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In a new weekly update for pv magazine, Solcast, a DNV company, says irradiance patterns across South America Last month they were affected by El Niño humidity, high pressure and the Andes, but the smoke from the Bolivian forest fires is presented as an “anomaly.”
El Niño humidity, high pressure and the Andes mountain range played a role in irradiance patterns across South America in November, but smoke from forest fires in Bolivia is clearly present in the months irradiance anomaly, according to the analysis performed with data from the Solcast API.
Smoke aerosols in the atmosphere absorb and disperse direct irradiance, decreasing global irradiance and increasing the diffuse fraction of irradiance. These effects reduced irradiance over Paraguay, northern Argentina, southern Brazil and Uruguay, while the west coast of South America also experienced lower than normal November irradiance due to increased humidity caused by El Niño. The Andes largely protected the rest of the continent from that moisture, and the additional effects of high pressure over central Brazil meant that large-scale solar energy from that region received much more irradiance than normal for this time of year. anus.
Forest fires in Bolivia generated aerosols that reduced irradiance to 30% below long-term averages in Paraguay, northern Argentina, southern Brazil and Uruguay. Although the fires were most active in mid-November, they were concentrated enough to be clearly reflected in the monthly average aerosol impact.
in the monthly average aerosol impact (Aerosol Optical Depth) , shown below.
Aerosols in the atmosphere have a significant impact on irradiance by scattering direct irradiance high in the atmosphere. As can be seen from this breakdown, aerosols had a significant impact in Sao Paulo, reducing irradiance.
Central and eastern Brazil suffered some effects from the smoke, but not enough to prevent irradiance from being 20% ??to 30% above the November average. A high pressure system in the upper atmosphere suppressed storm formation, resulting in clearer skies and higher irradiance. This marks a change from the usual patterns in November, when warm, humid air fuels showers and storms across Brazil. This year, the many large-scale Brazilian solar assets located in this region have benefited from the anomalous high pressure system, which has moved humidity away from the area.
El Niño received its full name “The Christmas Child” in the 17th century from fishermen who observed warmer ocean temperatures off the South American coast in December of stormy years. The warmer waters of the Pacific are a key indicator of the phenomenon and bring with it an increase in atmospheric humidity and storms along the western coast of South America, hence the interest of fishermen. This year these effects are already being observed, with an increase in cloud activity until November along the coast that causes irradiance around 10% lower than the long-term averages. The Andes mountain range forms a natural barrier that prevents additional moisture from moving to the east of the continent, keeping the greatest effects of El Niño on the western coast.
Interestingly, northern Chile recorded the highest average irradiance of the entire continent, but lower than normal for November. This pattern has also been present in other months, since the region from the Atacama Desert to the Altiplano plateau is one of the most irradiated places
in the world. |
