inter-annual and global change

Question 1

what was the weather bomb in 2004?

Answer 1

Storm produced in the whole of the UK. Biggest waves in this region which affected UK. Explosive cyclogenesis: when the isobars low deepens. Intense jet stream. Weather buoys record the wave height during the storm.

Question 2

what is El Nino?

Answer 2

an irregularly occurring and complex series of climatic changes affecting the equatorial Pacific region and beyond every few years, characterized by the appearance of unusually warm, nutrient-poor water

Question 3

what triggers El Nino?

Answer 3

• Weakening of the trade winds
  
  • Westerly winds burst in the western equatorial pacific
  • Gives a slackening of the force piling water up in the W. Pacific
  • Results in eastwards- propagating kelvin wave that initiates el Nino.

Question 4

how is El Nino forced by other events?

Answer 4

• Volcanic eruptions; climatic records show than El Nino events follow strong volcanic events in tropics. But volcanic aerosols trigger cooling, so how does this work? In east harder to change SST due to strong upwelling and shallow steep thermocline. In west, warmer SST and deeper thermocline makes cooling easier. So faster cooling in west reduces E-W SST gradient. And via negative feedback trade winds slacken.

Question 5

how do El Nino teleconnections work?

Answer 5

• They operate along equatorial belt. Change to walker circulation results in Knock-on effects modifying equatorial circulation cells.
  
  • Changes location of zones of convection and zones of sinking dry air along equator.

Question 6

what does PDO stand for?

Answer 6

pacific decadal oscillation

Question 7

what are meridional teleconnections?

Answer 7

• Meridional teleconnections in the atmosphere: the anomalous Hadley cell convection generated from an “atmospheric bridge”

Question 8

what is the connection to the stratosphere?

Answer 8

• There is also a connection to the stratosphere, deep convection generates atmospheric kelvin wave activity.
In the ocean: by northward propagating coastally trapper kelvin waves, also slower by rossby waves.

Question 9

what is the PDO?

Answer 9

The pacific decadal oscillation PDO: affect on ecosystems .fisheries noticed a similarity between the envelope of el Nino and the NW pacific salmon catch

Question 10

what are the 2 main characteristics distinguishing PDO from El Nino?

Answer 10

1. 20th century PDO events persisted 20-30 years, while el Nino events persisted 6-18 months
   
   2. The climatic fingerprints of the PDO are most visible in the N pacific, while secondary signatures exist in the tropics, the opposite is true for ENSO.

Question 11

what is the positive phase of the different regime of the PDO change productivity?

Answer 11

For california current regime: weaker winds, weaker upwelling, weaker current, lower productivity. This affects the whole food web- less phytoplankton, less zooplankton, less krill, less small fish. Less food for salmon

Question 12

what is the negative phase of the different regime of the PDO change productivity?

Answer 12

stronger winds along coast, stronger upwelling, stronger currents, high productivity.

Question 13

what is the phase of the different regime of the PDO change productivity in the Alaska current?

Answer 13

opposite phases, negative is worse for the salmon. Due to weaker sub artic gyre, weaker upwelling, lower productivity.

Question 14

how is the PDO index calculated?

Answer 14

This longer period envelope of El Nino is the PDO. The PDO index is calculated by looking at temperature anomalies between NE and tropical pacific.
Comparing PDO and salmon catches show relationship between Alaska and pacific climate

Question 15

what is the relationship between el nino and PDO

Answer 15

increased frequency of El Nino every 5-6 years
Sends PDO into warm phase. Oceanic- northward propagating coastally trapped kelvin waves. Atmospheric- el Nino is known to intensify the Aleutian low via an atmospheric bridge.

Question 16

how is PDO regarded as the ocean-atmosphere system response?

Answer 16

PDO may be regarded as the ocean-atmosphere system response to El Nino events. This response becomes lagged or delayed, due to the near-decadal time scales of the oceanic responses to equatorial stimulus.

Question 17

what do temperature anomalies show?

Answer 17

Temperature anomalies may also persist below mixed layer and re-emerge in successive winter.
Thus, north pacific integrates the effects of ENSO over years, especially during winters and spring.

Question 18

what is the rise of the linked to?

Answer 18

Link to do with global warming. Post 2000 halt due t this. 2014- goes into PDO positive again. Warmest year on record.

Question 19

how do we look for temporal variability?

Answer 19

Time series is a collection of observations of data, obtained through repeated measurements over time.
In time series analysis, we look for robust patterns or recurrence of event sat given timings. We are interesting in whether the frequency and magnitude of events change with time. We are interested in whether events are random or recur at regular, and so predictable time intervals.

Question 20

how can you use wavelet analysis?

Answer 20

• Wave interference: the process of wave addition and subtraction, called wave interference, is what causes waves to vary in height and irregular patterns.
Complex waves forms. We can thing of climate signal in the same wat and use the same techniques to separate and identify signals of different periods and frequencies .
Oceanographers use spectral analysis to analyse water surface wave fields. Use periodograms.

Question 21

what is SOI?

Answer 21

• SOI- southern oscillation index. Confidence levels show 90, 05 and 99%. Therefore high chance that a spectral peak about 95% confidence levels is district from the spectral background.

Question 22

what does SOI enable?

Answer 22

• This enables identification of changes in dominant frequencies over time. If the dominant frequencies change through time, then the signal is said to be “non-stationary”.

Question 23

what is the evidence for transmission of El Nino to high latitudes?

Answer 23

Analyse the time series of temperature and pressure records, from further afield to assess the influence of El Nino on the global climate.

Instrumental records of ENSO variability: ENSO periods evident in widespread records of northern hemisphere air temperature and atmospheric pressure.

Question 24

what happened in 1883?

Answer 24

1883, phenomenon known as Krakatoa sunsets which spread around the world. Caused by injection of sulphur dioxide to stratosphere, this reacts with water vapor to produce a thin layer of small sulphuric acid droplets. This persists for 2 years. Until flushed to troposphere.

Question 25

what did Russell find out about balloons?

Answer 25

Russell, reports first observations of the Krakatoa sunsets. Concluded that the plume first travelled zonally in band around 20 S- N. Complied a map showing a boundary of the plume. Day by day after eruption.
Balloons were launched from africa. Their eastwards transport at heights near troposphere gives the rise to the Berson westerlies, that supposedly lay beneath the krakatau easterlies.

Question 26

what happened in 1954?

Answer 26

1954- Sonde data and nuclear test showed that the winds changed directions and reversed at any given height.
This gave rise to the Quasi-biennial oscillation- oscillation in the average zonal winds in the tropical stratosphere from westerly to easterly and then back again.

Question 27

what are HRDI equatorial winds?

Answer 27

HRDI equatorial winds: warm colours indicate westerly winds with increasing speed. Cool colours indicate easterly winds with increasing speeds. Easterly phase is stronger and more persistent. Create large scale disturbances.
Any fluid body with an atmosphere has this- Saturn ahs this as well.

Question 28

what is NAO negative mode?

Answer 28

NAO negative mode: weakened pressure difference. Large Rossby wave meander. Omega block. Cold northern Europe

Question 29

what is NAO positive mode?

Answer 29

NAO positive mode: strengthened pressure difference. No waves in jet stream. Strong westerlies. Warm, wet and windy northern Europe.

Question 30

what is NAO?

Answer 30

Artic oscillation AO, explains more variance, more hemispherically symmetric. Very similar- positive and negative have similar traits

Question 31

what does NAO stand for?

Answer 31

North Atlantic oscillation

Question 32

where does ozone distribution form?

Answer 32

forms mainly in tropics where solar rays are most intense. Currents do this.
Things rise up in the tropical pipe. In winter, the cool off and sink, creating a vortex. If you north, you’ll be deflected to the right, this results in the polar vortex. Sinks, and turns to the right.

Question 33

what is polar vortex?

Answer 33

Polar vortex: like a cone at the top of the world. A tornado with the stratospheric polar vortex.

Question 34

why is there large variations in the polar vortex strength?

Answer 34

Large variations in strength of polar vortex, due to propagate downwards to earths surface extending from 32km to the surface in 3 weeks.

Question 35

why are polar vortex stronger during QBO westerly?

Answer 35

Polar vortex stronger during QBO westerly phase. Weaker during the QBO easterly phase.
Sudden stratospheric warmings: less likely during QBO westerly. More likely during QBO easterly. .

Question 36

why are polar vortex more likely during QBO easterly?

Answer 36

Why? QBO easterly phase is hemisphere asymmetric with shift to winter hemisphere resulting in greater flux of planetary waves to north pole .

Question 37

how does El Nino generate waves?

Answer 37

El Nino: generates planetary waves that propagate northwards and influence the polar vortex. Get el Nino signal in northern stratosphere periodicities.
Planetary waves; changes in tropical convection and divergent outflow stimulate and interact with atmospheric Rossby wave

Question 38

what weakens polar vortex?

Answer 38

Major weakening of polar vortex followed by anomalously low surface temperatures over north America, north Europe and E Asia for 2 months.

Question 39

what can demonstrate that the polar vortex winds are coupled with tropospheric westerlies?

Answer 39

Annular mode anomalies are long lasting in the stratosphere and descend through time. Demonstrates that the polar vortex winds are coupled to the tropospheric westerlies.