Papers by Arturo Quintanar
Journal of Hydrometeorology, 2015
The authors analyzed an extensive precipitation dataset available for the Mexico City basin that ... more The authors analyzed an extensive precipitation dataset available for the Mexico City basin that included hourly precipitation in various sectors of the city from 1993 to 2007. Observations indicated that significant changes occurred in the timing and number of intense events (precipitation rate >20 mm h−1) over this time period. Alternative hypotheses that changes in the emission of aerosol pollutants or in the land use can result in the observed variations are tested. The Weather Research and Forecasting Model was used to simulate September precipitation from 2002 to 2011 at the peak of the wet season. Changes were introduced to the microphysical scheme as a proxy for differences in the aerosol population and the droplet activation spectra. Simulations were also performed with the land use of the urban areas set up to represent older and more current conditions. Results indicate that increased pollution (decreased urban area) led to an average precipitation decrease over the mo...
Journal of Hydrometeorology, 2015
The authors analyzed an extensive precipitation dataset available for the Mexico City basin that ... more The authors analyzed an extensive precipitation dataset available for the Mexico City basin that included hourly precipitation in various sectors of the city from 1993 to 2007. Observations indicated that significant changes occurred in the timing and number of intense events (precipitation rate >20 mm h−1) over this time period. Alternative hypotheses that changes in the emission of aerosol pollutants or in the land use can result in the observed variations are tested. The Weather Research and Forecasting Model was used to simulate September precipitation from 2002 to 2011 at the peak of the wet season. Changes were introduced to the microphysical scheme as a proxy for differences in the aerosol population and the droplet activation spectra. Simulations were also performed with the land use of the urban areas set up to represent older and more current conditions. Results indicate that increased pollution (decreased urban area) led to an average precipitation decrease over the mo...
Eos Transactions American Geophysical Union
Northwestern Mexico experiences large variations in water vapor on seasonal time scales in associ... more Northwestern Mexico experiences large variations in water vapor on seasonal time scales in association with the North American monsoon, as well as during the monsoon associated with upper-tropospheric troughs, mesoscale convective systems, tropical easterly waves, and tropical cyclones. Together these events provide more than half of the annual rainfall to the region. A sufficient density of meteorological observations is required to properly observe, understand, and forecast the important processes contributing to the development of organized convection over northwestern Mexico. The stability of observations over long time periods is also of interest to monitor seasonal and longer-time-scale variability in the water cycle. For more than a decade, the U.S. Global Positioning System (GPS) has been used to obtain tropospheric precipitable water vapor (PWV) for applications in the atmospheric sciences. There is particular interest in establishing these systems where conventional operational meteorological networks are not possible due to the lack of financial or human resources to support the network. Here, we provide an overview of the North American Monsoon GPS Transect Experiment 2013 in northwestern Mexico for the study of mesoscale processes and the impact of PWV observations on high-resolution model forecasts of organized convective events during the 2013 monsoon. Some highlights are presented, as well as a look forward at GPS networks with surface meteorology (GPS-Met) planned for the region that will be capable of capturing a wider range of water vapor variability in both space and time across Mexico and into the southwestern United States.
Eos, Transactions American Geophysical Union, 2014
Eos Transactions American Geophysical Union
Intense precipitation (>20mm/hr) over the Mexico City Metropolitan Area (MCMA) has seen its fr... more Intense precipitation (>20mm/hr) over the Mexico City Metropolitan Area (MCMA) has seen its frequency and timing changed substantially over the last 60 years of recorded hourly precipitation. A frequency increase has mainly been observed where high rates of urban development have taken place over the recorded period. Also, the initiation of intense precipitation has shifted from late night hours towards the afternoon from the 60s towards the 90s.Notably, by 2009, 77% of intense events occurred between 7pm and midnight reverting back to conditions only seen in the 40s. In this study, two alternative hypotheses are adopted, namely, that observed changes in precipitation patterns and intensity are the result of different type and emission of aerosol pollutants present in different periods in the past and that urbanization-induced land surface changes have also been a major player. To that end the regional atmospheric model WRF-ARW has been used over the MCMA to study the sensitivity...
Eos, Transactions American Geophysical Union, 2014
Water, Air, & Soil Pollution, 2011
The concentration of p-cresol and p-ethylphenol, two malodorants typical of swine waste, were mea... more The concentration of p-cresol and p-ethylphenol, two malodorants typical of swine waste, were measured at 0.5 and 1.5 m above a waste treatment lagoon during two separate campaigns encompassing late winter through early spring and late spring through early summer. Concomitant collection of air temperatures, humidities, insolation, and wind speeds, as well as water column temperatures were done so that heat fluxes could be computed using an energy budget method and Bowen ratio estimates. The empirical model that was found to correlate best with variations in malodorant concentrations and gradients above the lagoon had the terms describing evaporation from the lagoon surface and net available energy at the lagoon surface. Emissions were found to be much higher during the cool season than the warm season. This was despite much higher evaporation rates during the warm season. This could be explained by much lower lagoon concentrations of the malodorants in the warm season than in the cool season. Results of this work are being used to determine appropriate models to estimate malodorant emissions from lagoons and devise techniques for the abatement of nuisance emissions.
Theoretical and Applied Climatology, 2011
... 4e). Furthermore, positive trends in precipi-tation were observed during the peak rabi season... more ... 4e). Furthermore, positive trends in precipi-tation were observed during the peak rabi season and the overall zaid and the peak zaid seasons. Finally, in case of eastern Madhya Pradesh, the trends were similar to that of western Madhya Pradesh (Fig. 4f). ...
Physical Geography, 2008
... in Chen and Dudhia, 2001). The dominant Page 8. MM5-NOAH LAND SURFACE MODELBASED ASSESSMENT ... more ... in Chen and Dudhia, 2001). The dominant Page 8. MM5-NOAH LAND SURFACE MODELBASED ASSESSMENT 61 vegetation cover for this region was represented by crop and woodland. Except for the case of horizontal ...
Global and Planetary Change, 2011
Keywords: land use induced land cover change vegetation fraction MM5 planetary boundary layer sur... more Keywords: land use induced land cover change vegetation fraction MM5 planetary boundary layer surface energy balance Changes in land use land cover (LULCC), vegetation fraction (FV), and soil moisture affects land surface atmosphere interactions, characteristics of planetary boundary layer (PBL), and near surface atmospheric moisture content. Previous studies have investigated impacts of LULC, FV, and soil moisture changes on atmosphere separately. The present study investigates the combined impacts of changes in LULC, FV, and soil moisture, on PBL atmosphere and near surface atmospheric moisture content. The study is set in western region of Kentucky, USA. We have used the Noah land surface scheme and MM5 model for this purpose. The study used two nested domains. The current land use land cover of the inner domain was changed to grass, forest, and bare soil to represent historical changes and potential near future modifications. Subsequently, FV and soil moisture were systematically changed for each of the land uses. The simulations have found that changes of current land use to grass within the inner domain increases latent heat flux, dew point temperature, relative humidity, and equivalent potential temperature. It was found that height of the PBL was reduced and development of circulation cells was visible along land use land cover discontinuity. Changes in horizontal and vertical wind field were also reported. FV changes for grass further magnified these impacts. For example, decrease or increase in FV has decreased or increased latent heat flux. Similar response of other PBL parameters could be found for changes in FV along with LULC. It was also found that if we replaced forest with lower FV by grass with higher FV, the impacts could cancel each other. Changes to forest and bare soil land use types and lower FV for forest also produced generally similar types of responses. Soil moisture changes, particularly drying, further impacted these responses. This study finds that increase in FV counteracts impacts of soil moisture reduction up to a level. Overall, grass produced moister PBL and lowered the height of PBL and LCL. It is interesting to note that during nighttime the impacts of LULC, FV and soil moisture changes were diminished. These changes not only modified meso-scale wind fields but also potential for convective development. It was concluded that similar experiments needed to be undertaken for convectively conducive environments to better understand the combined impacts of changes in LULC, FV and soil moisture.
Geophysical Research Letters, 1995
The dispersion of passive tracer within and out of the Arctic region is studied using a threedime... more The dispersion of passive tracer within and out of the Arctic region is studied using a threedimensional general circulation model with a Lagrangian particle module. Emphasis is placed on the lower troposphere by releasing numerical tracer particles in a layer near the surface within the Arctic circle to mimic the potential release of aerosol particles from the Arctic Ocean and the observed variability of Arctic haze. This study is also intended to investigate the characteristics of the quasi-horizontal mixing in transporting the air from high latitudes to mid-and low latitudes; a process which has extensively been studied mostly for the stratospheric regime. The model calculation shows that the Lagrangian passive tracer contours can correlate well with the isentropic potential vorticity field. This indicates that the identified large-scale mixing processes due to Rossby wave breaking and chaotic advection in the stratosphere may also occur in the lower troposphere.
Bulletin of the American Meteorological Society, 2010
Regional variations in radiative forcing may have important regional and global climatic implicat... more Regional variations in radiative forcing may have important regional and global climatic implications that are not resolved by the concept of global mean radiative forcing. Tropospheric aerosols and landscape changes have particularly heterogeneous forcings. To date, there have been only limited studies of regional radiative forcing and response. Indeed, it is not clear how best to diagnose a regional forcing and response in the observational record; regional forcings can lead to global climate responses, while global forcings can be associated with ...
Atmospheric Environment, 2009
In this study, the sensitivity of trajectory paths to anomalous soil moisture was analyzed during... more In this study, the sensitivity of trajectory paths to anomalous soil moisture was analyzed during three different synoptic episodes in June 2006. The MM5 and Noah land surface models were used to simulate the response of the planetary boundary layer. The HYSPLIT model was used for trajectory analysis. It was found that the response in horizontal lower-level wind field was larger at regions where vertical wind velocity changes were also large. In addition, the sensitivity to soil moisture changes was significant and localized where convective activity was well developed and synoptic effects did not dominate. A nonlocal effect was felt over the rest of the domain where convection was not present since the model atmosphere reacted as a whole to compensate for induced changes in vertical velocity. This finding was supported by the fact that domain averaged vertical velocities changes were of the order of 0.2 cm s À1 or less at about 650 hPa and about 200 times smaller than modeled local vertical velocity changes. The largest change in horizontal wind field near the surface was found for weak synoptic events on June 11-12 and June 22-23 while the stronger synoptic event of June 17-18 showed smaller differences. These changes in wind field conditions impacted the transport and dispersion of pollutants. To quantify the sensitivity of air quality estimates to soil moisture uncertainty, we have used three well known measures of trajectory differences: the absolute horizontal transport deviation (AHTD), the relative horizontal transport deviation (RHTD) and the absolute vertical transport deviation (AVTD) for an ensemble of 98 trajectories departing from a region well within the computational domain. For the June 11-12 event it was found that for wet and dry soil moisture experiments, AHTD, RHTD, and AVGTD can reach values in the range 60-100 km, 10-20% and 500-900 m at 24 h run time, respectively. For the June 17-18 and June 22-23 events these values of trajectory differences were reduced more than half. These differences in behavior between time periods are largely attributed to the combined effects of synoptic forcing and the sensitivity of planetary boundary layer to soil moisture changes during well developed convection. The implication for air quality studies is that the soil moisture anomaly and related uncertainty in planetary boundary layer response needs to be incorporated in order to construct an ensemble of the most probable scenarios in which pollutants are released and transported throughout a given target region.
Atmospheric Environment, 2003
The latest phase of the program to improve the air quality in the Valley of Mexico, also known, a... more The latest phase of the program to improve the air quality in the Valley of Mexico, also known, as Pro Aire is about to go into effect for the next 10 years. Pro Aire puts emphasis on agricultural wind erosion and associated dust emissions impacting downwind air quality. The main objective of this investigation was to use an empirical USEPA erosion model coupled to a meteorological/transport-dispersion prediction model, CALMET/CALPUFF, to estimate dust emissions and concentrations in the Mexico City Basin. The model simulations for particulate matter (PM 10 ) are validated against observations taken at the most recent research field study, the IMADA-AVER field campaign, conducted during the spring of 1997 to provide information about high ozone, particulate matter concentrations and visibility impairment. The spatial and temporal PM distribution in the region is presented for a specific wind blown dust event consisting of two IMADA days, in order to understand how soil dust emissions from agricultural fallow land affect downwind areas during the dry season. Results show good agreement with the main spatial features of the local wind circulation and wind blown dust concentrations. A correlation coefficient of nearly 0.8 between predictions and observations for a modeled day suggests that an important portion of the total measured concentration had geological origin. This work constitutes an essential advancement on the mesoscale air quality problem on the MCMA due to wind erosion. r
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Papers by Arturo Quintanar