Equilibrium climate sensitivity (ECS) measures the long-term global surface temperature response to a doubling of preindustrial carbon dioxide. While greenhouse gases are the primary driver of warming, atmospheric aerosols and chemical processes also influence how the climate system responds. In this study, GFDL scientists used simplified but closely related configurations of two GFDL models to isolate the role of atmospheric chemistry and composition. Read More…
GFDL Research Highlights
The Gulf Stream in the North Atlantic and the Kuroshio–Oyashio Extension in the North Pacific are western boundary current systems that transport heat and shape regional ocean conditions. Variations in sea surface temperature in these regions can interact with atmospheric circulation and affect climate variability across the Northern Hemisphere. The authors examine observations and climate model simulations to investigate how variability in these two ocean regions is connected. Read More…
Changes in tropical rainfall can strongly affect water resources, agriculture, and communities across regions influenced by the Atlantic Ocean circulation. In this study, the authors used a high-resolution coupled atmosphere-ocean model and targeted freshwater-forcing experiments to understand how changes in Atlantic Ocean circulation influence tropical rainfall. Read More…
Fire seasons in the western United States are becoming longer, drier, and more intense. As rising temperatures and lower humidity are increasing the atmosphere’s evaporative demand, seasonal forecasts of atmospheric dryness are gaining importance for wildfire preparedness. Vapor pressure deficit (VPD), a measure based on temperature and humidity, serves as a useful indicator of fuel drying and fire-weather risk. Read More…
Ocean conditions along the U.S. West Coast influence fisheries, marine ecosystems, and coastal economies. These conditions vary across the Northeast Pacific, from the eastern Bering Sea and Gulf of Alaska to the California Current System, which presents challenges for regional ocean modeling. In this study, the authors describe the development of the NEP10k, designed specifically for this region. Read More…
Santa Ana winds (SAWs) are hot and dry winds that blow from the Great Basin (Nevada and adjacent areas) to coastal Southern California. SAW events usually last several days, and occur in Fall and WInter (see upper left panel of Figure). These hot, dry winds increase the likelihood and intensity of wildfires and their associated damage. Predicting how these winds will change in the future is challenging because most current-generation climate models struggle to simulate SAWs accurately. Read More…
Ozone is a powerful greenhouse gas that efficiently traps heat, especially in the tropical upper troposphere. In this study, the authors used GFDL’s Atmospheric Model v4.1 (AM4.1) to investigate how the El Niño-Southern Oscillation (ENSO) influences three key processes affecting ozone: biomass burning, lightning-produced nitrogen oxides, and stratospheric ozone intrusion. These findings show that tropospheric ozone’s radiative effects strengthen during La Niña and weaken during El Niño. Read More…
Winter high-elevation snowpack is a primary source of freshwater in the Western United States. Focusing on wintertime precipitation in the coastal western U. S., the authors evaluated simulations from a global storm-resolving model, the eXperimental System for High-resolution prediction on Earth-to-Local Domains (X-SHiELD). Developed at GFDL, X-SHiELD operates at global 3 km resolution, allowing for the simulation of both broad atmospheric patterns and localized precipitation features. The model reproduces observed precipitation distributions over complex terrain more accurately than traditional global models. Read More…
Winter atmospheric rivers (ARs) are crucial for water supply and extreme weather events in both the western (WUS) and eastern United States (EUS), yet their long-term trends and interactions remain unclear. The authors address this by analyzing multiple observational AR datasets spanning the past four decades. They identified contrasting yet interrelated trends in AR frequency, intensity, and associated mean precipitation, and explain these trends based on large-scale atmospheric and oceanic variability in the Pacific. Their findings offer a unified explanation for the observed AR trends and carry important implications for mitigating risks related to AR-induced extreme events in both densely populated coastal regions. Read More…
June 10th, 2025 - Closing the gap — Hurricane Prediction Advances in the US FV3-based Models
Hurricanes are one of the most destructive natural events on Earth. Improving the skill of hurricane forecasts, especially for those in the North Atlantic basin, has always been an important objective for government weather forecast agencies, emergency managers, and the atmospheric science research community in the United States. The model developed by the European Centre for Medium-range Weather Forecasts (ECMWF) has been recognized as providing the most skillful guidance for track forecasts for years. However, the performance of American models for hurricane forecasting has been catching up. Read More…