In a new weekly update for pv magazineSolcast, a DNV company, reports that the destabilized polar circulation in February caused wet and cloudy conditions in some parts of North America, while the central and eastern regions enjoyed increased irradiance under brighter conditions.
A combination of stratospheric warming and a disrupted polar vortex produced sharply contrasting radiation patterns in North America in February, according to analysis using Solcast API. The destabilized polar circulation brought wetter and cloudier conditions to parts of the north, while the central and eastern regions remained under brighter conditions and increased insolation. These opposing patterns created a clear gap in solar performance across the continent, with several inland networks experiencing stronger than normal conditions, while coastal areas experienced suppressed insolation.
A major driver of this pattern was stratospheric warming – a rapid warming of the upper atmosphere that disrupts the polar vortex that weakened and disrupted northern circulation patterns in February. This disruption allowed the jet stream to develop waves, shifting storm tracks and cloud distribution across North America. The resulting circulation pattern supported higher insolation over much of the United States, despite persistent winter weather in some regions. Western areas experienced reduced solar energy resources due to uncertain conditions, while the central and eastern United States saw clearer skies and greater radiation anomalies.
The odds were particularly high in the ERCOT and ISO-NE networks, where irradiance increases were nearly 20%, in addition to unusually high temperatures above 38°C (100°F) in some locations. Even a nor’eas, or winter, storm at the end of the month that brought heavy snow to the northeastern United States did not significantly reduce the broader pattern of increased solar conditions. The above-average insolation extended beyond the United States, reaching from the Rio Grande across the eastern coast of Mexico and southern Quebec.
Despite widespread improvements inland, several coastal areas experienced reduced solar energy resources due to anomalous weather systems. North and South Carolina recorded an approximately 15% reduction in insolation in February as snow and ice events increased cloud cover. Northern California saw similar declines as a series of atmospheric rivers brought persistent cloud cover and precipitation, suppressing radiation throughout the CAISO region. The Appalachian mountain range formed a clear boundary between areas of increased and decreased insolation along parts of the eastern seaboard.
February also marked a major change in solar conditions compared to January. Across much of the central and eastern United States, radiation patterns supported double-digit solar overperformance, with increases of about 15% to 25% over typical levels in February. ERCOT stood out within this pattern, where parts of Texas experienced exceptional solar conditions: longer days and seasonal improvements combined with unusually clear skies, leaving irradiance about 25% above seasonal norms, and +40% above January levels, as seen in Dallas, Texas.
Solcast produces these figures by tracking clouds and aerosols worldwide at a resolution of 1-2 km, using proprietary satellite data AI/ML algorithms. This data is used to drive irradiance models, allowing Solcast to calculate high-resolution irradiance, with a typical deviation of less than 2%, as well as cloud tracking predictions. This data is used by more than 350 companies that manage more than 300 GW of solar energy worldwide.
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