Grants will help scientists probe droughts, model fisheries

NOAA-funded projects focus on climate variability

Aug 24, 2020 - by Laura Snider

Three scientists at the National Center for Atmospheric Research (NCAR) will lead research projects funded by a program of the National Oceanic and Atmospheric Administration (NOAA) that aims to improve our ability to better understand and predict climate variability in both the short and long term.

The research funded by the grants from NOAA’s Modeling, Analysis, Predictions and Projects (MAPP) program will explore how droughts in the U.S. West affect – and are affected by – complex interactions with wildfires and snowpack; identify the intertwined factors that influence how severe a drought and its impacts will become; and extend an Earth system model to allow it to explicitly simulate fish, providing valuable information on how fisheries respond to climate.

Wildfire, snowpack, and drought in the West

In the western United States, snowpack and wildfires have a complex relationship with droughts. The three elements interact with each other in ways that can amplify, or dampen, their impacts. For example, scientists have found that wildfires reduce vegetation cover. The sparser canopy then allows a thicker snowpack to build up on the ground, but it also enables more sunlight to reach the snow, causing it to melt out earlier in the spring. This can then lead to drought conditions in the late summer and fall, which in turn favors more wildfires.

NCAR scientist Cenlin He will lead a MAPP-funded project to better quantify these types of relationships among drought, snowpack, and wildfire. With that knowledge, he will also evaluate how well models capture these relationships with the goal of improving them.

“I am really excited about this research, which will provide the community with not only a deeper and more integrated understanding of droughts but also an enhanced community model for future drought-related modeling and research,” He said. “This will help to enhance the U.S. drought monitoring, warning, and prediction systems, benefiting related stakeholders and policymakers.”

 Factors influencing drought evolution and severity

The latest version of NCAR’s flagship climate model, the Community Earth System Model 2 (CESM2), has a number of updates to its land component, allowing much more realistic simulations of the ways the atmosphere interacts with plants, soil, groundwater, and more. These new updates will allow researchers to explore the intertwined factors that determine how droughts evolve.

Climate scientists know that certain large-scale atmospheric patterns, such as persistent ridges of high pressure, can lead to a drought. But whether the drought becomes severe and long-lasting – or mild and transient – depends on a number of other conditions on land. The new research will use CESM2 to quantify those relationships and how much they matter.

“We will be able to determine whether there are important pre-conditioning factors that could govern the severity of drought,” said NCAR scientist Isla Simpson, who is leading the MAPP-funded project. “For example, if you have a given drought-inducing circulation pattern, how much difference does it make if your soil is drier or wetter in the period leading up to that?”

Ultimately, Simpson and her collaborator on the project, NCAR scientist David Lawrence, hope that what they learn can be used to help predict the impact of drought events and understand the relevant processes that need to be included to simulate the evolution of drought in Earth system models accurately. 

Adding fish to Earth system models

In recent years, scientists have learned that Earth system models have the potential to predict a number of factors that influence the ocean’s fisheries years in advance, including changes to ocean primary productivity, temperature, and dissolved oxygen

While these types of predictions are useful to resource managers, the direct impact on fisheries has to be inferred. The MAPP-funded research team led by NCAR scientist Matt Long plans to incorporate fish directly into an Earth system model.

“By actually having the fish in the model, we can capture complex feedback loops between fish and their environment, ultimately providing a much more realistic prediction of how fisheries may be impacted by climate variability and change,” Long said.

The team plans to interconnect an existing fisheries model, the Fisheries Size and Functional Type Model (FEISTY) with a widely used ocean model, which in turn, will allow the combination to be used in state-of-the-art climate models, including CESM2.

“Simulating fish in a fully coupled Earth system model framework is going to be very challenging, but if we succeed, I have no doubt our efforts will bring new insights into the function of the global marine ecosystem in the context of a dynamic climate,” Long said.

Long is also a co-investigator on two other MAPP-funded projects: One, which is led by Samantha Siedlecki at the University of Connecticut, will explore the predictability of oxygen in the ocean and its impacts on fish. The second, led by Colleen Petrik at Texas A&M University, will work on enhancing fisheries prediction on timescales that stretch from upcoming seasons to several years out.

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