Myrmidon Reef Automated Marine Weather And Oceanographic Station

This dataset contains meteorological and sea temperature data from the weather station moored on Myrmidon Reef on the Great Barrier Reef. These data are collected to support scientific research at AIMS. Data are made available on request to other researchers and to the public. The weather station is an AIMS Mk3 System.Data recorded: Sea Temperature (~2m, ~4m, ~7m and ~18m at MSL), Barometric Pressure, Air Temperature, Solar Radiation (PAR), Wind Direction True (vector averaged), Wind Speed True (30 min average).This weather station has been deployed in two different locations on Myrmidon Reef.Location 1: -18.2746, 147.3830 from 1987 until June 1999Location 2: -18.267, 147.367 from June 1999 to present.1. Operation and Weather SensorsThe weather stations collect and store data in electronic memory every half-hour. A central base station calls each remote station regularly using HF radio or telephone lines. The data is transmitted over the radio as a frequency shift keyed signal, organised as packets of information. Errors are detected using parity and check sum methods. Invalid packets are identified by the Base Station, which requests they be sent again. This concept allows recovery of a very high percentage of the data despite poor communications. Remote stations store data for 21 days. Features such as automatic operation, remote control, remote time setting, built in diagnostics, have been developed and incorporated.The sensors are a key part of a weather station. The following are chosen considering the cost, reliability and accuracy.* R.M.Young manufactures the wind sensor, a model number 05103. It is a propeller type with the advantages of being highly linear, highly interchangeable and having a low threshold. Wind direction is measured as the direction the wind is coming from.* The solar radiation sensor is an Under Water Quantum Sensor made by Licor. It measures light in terms of its "Photosynthetically Active Radiation" (PAR). The spectral response is defined and weighted. Drift due to aging of the filters has proven to be a problem, but this applies to similar units too.* Temperature sensors are all Omega Interchangeable Thermistors. These are interchangeable and have high accuracy, but reliability has proven a problem. We are considering alternatives.* The barometric sensor was a modified Aanderaa type on earlier stations. The Mk2 stations were fitted with a Weathertronics Unit. Now all stations are Mk3 stations fitted with a Vaisala barometer which is more interchangeable and more accurate.2. System AccuracySystem accuracy is calculated as the sum of errors caused by: * Calibration * Interchanging sensors * Drift with time * Effects of an ambient temperature range from 0-40 degrees C.The following are the specifications of the sensors used with Mk3 stations. A new sensor suite will be used with Mk5 stations, partly based on the Vaisala WXT510 weather sensor.Both the temperature and wind sensors are interchangeable, and not individually calibrated, though some individual sensors have been checked against standards.* Air Temperature: Interchangeable thermistor and electronics is within +/- 0.4 deg. C, with a 30 seconds settling time in air. There are additional errors due to the aspiration of the temperature screen at low wind speeds.* Water temperature: Interchangeable thermistor and electronics is within +/- 0.4 deg. C, with a 30 minutes settling time in water. A higher precision in situ calibration is normally used (around +/- 0.1 degrees), traceable to a 0.04 degrees standard.* Solar radiation (PAR): +/- 5% of reading. Sensor drift is approximately -4% per year initially.* Barometric pressure: +/- 1 hecto Pascal.* Wind speed: 2% of reading +/- 0.1% FSD.* Wind direction: 2% of reading +/- 0.1% FSD.Electrical settling time for solar radiation and wind parameters is 7 seconds. This is necessary for anti-aliasing filters. Mk1 and Mk2 stations averaged 16 samples over the 16 seconds before logging. Mk3 stations use a continuously averaging software system. The wind readings are vector averaged, so direction is accounted for properly.Calibration procedures and routines are detailed on the Engineering website.3. Wind Sensor SpecificationThe following are additional specifications of the wind sensors used with Mk3 stations. A new sensor will be used with Mk5 stations. Wind sensors are mounted at a nominal 10 meters above water. The R.M. Young sensor has the following characteristics:* Wind SpeedRange: 0-60 m/sPitch: 29.4 cm air passes per rev.Distance constant: 2.7 m for 63% recovery* Wind DirectionRange: 360 deg, with 5 deg electrically open at northDamping ratio: 0.25Delay distance: 1.5 m for 50% recoveryThreshold: 1.0 m/s @ 10 deg.Displacement: 1.5 m/s @ 5 deg. displacement Damped w/length: 7.4 mUndamped w/length: 7.2 m4. Underwater Temperature SensorsThese sensors are interchangeable thermistors in Mk3 stations. They can be mounted a significant distance from the weather station, using a 2 wire connection. The basic accuracy is due to the use of interchangeable units. However improved accuracy is obtained by calibrating against a precision reference sensor in situ. These are in turn calibrated against a standard traceable to 0.04 degrees.

本数据集包含部署于大堡礁（Great Barrier Reef）迈尔米顿礁（Myrmidon Reef）的锚定气象站所采集的气象与海水温度数据。这些数据旨在支持澳大利亚海洋科学研究所（Australian Institute of Marine Science, AIMS）的科研工作，可应其他研究人员及公众的申请对外共享。该气象站为AIMS Mk3系统。
所记录的数据包括：海水温度（位于平均海平面（Mean Sea Level, MSL）以下约2m、4m、7m及18m处）、大气压力、空气温度、光合有效辐射（Photosynthetically Active Radiation, PAR）太阳辐射、真风向（矢量平均）、真风速（30分钟平均值）。
该气象站曾在迈尔米顿礁的两个不同点位部署：
点位1：坐标为-18.2746, 147.3830，运行时段为1987年至1999年6月；
点位2：坐标为-18.267, 147.367，运行时段为1999年6月至今。

1. 运行机制与气象传感器
气象站每半小时采集并存储一次数据。中央基站通过高频（HF）无线电或电话线定期轮询各远程站，数据以频移键控信号形式通过无线电传输，封装为结构化信息数据包。基站通过奇偶校验与校验和方法检测传输错误，识别无效数据包并请求重传，该机制可在通信条件不佳的情况下恢复极高比例的有效数据。远程站可本地存储21天的采集数据，系统集成了自动运行、远程控制、远程时间设置及内置诊断等功能模块。
传感器是气象站的核心组成部分，选型综合考量了成本、可靠性与精度三项核心指标：
* 风速风向传感器由R.M.Young公司制造，型号为05103，为螺旋桨式传感器，具备高线性度、高互换性与低启动阈值特性，风向测量结果表征风的来向。
* 太阳辐射传感器为Licor公司生产的水下量子传感器，以光合有效辐射（PAR）为单位量化光照强度，其光谱响应已完成标准化定义与加权校准。传感器滤光片老化导致的漂移是已知共性问题，同类产品均存在该缺陷。
* 温度传感器均为Omega公司的互换式热敏电阻，具备良好的互换性与高精度特性，但实际应用中暴露出可靠性不足的问题，目前团队正在评估替代方案。
* 早期气象站搭载经过改装的Aanderaa型气压传感器，Mk2站点配备Weathertronics气压采集单元。当前所有站点均升级为Mk3系统，搭载互换性与精度更优的Vaisala气压计。

2. 系统精度
系统总精度由以下误差项之和计算得出：校准误差、传感器互换带来的误差、随时间产生的漂移误差，以及环境温度范围0~40℃带来的温度效应误差。
以下为Mk3站点所使用传感器的官方技术规格。Mk5站点将采用全新的传感器套件，部分选型基于Vaisala WXT510气象传感器。
温度传感器与风速传感器均具备互换性，无需单独定制校准，但部分传感器已通过国家级标准设备进行过精度校验：
* 空气温度：采用互换式热敏电阻与配套电子元件，测量精度为±0.4℃，在空气中的稳定响应时间为30秒；低风速条件下，温度防护罩的抽吸效应会引入额外测量误差。
* 海水温度：采用互换式热敏电阻与配套电子元件，测量精度为±0.4℃，在水中的稳定响应时间为30分钟；通常会通过现场高精度参考传感器进行二次校准，可将精度提升至±0.1℃左右，该参考传感器本身溯源至精度为0.04℃的国家标准。
* 太阳辐射（PAR）：测量误差为读数的±5%，传感器初始年漂移量约为-4%。
* 大气压力：±1百帕（hecto Pascal）。
* 风速：测量误差为读数的2% ± 0.1%满量程偏差（Full Scale Deviation, FSD）。
* 风向：测量误差为读数的2% ± 0.1%满量程偏差（Full Scale Deviation, FSD）。
太阳辐射与风速参数的电子稳定时间为7秒，该设置用于满足抗混叠滤波器的设计要求。Mk1与Mk2站点在数据记录前会对16秒内的16个采样点取算术平均，而Mk3站点采用连续平均的软件系统。风速读数采用矢量平均方式，可正确计算风向分量。
详细的校准流程与操作规范详见工程官方网站。

3. 风速传感器补充技术规格
以下为Mk3站点所使用风速传感器的补充技术规格。Mk5站点将采用全新的风速传感器方案。风速传感器的标称安装高度为距水面10米。R.M.Young型号05103传感器的核心特性如下：
* 风速：量程范围0~60 m/s；每转空气通过距离：29.4 cm；距离常数：2.7 m（对应63%的阶跃响应恢复）
* 风向：量程覆盖360°，正北方向电气开路误差为5°；阻尼比：0.25；延迟距离：1.5 m（对应50%的阶跃响应恢复）；启动阈值：1.0 m/s @ 10°入射风；位移灵敏度：1.5 m/s @ 5°风偏位移；阻尼长度：7.4 m；无阻尼长度：7.2 m

4. 水下温度传感器
Mk3站点的水下温度传感器为互换式热敏电阻，可通过两线制连接线缆实现远距离安装，脱离气象站本体。其基础精度来自于互换式元件的标准化设计，但通过现场使用高精度参考传感器进行原位校准，可获得更高的测量精度，而该参考传感器本身则溯源至精度为0.04℃的国家级温度标准。