Understand Precipitation, Better Apprehend the World

As the world slowly works its way through the COVID-19 pandemic and reflects on how it can better ready itself for future outbreaks, the situation also serves as a strong reminder that there are other impending high-impact issues we must prepare for, such as climate change and its cascading effects. For a sustainable aerospace industry, part of doing this means leveraging technologies to better understand and apprehend weather-related phenomena.

From sunny days to pounding rainstorms, dense fog to howling blizzards, planet Earth offers no shortage of variety when it comes to the types of weather its inhabitants must endure. At Project Monark, we are acutely aware of the essential role that the aviation sector plays in helping scientists better predict weather and weather-related events. We are helping to equip Airbus flying platforms with sensing technology to capture vital information from our atmosphere at unprecedented volumes—including measurements of water vapor, air pollution, and more—which could increase our current forecast accuracy by as much as 50%. This effort joins forces with the rising global trends of aircraft based atmospheric sensing, such as the World Meteorological Organization’s program called AMDAR.

The rising tide of aircraft-based atmospheric sensing. Credit: The World Meteorological Organization

But why go through all that trouble? Humanity has been forecasting since before the time of the Byzantines, and we’ve gotten pretty good at it. While this may be true, our work at Project Monark is based on the firm conviction that we can do much better, and that better forecasts will bring vast improvements not only to the effectiveness of the aviation sector but also to the everyday quality of life worldwide. To demonstrate why, let’s zero in on the ways in which increased water vapor measurements could help change the world.

The power of precipitation

Our planet’s weather represents the product of a dynamic system driven by astonishing complexity—often described in terms of chaos theory and the famous “butterfly effect.” From a simple point of view, the atmospheric phenomena that we think of as “weather” is the result of momentum and energy exchange between different kinds of air masses.

Precipitation can be a profoundly creative force. Rain and snow deliver water to communities built far away from freshwater lakes and other water resources, and it is the primary source for water tables and agriculture, the source of human life. Precipitation also has an enormous capacity for destruction. Wet pavement contributes to 76% of all weather-related traffic fatalities in the US. Heavy rains have the potential to flood whole cities, causing billions of dollars in property damage. Hurricanes and typhoons can easily wipe out whole communities.

Dynamic times call for better measurements

Water vapor is the “fuel” for big weather. Today, water vapor is measured in situ by balloon- and aircraft-based instruments, and remotely by satellite- and ground-based sensors. However, more accurate data with better geographical coverage is needed. In many cases, when it comes to stratospheric water vapor, the trends we see over time poorly match present-day models, demonstrating our lack of understanding of how water vapor enters the stratosphere. To improve our understanding, it’s important to utilize as many flying platforms as possible to enhance global three-dimensional observations in both frequency and distribution.

Factors that contributed to a reduction in European forecast model errors. Credit: European Centre for Medium-Range Weather Forecasts

The value of GNSS-RO

One of the highest impact water vapor measurements typically captured with spacecraft is GNSS-RO (Global Navigation Satellite Systems - Radio Occultation). Radio occultation is a remote sensing technique in which a radio signal is transmitted through the Earth’s atmosphere. As the signal passes through the atmosphere, it is refracted—with the extent of refraction (or bending) depending on the amount of water vapor in the air. Measuring the amount of bending allows forecasters to ingest the data for data assimilation and in doing so, improve the numerical weather forecasting models. This data helps to capture narrow rivers of atmospheric moisture that are easily missed by other sensing techniques, and can more easily analyze conditionally unstable areas where precipitation may or may not form. Satellites that capture measurements require space launch, and have long development cycles—making them expensive, prone to delays, difficult to replace and difficult to upgrade technology. Project Monark is testing sensing systems to capture GNSS-RO with existing commercial aircraft fleets.

Measuring the impact

Today, the United States’ National Oceanic and Atmospheric Administration captures over 2,000-4,000 RO soundings per day. The agency has laid out their ambitions to increase this number significantly, and aims to eventually capture 20,000 soundings per day with help from commercial partners. This plan is supported with funding requests of $23 million in 2021 and $33 million per year from 2022 through 2024. The increases in the amount of GNSS-RO data the agency receives will enable it to produce much more detailed precipitation forecasts, and provide a clearer picture of whether precipitation will occur, how much precipitation will occur and what form it will take.

Why does this matter?

Aviation Safety. A study produced by researchers from the US National Transportation Safety Board found 583 aircraft accidents and over 800 deaths between 1982 and 2000 that could be attributed to “icing,” which occurs when small cloud droplets freeze onto a plane’s exterior during flight. Increased water vapor sensing would enable aircraft to easily navigate around danger zones where icing is likely to occur.

Agriculture. Increased water vapor sensing would also enable farmers around the world to better manage water resources, while also helping them plan for weather-related disasters. As the world’s population races towards an estimated 9.8 billion by 2050, more efficient food production could mean the difference between a prosperous society and mass starvation.

Water Utilities. A growing global population will also require stable water utilities, not only for rural farmers, but also for citizens in urban and suburban settings. We already find ourselves in the midst of an international water crisis, with over 785 million people currently living without access to safe water, and 2 billion people living without access to effective sanitation. In addition, global warming is accelerating the climate change mechanisms which are altering the atmospheric water transport mechanisms in a way that already dry areas are trending towards even drier climates. Precipitation has always been humanity’s primary source of potable water, and increased accuracy in rain forecasting would enable improved resource management.

These are just a few of the ways in which Project Monark’s efforts to accelerate global weather sensing at scale could make the world a happier, safer place. To learn more about Project Monark, visit our project page.

- Mike Vergalla