Wind Circulation Patterns Research Articles

Modern‐Type Eolian Regime and Global Cooling‐Modulated Dust Provenance in the Late Paleogene of Central‐East Asia

AbstractAtmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi‐technique provenance analysis of a rare Paleogene (35–27 Ma) eolian dust sequence from Ulantatal, ∼400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene‐Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)‐like situation, and that the warm Eocene favored a long‐term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene‐Oligocene transition (EOT), long‐term positive phase of AO‐like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern‐type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern‐type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene.

A new strategy for risk assessment of PM2.5-bound elements by considering the influence of wind regimes

For regulatory purposes, air pollution has been reduced to management of air quality control regions (AQCR), by inventorying pollution sources and identifying the receptors significantly affected. However, beyond being source-dependent, particulate matter can be physically and chemically altered by factors and elements of climate during transport, as they act as local environmental constraints, indirectly modulating the adverse effects of particles on the environment and human health. This case study, at an industrial site in a Brazilian coastal city – Joinville, combines different methodologies to integrate atmospheric dynamics in a strategic risk assessment approach whereby the influence of different wind regimes on environmental and health risks of exposure to PM2.5-bound elements, are analysed. Although Joinville AQCR has been prone to stagnation/recirculation events, distinctly different horizontal wind circulation patterns indicate two airsheds within the region. The two sampling sites mirrored these two conditions and as a result we report different PM2.5 mass concentrations, chemical profiles, geo-accumulation, and ecological and human health risks. In addition, feedback mechanisms between the airsheds seem to aggravate the air quality and its effects even under good ventilation conditions. Recognizably, the risks associated with Co, Pb, Cu, Ni, Mn, and Zn loadings were extremely high for the environment as well as being the main contributors to elevated non-carcinogenic risks. Meanwhile, higher carcinogenic risks occurred during stagnation/recirculation conditions, with Cr as the major threat. These results highlight the importance of integrating local airshed characteristics into the risk assessment of PM2.5-bound elements since they can aggravate air pollution leading to different risks at a granular scale. This new approach to risk assessment can be employed in any city's longer-term development plan since it provides public authorities with a strategic perspective on incorporating environmental constraints into urban growth planning and development zoning regulations.

Impact of regional transport on total OX (NO2+ O3) concentrations observed at a tropical rural location

In general, local emissions and long-range transport will dictate the pollution levels over a given place. The former source will be based on the location whether it is urban/rural but there are no boundaries to the latter source. During most of the time in a year, long-range transport will decide the pollution levels. Here we present the experimental evidence for regional (long-range) transport impacts on the total OX (NO2 + O3) concentration at a tropical rural location. Two major independent events of the year 2020 in India, the COVID-19 lockdown and Deep depression in Bay of Bengal (BoB2) have been used to demonstrate the known fact of mixing of aged and freshly emitted ozone precursors on the total OX concentration and their influence on observed total OX. COVID-19 lockdown event happened in the summer season whereas, the BoB2 event happened during the post-monsoon period. Air mass transport during these events at the observational site is completely different which brings the regional transport influence. Further, total OX observed has no local contribution and is controlled entirely by the regional contribution. These observations have been well supported by the CWT analysis and wind circulation patterns during the events. This study provides a clear demonstration of the regional pollution transport influence on the total OX at a rural environment (which control the oxidative capacity of the rural atmosphere). Thus, caution is advised in designating the location as rural/urban based on local emissions alone.

Influence of meteorological patterns on the 2020 COVID-19 pandemic in the Mexico City region

Meteorology is a critical factor affecting respiratory infectious diseases such as MERS, SARS, and influenza, but its effect on the spread of the COVID-19 disease remains controversial. Nevertheless, since the infected people cough-jets produce plumes of droplets and aerosols that can travel for several meters in the atmosphere, the possible influence of wind circulation and atmospheric turbulence on the infectious plume's fate cannot be ignored. This paper applied cluster analysis for identifying the near surface wind circulation patterns and associated temperature and humidity distributions in the Mexico City Metropolitan Area (MCMA), then their influence on the spread of the COVID-19 disease during the 2020 pandemic was discussed. Meteorology data and daily numbers of confirmed COVID-19 infections were obtained from public sources. An intense infection activity occurred from October to December 2020, and notable spreading of the disease toward the southwest and south MCMA was observed. In the same period, temperature and humidity conditions that could favor the virus stability and replication were detected in the same sectors, besides 60% of the wind observations revealed considerable northerly components. These findings suggested the existence of correlations between both phenomena. For assessing the possible relationship, the Pearson coefficients between the daily confirmed infections and the temperature and inward flux were estimated, and values from -0.32 to -0.55 and 0.62 to 0.70 were obtained. Correlation was negligible for relative humidity. Multilinear regression for the daily infections in response to the meteorological variables produced coefficients of determination from 0.3839 to 0.6138. Because of its implications for public health, this topic deserves a more in-depth investigation.

Analysis of Vortex Development over Eastern Indian Ocean using Potential Vorticity

A vortex phenomenon may have a significant influence, especially on wind circulation patterns and extreme weather in Indonesia. The formation of the vortex, initially located over the eastern part of the Indian Ocean has drawn attention due to the highest frequency of its occurrence and as the source of the vortex over the Indonesian region. Vortices generated in this region is also suspected as one of contributing factor for flooding events at Jakarta in 2002 and 2007, studying both formation and development mechanism of these vortices is essential. The evolution of vortex development is investigated to characterize the vortex motion and development pattern in the Eastern Indian Ocean region. The study was conducted for 17 years starting from 1998 to 2016 on every December-January-February (DJF) period using ECMWF (European Center for Medium-Range Weather Forecast) ERA-Interim Reanalysis data. The analysis of vortex evolution was conducted for each event using a composite evolution of potential vorticity anomalies in the isentropic layer. The result shows 84 vortex systems identified with three characteristic patterns of vortex movement that occurred during 295 days of the observation period. Composite analysis of potential vorticity anomalies shows that the initial formation of vortices in the Eastern Indian Ocean is related to the emergence of negative potential vorticity anomalies from the west, which subsequently forming the vortices.

An appraisal of seasonal precipitation dynamics over the North‐West Himalayan region under future warming scenarios

ABSTRACTIn the context of widely reported climate change over the mountainous region, the present work addresses the notable changes in the seasonal precipitation dynamics over the NWH region under two different future warming scenarios [socioeconomic pathway 245 (SSP245) and socio economic pathway 585 (SSP585)]. Using three coupled climate models which participated in the Climate Model Inter‐comparison Project Phase 6 (CMIP6), we focus on the alterations of the spatio‐temporal pattern of solid and liquid precipitation in respective seasons under future warming (2066–2100) scenarios with respect to the historical time period (1981–2014). Intercomparative validation of the CMIP6 data sets has been carried out against the GPCP and ERA‐5 reanalysis datasets where the multimodel mean (MMM) product has performed well (r value = 0.63) compared with the individual model outputs in the historical scenario for last 35 years (1981–2014). Therefore, MMM has been used for analysis. Statistically robust K–S test suggests a remarkable variation in the cumulative distribution of the precipitation across the NWH region at 95% confidence level in both of the future warming scenarios as compared with the historical time period. Furthermore, significant increase in the JJAS rainfall (~25–30%) and decrease in the DJF snowfall (~20–25%) has been observed for ssp585 scenario whereas no significant results are noted under ssp245 scenario. Remarkable variations in the surface temperature distribution, large scale wind circulation pattern and mesoscale hydrometeorological balance under the warmest scenario (SSP585) elucidate the reason behind the noteworthy changes in the precipitation dynamics reflected from the normalized precipitation index (NPI) and changes in annual cycle and therefore illustrates the possibility of more extreme precipitation years in future. The overall investigation reflects the possible effect of climate change over the NWH region pertaining to the dynamics of the South West Monsoon and Western Disturbances.

Implications of slope aspect for landslide risk assessment: A case study of Hurricane Maria in Puerto Rico in 2017

Slope aspect is one of the topographic indices related to the rain-induced landslides. However, its role and importance are still debatable. We argue that due to the predictable patterns of hurricane wind circulations in various regional settings, the potential predominant landslide locations can be forecasted in advance of the approaching hurricanes by considering, in addition to other factors, the wind circulation patterns and the slope aspects. Recently (2019) published data from the United States Geological Survey (USGS) on the landslide distribution in Puerto Rico in relation to the impact of hurricane Maria (2017) provided a new opportunity to evaluate the role of the slope aspect on the occurrence of landslides.The results show association of the predominant number of landslides with the northern (NW, N, and NE) slope aspects followed by the SW and W aspects. This pattern is attributed to the wind circulation patterns and associated wind-driven rainfall during hurricane Maria impact on Puerto Rico. Vegetation damage (based on non-photosynthetic vegetation spectral response) was closely associated with landslides and the prevailing slope aspect in N and SW directions. Obtained results contribute to debates on the role of slope aspect in landslide risk assessment by providing an evidence of association between slope aspect and rain-induced landslide occurrences.

21st century precipitation and monsoonal shift over Pakistan and Upper Indus Basin (UIB) using high-resolution projections

There is research evidence that due to global warming, global precipitation and monsoon area have shown a shift which needs to be analyzed at regional scale. This study analyses future precipitation and monsoon spatial shift over Pakistan and Upper Indus Basin (UIB) based on latest Coordinated Regional Climate Downscaling Experiment - Coordinated Output for Regional Evaluations (CORDEX-CORE) high resolution projections (25 km) for the South Asian domain. Three global climate models from Coupled Model Intercomparison Project Phase 5 (CMIP5) (MIROC5, NorESM1-M and MPI-ESM-MR) provided the lateral boundary conditions for the Regional Climate Model (RegCM4) under Representative Concentration Pathways 2.6 (RCP2.6) and RCP8.5 scenarios. Results indicate that JJA precipitation over Upper Indus Basin (UIB which also includes North Pakistan) is projected to increase more under RCP8.5 and less under RCP2.6 while for Pakistan it shows slightly increase (decrease) in RCP2.6 (RCP8.5). The results also show a projected expansion in monsoon area in UIB and northward shift of MCR which corresponds with future precipitation changes in the area and hence indicate the penetration of monsoon system over UIB under higher warming scenario. The changes in monsoon precipitation and domain are related to the changes in wind circulation patterns at 850 hPa and 200 hPa atmospheric levels.

Dust from the Sahara to the American Continent: Health impacts.

The Saharan Air Layer is a mass of hot, dry air laden with dust that forms over the Sahara and moves towards the Atlantic Ocean. This air mass contains soil dust particles emitted by the action of winds on the African continent. Between June and August, the large-scale patterns of wind circulation transport dust from the Sahara across the tropical North Atlantic Ocean, affecting parts of the Caribbean, Central America, Mexico, even some regions of the United States, and the Mediterranean and Southern Europe. Between December and April, wind circulation patterns facilitate dust transportation from the Sahara to the northern parts of South America and the Amazon. This dust transportation a phenomenon of interest to geosciences and public health because of the potential health impacts of dust dispersion and circulation in the atmosphere. Thus, we assessed the relationship between exposure to Saharan dust (SahD) and its implications for human health in the Americas. We performed a nonsystematic review in the PubMed, Google Scholar, EMBASE, and Scielo databases of studies published between 2000 and 2020 in Portuguese, English, French, or Spanish using the search words "Saharan dust," or "mineral dust," or "desert dust," and "human health." The available direct air pollutants measurements indicate that the pollution level in the cities affected on a constant and prolonged basis is high versus acceptable standards. Further, this review also showed that the negative health effects of SahD are sparsely studied in the Americas.

The influence of upper level surrounding winds on tropical cyclone motion: a case study of the Bay of Bengal region

The study is an attempt to classify the observed tropical cyclone (TC) track patterns over the Bay of Bengal (BoB) region. It is hypothesized that winds at 200 hPa level can determine the direction of TC motion. We found that the mean TC genesis locations were shifted southward from October to December with the shifting of the regional wind circulation patterns. The wind circulation pattern during the straight moving TCs were very similar to the recurving TCs. Straight moving TCs were embedded in a deep easterly flow whereas the recurving TCs significantly moved further northward compared to the straight tracks which brought them under the influence of mid-latitude westerlies and changed their paths towards northeast. A TC track prediction scheme is presented to evaluate the effectiveness of 200 hPa level surrounding winds in TC motion prediction. Sea level pressure fall and relative vorticity advection also have been used as supportive factors. We found results comparable with other TC track prediction models which did not consider the upper level surrounding winds as a TC track predictor. Hence, the use of 200 hPa level winds might be beneficial to improve the existing TC track prediction models over the BoB region.

Human-Perceived Temperature Changes in South Korea and Their Association with Atmospheric Circulation Patterns

AbstractThis study investigates the spatiotemporal characteristics of human-perceived temperature (HPT) data, which describe the joint effects of temperature and humidity on the human body, and examines the related large-scale atmospheric circulation patterns for the summer season (July–August) in South Korea using trend and composite analyses. The increasing trend of HPT was stronger than that of the maximum, mean, and minimum temperatures during 1981–2018. There was an abrupt change in HPT between 1981–2009 and 2010–18, which is likely caused by the northward upper-level subtropical jet, strengthened downward motion, anomalous anticyclones around South Korea, and increased sea surface temperature over the western North Pacific Ocean, which are related to the enhancement and western expansion of the western North Pacific subtropical high (WNPSH). These results highlight the importance of the activity of the WNPSH in the variability of HPT in South Korea. When the western edge of the WNPSH is located in the northwest, a positive geopotential height anomaly at 500 hPa is centered over South Korea, which is associated with high temperatures and low relative humidity. The southwestern extension of the WNPSH modifies the wind circulation pattern and brings warm and moist air from the West (Yellow) Sea along the ridge line of the WNPSH. Eventually, it leads to extreme HPT, associated with high relative humidity and temperature over South Korea, particularly in the southern part of the country. Therefore, we concluded that monitoring and predicting the location of WNPSH and understanding the mechanism and factors influencing the movement of WNPSH under global warming are necessary for predicting and coping with extreme HPT.

New constraints on the palaeo-environmental conditions of the Eastern Paratethys: Implications from the Miocene Diatom Suite (Azerbaijan)

The Miocene Diatom Suite sediments of the Eastern Paratethys Sea, Azerbaijan, provide significant information to establish how Middle Miocene climate influenced erosion, sedimentation and deposition in the marine environments and continental source areas of Western Asia. Discriminant function analyses, ratios of Ti/Al, Si/Ca and Sr/Ca as well as mineralogical composition data indicate the Karaganian-Konkian sediments from the Pereküşkül-Diatom section were derived largely from the Greater Caucasus with a recognizable input from the Russian Platform during earliest Konkian. The chemical index of alteration and detrital clay mineral content document a change in climatic conditions from humid to relatively arid conditions occurred in the Greater Caucasus and Russian Platform area during the Karaganian-Konkian. The distribution of redox-sensitive elements across the Miocene Diatom Suite indicates oxic conditions prevailed in the Eastern Paratethys Sea Basin during the deposition of the Karaganian-Konkian sediments. Geochemical proxies suggest that, despite the Cenozoic been a period of global cooling, eastern Azerbaijan mainly characterised by a moderately humid to arid climate during this time. This indicates that warm climatic conditions, as seen during the mid-Miocene Climatic Optimum, were notably prolonged in the region of the Eastern Paratethys Sea basins and adjacent source areas, possibly reflecting palaeo-geographic changes in ocean and wind circulation patterns and/or local climate forcing associated with regional volcanic methane emissions.

Atmospheric circulation of Venus measured with visible imaging spectroscopy at the THEMIS observatory

Measuring the atmospheric circulation of Venus at different altitudes is important for understanding its complex dynamics, in particular the mechanisms driving super-rotation. Observationally, Doppler imaging spectroscopy is in principle the most reliable way to measure wind speeds of planetary atmospheres because it directly provides the projected speed of atmospheric particles. However, high-resolution imaging spectroscopy is challenging, especially in the visible domain, and most knowledge about atmospheric dynamics has been obtained with the cloud tracking technique. The objective of the present work is to measure the global properties of the atmospheric dynamics of Venus at the altitude of the uppermost clouds, which is probed by reflected solar lines in the visible domain. Our results are based on high-resolution spectroscopic observations with the long-slit spectrometer of the solar telescope THEMIS. We present the first instantaneous “radial-velocity snapshot” of any planet of the solar system in the visible domain, i.e., a complete radial-velocity map of the planet obtained by stacking data on less than 10% of its rotation period. From this, we measured the properties of the zonal and meridional winds, which we unambiguously detect. We identify a wind circulation pattern that significantly differs from previous knowledge about Venus. The zonal wind reveals a “hot spot” structure, featuring about 200 m s−1 at sunrise and 70 m s−1 at noon in the equatorial region. Regarding meridional winds, we detect an equator-to-pole meridional flow peaking at 45 m s−1 at mid-latitudes, i.e., about twice as large as what has been reported so far.

Atmospheric dispersion of methane emissions from sugarcane burning in Mexico

Methane is a potent greenhouse gas whose atmospheric dispersion may have different implications at distinct scales. One significant contributor to methane emissions is sugarcane farming in tropical areas like in Mexico, which has the sixth highest production level in the world. A consequence of the industrial use of this resource is that sugarcane preharvest burning emits large quantities of methane and other pollutants. The objective of this research is to estimate the methane emissions by sugarcane burning and to analyze their atmospheric dispersion under the influence of meteorological parameters, according to different concentration scenarios generated during a period. The methane emissions were investigated using the methodology of Seiler and Crutzen, based on the stage production during the harvest periods of 2011/2012, 2012/2013 and 2013/2014. Average of total emissions (1.4 × 103 Mg) at the national level was comparable in magnitude to those of other relevant sugarcane-producing countries such as India and Brazil. Satellite images and statistical methods were used to validate the spatial distribution of methane, which was obtained with the WRF model. The results show a dominant wind circulation pattern toward the east in the San Luis Potosi area, to the west in Jalisco, and the north in Tabasco. In the first two areas, wind convergence at a certain height causes a downward flow, preventing methane dispersion. The concentrations in these areas varied from 9.22 × 10−5 to 1.22 × 102 ppmv and 32 × 10−5 to 2.36 × 102 ppmv, respectively. Wind conditions in Tabasco contributed to high dispersion and low concentrations of methane, varying from 8.74 × 105 to 0.33 × 102 ppmv. Methane is a potent greenhouse gas for which it is essential to study and understand their dispersion at different geographic locations and atmospheric conditions.

PEMODELAN DINAMIKA ARUS PERAIRAN INDONESIA YANG DISEBABKAN OLEH ANGIN

Research on current dynamics modelling in Indonesian waters with wind employed as independent variable has been observed. The purpose of this study was to model the hydrodynamic equations due to the influence of the wind in Indonesia waters in the form of visualization described consisting of wind circulation pattern and pattern of current movement in the west and east monsoon season. To analyze the data obtained during the study, researchers used a descriptive approach. The results showed that the west wind season (December, January, and February) blow from the northeast to the southwest then turning southeast. Whereas the east wind season (June, July, and August) blows from the southeast to the northwest and then turn to the northeast. On the surface layer shows the current movement in general follows the movement of the wind direction in which the current speed is very dominant occurred in some waters, such as the Karimata Strait, the Java Sea, the South China Sea, and the Arafuru Sea. The dominant current velocity in the layer of 100-200 m in the water of eastern equator and the South China Sea in the west season has recorded a current speed reaches 20 cm / s. while in the east monsoon which occurs in the equatorial waters of the eastern part, in the Maluku Sea, the Seram Sea and nearby the Arafuru Sea current velocity reaches 40cm / s.

Spatial Uniformity in Sensitivity Coefficient of Reference ET in the Texas High Plains

<abstract> <b><sc>Abstract. </sc></b>Evapotranspiration (ET) is a major component of the agricultural water budget and accurate ET estimations are essential for effective irrigation scheduling. Therefore, it is an important aspect of production agriculture and agricultural research. Potential crop ET can be calculated by multiplying reference ET by an appropriate crop coefficient. Reference ET can be estimated from meteorological data obtained from weather stations sited on a reference crop surface, e.g., grass or alfalfa. However, weather station sensor inaccuracies may propagate measurement errors into the reference ET calculations. A sensitivity analysis of weather variables used in calculating ET (air temperature, wind speed, solar radiation, and relative humidity) can be used to determine relative effects of data inaccuracies on ET estimates, and conversely, the sensor accuracy levels needed for acceptably accurate ET estimates. In this study, sensitivity analyses of weather variables on daily reference ET were conducted using hourly data (1995-2008) from eight weather stations managed by the Texas High Plains ET network in the Texas Panhandle. Sensitivity coefficients were calculated for each of the weather variables. Comparison of the sensitivity coefficients for any one station indicated that reference ET was most sensitive to wind speed followed by air temperature. Comparison of sensitivity coefficients for any one weather variable (e.g., wind speed) across the region showed no significant differences in the sensitivity of reference ET to those variables by location. This indicates that the existing North-South air temperature gradient and variability in local wind circulation patterns have limited influence on the sensitivity of reference ET to individual weather variables. This indicated that a uniform maintenance protocol should be sufficient for weather stations located throughout the Texas High Plains.

Effect of Large-Scale Atmospheric Circulation and Wind on Storm Surge Occurrence

ABSTRACT Montreuil, A-L.; Elyahyioui, J., and Chen, M., 2016. Impact of local wind and atmospheric circulation patterns on coastal morphological changes along the Belgian coast. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 755–759. Coconut Creek (Florida), ISSN 0749-0208. Large scale atmospheric circulation is an important component of wind forcing which in turn control strom surge generation. The study aim is to evaluate the impact of large-scale atmospheric flow and wind on the occurrence of storm surges causing significant morphological impacts along the Belgian coast. An objective classification scheme of the atmospheric circulation affecting the North Sea basin is used for almost 150-years (1871–2014). The observed storm surge events associated with erosion are examined with respect to the circulation weather types (CWTs) and the winter No...

Montane ecosystem productivity responds more to global circulation patterns than climatic trends

Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies.

Improving landslide hazard and risk mapping in Guatemala using terrain aspect

Guatemala is in the path of numerous atmospheric hazards that trigger landslides by saturating mountain slopes with water reducing their safety factor. Available local studies of landslide characterization in Guatemala have indicated the importance of slope in hazard and risk mapping, but, for the most part, ignored another topographic index: aspect. However, many regional studies analyzing the effect of hurricanes on terrain show that Caribbean and Central American locations experience higher impact from hurricanes and storms on eastern, southeastern, southern and southwestern slopes. Since hazard and risk mapping focuses on infrastructure and settlements located on slopes with various orientations, this factor needs to be addressed. This study uses landslide data from three areas in Guatemala affected by hurricanes Stan (2005) and Mitch (1998). The results from the conducted spatial and statistical analyses show a high association of landslide prone slopes with aspect within the 76 to 260 range (i.e., eastern–southeastern–southern and southwestern slopes). We hypothesize that this is the result of the regional wind circulation pattern governing moisture distribution. Integrating aspect in landslide analysis may improve hazard and risk mapping in Guatemala and other Central American and Caribbean regions by taking into account the regional patterns of wind circulation and the dominant role of eastern–southeastern–southwestern slopes in landslide processes.

Cluster Analysis of the Wind Events and Seasonal Wind Circulation Patterns in the Mexico City Region

The residents of Mexico City face serious problems of air pollution. Identifying the most representative scenarios for the transport and dispersion of air pollutants requires the knowledge of the main wind circulation patterns. In this paper, a simple method to recognize and characterize the wind circulation patterns in a given region is proposed and applied to the Mexico City winds (2001–2006). This method uses a lattice wind approach to model the local wind events at the meso-β scale, and hierarchical cluster analysis to recognize their agglomerations in their phase space. Data of the meteorological network of Mexico City was used as input for the lattice wind model. The Ward’s clustering algorithm with Euclidean distance was applied to organize the model wind events in seasonal clusters for each year of the period. Comparison of the hourly population trends of these clusters permitted the recognition and detailed description of seven circulation patterns. These patterns resemble the qualitative descriptions of the Mexico City wind circulation modes reported by other authors. Our method, however, permitted also their quantitative characterization in terms of the wind attributes of velocity, divergence and vorticity, and an estimation of their seasonal and annual occurrence probabilities, which never before were quantified.