Definitions (Listed Alphabetically)

El Niño Southern Oscillation:

The El Niño Southern Oscillation (ENSO) is a coupled ocean-atmosphere phenomenon. The oceanic component relates to changing seas surface temperatures in the tropical Pacific. The atmospheric component reflects changes in surface pressure in the tropical Pacific. ENSO is a quasi-periodic oscillation which occurs at intervals ranging from two to seven years. The effects of this phenomenon can be felt globally in climate and weather anomalies. North Atlantic hurricane activity is thought to be depressed during El Niño years.

Related webpage: http://www.elnino.noaa.gov/


[back to previous page]

Hurricane categories:

Hurricane intensity is ranked using the Saffir-Simpson Hurricane wind scale. This scale represents wind speed on a scale of 1 to 5, Category 1 having the lowest wind speed (74-95 mph) and Category 5 having the greatest wind speed (>156 mph). All categories cause some damage and flooding but the potential amount of damage increases by a factor of four for every increase in category number. Category 4 and 5 storms can cause significant damages and seriously threaten human life.

Related webpage: http://www.nhc.noaa.gov/aboutsshws.shtml


[back to previous page]

Isotopes:

Isotopes of an element are nearly the same chemically, in that they have the same number of protons and electrons, but each a different number of neutrons and therefore different atomic masses. Due to these differing masses isotopes of the same element tend to be separated during chemical reactions and other natural processes. Stable isotopes commonly used in palaeoclimate research to reconstruct past climate are isotopes of carbon (12C and 13C) and oxygen (18O and 16O). These are normally referred to as the ratio of the heavy isotope to the light isotope and reported in parts per thousand or ‘per mil’.


[back to previous page]

North Atlantic Oscillation:

The North Atlantic Oscillation (NAO) is the dominant mode of atmospheric variability in the Northern Hemisphere and exerts a strong influence on climate in regions bordering the North Atlantic Ocean, particularly during the winter months. The NAO is a measure of the sea level pressure difference between the Icelandic High Pressure Centre and the Azores Low Pressure Centre. This pressure difference drives the westerly winds and storms that blow across the North Atlantic. When the pressure difference is greater the NAO is said to be in its ‘positive phase’ and the westerly storm track is strengthened and moves northward. In its ‘negative phase’ when the pressure difference is reduced, the westerly winds are weakened and shift southwards.

Related webpages:

http://www.ncdc.noaa.gov/teleconnections/nao/

http://www.cru.uea.ac.uk/~timo/datapages/naoi.htm


[back to previous page]

Trace Elements

The term ‘trace elements’ in stalagmite-based palaeoclimatology refers to cations commonly found in stalagmite geochemistry. The ratio of certain trace elements (e.g., Magnesium (Mg2+), Phosphorous (P3+), Sr (2+), etc.) to Calcium (Ca2+) in stalagmite calcite provides information on such parameters as water residence times in the aquifer, carbon dioxide degassing rates, soil bioproductivity, growth rate, and prior calcite precipitation along the fracture flow path. By examining stalagmite trace elements in addition to stable isotopes, it is easier to extract the true palaeoclimate signal from the stalagmite geochemistry that may be partially obscured by site-specific conditions.


[back to previous page]

Placeholder