scholarly journals Interdecadal Variability of the South American Precipitation in the Monsoon Season

2015 ◽  
Vol 28 (2) ◽  
pp. 755-775 ◽  
Author(s):  
Alice M. Grimm ◽  
João P. J. Saboia

Abstract Interdecadal variability modes of monsoon precipitation over South America (SA) are provided by a continental-scale rotated empirical orthogonal function analysis, and their connections to well-known climatic indices and SST anomalies are examined. The analysis, carried out for austral spring and summer, uses a comprehensive set of station data assembled and verified for the period 1950–2000. The presented modes are robust, consistent with previous regional-scale studies and with modes obtained from longer time series over smaller domains. Opposite phases of the main modes show differences around 50% in monthly precipitation. There are significant relationships between the interdecadal variability in spring and summer, indicating local and remote influences. The first modes for both seasons are dipole-like, displaying opposite anomalies in central-east and southeast SA. They tend to reverse polarity from spring to summer. Yet the summer second mode and its related spring fourth mode, which affect the core monsoon region in central Brazil and central-northwestern Argentina, show similar factor loadings, indicating persistence of anomalies from one season to the other, contrary to the first modes. The other presented modes describe the variability in different regions with great monsoon precipitation. Significant connections with different combinations of climatic indices and SST anomalies provide physical basis for the presented modes: three show the strongest connections with SST-based indices, and two have the strongest connections with atmospheric indices. However, the main modes show connections with more than one climatic index and more than one oceanic region, stressing the importance of combined influence.

Author(s):  
Whinda Rofika Arofah ◽  
Asep Yudi Permana ◽  
Riskha Mardiana

Indonesia has a lot of potential for nature tourism in the form of mountains, sea, and beaches. This is also an attraction for tourists to make Indonesia as the preferred natural tourist destination when on vacation. Especially West Java, West Java is one of the provinces that are in great demand by local and outside tourists.Besides being famous for its local culture and its unique culinary variety, West Java is also known for its cool air, especially in some parts that are still preserved in nature, the natural potential that is still good and is maintained as an attraction for West Java to attract tourists. One of the famous areas in the city of Bandung which is a tourist destination is the Lembang Region.From the last five years the lodging area in Lembang has increased, currently in Lembang sub-district itself has 13 lodging units in the form of resorts. The amount itself is influenced by the high demand for lodging accommodation especially when the holiday season arrives. But of that number, resorts that have complete and well-maintained facilities and conditions are still not completely even. Based on this fact, the purpose of designing this resort is expected to be the best tourist area in the region to be able to adjust to the conditions of the land conditions, be able to use and not damage the existing land on the design land.The study used in this design is based on the description that occurs today with the support of the literature that supports the theory and analysis that is done. Implementation analysis was carried out using macro and microanalysis methods. Macro analysis is an analysis on a regional scale. While microanalysis is an analysis of the design site, which includes activity analysis, function analysis, space analysis, site analysis, shape analysis, and display and structural analysis and utility.The concept of site and building in this design will produce a conceptual relationship that will later become a guideline in making a design. This concept includes the proposed concept of site design, form, structure, and utility.


2021 ◽  
Author(s):  
Gilby Jepson ◽  
Barbara Carrapa ◽  
Jack Gillespie ◽  
Ran Feng ◽  
Peter DeCelles ◽  
...  

<p>Central Asia is one of the most tectonically active and orographically diverse regions in the world and is the location of the highest topography on Earth resulting from major plate tectonic collisional events. Yet the role of tectonics versus climate on erosion remains one of the greatest debates of our time. We present the first regional scale analysis of 2526 published low-temperature thermochronometric dates from Central Asia spanning the Altai-Sayan, Tian Shan, Tibet, Pamir, and Himalaya. We compare these dates to tectonic processes (proximity to tectonic boundaries, crustal thickness, seismicity) and state-of-the-art paleoclimate simulations in order to constrain the relative influences of climate and tectonics on the topographic architecture and erosion of Central Asia. Predominance of pre-Cenozoic ages in much of the interior of central Asia suggests that significant topography was created prior to the India-Eurasia collision and implies limited subsequent erosion. Increasingly young cooling ages are associated with increasing proximity to active tectonic boundaries, suggesting a first-order control of tectonics on erosion. However, areas that have been sheltered from significant precipitation for extensive periods of time retain old cooling ages. This suggests that ultimately climate is the great equalizer of erosion. Climate plays a key role by enhancing erosion in areas with developed topography and high precipitation such as the Tian Shan and Altai-Sayan during the Mesozoic and the Himalaya during the Cenozoic. Older thermochronometric dates are associated with sustained aridity following more humid periods.</p>


2010 ◽  
Vol 10 (3) ◽  
pp. 8103-8134
Author(s):  
A. Font ◽  
J.-A. Morguí ◽  
X. Rodó

Abstract. A weekly climatology for 2006 composed of 96-h-backward Lagrangian Particle Dispersion simulations is presented for nine aircraft sites measuring vertical profiles of atmospheric CO2 mixing ratios along the 42° N parallel in NE Spain to assess the surface influence at a regional scale (102–103 km) at different altitudes in the vertical profile (600, 1200, 2500 and 4000 meters above the sea level, m a.s.l.). The Potential Surface Influence (PSI) area for the 96-h-backward simulations, defined as the air layer above ground with a thickness of 300 m, are reduced from the continental scale (~107 km2) to the watershed one (~104 km2), when a Residence Time Threshold Criteria (Rttc) greater than 500 s is imposed for each grid cell. In addition, this regional restricted information is confined during 50 h before the arrival for simulations centered at 600 and 1200 m a.s.l. At higher altitudes (2500 and 4000 m a.s.l.), the regional surface influence is only recovered during spring and summer months. For simulations centered at 600 and 1200 m a.s.l. sites separated by ~60 km may overlap 20–50% of the regional surface influences whereas sites separated by ~350 km as such do not overlap. The overlap for sites separated by ~60 km decreases to 8–40% at higher altitudes (2500 and 4000 m a.s.l.). A dense network of sampling sites below 2200 m a.s.l. (whether aircraft sites or tall tower ones) guarantees an appropriate regional coverage to properly assess the dynamics of the regional carbon cycle at a watershed scale (102–103 km length scale).


2006 ◽  
Vol 134 (12) ◽  
pp. 3774-3781 ◽  
Author(s):  
Anne W. Nolin ◽  
Eileen A. Hall-McKim

Abstract The interannual and intraseasonal variability of the North American monsoon is of great interest because a large proportion of the annual precipitation for Arizona and New Mexico arrives during the summer monsoon. Forty-one years of daily monsoon season precipitation data for Arizona and New Mexico were studied using wavelet analysis. This time-localized spectral analysis method reveals that periodicities of less than 8 days are positively correlated with mean daily precipitation during the 1 July–15 September monsoon period. Roughly 17% of the years indicate no significant periodicity during the monsoon period for either region and are associated with low monsoon precipitation. High- and low-frequency modes explain an equivalent percentage of the variance in monsoon precipitation in both Arizona and New Mexico, and in many years concurrent multiple periodicities occur. Wavelet analysis was effective in identifying the contribution of high-frequency modes that had not been discerned in previous studies. These results suggest that precipitation processes during the monsoon season are modulated by phenomena operating at synoptic (2–8 days) and longer (>8 days) time scales and point to the need for further studies to better understand the associated atmospheric processes.


2009 ◽  
Vol 22 (15) ◽  
pp. 4097-4116 ◽  
Author(s):  
Sally L. Lavender ◽  
Adrian J. Matthews

Abstract Observations show that rainfall over West Africa is influenced by the Madden–Julian oscillation (MJO). A number of mechanisms have been suggested: 1) forcing by equatorial waves; 2) enhanced monsoon moisture supply; and 3) increased African easterly wave (AEW) activity. However, previous observational studies are not able to unambiguously distinguish between cause and effect. Carefully designed model experiments are used to assess these mechanisms. Intraseasonal convective anomalies over West Africa during the summer monsoon season are simulated in an atmosphere-only global circulation model as a response to imposed sea surface temperature (SST) anomalies associated with the MJO over the equatorial warm pool region. 1) Negative SST anomalies stabilize the atmosphere leading to locally reduced convection. The reduced convection leads to negative midtropospheric latent heating anomalies that force dry equatorial waves. These waves propagate eastward (Kelvin wave) and westward (Rossby wave), reaching Africa approximately 10 days later. The associated negative temperature anomalies act to destabilize the atmosphere, resulting in enhanced monsoon convection over West and central Africa. The Rossby waves are found to be the most important component, with associated westward-propagating convective anomalies over West Africa. The eastward-propagating equatorial Kelvin wave also efficiently triggers convection over the eastern Pacific and Central America, consistent with observations. 2) An increase in boundary layer moisture is found to occur as a result of the forced convective anomalies over West Africa rather than a cause. 3) Increased shear on the African easterly jet, leading to increased AEW activity, is also found to occur as a result of the forced convective anomalies in the model.


2021 ◽  
pp. 1-53
Author(s):  
Meng Zuo ◽  
Wenmin Man ◽  
Tianjun Zhou

AbstractBoth proxy data and climate modeling show divergent responses of global monsoon precipitation to volcanic eruptions. The reason is however unknown. Here, based on analysis of the CESM Last Millennium Ensemble simulation, we show evidences that the divergent responses are dominated by the pre-eruption background oceanic states. We found that under El Niño-Southern Oscillation (ENSO) neutral and warm phases initial conditions, the Pacific favors an El Niño-like anomaly after volcanic eruptions, while La Niña-like SST anomalies tend to occur following eruptions under ENSO cold phase initial condition, especially after southern eruptions. The cold initial condition is associated with stronger upper ocean temperature stratification and shallower thermocline over the eastern Pacific than normal. The easterly anomalies triggered by surface cooling over the tropical South America continent can generate changes in SST through anomalous advection and the ocean subsurface upwelling more efficiently, causing La Niña-like SST anomalies. Whereas under warm initial condition, the easterly anomalies fail to develop and the westerly anomalies still play a dominant role, thus forms an El Niño-like SST anomaly. Such SST response further regulates the monsoon precipitation changes through atmospheric teleconnection. The contribution of direct radiative forcing and indirect SST response to precipitation changes show regional differences, which will further affect the intensity and sign of precipitation response in submonsoon regions. Our results imply that attention should be paid to the background oceanic state when predicting the global monsoon precipitation responses to volcanic eruptions.


2021 ◽  
Author(s):  
Meng Zuo ◽  
Tianjun Zhou ◽  
Wenmin Man

<p>Both proxy data and climate modeling show divergent responses of global monsoon precipitation to volcanic eruptions. The reason is however unknown. Here, based on analysis of the CESM Last Millennium Ensemble simulation, we show evidences that the divergent responses are dominated by the pre-eruption background oceanic states. We found that under El Niño-Southern Oscillation (ENSO) neutral and warm phases initial conditions, the Pacific favors an El Niño-like anomaly after volcanic eruptions, while La Niña-like SST anomalies tend to occur following eruptions under ENSO cold phase initial condition, especially after southern eruptions. The cold initial condition is associated with stronger upper ocean temperature stratification and shallower thermocline over the eastern Pacific than normal. The easterly anomalies triggered by surface cooling over the tropical South America continent can generate changes in SST through anomalous advection and the ocean subsurface upwelling more efficiently, causing La Niña-like SST anomalies. Whereas under warm initial condition, the easterly anomalies fail to develop and the westerly anomalies still play a dominant role, thus forms an El Niño-like SST anomaly. Such SST response further regulates the monsoon precipitation changes through atmospheric teleconnection. The contribution of direct radiative forcing and indirect SST response to precipitation changes show regional differences, which will further affect the intensity and sign of precipitation response in submonsoon regions. Our results imply that attention should be paid to the background oceanic state when predicting the global monsoon precipitation responses to volcanic eruptions.</p>


Author(s):  
Jesus David Gomez Diaz ◽  
Alejandro I. Monterroso ◽  
Patricia Ruiz ◽  
Lizeth M. Lechuga ◽  
Ana Cecilia Conde Álvarez ◽  
...  

Purpose This study aims to present the climate change effect on soil moisture regimes in Mexico in a global 1.5°C warming scenario. Design/methodology/approach The soil moisture regimes were determined using the Newhall simulation model with the database of mean monthly precipitation and temperature at a scale of 1: 250,000 for the current scenario and with the climate change scenarios associated with a mean global temperature increase of 1.5°C, considering two Representative Concentration Pathways, 4.5 and 8.5 W/m2 and three general models of atmospheric circulation, namely, GFDL, HADGEM and MPI. The different vegetation types of the country were related to the soil moisture regimes for current conditions and for climate change. Findings According to the HADGEM and MPI models, almost the entire country is predicted to undergo a considerable increase in soil moisture deficit, and part of the areas of each moisture regime will shift to the next drier regime. The GFDL model also predicts this trend but at smaller proportions. Originality/value The changes in soil moisture at the regional scale that reveal the impacts of climate change and indicate where these changes will occur are important elements of the knowledge concerning the vulnerability of soils to climate change. New cartography is available in Mexico.


2011 ◽  
Vol 24 (15) ◽  
pp. 4109-4125 ◽  
Author(s):  
Makoto Saito ◽  
Akihiko Ito ◽  
Shamil Maksyutov

Abstract This study evaluates a modeled precipitation field and examines how its bias affects the modeling of the regional and global terrestrial carbon cycle. Spatial and temporal variations in precipitation produced by the Japanese 25-yr reanalysis (JRA-25)/Japan Meteorological Agency (JMA) Climate Data Assimilation System (JCDAS) were compared with two large-scale observation datasets. JRA-25/JCDAS captures the major distribution patterns of annual precipitation and the features of the seasonal cycle. Notable problems include over- and undersimulated areas of precipitation amount in South America, Africa, and Southeast Asia in the 30°N–30°S domain and a large discrepancy in the number of rainfall days. The latter problem was corrected by using a stochastic model based on the probability of the occurrence of dry and wet day series; the monthly precipitation amount was then scaled by the comparison data. Overall, the corrected precipitation performed well in reproducing the spatial distribution of and temporal variations in total precipitation. Both the corrected and original precipitation data were used to simulate regional and global terrestrial carbon cycles using the prognostic biosphere model Vegetation Integrative Simulator for Trace Gases (VISIT). Following bias correction, the model results showed differences in zonal mean photosynthesis uptake and respiration release ranging from −2.0 to +3.3 Pg C yr−1, compared with the original data. The difference in the global terrestrial net carbon exchange rate was 0.3 Pg C yr−1, reflecting the compensation of coincident increases or decreases in carbon sequestration and respiration loss. At the regional scale, the ecosystem carbon cycle and canopy structure, including seasonal variations in autotrophic and heterotrophic respiration and total biomass, were strongly influenced by the input precipitation data. The results highlight the need for precise precipitation data when estimating the global terrestrial carbon balance.


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