Atlantic Niña on the verge of developing. Here's why we should pay attention. | NOAA Climate.gov
Atlantic Niña on the verge of developing. Here's why we should pay attention. | NOAA Climate.govThis summer cooling is because of winds that act on the ocean surface. Earth has a year-round rainfall band around the tropics. Driven by stronger solar heating, this rainfall band migrates northward during the summer in the Northern Hemisphere. The regular rainstorms draw in air from the southeast over the equatorial Atlantic.
These steady southeasterly winds are strong enough to drag surface waters away from the equator, which brings relatively cold water from deeper ocean layers to the surface. This process, known as equatorial upwelling, forms a tongue of relatively cold water along the equatorial Atlantic during the summer months.
Only south of 5 degrees South were the southeasterly trade winds stronger than usual. As of now, these atmosphere-ocean conditions, apparently unfavorable for the developing Atlantic Niña event, are quite perplexing. We will need to dig deeper to reveal the exact causes of this seemingly unusual event.
One might think that a temperature difference of ±0.5 degrees Celsius (± 0.9 degrees Fahrenheit) in the tropical Atlantic does not seem like a big deal, but this difference can have a huge impact on rainfall over the surrounding continents. Reduced rainfall over the Sahel region, increased rainfall over the Gulf of Guinea, and seasonal shifts of the rainy season in northeastern South America have all been attributed to Atlantic Niño events.
Plus,
Atlantic Niños have been shown to increase the likelihood of powerful hurricanes developing near the Cape Verde islands. NOAA’s seasonal forecast of
above-normal 2024 hurricane activity is based in part* on expected La Niña conditions in the equatorial Pacific and warm ocean temperatures in the tropical North Atlantic. It will be interesting to monitor whether this Atlantic Niña fully develops, and if so, whether it has a dampening effect on hurricane activity as the season progresses. [Edited on August 22, 2024, to add "in part".]
