Climate and freshwater resources in northern Mexico: Sonora, a case study
Magaña VO, Conde C
ENVIRONMENTAL MONITORING AND ASSESSMENT
61: (1) 167-185 MAR 2000
Abstract:
An
analysis of current trends in water availability in the Mexican
border state of Sonora is presented to illustrate what may
be faced under climate change conditions. Precipitation, streamflow
and even dam levels data are examined to estimate what changes
have been experienced in recent decades. There are indications
that the more frequent occurrence of EL Nino/Southern Oscillation
(ENSO) events have resulted in more winter precipitation and
consequently in a slight increase in water availability in
northwestern Mexico. However, water demands grow much faster
than such trends in water availability, mainly due to a rapid
increase in population in urban areas and in socio-economic
activities such as those related to agriculture, industry
and power generation. Some strategies to adapt or mitigate
climate change conditions are proposed.
Feedbacks between hydrological processes in tropical South
America and large-scale
ocean-atmospheric phenomena
Poveda G, Mesa OJ
JOURNAL OF CLIMATE
10: (10) 2690-2702 OCT 1997
Abstract:
The
hydroclimatology of tropical South America is strongly coupled
to low-frequency large-scale oceanic and atmospheric phenomena
occurring over the Pacific and the Atlantic Oceans. In particular,
Fl Nino-Southern Oscillation (ENSO) affects climatic and hydrologic
conditions on timescales ranging from seasons to decades.
With some regional differences in timing and amplitude, tropical
South America exhibits negative rainfall and streamflow anomalies
in association with the low-warm phase of the Southern Oscillation
(El Nino), and positive anomalies with the high-cold phase.
Such dependence is illustrated in the hydroclimatology of
Colombia through several empirical analyses: correlation,
empirical orthogonal functions, principal component, and spectral
analysis, and discussion of the major physical mechanisms.
Observations show that ENSO's effect on river discharges occurs
progressively later for rivers toward the east in Colombia
and northern South America. Also, the impacts of La Nina are
more pronounced than those of El Nino. Evidence is also presented
to show that processes arising from land-atmosphere interactions
in tropical South America affect sea surface temperatures
in the Caribbean and the north tropical Atlantic. A hypothesis
is formulated to explain these feedback mechanisms through
perturbations in precipitation, soil moisture, and evapotranspiration
over the continent. To begin with, the occurrence of both
phases of ENSO affects all those fields. The proposed mechanisms
would constitute the ''land-atmosphere'' bridge connecting
Pacific and Atlantic SST anomalies.
Seasonality
in ENSO-related precipitation, river discharges, soil moisture,
and vegetation index
in Colombia
Poveda G, Jaramillo A, Gil MM, Quiceno N, Mantilla RI
WATER RESOURCES RESEARCH
37: (8) 2169-2178 AUG 2001
Abstract:
An
analysis of hydrologic variability in Colombia shows different
seasonal effects associated with El Nino/Southern Oscillation
(ENSO) phenomenon. Spectral and cross-correlation analyses
are developed between climatic indices of the tropical Pacific
Ocean and the annual cycle of Colombia's hydrology: precipitation,
river flows, soil moisture, and the Normalized Difference
Vegetation Index (NDVI). Our findings indicate stronger anomalies
during December-February and weaker during March-May. The
effects of ENSO are stronger for streamflow than for precipitation,
owing to concomitant effects on soil moisture and evapotranspiration.
We studied time variability of 10-day average volumetric soil
moisture, collected at the tropical Andes of central Colombia
at depths of 20 and 40 cm, in coffee growing areas characterized
by shading vegetation ("shaded coffee"), forest,
and sunlit coffee.
The annual and interannual variability of soil moisture are
highly intertwined for the period 1997-1999, during strong
El Nino and La Nina events. Soil moisture exhibited greater
negative anomalies during 1997-1998 El Nino, being strongest
during the two dry seasons that normally occur in central
Colombia. Soil moisture deficits were more drastic at zones
covered by sunlit coffee than at those covered by forest and
shaded coffee. Soil moisture responds to wetter than normal
precipitation conditions during La Nina 1998-1999, reaching
maximum levels throughout that period. The probability density
function of soil moisture records is highly skewed and exhibits
different kinds of multimodality depending upon land cover
type.
NDVI exhibits strong negative anomalies throughout the year
during El Ninos, in particular during September-November (year
0) and June-August (year 0). The strong negative relation
between NDVI and El Nino has enormous implications for carbon,
water, and energy budgets over the region, including the tropical
Andes and Amazon River basin.
Trends in streamflow and rainfall in tropical South America:
Amazonia, eastern Brazil, and
northwestern Peru
Marengo JA, Tomasella J, Uvo CR
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
103: (D2) 1775-1783 JAN 27 1998
Abstract:
Long
hydrological records, from the Amazon Basin, northeastern
Brazil, and northwestern Peru spanning most of this century,
are examined for trends in rainfall (three wettest months)
and runoff (three months of highest flow) or stage, where
no rating curves exist. Trends are tested for significance
using the Mann-Kendall statistic. In basins where large soil,
aquifer, or man-made reservoirs give rise to appreciable over-year
storage, flows and water levels may be serially correlated.
Where serial correlation exists, the usual statistical tests
(linear regression, t-test, and Mann-Kendall) will overestimate
the significance of trends, showing significance where none
exists. Analysis for trend therefore requires particular care
when data are serially correlated, and to avoid misleading
results, additional supportive evidence must be sought. For
example, rainfall records within the same river basin can
be checked for trends; serial correlation in rainfall records,
in particular, is less likely to be present, so the validity
of any trends in rainfall is less open to question. Strong
negative trends were found in flow data from the coast of
northern Peru and the Sao Francisco River, while positive
significant trends were detected in the Parnaiba River basin.
No significant trends were found in the discharge or stage
records from Amazonia, while rainfall in northeastern Brazil
shows a slow increase over long periods. In the Parnaiba and
in some rivers of northern Peru unusually large discharges
at the beginning or end of the records seem to account for
the direction and significance of trends.
ON THE FUNCTIONING OF THE SOUTHERN OSCILLATION IN THE SOUTH-AMERICAN
SECTOR .1.
SURFACE CLIMATE
ACEITUNO P
MONTHLY WEATHER REVIEW
116: (3) 505-524 MAR 1988
=====================================
AMAZON RIVER DISCHARGE AND CLIMATE VARIABILITY - 1903 TO
1985
RICHEY JE, NOBRE C, DESER C
SCIENCE
246: (4926) 101-103 OCT 6 1989
FURTHER WORK ON THE PREDICTION OF NORTHEAST BRAZIL RAINFALL
ANOMALIES
HASTENRATH S, GREISCHAR L
JOURNAL OF CLIMATE
6: (4) 743-758 APR 1993
Abstract:
This
study expands our earlier climate prediction work for Brazil's
Nordeste to develop methods of forecasting the March-June
precipitation with differing lead times by exploring the potential
of various data sources and options of information extraction.
Observations include indices of Nordeste rainfall, an index
of sea surface temperature (SST) in the equatorial Pacific,
and the fields of meridional wind component and SST in the
tropical Atlantic. Empirical orthogonal function (EOF) analysis
was applied to construct indices of the meridional wind component
and SST. These series formed the input to stepwise multiple
regression models, an experimental neural network model, as
well as to linear discriminant analysis. The dependent dataset
1921-57 (excluding 1943-47) was used for the method development,
while the independent dataset 1958-89 was reserved for prediction.
Of
primary interest is the prediction of March-June rainfall
from information through January. A new SST dataset with improved
quality control proved useful, especially with the EOF analysis
confined to the more sensitive portion of the tropical Atlantic.
The cardinal predictor is, the preseason rainfall. Using indices
of the Atlantic meridional wind and SST fields in conjunction
with this allows one to predict half to three-fourths of the
interannual rainfall variability in the independent dataset.
Regarding predictions with greater lead times, about one-fourth
of the variance of March-June precipitation can be forecast
from the Atlantic SST field in December. Prediction from the
February meridional wind and SST fields and preseason rainfall
yields no improvement over the forecasts based on information
through January. With similar skill, the April-June rainfall
is predictable from the end of March. Experiments with neural
networking revealed no advantage over regression. Linear discriminant
analysis performed best in forecasting extremes.
The
essential input information for Nordeste climate prediction
consists of accumulated regional rainfall and quality-controlled
databases of the Atlantic meridional wind and SST fields,
as well as equatorial Pacific SST. For an operational prediction
system three phases are found realistic: an early warming
from the December SST field; the main forecast of March-June
precipitation from rainfall, meridional wind, and SST information
by the end of January; and a prediction for the April-June
tail of the rainy season based on corresponding information
through March. The remarkable recent communal effort in updating
datasets was crucial for a real-time forecast of the 1992
Nordeste rainy season.
Variations
of sea surface temperature, wind stress, and rainfall over
the tropical Atlantic and
South America
Nobre P, Shukla J
JOURNAL OF CLIMATE
9: (10) 2464-2479 OCT 1996
Abstract:
Empirical
orthogonal functions (EOFs) and composite analyses are used
to investigate the development of sea surface temperature
(SST) anomaly patterns over the tropical Atlantic. The evolution
of large-scale rainfall anomaly patterns over the equatorial
Atlantic and South America are also investigated. The EOF
analyses revealed that a pattern of anomalous SST and wind
stress asymmetric relative to the equator is the dominant
mode of interannual and longer variability over the tropical
Atlantic. The most important findings of this study are as
follows.
Atmospheric
circulation anomalies precede the development of basinwide
anomalous SST patterns over the tropical Atlantic. Anomalous
SST originate off the African coast simultaneously with atmospheric
circulation anomalies and expand westward afterward. The time
lag between wind stress relaxation (strengthening) and maximum
SST warming (cooling) is about two months.
Anomalous
atmospheric circulation patterns over northern tropical Atlantic
are phase locked to the seasonal cycle. Composite fields of
SLP and wind stress over northern tropical Atlantic can be
distinguished from random only within a few months preceding
the March-May (MAM) season.
Observational evidence is presented to show that the El Nino-Southern
Oscillation phenomenon in the Pacific influences atmospheric
circulation and SST anomalies over northern tropical Atlantic
through atmospheric teleconnection patterns into higher latitudes
of the Northern Hemisphere.
The
well-known droughts over northeastern Brazil (Nordeste) are
a local manifestation of a much larger-scale rainfall anomaly
pattern encompassing the whole equatorial Atlantic and Amazon
region.
Negative rainfall anomalies to the south of the equator during
MAM, which is the rainy season for the Nordeste region, are
related to an early withdrawal of the intertropical convergence
zone toward the warm SST anomalies over the northern tropical
Atlantic. Also, it is shown that precipitation anomalies over
southern and northern parts of the Nordeste are out or phase:
drought years over the northern Nordeste are commonly preceded
by wetter years over the southern Nordeste, and vice versa.
Variability in subtropical Andean Argentinean Atuel river;
a wavelet approach
Compagnucci RH, Blanco SA, Figliola MA, Jacovkis PM
ENVIRONMETRICS
11: (3) 251-269 MAY-JUN 2000
Abstract:
A
wavelet filter was employed for removing the strong annual
wave in the Atuel river runoff data to analyze for other wavelength
phenomena of interest and to examine the influence of the
ENSO events.
After this removal, the influence of ENSO signal in different
frequency bands and indications of climatic changes in bands
larger than 10 years could be observed, Other significant
phenomena were also observed. As the Andean Argentinean rivers
in the Cuyo region have significant similarities, the conclusions
about the Atuel river could be extended to other rivers in
this region. Copyright (C) 2000 John Wiley & Sons, Ltd.
Inter-annual
variability of the Cuyo rivers' streamflow in the Argentinean
Andean mountains and
ENSO events
Compagnucci RH, Vargas WM
INTERNATIONAL JOURNAL OF CLIMATOLOGY
18: (14) 1593-1609 NOV 30 1998
Abstract:
The
main source of the Cuyo rivers' water Volume is the melting
of winter accumulated snow over the Andes subtropical high
mountains. Particularly between 30 and 40 degrees S, Andean
winter precipitation (April-September) shows both spatial
coherence and significant correlations with the Santiago precipitation.
That is why this zone, which corresponds to the Cuyo rivers'
basin areas, is homogeneous with respect to the streamflow's
inter-annual variability.
The
streamflows of the rivers in this region are highly correlated
to each other. Therefore, the Mendoza river, which is one
of the Cuyo rivers is taken as reference for all these rivers
to study the summer streamflow inter-annual variability (October-March)
and the association with ENSO events.
This
river exhibits behaviour associated with equatorial Pacific
Ocean anomalies. Above average streamflow is more likely to
occur during a mature phase of El Nino event in the southern
summer. This implies abundant and frequent snowfalls during
the previous winter over the high subtropical Andes.
Abundant and frequent snowfalls in the winter after an El Nino
year, and the subsequent high flows during the following summer,
are less likely to occur. This teleconnectivity is not absolute
since some warm events were recorded and simultaneous flows
remained below average. Instead, values under the mean flow
are more likely during cold event years, with exceptions being
quite rare.
This
atmospheric circulation study involves principal component
analysis of daily surface pressure fields from 1972 to 1983.
It reveals identifiable characteristics for Andean winters
with above average precipitations. Wet winters are charecterized
by both less explained variance by the first principal component,
whose pattern corresponds to a high zonal flow component,
and more explained Variance of those patterns matching low
pressure systems and cold frontal passages which have a high
meridional flow component. The inverse occurs in dry winters.
Generally, patterns corresponding to post-frontal anticyclones
show no significant correlation with the precipitation over
the high subtropical Andes. (C) 1998 Royal Meteorological
Society.
ARCHAEOLOGICAL EVIDENCE FOR THE IMPACT OF MEGA-NINO EVENTS
ON AMAZONIA
DURING THE PAST 2 MILLENNIA
MEGGERS BJ
CLIMATIC CHANGE
28: (4) 321-338 DEC 1994
Abstract:
Recent
recognition of teleconnections between El Nino and climatic
anomalies elsewhere on the planet identify northern lowland
South America as a region experiencing drought. Extensive
archeological survey along the major tributaries of the Amazon
during the past 15 years has defined the temporal and spatial
distributions of numerous ceramic phases and traditions. An
unexpected result has been identification of discontinuities
in most local sequences. Large numbers of carbon-14 dates
establish their contemporaneity ca. 1500, 1000, 700, and 400
B.P. These dates correlate closely with archeological evidence
on the north coast of Peru for destructive mega-Nino events.
Observations of the impact of milder recent episodes on the
flora and fauna imply catastrophic deterioration in local
subsistence resources during prehistoric events, forcing the
repeated human dispersals reflected in the linguistic and
genetic heterogeneity of surviving indigenous lowland South
American populations.
DYNAMICS
OF CLIMATIC HAZARDS IN NORTHEAST BRAZIL
HASTENRATH S, HELLER L
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
103: (435) 77-92 1977
ELNINO - 2
Large-scale
impoverishment of Amazonian forests by logging and fire
Nepstad DC, Verissimo A, Alencar A, Nobre C, Lima E, Lefebvre
P, Schlesinger P, Potter C, Moutinho P,
Mendoza E, Cochrane M, Brooks V
NATURE
398: (6727) 505-508 APR 8 1999
ELNINO 7
Abstract:
Amazonian
deforestation rates are used to determine human effects on
the global carbon cycle(1-3) and to measure Brazil's progress
in curbing forest impoverishment(1,4,5). But this widely used
measure of tropical land use tells only part of the story.
Here we present field surveys of wood mills and forest burning
across Brazilian Amazonia which show that logging crews severely
damage 10,000 to 15,000 km(2) yr(-1) of forest that are not
included in deforestation mapping programmes. Moreover, we
find that surface fires burn additional large areas of standing
forest, the destruction of which is normally not documented.
Forest impoverishment due to such fires may increase dramatically
when severe droughts provoke forest leaf-shedding and greater
flammability; our regional water-balance model indicates that
an estimated 270,000 km(2) of forest became vulnerable to
fire in the 1998 dry season. Overall, we find that present
estimates of annual deforestation for Brazilian Amazonia capture
less than half of the forest area that is impoverished each
year, and even less during; years of severe drought. Both
logging and fire increase forest vulnerability to future burning(6,7)
and release forest carbon stocks to the atmosphere, potentially
doubling net carbon emissions from regional land-use during
severe El Nino episodes. If this forest impoverishment is
to be controlled, then logging activities need to be restricted
or replaced with low-impact timber harvest techniques, and
more effective strategies to prevent accidental forest fires
need to be implemented.
Climate
variability in southern South America associated with El Nino
and La Nina events
Grimm AM, Barros VR, Doyle ME
JOURNAL OF CLIMATE
13: (1) 35-58 JAN 1 2000
Abstract:
A comprehensive view is given of the precipitation and circulation
anomalies associated with the various stages of El Nino (EN)
and La Nina (LN) events all over southern South America (SSA).
This view comprises the delineation of coherent regions with
respect to precipitation anomalies, the identification of
the seasons of maximum anomalies, the indication of their
magnitude, and the assessment of their consistency during
those events. In addition, the spatial and temporal variability
of these anomalies is detailed by calculating the expected
precipitation percentiles and the consistency of wet and dry
anomalies for each station and each three-month running season
during EN and LN events. Composites of circulation anomalies
and an assessment of their consistency are also presented
and their connection with the precipitation anomalies is discussed.
Southern Brazil presents the strongest average signal in EN
events. The general behavior toward opposite signals in the
precipitation and circulation anomalies over SSA during almost
the same periods of the EN and LN events indicates a large
degree of linearity in the response to these events. The timing
of the anomalies changes throughout SSA, leading to the identification
of eight different coherent regions in the EN case and six
in the LN case. This regionalization is mostly caused by different
processes leading to precipitation anomalies in SSA during
those events. All these regions show a significant response
in some part of each event.
The magnitude and consistency of this response show a large
spatial variability and some areas present very strong and
consistent anomalies sometimes not disclosed when large coherent
regions are analyzed. In spite of the differences in timing,
some features of the precipitation anomalies are rather uniform
throughout the region during EN and LN events. In EN episode,
there is a tendency to lower than median precipitation in
the year before the event, which continues until March of
the year of the event. In a Vast region, east of the Andes,
the strongest positive precipitation anomalies occur in spring
of this year, when the circulation anomalies concur to enhance
rainfall over several regions. During the summer of the mature
stage the positive precipitation anomalies almost disappear
and then reappear in some regions in late summer-early autumn
and in winter of the year following the starting year of the
event. This description holds partially for the LN event,
but with opposite signs, although there is a larger spatial
variability in the LN-related anomalies in the following year
and some shifts in timing. As for precipitation, the symmetry
of the geopotential height anomaly fields with opposite signs
between LN and EN cases is also remarkable, especially during
the year (0).
Variabilidade
interanual de la precipitación: señales del
ENSO y del gradiente meridional hemisférico de temperatura.
Barros V, Castañeda ME, Doyle M
Impacto de las Variaciones Climáticas em el Desarrolllo
Regional un Análisis Interdisciplinario
VII Congreso Latinoamericano e Ibérico de Meteorologia
321-322, 1996
Estudio
de Vulnerabilidad de los Oasis Comprendidos entre 29º
y 36º S ante Condiciones más Secas en los
Andes Altos.
Canziani OF, Quintela RM, Prieto
Projecto UNDP ARG/95/G/31, Programa Naciones Unidos para el
Desarrollo, Argentina
Cap. 10, 116 pp., 1997
Incidencia del fenómeno El Niño em la Hidroclimatolgía
del Valle del río Cauca em Colombia
Carvajal Y, Jiménez H, Materón H.
http://www.unesco.org.uy/phi/libros/enso/indice.html, 1999
Anomalias de precipitação do sul do Brasil
em eventos de El Niño.
Grimm A, Teleginsky SE, Freitas EED
Congresso Brasileiro de Meteorologia, Anais Sociedade Brasileira
de Meteorologia
Brasil, 1996
Impacto del Fenómeno "El Niño"
sobre la Producción de Cultivos em la Región
Pompeana
Magrin GO, Grondona MO, Travasso MI, Boullón DR, Rodriguez
CD, Messina CD
INTA-Boletín de divulgación
16 pp, 1998
Interannual variability of surface climate in the Amazon
basin.
Marengo J
International Journal of Climatology
12: 853-863, 1992
Águas atmosféricas.
Silva Dias P, Marengo J
Águas Doces no Brasil-capital Ecológico Usos
Múltiplos, Exploração Racional e Conservação
[da Cunha Rebouças, ª, B. Braga Jr., e J.G. Tunizi].
IAE/USP
65-116, 1999
Acerca del fenómeno El Niño sobre la precipitación
en la Pampa Húmeda Argentina.
Tanco R, Berri G
Impacto de las Variaciones Climáticas en la Desarrollo
Regional un Análisis Interdisciplinario
VII Congreso Latinoamericano e Ibérico de Meteorologia
319-320, 1996
Influence of Sea Surface Temperature on Rainfall and Runoff
in Northeastern South America
Uvo C
Analysis and Modelling Diss Department of Water Resources
Engineering
Lund University, Lund, Sweden, 120 pp, 1998
Introducción al estudio de las relaciones entre
los ciclos de ENSO y la temperatura media en la República
Argentina.
Vila DA, Berri G
Impacto de las Variaciones Climáticas en el Desarrollo
Regional un Análisis Interdisciplinario.
VII Congreso Latinoamericano e Ibérico de Meteorologia
311-312, 1996
Estudio preliminar sobre las relaciones del ENSO y la frecuencia
de días com lluvia en la Pampa Húmeda
Vila DA, Grondona MO
Impacto de las Variaciones Climáticas en el Desarrollo
Regional un Análisis Interdisciplinario.
VII Congreso Latinoamericano e Ibérico de Meteorologia
309-310, 1996
Sobre impactos de eventos El Nino e La Niña sobre a
precipitação em todo o Brasil na primavera-verão:
Grimm, A. M., 2003: The El Niño impact on the summer
monsoon in Brazil:
regional processes versus remote influences. Journal of Climate,
16, 263-280.
Grimm, A. M., 2003: How do La Niña
events disturb the summer monsoon system in Brazil?
Publicado por Climate Dynamics on line em dezembro de 2003
e ainda sem referência na versão impressa.
Sobre impactos de eventos El Nino e La Niña sobre a
temperatura no Cone Sul da América do Sul:
Barros, V. R., A. M. Grimm, e M. E. Doyle, 2002: Relationship
between temperature and circulation in
Southeastern South America and its influence from El Niño
and La Niña events.
Journal of the Meteorological Society of Japan, 80, 21-32.