Extended Forecasting (Atmospheric Oscillations) Flashcards
What does MJO stand for?
Madden-Julian Oscillation
The MJO is an _____ ______ or “wave” occurring in the global tropics
intraseasonal fluctuation
The MJO results in variations in several important atmospheric and oceanic parameters including:
- lower and upper-level wind speed and direction (divergence)
- cloudiness and rainfall
- surface pressure
- sea surface temperature (SST)
The MJO is a naturally occurring component of our coupled ____-____ system
ocean-atmosphere
The typical length of the MJO cycle or wave is approximately ___-___ days
30-60 days
The MJO is characterized by ____ propagation of regions of enhanced and suppressed tropical rainfall, primarily over the ____ and ____ Oceans
eastward
Indian and Pacific
The anomalous rainfall is often first evident over the ___ Ocean, and remains apparent as it propagates eastward over the very warm waters of the ____ and ____ tropical Pacific
Indian
western and central
Over the cooler ocean waters of the eastern Pacific, the pattern of tropical rainfall generally becomes ____, but often reappears over the tropical ____ and ___
nondescript
Atlantic and Africa
Along with these variations in tropical rainfall with MJO, there are distinct patterns of ___ and ____-level divergence and atmospheric circulation anomalies in the ____ and ____
lower- and upper-level
tropics and subtropics
These features extend around the globe and are not confined to the eastern hemisphere. they provide important info regarding the regions of ___ and ____ motion associated with particular phases of the ____
ascending and descending
oscillation
As active convection moves eastward from the central Pacific to the Atlantic, the feature ____ as it moves into the Western Hemisphere
weakens
When convection is active in the Indian Ocean and Indonesia, in the ___ levels, anomalous easterlies exit the area of enhanced convection in the upper levels of the atmos associated with ____ gyres stradding the equator in both hemispheres ____ and to the ___ of the convection.
upper
anticyclonic
west
Conversely in the upper levels, ____ gyres straddle the equator to the ___ in areas of suppressed convection in both hemispheres
cyclonic
east
When convection is active in the Indian Ocean and Indonesia, in the ___ levels, anomalous easterlies are evident to the ___ of the area of enhanced convection, associated with ____ gyres straddling the equator in both hemispheres
lower
east
anticyclonic
in the lower levels, anomalous ____ are evident within and to the west of the area of enhanced convection, associated with ___ gyres straddling the equator in both hemispheres
westerlies
cyclonic
The low level gyres are generally ___ than those at upper levels
weaker
As the MJO propagates ____ through the central Pacific and eastern Pacific, the lower and upper level cyclonic/anticyclonic circulation anomalies become ___ recognizable and coherent but remain an important component in redistributing mass and convergence/divergence around the global tropics
less recognizable
Enhanced ____ often accompanies the upper level ____ phase of the MJO
rainfall
U/L divergent
However, with MJO, rainfall may be suppressed across portions of the equatorial eastern Pacific Ocean due to ____ ocean water there
colder
Anomalously strong 850mb ____ occur in the tropics within the lower-level ___ (___) phase of the MJO
easterlies
divergent (dry)
Anomalously strong 850mb ____ occur in the tropics within and immediately west the lower-level ____ (___) phase of the MJO
westerlies
convergent (wet)
850 mb equatorial westerlies south of Mexico are often associated with an enhanced ____ ____ over the NW Caribbean and southern Gulf of Mexico
monsoon trough
Equatorial westerlies produce ____ shear across the NW Caribbean and southern Gulf of Mexico, which favors ____ ____ formation there.
cyclonic
tropical cyclone
The MJO can substantially modulate the _____ of monsoon systems around the globe
intensity
When does the MJO substantially modulate the intensity of monsoon systems for the following areas?:
- The Australian Monsoon?
- The Asian Monsoon?
- The South American Monsoon?
- The North American Monsoon?
- Australian: SH summer
- Asian: NH summer
- S Am.: SH summer
- N Am.: NH summer
The _____ (___) phase of the MJO can affect both the timing of the monsoon onset and the intensity of the monsoon
divergent (wet)
The ____ (___) phase of the MJO can prematurely end a monsoon and also initiate breaks during already existing monsoons
convergent (dry)
There is evidence that the MJO influences the ___/___ cycle
El Nino/La Nina cycle
The MJO does not cause El Nino, but can contribute to the ___ of development, and perhaps the overall ___ of El Nino episodes
speed of development
overall intensity
The MJO is known to ____ tropical cyclone activity in the Indian, Pacific, Atlantic Oceans, and the Gulf of Mexico
modulate
The MJO modulates this activity (particularly for the strongest storms) by providing a ___-scale environment that is favorable or unfavorable for development
large-scale
Westerly wind anomalies at the ____ in and just behind the MJO’s area of enhanced convection may generate mirror-image ____ gyres straddling the equator respectively
surface
cyclonic
At the same time, in the ___ levels, mirror-image ____ gyres develop along and just behind the area of convection
upper-levels
anticyclonic
The net result of the mirror-image cyclonic gyres at the surface, and anticyclonic gyres at the U/L is:
1) A reduction of U/L wind shear for westward-moving tropical cyclones
2) an increase in U/L divergence
The strongest tropical cyclones tend to develop during the upper-level ____ (__) phase of the MJO
divergent (wet)
As the MJO progresses eastward, the favored region for tropical cyclone activity also shifts ___ from the Indian Ocean to the Pacific Ocean and eventually to the Atlantic Ocean
eastward
Sea Surface Temperatures must be sufficiently ___ and vertical wind shear must be sufficiently ___ for tropical cyclones to form and persist
warm
weak
Enhanced tropical rainfall in the ___ and ___ Pacific can contribute to extreme rainfall events in ___ North America
western and central Pacific
western North America
A ____ ____ is an event in which an eastward moving upper level divergent (wet) phase of the MJO in the central or eastern tropical Pacific and a retrograding (i.e. westward moving) mid-latitude jet stream trough in the high latitudes.
Pineapple Express
There is a strong year-to-year variability in MJO activity, with periods of ____ activity followed by long periods in which the oscillation is ___ or ____
strong activity
weak or absent
There is evidence that the _____ variability of the MJO is partly linked to the El Nino cycle
interannual
Strong MJO activity is often observed during ___ La Nina yeras or during times when El Nino or La Nina is ____
weak
absent
Weak or absent MJO activity is typically associated with ___ El Nino episodes
strong
The ____ ____ is a zonal (east-west) direct circulation in the tropical Pacific
Walker Circulation
A ___ circulation is oriented parallel to latitude lines
zonal
A ____ circulation is composed of a circulation where warm air is rising and cold air is sinking
direct
Warm air ____ over the west Pacific during a normal Walker circulation regime
rises
Cooler air ___ over the cooler water of the east Pacific
sinks
Under normal conditions, the west Pacific experiences ____ rainfall, whereas the east Pacific (particularly along and south of the equator) is ___
heavy
dry
With the Walker Circulation, through which months are there normal conditions?
December-February
At the ____, the West and East Pacific are linked by westward-directed trade winds
surface
In the ____-___, the West and East Pacific are linked by eastward-directed winds
upper-troposphere
When the Walker Circulation is strong, ____ pressure resides over the tropical West Pacific
low
When the Walker Circulation is strong, ____ pressure resides over the tropical East Pacific
high
When the Walker Circulation is strong, the ____ winds are strong over the Pacific
trade winds
When the Walker Circulation is strong, the ___ Pacific is wet and stormy
West
When the Walker Circulation is strong, the ____ Pacific is dry and tranquil
East
______ isadisruptionoftheocean‐atmosphere
systeminthetropicalPacifichavingimportant
consequencesforweatheraroundtheglobe.
ElNiño
ElNinoischaracterizedbyamajor_____of
watersinthe________and_______ _____ Ocean.
warming | tropicalcentral | easternPacific
Ocean
El Nino is called “___ ____” because it occurs or was first noticed along the west coast of South America around ____ time
“The Child” | Christmas Time
El Nino occurs every ___ - ___ years and is characterized by a major ____ or even total ____ of the ____ Circulation
2-10 years | major weakening | total reversal | Walker Circulation
Drastic changes in ____ _____ are experienced not only over the tropical Pacific, but throughout the world
weather patterns
El Ninos are characterized by a “_____” SOI
negative
What does SOI stand for?
Southern Oscillation Index
SOI = _____ - _____
SOI = Tahiti SLP - Darwin SLP
When Tahiti SLP is significantly ____ than Darwin, the SOI is _____ and an El Nino may be occurring
lower | negative
In December 2008, the Climate Prediction Center started using the ____ ___ ___ to monitor El Nino
Oceanic Nino Index (ONI)
El Nino-related atmospheric and oceanic data is routinely measured by an array of ____ in the Central and Eastern Tropical Pacific
buoys
ONI is based on ____ departures from average in the Nino ___ region, and is now the principle measure of monitoring and assessing El Nino
SST departures | 3.4
The ONI is based on a ____-month running mean of SST departures in the Nino 3.4 Region
3-month
The ONI is used to place current events into a _____ perspective
historical
NOAA’s operational evaluation of El Nino and La Nina are keyed to the ____
ONI
____ ____ is characterized by a ____ ONI greater than or equal to +0.5 deg C
El Nino | positive
___ ____ is characterized by a ____ ONI less than or equal to -0.5 deg C
La Nina | negative
By historical standards, to be classified as a full-fledged El Nino or La Nina episode, these thresholds must be exceeded for a period of at least ___ consecutive overlapping ___-month seasons
5 consecutive | 3-month seasons
CPC considers El Nino or La Nina conditions to occur when the monthly Nino 3.4 SST departures ____ or ____ +/- 0.5 deg C along with consistent atmospheric features
meet or exceed
These anomalies must also be _____ to persist for ___ consecutive months
forecasted | 3 consecutive months
The most recent ONI value (January-March 2014) is ___ deg C
-0.7 deg C
When the Walker Circulation is weak (or reversed), ____ forms
El Nino
When the Walker Circulation is ___ (or _____), great havoc occurs in the world’s weather patterns
is weak (or reversed)
When the Walker Circulation is weak (or reversed), great hardship is experienced by many ____ and much ____ across the world
many people | much wildlife
When an El Nino is occurring, ___ pressure moves to the tropical Central and East Pacific
Low
When an El Nino is occurring, ____ pressure forms over the tropical West Pacific
High
When an El Nino is occurring, the ____ winds weaken or reverse over the Pacific
trade winds
When an El Nino is occurring, the ____ ____ becomes dry (drought is common in rainforests)
West Pacific
When an El Nino is occurring, the ____ and ___ Pacific become very stormy
Central and East Pacific
During the formative stage of El Nino (late summer and fall), the Walker Circulation _____
weakens
During the formative stage of El Nino (late summer and fall), pressure ___ in east Pacific and ____ in West Pacific
falls | rises
During the formative stage of El Nino (late summer and fall), the SOI becomes ____
negative
During the formative stage of El Nino (late summer and fall), the ONI becomes ____
positive (>0.5 deg C)
During the formative stage of El Nino (late summer and fall), trade winds ____ (_____)
fail (weaken)
During the formative stage of El Nino (late summer and fall), an _____ ____ wave moves from West to East Pacific
Equatorial Kelvin Wave
During the formative stage of El Nino (late summer and fall), ____ SST’s shift eastward as sea level mound moves eastward
warm SST’s
During the formative stage of El Nino (late summer and fall), ____ in East Pacific weakens
upwelling
During the formative stage of El Nino (late summer and fall), convection and precipitation shifts _____
eastward
During the mature stage of El Nino (Winter and Spring), the Walker Circulation ____
reverses
During the mature stage of El Nino (Winter and Spring), ____ pressure resides in central and east Pacific
Low pressure
During the mature stage of El Nino (Winter and Spring), ____ pressure resides in west Pacific
high
During the mature stage of El Nino (Winter and Spring), the SOI becomes strongly ____
strongly negative
During the mature stage of El Nino (Winter and Spring), the ONI becomes strongly ____
strongly positive
During the mature stage of El Nino (Winter and Spring), trade winds ___ or actually ____
calm or actually reverse
During the mature stage of El Nino (Winter and Spring), Equatorial Kelvin Wave moves from ____ to ___ Pacific
West to East
During the mature stage of El Nino (Winter and Spring), warm SST’s cover ____ and ___ Pacific
central and east Pacific
During the mature stage of El Nino (Winter and Spring), sea level ___ resides in east Pacific (higher sea level along South American Coast)
Sea Level Mound
During the mature stage of El Nino (Winter and Spring), upwelling of cold water in East Pacific is ____
absent
During the mature stage of El Nino (Winter and Spring), ____ _____ cover central and east Pacific
heavy thunderstorms
During the dissipating stage of El Nino (late spring and summer), the Walker Circulation begins to ____
strengthen
During the dissipating stage of El Nino (late spring and summer), pressure ____ in west Pacific and ____ in east Pacific
falls | rises
During the dissipating stage of El Nino (late spring and summer), the SOI becomes ____
positive
During the dissipating stage of El Nino (late spring and summer), the ONI becomes ____ or slightly ____
neutral or slightly negative (<0.5 deg C)
During the dissipating stage of El Nino (late spring and summer), trade winds ____
strengthen
During the dissipating stage of El Nino (late spring and summer), the Equatorial Kelvin Wave ____
dissipates
During the dissipating stage of El Nino (late spring and summer), warm SSTs ____ back to the west Pacific
slosh back
During the dissipating stage of El Nino (late spring and summer), sea level mound ____ in east Pacific (sea level ____ in west Pacific_
disappears | rises in west Pacific
During the dissipating stage of El Nino (late spring and summer), upwelling of cold water in East Pacific ____
resumes
During the dissipating stage of El Nino (late spring and summer), heavy thunderstorms move back to ____ Pacific
west
During the dissipating stage of El Nino (late spring and summer), ____ weather returns to east Pacific
dry
___ ____ is a major cooling of the tropical east Pacific Ocean
La Nina
La Nina generally (but not always) follows a strong ___ ____ event and is characterized by an overly-strong ____ _____
El Nino | Walker Circulation
La Ninas are characterized by a “____ ____” SOI
strongly positive
La Ninas are characterized by a “____ ____” ONI
strongly negative
There is growing evidence that anomalously strong MJO activity often ____ major El Nino warm events by __ - ___ months
precedes | 6-12 months
Vigorous bursts of equatorial westerly winds, associated with the frequent positive phases of the MJO, may develop an oceanic ____ ____ which forces a dome of warm water eastward from the West Pacific.
Kelvin wave
This Kelvin Wave would help suppress cold upwelling in the East Pacific, helping to ____ SLP, ___ the zonal SLP gradient across the Pacific, and ___ the trade winds, thus ____ an El Nino
lower SLP | relax zonal SLP gradient | relax trade winds | initiating an El Nino
The strength of El Nino events appears to ____ with the strength of preceding MJO activities
increase
_____ variability in the atmosphere (wind and pressure), which is often related to the Madden-Julian Oscillation (MJO), can significantly impact ____ and _____ conditions across the Pacific Ocean
Intraseasonal | surface and subsurface
Significant weakening of the low-level easterly winds usually initiates an ____-propagating oceanic Kelvin wave
eastward
What does NAO stand for?
North Atlantic Oscillation
The NAO Index is defined as the difference of ____ (or ___ ____) anomalies between two regions: One near the ____ and one near ____
SLP (or 500mb heights) | Azores region and Iceland
NAO Index = (SLP anomalies (____) - SLP anomalies (____))Regions
Azores - Iceland
After ___ ____, the NAO pattern is one of the most dominant modes of global climate variability
El Nino
The temperature see-saw in Greenland is now known to be a manifestation of the ___
NAO
The ____ dictates climate variability from the eastern seabord of the US to Siberia and from the Arctic to the subtropical Atlantic, especially during Winter
NAO
The ____ index (i.e. ____) NAO is associated with a net displacement of air from over the Arctic and Icelandic regions towards the subtropical belt near the Azores and the Iberian peninsula
high index (i.e. Positive) NAO
The mass displacement of air associated with a Positive NAO _____ the Icelandic Low near the SE coast of Greenland and also ____ the subtropical H in the Atlantic
strengthens | strengthens
The mass displacement of air associated with a Positive NAO results in more intense _____ over the N Atlantic ocean
westerlies
_____ temperatures are also observed over the W Atlantic and eastern US
Warmer
The stronger Atlantic Subtropical High also strengthens the ____ ____ over the Tropical Atlantic
trade winds
___ ____ is often blown across the tropical Atlantic toward the Caribbean and FL
African dust
Increased _____ of cold water off the NW coast of Africa help to keep sfc temps cooler over the tropical E Atlantic. ___ weather often is enhanced here as well
Upwelling | dry weather
The ____ index (i.e. ____) NAO is associated with a net displacement of air from over the subtropical belt near the Azores and Iberian Peninsula northward to the Arctic and Icelandic regions
Low Index (i.e.: Negative)
The net displacement associated with a Low/Negative NAO Index ____ the Icelandic Low and forces it to become much more ____ in location. It also ___ the subtropical H in the Atlantic, resulting in ___ intense westerlies over the N Atlantic ocean
weakens | more variable in location | weakens subtropical H | less intense westerlies
With a negative NAO, ____ patterns often develop in the Atlantic jet stream pattern
Blocking patterns
With a negative NAO, Arctic High pressure is better developed in the ___ regions and often ____ into northern and central Europe when significant blocking patterns develop over the Atlantic
polar | invades
With a negative NAO, ___ than normal European winters are often experienced with much more ____ and precipitation in the eastern Mediterranean Sea area
colder than normal | more storminess
With a negative NAO, a ____ subtropical H promotes ____ trade winds in the tropical Atlantic
weaker | weaker
With a negative NAO, ____ upwelling of cold water off the NW coast of Africa help to keep surface temperatures _____ over the tropical eastern Atlantic
reduced | warmer sfc temps
Blocking in the N Atlantic is much more prevalent during ____ phases of NAO
negative phases of NAO
During a negative NAO event, deep _____ reside over E N Am and Europe, bringing unusually ____ conditions
deep troughs | unusually cold
It appears that the link between El Nino in the tropical Pacific, and the NAO, is relatively ____
weak
The NAO may arise from what influences?
1) Stochastic interaction between storms
2) Climatologial stationary eddies
3) Time-mean jet stream pattern
4) Long-term stratospheric influences on the troposphere
5) The intensity and distribution of tropical convection
6) Long-term feedback from oceanic circulation patterns and sea ice changes
With the long-term statospheric influences on the troposphere, the influence of volcanic ash tends to promote ___ phase
+ PNA
With the long-term statospheric influences on the troposphere, ozone depletion tends to promote ____ phase
+ PNA
With the long-term statospheric influences on the troposphere, greenhouse gas accumulation may promote ___ phase
+ PNA
The month-to-month and year-to-year changes in the phase and amplitude of the NAO are largely _____
unpredictable
External forces may be able to ____ the NAO pattern into positive and negative phases over a particular month or season
nudge
What does AO stand for?
Arctic Oscillation
The __ is the dominant pattern of non-seasonal SLP variations N of 20N
AO
The AO is characterized by ____ anomalies of one sign in the Arctic and anomalies of opposite sign centered in the mid-latitudes
SLP anomalies
AO Index = (SLP Anom (____) - SLP Anom (___)) Regions
Mid-Latitude | Arctic
Positive AO is associated with ___ pressure in the mid-latitudes and ____ pressure near the N Pole
HIGHER | LOWER
Positve AO is associated with ___ zonal flow of westerlies across the mid-latitudes
fast strong zonal flow
Positive AO is associated with ___ winter weather in US and Europe
mild winter weather
Positive AO is associated with ____ arctic sea ice
melting
Positive AO is known as the ____ phase of the AO
warm phase
Negative AO is associated with ____ pressure in mid-lat and ____ pressure near N Pole
LOWER | HIGHER
Negative AO is associated with significant high-lat ___ in jet stream, which leads to ____ meridional flow and ___ zonal flow of westerlies in mid-lat
blocking | greater merid | weaker zonal flow
Negative AO is associated with ____ cold winter weather in US and Europe, and ____ arctic sea ice
severe | expanding
Negative AO is known as ___ phase of AO
cold phase
The month-to-month and year-to-year changes in phase and amplitude of NAO and AO are largely ____
unpredictable
What does PNA stand for?
Pacific-North American Pattern
The PNA is associated with a ___ wave pattern with centers of action over the N Pacific and over N Am
Rossby wave pattern
A positive PNA is characterized by ___ 500 mb height anomalies over the N Pacific and E N Am/W Atlantic
low 500 mb heights
A positive PNA is characterized by ____ 500 mb height anomalies over W N Am
high 500 mb heights
What does PDO stand for? When was it discovered?
Pacific Decadal Oscillation. 1997
____ ___ play a huge role in the short and long-term climate variability
Natural Cycles
The Earth has shown no statistically significant warming in approximately the last __-__ years
15-17 years
The ____ is a long-lived El-Nino-like pattern of Pacific climate variability
PDO
The PDO Index is defined by the N Pacific monthly __ ____ ___ variability
monthly SST variability
PDO Index = SST (___) - SST (___)
SST (E Pacific) - SST (Central Pacific)
Warm (____) Index periods contain ____-than-normal waters in N central Pacific Ocean and ____-than-normal waters along W coast of N Am
(+PDO) | cooler | warmer
Cold (___) Index periods contain ___-than-normal waters in N central Pacific Ocean and ___-than-normal waters along W coast of N Am
(-PDO) | warmer | cooler
20th century PDO “events” persisted for __-__ years, while typical ENSO events persisted for __-___ months
20-30 years | 6-18 months
The climatic fingerprints of the PDO are most visible in the ___ ___/___ ___ sector, while secondary signatures exist in the ____ - the opposite is true for ENSO
most visible in N Pacific/N Am | secondary exist in tropics
The effects of the PDO are most drastic in the ____ ____
Pacific Northwest
A positive PDO generally correlates with ___ conditions and ___ temperatures
dry conditions | warmer temperatures
A negative PDO generally correlates with ___ conditions and ___ temperatures
wet conditions | cooler temperatures
Warm eras have seen ___ coastal ocean biological productivity in Alaska and ____ productivity off W coast of US
enhanced in Alaksa | inhibited off W coast
Cold PDA eras have seen ____ marine ecosystem productivity in Alaska and ___ productivity off W coast of US
Inhibited | enhanced
True or False? Causes of PDO are not currently known.
True!
Research indicates that there may be indicators up to ___ years in advance
10 years
If the PDO unexpectedly changes phase during the forecast period, then error ____ in extended weather predictability
increases
Some new research indicates that PDO cycle may be related to ___ cycles
solar
