Sentences with phrase «negative ao»

Negative AO reduces ice extent at the margins in the North Atlantic

This year, we saw El Nino heat plus a negative AO, so what else could we get but more snow further south.

Combine the record warmth with the extremely negative AO index... and bingo!

The moisture that fell on Florida, Washington, NY, Germany, and all the other places affected by the negative AO this winter was evaporated from warm oceans and carried to the point that it collided with cold air brought down from the arctic.

Secondly the negative AO now could be the reason the ozone is recovering and the stratosphere warming.

The negative AO changing the shape of the jet stream that now favors central and western Europe.

If a more active sun were to warm the stratosphere I would expect to see a negative AO from an intensified inversion at the tropopause with more equatorward jets and not a positive AO with more poleward jets.

I have already said twice that the «tail» does not need to change the global temperature, merely redistribute the energy in the troposphere to give colder mid latitudes via a more negative AO.

A negative AO changes pressure patterns at higher latitudes which influence the shape of the jet stream.

Here we identify lower tropospheric circulation anomalies and anomalous upward energy fluxes that precede large negative AO events in both the troposphere and the stratosphere by four to as much as six weeks.

Here too an increasingly unstable atmosphere over stretches of open Arctic Ocean would be leading to first depression formation, followed by the formation of high pressure systems later on — and therefore a transition from a positive to a negative AO index.

The authors however believe a positive AO and NAO leads to atmospheric wave train patterns which may have delayed opposite effects — leading to a negative AO and NAO later on in the season — and that is where especially associated European cold spells would originate from.

Especially the route where a positive AO is required to generate a negative AO, simply feels a bit too fabricated.

Negative AO / NAO episodes have increased from 1995 to 1998, and again from 2005, leading to a warm AMO, and the acceleration of sea ice loss.

In regards to the first question, J. Stroeve (personal communication) notes that in the present warmer climate state, the tendency for a negative AO winter pattern to promote increased transport of ice into the western Beaufort / Chukchi seas — a pattern that historically has helped to reduce summer ice loss — actually enhances summer ice loss.

However, we do not yet know if the strongly negative AO will persist through the winter, or what its net effect will be.

The negative AO is often associated with milder weather in the Arctic but severe winter weather, including cold - air or Arctic outbreaks and snowstorms across the mid-latitudes including the Eastern United States, Europe and East Asia.

In this way, a negative AO could help retain some the second - and third - year ice through the winter, and potentially rebuild some of the older, multiyear ice that has been lost over the past few years.

The negative AO phase is characterized by a high - pressure center anomaly over the entire Arctic basin or polar cap and low - pressure center anomalies in each ocean basin in the mid-latitudes.

While a negative AO leads to warmer temperatures over the Arctic, it also tends to reduce the flow of sea ice out of the Arctic by affecting the winds that can export the ice to warmer waters, where it melts.

Numerous recent studies based on both observations and model simulations indicate that reduced Barents - Kara sea ice in late fall favors a strengthened and northwestward expansion of the Siberian high, increased poleward heat flux, weakened polar vortex, and ultimately a negative AO.

And I predict a negative AO / NAO and El Nino bias through to around the next sunspot maximum, with California continuing a generally wetter phase until then.

Negative AO certainly matches solar minimum for the last 5 cycles.

The 2010/2011 Northern Hemiphere winter saw a very late start to the eastern Canadian Arctic / Hudson Bay freeze due to primarily due to the extended period and location of a strongly negative AO (NSIDC discusses it here: http://nsidc.org/arcticseaicenews/2011/020211.html).

Along with the negative AO index, we've seen an increased frequency of the the Arctic Dipole Anomaly, whereby the deep polar closed low that normally keeps the Arctic air contained is split into a pressure zones on both sides of the pole (i.e. a dipole) creating zonal winds across the Arctic shunt both cold air (and ice) more vigorously out of the Arctic.

It has been fairly well understood that a positive AO results in warmer temperature in lower latitudes, and a negative AO results in colder temperatures in lower latitudes.

But if we consider a second natural parameter, the strength and direction of the stratospheric wind in the Tropics (the Quasi-Biennial Oscillation index, QBO) I found a very interesting result: During periods of low solar activity (few or no sunspots) an easterly QBO causes a negative AO, but a westerly QBO causes a positive AO.

It is pretty obvious that the early 90's positive AO dwarfs the 2006 positve AO and 2004/2005 negative AO, however, the fact that the winds were going in the opposite direction then, seems to indicate to me that they were not favorable to ice export.

I haven't read the entire Noren paper yet, but it does not surprise me that severe flooding in the northeast could be linked with periods of negative AO [Arctic Oscillation].

In other words, the current trend of negative AO should introduce a cold bias in the global average temperature.

While a negative AO and NAO combination far from guarantees a cold and snowy period, our chances of a meaningful snow event are much greater than without it.

Not exact matches

The AO has been described as «a seesaw pattern in which atmospheric pressure at polar and middle latitudes fluctuates between positive and negative phases.

That occured at the moment that the whole NH was (slightly) cooling and midst of a negative NAO, AO and PDO.

When the AO is negative, the jet stream tends to be wavier, just like the situation we're in now, which favors slow - moving weather systems that can cause floods.

It seems very possible that the low solar activity forced areas of low pressures into a southern route or caused a negative Arctic Oscillation, AO, which in turn allowed cold air from the North Pole to flow across Europe.

Circulation anomalies of the same sign in the troposphere tend to follow this weakening of the stratospheric vortex leading to a negative phase of the AO in the troposphere.

While this year the very stongly + AO and NAO has the ice levels at normal levels in those areas but the Barents and Kara Seas have the negative sea ice anomolies while the Bering Sea has a positive anomoly.

Are you saying the open Arctic impacts the Arctic Oscillation and when AO is negative / positive then open Arctic will amplify / detract from AO influence on winter weather in regions of Northern Hemisphere?

There should be accelerated warming in the Arctic since 1996 due to the increasingly negative NAO / AO episodes.

Story: Peak petroleum; Story: Strong negative phase of the Arctic Oscillation (AO); Story: Polar Amplification Effect & Current Polar Conditions; Story: Mass tree deaths in Amazon; Story: GOP pushes to drop climate change research funding; Story: House Energy & Commerce Committee pushes to repeal EPA's authority to regulate greenhouse gases;

Substantial weakening of the polar cell due to increase in sea - level pressure over polar latitudes leads to a negative trend of the winter AO index.

My solar based long range forecast for 2014 included deterministic forecasts for negative NAO / AO and US Arctic outbreaks from around 7 Jan (for ~ 2 months), 10/11 Nov (for ~ 2 weeks), 26/27 Dec (for ~ 3 weeks).

Whilst I failed to persuade GRL to require Forest to provide any verifiable data or computer code, he had a change of heart — perhaps prompted by the negative publicity at Climate Etc — and a month later archived the complete code used for Forest 2006, along with semi-processed versions of the relevant MIT model, observational and AO - GCM control run data — the raw MIT model run data having been lost.

El Nino intensity and frequency increase during solar minima because negative NAO / AO increases, and major stratospheric volcanic aerosol events increase, also increasing El Nino conditions.

vii) AO and AAO becoming more negative with record AO negativity around the time of the minimum between cycles 23 and 24.

I think what needs explaining, is why negative NAO / AO conditions occur when the solar wind is weak:

«Based on relationships established in previous studies, the extreme negative phase of the Arctic Oscillation (AO) that characterized winter of 2009/2010 should have favored retention of Arctic sea ice through the 2010 summer melt season.

The AMO warming is dependent on negative NAO / AO, while increased CO2 forcing of the climate is expected to increase positive NAO / AO.

With the AO in its negative phase this season, the Arctic is warmer than average, while parts of the middle latitudes are colder than normal.

When the AO index is negative there tends to be low pressure in the polar region, weaker zonal winds, and greater movement of frigid polar air into middle latitudes.