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NWS Alaska Region - Surface Observing Network Assessment
There are a number of surface observation networks in Alaska that support weather forecasting activities, as well as meet the needs of various user communities (mariners, pilots, commuters, etc.) and partners (U.S. Coast Guard, Emergency Management, Federal Aviation Administration, etc.). Over time, new networks have been established, and as a result, some areas of Alaska have a relative abundance of real-time weather reports available while there are significant gaps in others.
To address this issue a Working Group on Aviation Weather Observations was formed that reviewed the NWS surface observing networks in the interest of optimizing our investments in this area. As part of this activity, a team consisting of both NWS and FAA members examined; (1) the effectiveness of one particular observing network (the "A-Paid" program) and (2) developed recommendations toward meeting mission requirements as they pertain to aviation operations. The role of the FAA in this group was primarily advisory in nature.
The NWS has also solicited input from various interest groups that included aviation, marine, and the general public on the current state of the surface observing program. Industry and private aviation operators were briefed earlier this year on possible changes to the A-Paid network through the Alaska Aviation Coordination Council. In addition, a web survey was also conducted for two months to gather public comment on the current surface observation network. Feedback was provided by a variety of respondents which shed light on which locations were most and least useful, as well as where observational gaps existed.Background:
Surface weather observations are fundamental data for forecasting weather, issuing warnings, and monitoring the climate worldwide. Observations can be taken manually, by a weather observer, by computer through the use of automated weather sensors, or in a hybrid scheme using weather observers to augment the otherwise automated weather station. Airport observations (automated or hybrid) are transmitted worldwide through the use of the METAR observing code. Other observation networks (Citizen Weather Observer Program, Cooperative Weather Observer Program, etc.) are generally done manually by volunteers who take observations once a day and may not be available in real-time. A thirty-year average of a location's weather observations is traditionally used to determine the station's climate.
For over a century, reports from the world's oceans have been received real-time for safety reasons and to help with general weather forecasting. The reports are coded using the synoptic code, and relayed via radio or satellite to weather organizations worldwide. Buoy reports are automated, from moored locations both near the shore and farther out at sea. Buoy maintenance is costly and difficult logistically, so a "voluntary observing ship program," known as VOS, was set up to train crews how to take weather observations while at sea. Automated coastal wind stations and small low-profile wave buoys also provide critical data for marine forecasting and are somewhat hardier than the traditional buoys and easier to maintain.
Currently there are 18 Aviation Paid (A-Paid) observation stations in Alaska, located primarily in small villages consisting of a gravel airstrip and a small cluster of homes or businesses (i.e., not at airports). A-Paid observers are individuals who are certified by the NWS to take surface observations (i.e., hourly reports of temperature, dew point, estimated cloud cover, estimated visibility, pressure, weather, and wind direction and speed) using equipment provided by the NWS. As their name suggests, these observers are compensated for their work on a per-observation basis. The purpose of A-Paid observations is to provide information necessary to support aviation forecasting by the NWS. The FAA has no direct requirement for A-Paid stations, however they support the program by funding five stations in Alaska.Analysis/Findings:
The three most important weather elements to the aviation forecaster are clouds, ceiling, and visibility. A-Paid observers estimate these elements using landmarks within view of their location. In the dark and in the poorest of weather conditions, these estimates are most difficult and least reliable. Some locations are poorly sited, and several have ongoing equipment problems that will be expensive to correct.
Most sites transmit intermittently, and observations may be several hours old when they reach their intended audience. By the time an A-Paid observation is available to a pilot or forecaster, it is potentially unrepresentative of current weather conditions. In addition, a considerable number of observations are not transmitted at all. During Fiscal Year 2010, only 78% of the contracted observations were received by the NWS. Also, A-Paid observers generally do not have backups, so if they go out of town or become ill, no observations are made or transmitted.
These deficiencies, compared to automated systems, are not well-known by users of the data outside of the NWS. A-Paid observations, while in existence to support weather forecasting by NWS, have become valued by the aviation community. Feedback indicates pilots are using the data for "go, no-go" decisions. The observations are considered by the user to be similar to an automated site (ASOS or AWOS) even though they are not of the same accuracy or reliability.
The cost of the legacy A-Paid program is steep when compared to automated weather observing systems - which provide highly accurate and reliable hourly observations 24x7. The average annual cost of an A-Paid station is $32,000. Observations are only taken on a part time basis (9 to 10 a day average, per station). In addition to these costs, the NWS and FAA spend approximately $200,000 annually for maintenance and program management.
A fully automated aviation weather system has a one-time cost of approximately $42,000, plus installation ($2500). Fully automated marine weather systems are less - about $15,000, plus installation. The annual recurring cost of an automated weather system includes power, communications, and maintenance costs (approximately $3000). The annual recurring cost of an automated observation is reduced by over 90% after a 16-month cost recovery period for the initial investment for the aviation system (6-month cost recovery for the marine system).
In addition to reviewing the observation methods/techniques, the A-Paid locations were evaluated based upon input from NWS forecast offices and feedback collected last winter through a web-based feedback survey. All input, from a range of sources including state and federal government, pilots and mariners, and the general public, was organized according to the following criteria:
Critical observational gaps were also identified during the public comment period. Based on this analysis, the following sites were identified as mission critical and are recommended to be replaced with automated sensors for 24x7 hourly coverage:
The following sites were deemed as supplemental (i.e., not mission-critical) and are recommended for closure:
The resulting optimization of the current surface observing network through the closure/automation process may provide opportunities for new investments in automated observing systems to fill critical gaps in the observing network serving both the marine and aviation communities. The following are considered to be a high-priority, gap-filling locations: