The Earth’s climate system is a complex and interconnected web, intricately crafted by the multitude of interactions between the land and the atmosphere alongside other contributing factors. Among these interactions, the influence of surface properties, especially moisture content, on atmospheric behavior during the summer season has gained increasing attention. Understanding the mechanisms driving these interactions is crucial for a wide range of applications, from improving daily weather forecasts to addressing the long-term challenges of climate change. Gaining insight into these fundamental processes that govern land-atmosphere interactions provides a better understanding of how the Earth’s surface conditions can influence atmospheric behavior, resulting in changes in cloudiness and weather patterns.
In a new Journal of Hydrometeorology article, authors Finley Hay-Chapman and Paul A. Dirmeyer use a simplified single-column mode to focus on and examine the fundamental processes that regulate the interaction between the Earth’s surface and the atmosphere. This model finds a middle ground between the principles of land-atmosphere interactions and the intricate specifics of high-resolution models.
It was found that surface evaporative fraction (EF), how much of the available energy at the Earth’s surface is being used to evaporate water, is a crucial driver of local weather variations during the summer months. Researchers identified two distinct feedback regimes: a positive feedback regime, where cloudiness increases with higher EF, and a negative feedback regime, where clouds intensify with decreasing EF. The positive regime is prominent in shallow convection situations, while the negative regime is prevalent when large-scale deep convection systems traverse the region. In both cases, the exchange of moisture and heat between the surface and the atmosphere is pivotal in shaping cloud formation and weather patterns.
Funding for this project was partly provided by the NOAA Climate Program Office, MAPP program.
For more information, contact Courtney Byrd.