"What If?" Or The Importance of Standards

What if weather observations were made differently in each country, or even by State or region? 

We compare observations to understand weather phenomenon in order to predict future conditions and document historical ones. We traditionally do that by plotting the observations on “synoptic” maps to allow us to observe spatial and temporal patterns.  If each location took their observations differently, we would never be able to understand what we are looking at — especially since we are often trying to see relatively small differences in observations from one location or time to another.  So we all need to agree on exactly how we will take those observations across the nation and around the globe in order for them to be useful. And that leads us to meteorological standards.

How do we make weather observations comparable?

Comparing observations starts with an agreement on what, where, when, and how atmospheric characteristics are observed for a given purpose. “What” seems pretty basic, such as temperature, humidity, pressure, precipitation, wind, and sky conditions. “Where” involves recording the observation location and instrument exposure, such as height above ground and surroundings. “When” refers to frequency and time of observations, as well as the relevant time period observed. All this leaves us with “how” the weather is observed and recorded. Welcome to standardization!  Still, it is no small feat to get every observer in every country to agree on the types of instruments that will be used and their guaranteed level of accuracy; how they will be installed; and when the observations will be made.  I have devoted a significant portion of my career to helping define those standards and achieve the required universal agreement for them.

But when is a standard really a standard?

The standards for some observations may seem easy.  For example, for temperature, we can use any standard thermometer that is calibrated to be accurate to within some acceptable amount, right?  But, even then, there are questions that need to be answered, such as where do we place the thermometer so that it is not affected by direct sunlight or cold raindrops falling on it, and how high above the ground does it need to be, and many other issues that must be carefully specified in order for the observations to be useful.

Descriptive observations, like clouds, can be even more challenging. Thank you, Luke Howard, for stepping forth in 1802 to fill a void for an agreeable method to describe clouds. (And thank you to many others who expanded on his system and also developed the collection of symbols to use on weather maps to display this information).

Do standards really matter that much?  

The guidance provided by accepted meteorological standards allows the production of high quality and useful information, as long as those creating the information perform the action correctly. Because of standards, a simple program made up almost completely of volunteer observers can create lots of high-quality data that is extremely valuable for scientific work. A great example is CoCoRaHS (see: https://www.cocorahs.org/), a network of volunteer observers who report daily precipitation (with oversight and support from just a few professionals).

To see the range of meteorological standards, check out the U.S. National Weather Service  “observer handbook”, or see the World Meteorological Organization’s Commission for Instruments and Methods of Observation (CIMO).  It does not take long in scanning either of these documents to realize how much complexity and detail there is in defining the methods used by weather-related agencies to produce data to fuel their information appetites.  This complexity has grown out of many decades of refining the standards based on the demonstrable success achieved by doing so.

Looking beyond observations

But what about the instructional norms for testing meteorological equipment performance characteristics? And properly establishing and operating observing programs, all using legally binding terms like “shall” and not “should”? Again, welcome to standardization.

Allow me to describe a specific type of standardization that I find fascinating: voluntary consensus standards to establish observation and testing methods and practices. Consensus means participation and agreement by technical experts representing instrument and service producers, consumers, and regulators. Standards produced in this process create a benchmark for producing and acquiring equipment and services.  Government agencies, even at the local government level, may legally require that these standards be met by contractors as a way to ensure the information acquired is reliable.  The standards are maintained by an international organization that covers not just meteorological standards but a wide array of other standards. 

Since 1972, ASTM International (previously known as the American Society for Testing and Materials) has promoted meteorological standards administered by its subcommittee referred to as “D22.11.” Exploring D22.11 on the ASTM International website shows information on the thirteen current and more developing standards, and how you can be involved in the process. ASTM Standards provide the basis for other standards and guides tailored to specific applications of acquiring weather information, such as in environmental and nuclear agencies and industries. One other example of an organization that promotes standards is the International Organization for Standardization (ISO); with meteorological standards housed in subcommittee 5 (SC5) in technical committee 146.

I hope this provides a glimpse of the importance of meteorological standards and at least a hint at how they are created and maintained.  You can rest assured that the American Meteorological Society continues to promote the work of D22.11 and SC5, and AMS members like me are doing our part to make sure that the observations needed for analysis and forecasting can be trusted.

Paul Fransioli, CCM, has over 40 years of expertise with applied meteorology and air quality monitoring and analyses programs, generally for private sector energy projects following EPA and NRC regulations and guidance. He is actively engaged in meteorology subcommittees in ASTM International and ISO.