This document investigates the correlation between rainfall in equatorial Africa and tropical cyclone activity in the North Atlantic. It discusses how rainfall anomalies in Africa can impact the formation of African waves that seed tropical cyclones. Two studies are compared - one analyzing paleo-pollen data from Africa and the other a statistical model of tropical cyclone activity. There are some correlations found, particularly between low rainfall periods in Africa and fewer tropical cyclones. However, correlations are not as clear during high rainfall periods, suggesting other factors also influence tropical cyclone formation.
Telluric currents are the currents that are responsible for the generation of earth's magnetic field. Also the help the earth to bound onto the solar path around the sun.
Telluric currents are the currents that are responsible for the generation of earth's magnetic field. Also the help the earth to bound onto the solar path around the sun.
What occurred in 1811 was a meteor impact from the close passing of sungrazer comet c/1811f1... This comet produced a serial impact and caused the mini-ice age from 1811-1817...
What occurred in 1811 was a meteor impact from the close passing of sungrazer comet c/1811f1... This comet produced a serial impact and caused the mini-ice age from 1811-1817...
Large-scale dendrochronology and low-frequency climate variabilityScott St. George
Large-scale low-frequency variability has emerged as a priority for climate research, but instrumental observations are not long enough to characterize this behavior or gage its impacts on dependent geophysical or ecological systems. As the leading source of high-resolution paleoclimate information in the middle- and high-latitudes, tree rings are essential to understand low-frequency variability prior to the instrumental period. But even though tree rings possess several advantages as climate proxies, like other natural archives they also have their own particular impediments. In this lecture, Dr. St. George will describe the structure and characteristics of the Northern Hemisphere tree-ring width network, and outline how the fingerprint of decadal and multidecadal climate variability encoded within ancient trees varies across the hemisphere.
The decadal character of northern California's winter precipitationScott St. George
Starting in the 1930s, northern California has experienced major decade-to-decade swings in the amount of precipitation that falls during winter. Is this behavior
Impact of Climate Modes such as El Nino on Australian RainfallAlexander Pui
The relationship between seasonal aggregate rainfall and large scale climate modes, particularly the El Niño-Southern Oscillation (ENSO), has been the subject of a significant and on-going research effort. However, relatively little is known about how the character of individual rainfall events varies as a function of each of these climate modes. This study investigates the change in rainfall occurrence, intensity, and storm inter-event time at both daily and sub-daily timescales in East Australia, as a function of indices for ENSO, the Indian Ocean Dipole (IOD), and the Southern Annular Mode (SAM), with a focus on the cool season months. Long record data sets have been used to sample large variety of climate events for better statistical significance. Results using both the daily and sub-daily rainfall data sets consistently show that it is the occurrence of rainfall events, rather than the average intensity of rainfall during the events, which is most strongly influenced by each of the climate modes. This is shown to be most likely associated with changes to the time between wet spells. Furthermore, it is found that despite the recent attention in the research literature on other climate modes, ENSO remains the leading driver of rainfall variability over East Australia, particularly further inland during the winter and spring seasons.
(3) References for el nino cause and effects essayBelow are 3 fu.docxkatherncarlyle
(3) References for el nino cause and effects essay
Below are 3 full text sources from Proquest data base to be used for this essay. Please use in text citations in the body of the essay and create a works cited section at the end of the essay. I have already cited each source for you at the beginning of each source above the title (see below).
Perera, J. (1997, Dec 26). EL NINO - THE GLOBAL WEATHER PHENOMENON. Inter Press Service Retrieved from http://search.proquest.com/docview/446072605?accountid=8289
EL NINO - THE GLOBAL WEATHER PHENOMENON
LONDON, Dec. 26 (IPS) -- In March 1997, sea-surface temperatures in the Pacific Ocean began increasing -- the beginning of the "El Nino" weather system that, linked with the so-called "Southern Oscillation," has become notorious its global effects.
The El Nino of 1982-83 caused severe flooding and weather damage in Latin America as well as drought in parts of Asia. The last event, in 1991-92 brought severe drought to Southern Africa.
This year's El Nino is regarded by various experts as one of the most severe this century with record Pacific surface temperatures.
It is expected to continue well into 1998.
El Nino was the name given by the fishermen of northern Peru during the 19th century to describe the flow ofwarm equatorial waters southward around Christmas time. Normally the waters were cold and flowed from south to north.
But periodically the waters would reverse their flow and become warm. This caused the fish food chain to collapse as the warm current blocked the nutrient-rich cold water that rises from the bottom of the ocean. The fish died or moved away and catches would fall. This usually reached its peak around Christmas holiday, and the sailors named it "El Nino" (the Christ Child).
However, Peruvian scientists later linked more intense changes that took place every few years with catastrophic seasonal flooding along the normally arid coast.
At the beginning of the 20th century, British climatologist Gilbert Walker, head of the Indian Meteorological Service, began to investigate connections between the Asian monsoon and other climatic changes. He had been asked in 1904 to find a way to predict the pattern of India's monsoons after an 1899 famine caused by monsoon failure.
Unaware of El Nino, he discovered a periodic fluctuation of atmospheric pressure over the tropical Indo-Pacific region, which he called the Southern Oscillation (SO). When rainfall was sparse over northern Australia and Indonesia, pressure in that region was unusually high and wind patterns were changed.
At the same time, pressures were unusually low in the eastern South Pacific. Walker devised a "Southern Oscillation Index" (SOI), based on pressure differences between the two regions (east minus west) and in papers published during the 1920s and 1930s, he presented evidence for worldwide climatic changes associated with the SOI pressure "seesaw."
In the 1950s, the low-phase years of the SOI were found to corresponded ...
Disentangling the decadal ‘knot’ in high-resolution paleoclimatologyScott St. George
Even after more than a century of coordinated monitoring, instrumental weather observations are still too short to adequately constrain decadal or multidecadal behavior in the Earth’s climate system. Leading climatologists and climate modelers have called for the wider application of high-resolution proxy records to decadal variability and prediction studies, and our community has responded by producing new paleoclimate products that specifically target this type of ‘intermediate-term’ behavior. But we now also know our medium changes that message: the biological and geological systems that encode climate information into natural archives often also alter the original ‘input’, usually due to either seasonal filtering or non-climatic persistence. In this talk, we’ll discuss some of the challenges inherent to the use of high-resolution proxies to study decadal or multi-decadal climate variability, and suggest strategies that might clarify how climate acts on those timescales. And we’ll also present a new theoretical framework that could help paleo-scientists evaluate competing ideas about the causes of decadal- or multi-decadal events known to have occurred during the past one or two millennia.
Geosystem Approach: El Nino Southern Oscillation EffectsKamlesh Kumar
Earth system as a whole is very complex and dynamic, for that matter we prepare models to represent the functioning linkages and processes for better understanding. However, the geo-systems can not be summed up in just one model. Hence, we use system analysis approach, if we see Earth as a giant system, there're many sub-systems for better comprehension representing only a particular component of the system.
Here, I've tried to cover the geo-system approach siting a globe affecting example of the El Nino Southern Oscillation (ENSO) phenomena.
Martin P. Hoerling, a federal research meteorologist specializing in climate dynamics, has written the following expansion and defense of his criticism of some assertions made in an Op-Ed article on climate change by James E. Hansen of NASA. His initial criticism was posted on the Dot Earth blog.
diurnal temperature range trend over North Carolina and the associated mechan...Sayem Zaman, Ph.D, PE.
This study seeks to investigate the variability and presence of trends in the diurnal surface air temperature range
(DTR) over North Carolina (NC) for the period 1950–2009. The significance trend test and the magnitude of trends were determined using the non-parametric Mann–Kendall test and the Theil–Sen approach, respectively.
Statewide significant trends (p b 0.05) of decreasing DTR were found in all seasons and annually during the analysis period. The highest (lowest) temporal DTR trends of magnitude −0.19 (−0.031) °C/decade were found in summer (winter). Potential mechanisms for the presence/absence of trends in DTR have been highlighted. Historical
data sets of the three main moisture components (precipitation, total cloud cover (TCC), and soil moisture) and
the two major atmospheric circulation modes (North Atlantic Oscillation and Southern Oscillation) were used for
correlation analysis. The DTRs were found to be negatively correlated with the precipitation, TCC, and soil moisture across the state for all the seasons and annual basis. It appears that the moisture components related better to the DTR than to the atmospheric circulation modes.
diurnal temperature range trend over North Carolina and the associated mechan...
MET 452 Poster
1. Investigating the Correlation Between Equatorial African Rainfall and Tropical Cyclone Activity in the
North Atlantic Basin
Michael Willette
University of Northern Colorado, MET 452, Spring 2016
Introduction
The North Atlantic’s tropical cyclone season has the
potential to affect millions of people living along the eastern
seaboard of the United States, Mexico, and the Caribbean.
Predicting the variability of tropical cyclone activity each
year is vital for human safety and the protection of economic
interests. Although interdecadel oscillations, such as the
NAO, may be responsible for some of this variability, the
formation and movement of African waves that act as
“seeds” for tropical cyclones is likely more important. This
study acts to investigate this possible correlation between
the North Atlantic tropical cyclone activity and rainfall
anomalies in Equatorial Africa.
Fig. 1. A figure from Jackson, Nicholson, and Klotter (2009) that shows the five-year
mean number of lightning flashes for the year and for the SON season. These areas of
lightning maximas are indicative of the genesis of MCCs and African waves that will move
out to the Atlantic ocean,
Figure 2: A storm track density analysis from Hopsch et al. ((2007) relating the origination of storm tracks in
equatorial Africa to the positioning of tropical cylcone formation in the Atlantic ocean basin. Notice that the
origination comes from two hotspots in northern and central Africa.
Movement into the Atlantic Basin
In order to get a comprehensive analysis of the link between
tropical cyclone genesis in the North Atlantic basin and
rainfall in equatorial (and specifically the Sahel region of
Africa), the location of where these equatorial waves move
off the western African coast into the North Atlantic is vital.
Hopsch et. al. (2006) state that there is year-to-year
variability in the positioning of the storm tacks of equatorial
waves as they move off the coast of western Africa.
Although SSTs and west African Rainfall can explain some of
the variability, variation of the meridional wind shows the
strongest positive correlation with tropical cyclone activity in
year-to-year time scales. (Hopsch et. al., 2006) There ends
up being two sources for storm tracks over the Atlantic;
north and south of 15˚N in North Africa (Hopsch et. al.,
2006), and that the southern storm track provides the
highest amount of tropical cyclone activity.
The Origination of African Waves
The western portion of equatorial Africa undergoes some of
the most unstable processes leading to intense
thunderstorms and arguably some of the least understood.
The climate is warm, wet, and volatile meteorologically. The
area of maximum radiation from the sun and its associated
ITCZ Studies show that wind patterns largely drive the
location and intensity of these convective events. With the
core at 600mb, the positioning of the African Easterly Jet
corresponds well with convective and lightning maximums in
equatorial Africa. (Jackson et. al., 2009) Specifically, the
location of the right front quadrant of jet streaks associated
with the African Easterly Jet appears to focus the most
intense convective development. (Jackson et. al., 2009)
Figure 3: A comparison of Burundi Highlands Precipitation Anolamlies from data produced by Bonnefille and
Chalie (2000) on the left and a statistical model of tropical cyclone activity from Mann et al. (2009). Both sets of
data were then compiled in Excel in this study. There are some correlations between the two plots, mostly being
correlations when precipitation and tropical cyclone activity are both low.
Discussion of Methods and Results
To investigate this correlation, a comparison of data
sets between two studies is used. Paleo-pollen proxy
data from Bonnefille and Chalie (2000) is compared
with a statistical model produced by Mann et al.
(2009). The results are shown in figure 3 and some
interesting correlations (or lack thereof) are seen.
• Positive correlations are hard to find. A good
correlation can be seen at 600 AD.
• There seems to be some sort of lag in correlations,
but is hard to determine.
• Negative anomalies seem to correlate better than
positive anomalies
• The decrease in tropical cyclone activity starting at
1000AD is not reflected in the precipitation
anomalies
• The lack of data points in the precipitation
anomalies makes it hard for correlation with the
statistical model
Summary
Overall, there is evidence for correlation between
equatorial rainfall in Africa and tropical cyclone activity
in the North Atlantic. Theoretically, there should be a
nice correlation between the two regions with time
periods of high equatorial African rainfall correlating
with areas of high tropical cyclone activity and vice
versa. There are areas of local minima in the TA activity
that correlate with minima’s in rainfall in Africa,
specifically at 1380AD, 1150 AD, and 580 AD. Since low
rainfall in Equatorial Africa would produce fewer
waves that propagate out to the eastern Atlantic and
provide the “seeds” for tropical cyclone development,
less tropical cyclones would form. What is interesting is
that this correlation does not apply to maximas.
Possibly, there are other forces that are responsible for
letting these equatorial waves become tropical
cyclones, such as wind shear, sea surface
temperatures, and multi-decadal weather/ocean
patterns not investigated in this study.
References
Hopsch, S. B., Thorncroft, C. D., Hodges, K. and Aiyyer, A., 2007: West African storm
tracks and their relationship to Atlantictropical
cyclones. J. Climate, 20, 2468-2483, doi: 10.1175/JCLI4139.1
Bonnefille, R., Chalie, F., 2000: Pollen-inferredtime-series from equatorial
mountains, Africa, the last 40 kyr BP. Global and Planetary
Climate Change, 26, 25-50.
Mann, M. E , Kozar, M. E.,. Emanuel, K. A., and Evans, J. L., 2009: Long-term
variations of North Atlantic tropicalcyclone activity
downscaled from a coupled model simulation of the last
millennium.Journal of Geophysical Research: Atmospheres, 118,
13383-13392.