National Weather Service United States Department of Commerce

Interest in accurate and timely weather and climate observations has grown tremendously over the past decade. Applications range from managing multi-billion dollar economic weather risk for business and industry to understanding the impact of climate variability. Assuring data quality from the point of observation to the point of delivery is critical. The National Oceanic and Atmospheric Administration (NOAA) plays a critical role in the collection, quality control, archiving, and dissemination of accurate, secure surface climate and weather observations. These data are used by the agency to fulfill its mandate to describe the nation’s climate and detect, monitor and predict climate variability and change, including characterization of socio-economic impacts. Customers consider NOAA the neutral broker” for climate data services.

The NWS establishes and maintains the observation networks and instrumentation, collects the preliminary data, makes that data available to users, and delivers the data to NESDIS’s National Centers for Environmental Information (NCEI), where it is quality-controlled, archived, and disseminated as final certifiable data to users in a variety of formats.

Improvements in Data Collection

  • Training
  • Data continuity
  • Policy for assigning station numbers when a site is relocated
  • Use of backup site data at ASOS Primary LCDs
  • Estimating missing data
  • Electronic data collection for the climate record
  • Use of snow measurement boards for snow measurements
  • Rain gauge upgrade at FAA ASOS sites
Climate data continuity principles require network operators to conduct a series of parallel observations between old and replacement equipment when network changes (e.g., replacing sensors, moving stations, environmental change, etc.) are introduced that could cause artificial discontinuities. This includes conducting tests for COOP, ASOS, and the upper air networks. Compliance with this policy allows NOAA and other data users to correct for artificially-induced apparent climate changes. Doing so ultimately allows more accurate analyses of climate change and variability.


Another significant policy change was related to COOP station relocation. Existing policy allowed stations to retain their identification number for moves within 100 vertical feet and/or 5 horizontal miles of the original location. The problem with this practice was that analyses clearly showed that for most relocations within these distances, the climate record from the new site was significantly different than the original site. Allowing the station to retain its identification number misleads the unwary user. This increases the risk of analysts coming to incorrect conclusions regarding climate analysis at that location. The new policy places the burden on retention of a station identification number on a rigorous demonstration of data continuity regardless of horizontal and vertical distance changes involved in the relocation.


Inconsistencies related to the use of backup data when primary precipitation data were unavailable introduced discrepancies in the precipitation record of ASOS Primary LCD stations. NWS now requires NOAA-published LCD ASOS sites to use backup site data only when the primary ASOS instrumentation is either not functioning or when, in the judgment of the WFO staff, the primary ASOS report is spurious (NWS 2006)


Backup electrical power has been installed for 152 hurricane-prone LCDs within 300 miles of the coastline.


NWS also addressed the problem of estimating missing data. Without a policy in place estimation methods varied from office to office and even among staff within offices, and were often not documented. New policy now instructs NWS WFOs not to estimate missing data (NWS, 2006). The result is an improved climate record with traceable data values.


Our cooperative observers have been supplied PVC snow measurement boards. The new boards replace the home-made white-painted plywood boards the observers have constructed themselves. The PVC are long-lasting and the surface is much easier for observers to clean and maintain.


Most of the rain gauges at the FAA ASOS sites have been replaced with new All-Weather Precipitation Accumulation Gauges (AWPAG) to improve the accuracy of the liquid water measurement during frozen precipitation events.


The COOP observer uses either a web based or telephone based system to submit data and the observations populate the same database. The system employs redundant backup. Benefits of the electronic collection systems include greatly enhanced on-site data quality control and improved data quality, automated electronic data collection for NWS forecast applications, daily data availability, and electronic transmission to NCEI for greatly improved timely data quality control and data availability. This improvement will result in thousands of additional COOP stations’ data being available on a daily basis.
Datzilla is a web-based system that reports and tracks data discrepancy resolution in historical NOAA data sets and products. It was developed by our partners at the Southern Regional Climate Center in 2004. Data discrepancy reports may involve observed climate data, data access or management systems, or metadata. Datzilla is an interactive system that allows both authorized error reporters (e.g., NWS WFO CSFPs, Observations Program Leaders, or Data Acquisition Program Managers; SCs, climate community partners; etc.) and data managers to communicate with each other, to report data discrepancies, and to monitor the error reporting process from start to finish.


The Climate Database Modernization Program (CDMP) was a program to image and key paper and microfilm records and to make them available on the web to members of the climate and environmental research community. Spanning 12 years, from 2000 to 2011, the program produced almost 56 million digital images from all types of physical media and enabled data keying projects to integrate new data into digital datasets.

The vast majority of the images scanned under CDMP are accessible through the NCEI-developed Environmental Document Access and Display System, Version 2 (EV2) application. Access to EV2 is available to United States government employees and their contractors, educational institutions doing environmental research, and other researchers associated with NOAA projects. If you would like an account in EV2, please contact Commercial customers should call NCEI customer service at 828-271-4800 or e-mail for their data needs.

Access to historical climatological observations scanned under CDMP is available to the public through the NCDC Images and Publications System (IPS). The IPS system is a web interface for records stored within the EV2 system.



ACIS is a custom-designed interface which provides NOAA personnel with access to historical and near real-time climate data products through a suite of standard climate analyses features via the Internet. This tool relieved individual WFOs of database maintenance and provided a central set of tools upon which to receive new products, tools, and services. This data mining tool allows internal NOAA staff to conduct historical data analyses on all stations (COOP and ASOS) that have 1981-2010 normals (several thousand stations nationwide). A huge improvement resulting from the use of xmACIS is that there is now a single validated database replacing the multiple databases and the inherent inconsistencies.


NOWdata is a self-service climate data tool, based on a portion of the same ACIS climate data base that also feeds xmACIS. Free public access is available from the NOWData tab on every NWS WFO climate page found through Users can access a wide range of climate products for over 3,900 locations nationwide. Daily past weather is available for the last two years with climate averages for the standard 30-year period (1981-2010) and extremes for the entire record. NOWData greatly increases the public’s ability to quickly acquire climate data that previously would require significant effort to locate and obtain.


The ThreadEx project provides consistent data sets for calculating historical daily extremes of temperature and precipitation at most large metropolitan areas frequently cited to the public by both the media and NOAA. It addresses the challenge of how to treat the inevitable fragmentation of station information over time due to station relocation. The period of record for any location will be extended as far back as possible using the currently active station. Other stations in the region are then used to extend the “thread” further back in time using NOAA data in digital form. Thus, an “authorized” threaded station record is established for daily extremes for media purposes, but not for research.