Garden Cove gauges by using a portable computer to download the data loggers. The connector for this is in the enclosure by the solar panels allowing the loggers to be accessed during bad weather.\n \n Documentation dated 2008-10-17\n 1. In April 2007, the dataloggers and radio modems at Macquarie Island Tide Gauge site were replaced with Campbell Scientific CR1000 dataloggers.\n 2. This change enabled data to be streamed from the pressure sensor datalogger every 30 seconds.\n 3. There has been no change to scaling of records from the Aquatrak sensor as generation of ranges is done by the Aquatrak controller, the datalogger only saving and transmitting the records.\n Records from the pressure sensor however are now not converted to heights but saved and streamed as raw A/D conversion values.\n It is intended that appropriate scales and offsets for this sensor be derived after a Floating GPS Buoy exercise.\n 4. Data is streamed from the pressure sensor logger as this is the only sensor that can be supply 30 seconds average values.\n This logger also streams 3 minute average values.\n 5. The aquatrak sensor logger streams 3 minute average value ranges.\n 6. Data is streamed in NVP (name/Value Pair) format as defined by BoM.\n 7. Embedded in the streams are battery voltage and aquatrak waveguide temperature values.

麦夸里岛采用两套传感器开展潮汐观测，一套为声学高度测量系统，另一套为压力测量系统。原始观测记录存储于AADC。
所获原始记录由国家潮汐中心（National Tidal Centre）进行处理，以生成潮汐记录、潮汐预报值及残差数据。

**文档日期：2001年6月12日**
麦夸里岛潮位站系统
麦夸里岛潮位计于1993年11月首次投入运行，此后运维团队每年都致力于提升该系统的运行性能。
下一阶段的升级计划部署无线电调制解调器，以实现潮位计数据记录仪与网络的连接；此外还计划利用波导温度数据，修正因波导内温度梯度导致的空气声速变化所引起的水位高度计算误差。

该系统的两套独立传感器分别安装于花园湾（Garden Cove）北侧岩架的独立防护外壳内，其中一套为Aquatrack声学传感器，另一套为Druck压力传感器。每套防护外壳内均搭载一台Platypus Engineering数据记录仪与一块蓄电池。每套外壳均采用海军上将青铜（Admiralty Bronze）环形螺栓固定于混凝土基座之上，并搭配一块玻璃纤维增强材质的外盖，由单根中央螺栓与螺母紧固。

两套观测装置的主电源均来自岩架后方山脊北侧安装的太阳能电池板阵列。太阳能电池板固定于铝制支架，该支架通过螺栓连接至镀锌钢框架，而镀锌钢框架则通过水泥锚固于岩壁钻孔内。所有螺栓均采用尼龙材质并搭配尼龙垫圈，以避免铝制支架与镀锌框架直接接触。

电池板下方安装有带铰链门的密封塑料接线盒。多芯数据电缆从该接线盒延伸至潮位计防护外壳，与电力电缆一同敷设于塑料穿线管内。穿线管隐蔽于植被中，下段则通过水泥锚固于岩壁开凿的线槽内。

防护外壳内的蓄电池由太阳能板充电，但通过功率二极管实现电气隔离——每套外壳内各配备一枚二极管。可单独或同时拆卸两套外壳内的蓄电池，也可仅拆卸太阳能板侧的蓄电池，均不会中断数据记录工作。通过查询对应的数据记录仪，即可获取任意一套外壳内蓄电池的电压值。

潮位计钻孔
两套潮位计均通过约12米长的斜孔与海洋连通，斜孔与水平面的夹角分别约为34度与39度。两个钻孔均预埋不可拆卸的塑料衬管。在Aquatrack传感器的钻孔内，一根50mm口径的ABS压力管敷设于衬管内部，其下端安装有黄铜滤水器与孔口，该滤水器突出于海底上方一定距离（详见示意图）。50mm压力管内部还布设了一根直径15mm的塑料管道，其下端连接一段600mm长的红黄铜管，末端距离管道底部孔口约100mm。15mm管道通过每隔1米设置的三爪支撑架固定于50mm管道的中心位置。两根管道的顶端均通过带双O形密封圈与不锈钢螺钉的法兰盘固定。15mm管道的顶端安装有Aquatrack声学传感器，该管道同时作为传感器声波脉冲的波导（详见示意图）。Aquatrack传感器通过测量传感器参考点至水面的距离获取水位数据。在波导下方约1米处设有一个小孔，具备两项功能：一是作为通气孔，允许波导内的水位随海洋水位升降；二是在波导内已知距离处提供声波反射点，用于补偿因温度变化导致的声速改变。

Aquatrak波导沿其长度方向布设了一系列热敏电阻：最底部的热敏电阻始终浸没于海水中，用于测量海水温度；最顶部的热敏电阻安装于传感器下方，其余热敏电阻沿波导长度均匀分布。利用这些热敏电阻的温度读数，可以补偿因海水密度变化导致的声速改变，但该功能尚未投入使用。

Druck传感器旁侧安装有一枚热敏电阻，用于测量海水温度。

系统组成部件
Aquatrack观测装置包含四大核心部件：
1. Aquatrack传感器与波导组件：传感器封装于防水塑料管内，配套带有防水连接器的电缆，可接入Bartek控制器。
2. Bartek控制器：封装于带防水连接器的压铸防水盒内，安装于观测装置防护外壳的中央位置。
3. Platypus Engineering数据记录仪
4. 蓄电池：15Ah、12V密封胶体铅酸蓄电池，通过二极管由太阳能板充电，安装于主防护外壳内与数据记录仪相对的一侧。

Druck观测装置同样包含四大核心部件：
1. Druck压力传感器：连接于13米长电缆的末端，浸没于钻孔下方约10米的海水中。该电缆内含5根导线与一根通气管。
2. 压力传感器放大器：封装于压铸防水盒内，该盒带有通气管道，连接至填充有硅胶的通气瓶，以维持传感器通气口的干燥环境。
3. 数据记录仪：与前述规格一致
4. 蓄电池：与前述规格一致

太阳能电池板装置包含三大组成部分：
1. 三块光伏太阳能电池板：两块60W与一块30W，安装于铝制支架，该支架通过绝缘螺栓连接至热浸镀锌钢框架。
2. 电池板下方的密封塑料接线盒：内置12V 24Ah蓄电池、电压调节器与无线电调制解调器设备（目前尚未安装调制解调器）。
3. 天线与电缆：采用柔性穿线管进行防护。

数据获取
工作人员通常每隔约30天使用便携式计算机连接数据记录仪，从花园湾潮位计处下载观测数据。数据下载接口位于太阳能板旁的防护外壳内，便于在恶劣天气下开展数据获取工作。

**文档日期：2008年10月17日**
1. 2007年4月，麦夸里岛潮位站的数据记录仪与无线电调制解调器已升级为Campbell Scientific CR1000数据记录仪。
2. 此次升级实现了压力传感器数据记录仪每30秒一次的数据流式传输。
3. Aquatrak传感器的记录缩放比例未作调整，因为量程生成工作由Aquatrak控制器完成，数据记录仪仅负责存储与传输记录数据。但压力传感器的记录数据不再转换为水位高度，而是以原始模数转换（A/D）值的形式存储并流式传输。后续计划通过浮动GPS浮标试验，为该传感器推导合适的缩放系数与偏移量。
4. 压力传感器记录仪会持续流式传输数据，因其是唯一可提供30秒平均值的传感器，该记录仪同时还会传输3分钟平均值。
5. Aquatrak传感器记录仪会传输3分钟平均值的量程数据。
6. 数据以BoM（澳大利亚气象局，Bureau of Meteorology）定义的NVP（名称/值对，Name/Value Pair）格式进行流式传输。
7. 流式传输的数据中包含蓄电池电压与Aquatrak波导温度值。