Gisteren liet ik jullie Glosea5 zien: positieve NAO, die zich in de loop van de winter versterkt. Drama voor de winterliefhebbers. Ik vertelde wat de oorzaak is van deze treurige setting. We zagen een sterke La Nina van het type Central Pacific. E.e.a wil ik verder toelichten mbv een aantal Engelstalige teksten.
Allereerst uitvoer van Glosea5.
We zien positieve NAO. Het luchtdrukverschil tussen IJsland en de Azoren is hoger dan normaal.
La Nina. Het zeewater bij de evenaar in de Pacific is koeler dan normaal.
Wat is een CP La Nina?
Central Pacific (CP) La Nina (Modoki)
The SST anomaly center associated with the CP La Niña is shifted westward into the CP west of 150°W and small cooling SST anomaly is found over the EP". In contrast to the canonical EP event, which advances somewhat westward to as much as 150longitude and decays faster, the CP event decays more slowly and remains in place, while propagating only a small amount in either direction". These differences in zonal location of SST anomaly and their evolutions suggest the possibility of different underlying dynamics, which is indeed the case. Modoki la nina are largely the product of a local air-sea interaction that develops and decays in place over the central Pacific. The reduced cooling over the east may also be further attenuated by a modified Walker cycle, according to Zhang, which features a displacement to the west of the easterly trades responsible for upwelling. In the modoki la nina, the EP trades are replaced with an anticyclone, as a direct result of the cool SST anomalies being shifted west to the CP.
The EP and WP [Pacific] forcing associated with the "modoki" la nina generally features an inverse pattern from that of a modoki el nino across North America. This resultant N. American pattern is more akin to an east-based, canonical el nino. however, we obviously have the prominent Aleutian high as opposed to the Aleutian low during el nino due to opposite anomalies over the tropical Pacific. The Aleutian high is in this composite is appreciably flatter and displaced to the southeast in relation to its canonical counterpart, as alluded to.
Let eens op de grote overeenkomst tussen Glosea5 en de CP La Nina. Het model verwerkt de informatie dus op een adequate manier. Nu is de vraag, wordt het wel een CP La Nina. Later meer daarover...
Edit. Dank Mark.