Appendix G National Weather Service Plan For Modernizing The Cooperative Observer Network And Technical Specifications1
A.1.5 Timeliness Of Data Availability
Currently, observation availability varies with station type and equipment. The vast majority of cooperative climate station observations are not available until after month's end, while observations from many hydrologic stations are available daily or when a given threshold of precipitation is reached. All climate and hydrologic station data need to be available daily to support NWS forecast and warning operations. For climate stations, daily maximum and minimum temperatures, 24-hour precipitation, and snowfall and snow depth are needed for improving both NWS zone and hydrologic forecasts. The previous week's daily climate station data are needed by the CAC the day after the week ends for their near-real-time climate assessment work. Monthly climate station data are needed as soon as possible after the month's end at the NCDC so that quality control, archiving, publication, and dissemination of the data can begin.
For hydrologic stations, precipitation (or river stage) observations continue to be needed daily or near-real-time if significant events occur to support NWS forecast and warning operations. Also, with the implementation of the WSR-88D, there will be a great increase in the need for real-time ground-based precipitation measurements to support radar information.
A.2 System Requirements
The system for the cooperative observer network will continue to consist of observers and their equipment. The new complete system must have the following general capabilities:
- Provide its own power supply
- Take temperatures and/or other identified observations automatically
- Store all observations digitally through either automated or manual input
- Transmit data automatically from observation site to NWS offices and NCDC
- Allow local readout of data
- Be modular in design to allow for easy future expansion of observing capabilities
- Have programmable memory to allow for the manual entry of data, notes (including maintenance visits), and a variety of transmission schedules
- Be able to operate (take and send observations) on its own power supply and communication equipment (not observers).
It should be noted that not all stations will have a requirement for all capabilities. In addition, somewhat different requirements could exist at individual stations, such as those that lose their observer and are in jeopardy of closing. Special situations and general requirements will be refined as more information becomes available during Phase 1.
A.2.1 Mandatory Design Requirements
The following general design requirements are mandatory features for new equipment:
1. Environment
The sensor elements of the observing equipment will be installed in outdoor environments at both private and public facilities. The climatic conditions will vary from hot desert to arctic. Therefore, the equipment must be sturdy and as inconspicuous as possible.
2. Power Supply
The equipment must have its own power supply and be operable with DC power. This is necessary to minimize
observation failures (especially for severe weather events when AC power is prone to failure) and allow for more flexible siting of new equipment. Batteries should be of the "standard" type that are stocked routinely at most retail outlets.
3. Maintenance
A once-a-month calibration and maintenance check by the observer is required. The equipment design should provide simple built-in check routines for all major components of the system. Servicing should be accomplished by the simple replacement of defective modular units. The system calibration should operate in a manner that does not affect the data storage of the sensor. A visit by a technician should not be required more than once a year.
4. Equipment Life Expectancy
The equipment should be designed to last a minimum of 20 years, with a mean time between failure for individual components of 2 years.
5. Type of Record
In addition to the digitally store record, there will be a visual display at the site. Both will be capable of providing all data in both metric and English units. The interactive data terminal will allow manual entry of both administrative information and manually derived observations into the digital record. Administrative information, including observer name, station name and number, latitude, longitude, elevation, etc., shall be protected from change. Manually derived records may include observations of precipitation, temperature, snowfall, snow depth, special phenomena such as hail, and notes.
6. Data Collection
The on-site equipment must allow for both automated and human interaction. The equipment must be able to accept and quality control, process, store, and transmit all data/information from: the cooperative observer or NWS employees (manually entered), or from automated observing equipment.
Software allowing for human interaction must be extremely user-friendly (many cooperative observers are not experienced with computer technology).
The on-site equipment will be capable of automatically transmitting observed data in a self-timed mode and on a criteria basis. Generally, in the self-time mode, data will be transmitted at 7 a.m., 4 p.m., and midnight local time. In addition to current data, redundant data for the past seven transmissions will also be transmitted. The on-site system should also be able to store up to 68 days of data in digital (ASCII) format in a circular file.
7. Frequency of Recording
Temperatures will be recorded hourly. Maximum and minimum temperatures and precipitation will be recorded daily, at 7 a.m., 4 p.m., and midnight local time, or at other times to be determined. "At observation" (midnight) temperatures shall also be recorded. For automated precipitation stations, hourly precipitation shall also be recorded. One-minute and 15-minute hydrologic station data may also need to be recorded (during precipitation events only).
8. Length of Record and Frequency of Data Retrieval
The equipment should have the capacity to digitally record and store observations for 68 days. This will cover data for two calendar months data plus an additional week to allow for transmission delays and other problems. Data may be retrieved and transmitted hourly, three times daily, and monthly.
9. Maintenance
The equipment design should provide simple built-in check routines, and servicing should be accomplished by the simple replacement of defective modular units. A visit by a technician should not be required more than once a year.
10. Quality Control
The equipment will have some ability to detect and visually flag erroneous data entered into the record by an automated sensor or an observer. Data flags will be stored and transmitted as part of the digital data record.
11. The equipment will allow for calibration checks to be performed on all major components of the system by an NWS technician.
A.2.2 Desirable Design Considerations
The following design considerations, although not required, are considered desirable features of the equipment:
1. Cost
Low-cost equipment is very desirable. The cost of each complete stand-alone system should not exceed $5,000.
2. Maintenance
The equipment should be reliable and of modular design so that an observer can easily replace broken parts. The radiation shelter should be easy to clean. Replacement parts should be readily available and reasonably priced.
