Cape Bowling Green Automated Marine Weather And Oceanographic Station

This dataset contains meteorological data from the weather station located on Cape Bowling Green in North Queensland which has been collected since 31 July 1987.

Historical records for the period 9-7-1983 to 4-10-1985 have been retrospectively added to the dataset from a former Cape Bowling Green outstation (at the same location) after conversion from the original Fortran files. Note that there is a break in this middle of this data series as the outstation source was moved to Cape Ferguson (AIMS Wharf) and collected data there for the period 1-11-1983 to 30-5-1984. These historic data were collected using telemetery to send binary data daily to a computer controlled base station. Data were verified by comparing three sets of the same data, received over three days. The base station passed data to the central computing facility at AIMS for processing. Lightning destroyed this system in 1985.

Data recorded: Barometric Pressure, Air Temperature, Solar Radiation (PAR), Wind Direction True (vector averaged), Wind Speed True (30 min average).

These data are collected to support scientific research at AIMS. Data are made available on request to other researchers and to the public.

The current weather station is an AIMS Mk3 System.

1. Operation and Weather Sensors

The 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 Accuracy

System 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.
* 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 Specification

The 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 Speed
Range: 0-60 m/s
Pitch: 29.4 cm air passes per rev.
Distance constant: 2.7 m for 63% recovery
* Wind Direction
Range: 360 deg, with 5 deg electrically open at north
Damping ratio: 0.25
Delay distance: 1.5 m for 50% recovery
Threshold: 1.0 m/s @ 10 deg.
Displacement: 1.5 m/s @ 5 deg. displacement
Damped w/length: 7.4 m
Undamped w/length: 7.2 m

本数据集收录了澳大利亚昆士兰州北部鲍灵格林角（Cape Bowling Green）气象站自1987年7月31日起采集的气象数据。

1983年7月9日至1985年10月4日期间的历史记录，系从原鲍灵格林角分站（位于同一地点）的原始Fortran文件转换后，回溯增补至本数据集。需注意，该数据序列的中段存在一处中断：原分站曾迁至弗格森角（AIMS码头），并于1983年11月1日至1984年5月30日期间在此采集数据。上述历史数据通过遥测技术每日将二进制数据传输至计算机控制的基站进行采集，通过比对三天内接收的三套相同数据完成核验。基站将数据传输至澳大利亚海洋科学研究所（AIMS）的中央计算设施进行处理，1985年该系统因雷击损毁。

记录数据包括：气压、气温、光合有效辐射（Photosynthetically Active Radiation, PAR）、真风向（矢量平均）、真风速（30分钟平均）。

本数据集采集目的为支撑AIMS的科学研究，可应其他研究人员及公众的申请对外提供。

当前使用的气象站为AIMS Mk3系统。

1. 系统运行与气象传感器

气象站每半小时采集并存储数据至电子内存。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，封装为信息数据包。系统采用奇偶校验与校验和方法检测传输错误，基站识别无效数据包后请求重传，即便通信条件不佳，仍可恢复绝大多数数据。远程站可存储数据达21天，集成了自动运行、远程控制、远程授时、内置诊断等功能。

传感器是气象站的核心组成部分，本次选用的传感器均兼顾了成本、可靠性与精度：
* R.M.Young公司生产的05103型风速风向传感器：采用螺旋桨式设计，具备高线性度、高互换性与低启动阈值的优势。风向测量以风的来向为基准。
* 太阳辐射传感器：采用LI-COR公司生产的水下量子传感器，以光合有效辐射（Photosynthetically Active Radiation, PAR）为指标测量光照，具备标准化的光谱响应与加权特性。过滤器老化导致的信号漂移是已知问题，但同类传感器均存在该现象。
* 温度传感器：全部采用Omega公司的可互换热敏电阻，具备互换性强、精度高的特点，但可靠性存在短板，目前我方正考虑替换方案。
* 气压传感器：早期气象站采用改装后的Aanderaa型传感器，Mk2型气象站搭载Weathertronics单元；当前所有气象站均为Mk3型，搭载互换性与精度更优的Vaisala气压传感器。

2. 系统精度

系统精度误差由以下因素的误差之和计算得出：
* 校准误差
* 传感器互换误差
* 随时间产生的漂移误差
* 0~40℃环境温度范围带来的影响

以下为Mk3型气象站所用传感器的规格参数。Mk5型气象站将采用全新的传感器套件，其选型部分基于Vaisala WXT510气象传感器。

温度传感器与风速风向传感器均具备互换性，无需单独校准，但部分传感器已对照标准完成核验。
* 气温测量：可互换热敏电阻与电子模块的误差范围为±0.4℃，空气中的响应时间为30秒。低风速环境下，温度防护罩的抽吸效应会带来额外误差。
* 光合有效辐射（PAR）：测量误差为读数的±5%，初始阶段传感器年漂移量约为-4%。
* 气压测量：误差为±1百帕（hPa）。
* 风速测量：误差为读数的2% ±0.1%满量程（FSD）。
* 风向测量：误差为读数的2% ±0.1%满量程（FSD）。

太阳辐射与风速参数的电响应时间为7秒，该设置适配抗混叠滤波器的需求。Mk1与Mk2型气象站在数据记录前，会对16秒内的16组采样数据取平均；Mk3型气象站则采用连续平均的软件系统。风速读数采用矢量平均法，可准确反映风向信息。

校准流程与操作规范详见工程网站。

3. 风速风向传感器规格

以下为Mk3型气象站所用风速风向传感器的补充规格参数。Mk5型气象站将采用全新的风速风向传感器。传感器安装于水面以上标称10米高度处。

R.M.Young公司的05103型传感器具备以下特性：
* 风速：量程0~60 m/s；桨距：每转空气流经距离为29.4 cm；63%响应对应的距离常数为2.7米
* 风向：量程360°，北向存在5°电气开路区间；阻尼比：0.25；50%响应对应的延迟距离为1.5米；启动阈值：10°风向角下为1.0 m/s；位移误差：5°位移对应1.5 m/s的误差；阻尼振荡波长：7.4米；无阻尼振荡波长：7.2米