Given the enormity of the task, private weather data providers have entered the market to provide the data to the insurance companies for a fee. The loss of the data for some of the meteorological parameters, e.g. amount of cloud cover, sudden changes in weather, etc. The quality and lifespan of the AWS station is completely dependent on the data logger.
The quality of the AWS data is solely dependent on the quality of the sensors in all weather conditions. The detailed specifications of the various sensors can be determined by studying the climatology of the region. This antenna must not be placed in a central location, otherwise the entire network becomes a slave to the centrally located GPS antenna.
At the ground station, the data from the satellite-based AWS/ARG is received and processed on the server. The data from the GSM/GPRS based AWS/ARG station is received on the server using the GSM/GPRS based network and further processed. Here the health status of the entire network can be monitored and a rigorous check on the quality of the data can be imposed before it is sent to the user unit.
All components of the AWS must be robust enough to operate in a tropical environment.
General Guidelines for the format of the data
GENERAL GUIDELINES FOR SELECTION OF AN AWS SITE
The AWS should be placed on a flat area of ground covered with short grass or natural soil measuring approximately 5 meters X 7 meters. Adequate attention should be paid to the security aspect to prevent theft of AWS equipment. The site should preferably be on the same level as the station's surroundings.
The site should be selected in such a way that the distance between the site fence and the proposed AWS mast should be at least 6 feet (2 meters). This distance is recommended to minimize the effect of the fence on the sensor readings, especially when weeds and/or dirt on the fence act as a horizontal obstacle. Location of the site on the edge of a slope, hills, cliff or inside a valley iii.
GENERAL Guidelines for selecting an ARG location (i) The ARG location should be of 4m x 3m dimensions.
GENERAL Guidelines for selection of an ARG site (i) The ARG site should be of dimension 4m x 3m
GENERAL Guidelines for selecting an ARG site (i) The ARG site must have dimensions of 4m x 3m. ii) The site must be free of nearby tall buildings, trees, large bodies of water, industrial heat sources and high voltage cables (both overhead and underground). iii). The site with steep slopes, tall vegetation, low-lying place that holds water after rain should not be considered for installation of ARG.
General Guidelines for Documentation needed for Site Selection i. The site location should be documented with maps and photographs
Exposure conditions for main sensors of meteorological parameters Wind speed and direction (wherever these parameters are used in weather
The sensor must be placed at a distance of at least four times the height of obstacles such as trees, buildings, etc. The sensors are generally located in an open flat area that is at least 5m in diameter. Large paved areas, bitumen surfaces in the vicinity of at least 30 m must be avoided.
Since the atmospheric pressure is an important meteorological parameter, the height of the station to which the station pressure relates is very important, and therefore the chosen site must be located in a flat terrain. The rain sensor (tip bucket) is placed as far as possible in an open area at a distance of at least four times the height of any obstacle. Solar radiation sensors must be mounted at a height of at least 3m to ensure easy leveling and cleaning.
GENERAL GUIDELINES FOR AWS SITE PREPARATION
The rain sensor (tip bucket) is placed as far as possible in an open area at a distance of at least four times the height of any obstacle. ii. The approach to the site should be made clear of obstructions like bushes, trees etc. and a suitable cement platform should be laid to approach the site. The fencing of the AWS/ARG site should be done in such a way as to ensure the safety of the instruments at the remote sites.
It must be strong enough to support the weight of the mast of the AWS/ARG instrument also in adverse weather. The foundation of the rain gauge must be such that it can support the sensor even in the event of very heavy rain. It is a common perception that most of the outdoor tools start malfunctioning due to the improper grounding.
To protect the AWS from environmental hazards and avoid penetration, the AWS and its various components should be painted accordingly.
Common Problems related to AWS/ARG Network 1) The availability of the proper site
Preventive maintenance (Cutting the grass on the site, Cleaning the sensors & solar panel etc.) should be done at an interval of at most three months.
Points to be considered before commencement of the project
Quality Control of the AWS data
All sensors must be installed according to the specified norms. of the transmission of data is completely dependent on the service provider.
AWS data quality can be monitored on the ground station server according to the IMD standard.
Guidelines for Automatic Weather Station, Installation and Maintenance
- General
- Automatic weather station hardware
- Sensors
- Central processing unit
- Quality control
- Maintenance and calibration: Data validation flowchart
- Elements of a Metadata Database related to an AWS
For example, the manufacturer may state the response time for the humidity sensing element, but not the total response time of the sensing element, electronics and filter, which may be an order of magnitude longer; likewise, the manufacturer may state the accuracy for a device such as a pressure sensor, but not state the confidence limits of the specification. Repeatability - the ability of a sensor to measure a parameter more than once and produce the same result under the same circumstances. Hysteresis - the ability of a sensor to make the same measurement whether the phenomenon is increasing or decreasing.
The usefulness of the data obtained from a sensor is highly dependent on the calibration of the sensor. This is often difficult to establish, especially with inferior sensors, but is of equal importance regardless of sensor quality. The general principle is that a station should provide measurements that are and remain representative of the surrounding area, the size of which depends on the meteorological application.
In the case of an Automatic Rainway Station (ARG), the size of the plot may be 10 m x 7 m. 3) The proposed AWS site should be free from obstacles such as tall buildings, trees, etc. In view of the increasing reliability of the electronic components in an AWS, preventive maintenance, including servicing and sensor calibration, will become the controlling factor in maintenance. Since software plays a very important role in each AWS and in the central network processing system, personnel with in-depth knowledge of AWS and the central network system software are required.
Since signal conditioning modules and data acquisition and transmission equipment are also part of the measurement chain, their stability and correct operation must also be periodically checked or calibrated. Field Inspection: The periodic comparison of AWS sensors with travel standards at the station is an absolute requirement to monitor the performance of the sensors. Before and after field inspections, the traveling standards and reference sources should be compared to the calibration laboratory working standards.
Attention should also be paid to the calibration of the various components that form the measurement and telemetry chain, in particular the signal conditioning modules. A schedule should be established to periodically compare the secondary calibration laboratory standards with the WMO primary standards. As explained above, station placement and exposure have a significant impact on station performance and data quality.
Occasional missing values or recording of erroneous data are common in most systems, as the automatic methods point out possible erroneous observations; they are unable to estimate the correct observed values. To maintain the sanctity of the process, it is suggested that the accreditation process be conducted by a competent third party.
Vendor requirements for “Automatic Weather Stations and Data Quality Certification” by the third party Agencies
Supplier Requirements for "Automatic Weather Stations and Data Quality Certification" by third-party agencies. Sufficient manpower and resources to perform pan-India data quality and accreditation services as may be required by the weather data providers and users. Exposure/experience of meteorological satellite and experience in handling weather data from these satellites.
Based on the criteria stated above, a panel of three to five vendors / competent firms will be panelised. The vendor/competent firm joined shall in no way be directly or indirectly related to or promoted by the weather data provider in the market. A vendor / competent firm will be jointly selected by the weather data provider and the user agency for a particular activity.
Professional fees / fees of the certification and accreditation vendor / competent firm will be borne by the weather data provider.
