Avelino F. Arellano

Investigating the haze transport from 1997 biomass burning in Southeast Asia: its impact upon Singapore

Abstract The 1997 Indonesia forest fires was an environmental disaster of exceptional proportions. Such a disaster caused massive transboundary air pollution and indiscriminate destruction of biodiversity in the world. The immediate consequence of the fires was the production of large amounts of haze in the region, causing visibility and health problems within Southeast Asia. Furthermore, fires of these magnitudes are potential contributors to global warming and climate change due to the emission of large amounts of greenhouse gases and other pyrogenic products.The long-range transport of fire-related haze in the region is investigated using trajectories from the CSIRO Division of Atmospheric Research Limited Area Model (DARLAM). Emission scenarios were constructed for hotspot areas in Sumatra and Kalimantan for the months of September and October 1997 to determine the period and fire locations most critical to Singapore. This study also examines some transport issues raised from field observations. Results show that fires in the coastal areas of southeast Sumatra and southwest Kalimantan can be potential contributors to transboundary air pollution in Singapore. Singapore was directly affected by haze from these areas whereas Kuala Lumpur was heavily affected by the haze coming from Sumatra. In most cases, Singapore was more affected by fires from Kalimantan than was Kuala Lumpur. This was mainly a result of the shifting of monsoons. The transition of monsoons resulted in weaker low-level winds and shifted convergence zones near to the southeast of Peninsular Malaysia. In addition to severe drought and massive fire activity in 1997, the timing of the monsoon transition has a strong influence on haze transport in the region.

Time-dependent inversion estimates of global biomass-burning CO emissions using Measurement of Pollution in the Troposphere (MOPITT) measurements

We present an inverse-modeling analysis of CO emissions using column CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) instrument and a global chemical transport model (GEOS-CHEM). We first focus on the information content of MOPITT CO column retrievals in terms of constraining CO emissions associated with biomass burning and fossil fuel/biofuel use. Our analysis shows that seasonal variation of biomass-burning CO emissions in Africa, South America, and Southeast Asia can be characterized using monthly mean MOPITT CO columns. For the fossil fuel/biofuel source category the derived monthly mean emission estimates are noisy even when the error statistics are accurately known, precluding a characterization of seasonal variations of regional CO emissions for this source category. The derived estimate of CO emissions from biomass burning in southern Africa during the June–July 2000 period is significantly higher than the prior estimate (prior, 34 Tg; posterior, 13 Tg). We also estimate that emissions are higher relative to the prior estimate in northern Africa during December 2000 to January 2001 and lower relative to the prior estimate in Central America and Oceania/Indonesia during April–May and September–October 2000, respectively. While these adjustments provide better agreement of the model with MOPITT CO column fields and with independent measurements of surface CO from National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory at background sites in the Northern Hemisphere, some systematic differences between modeled and measured CO fields persist, including model overestimation of background surface CO in the Southern Hemisphere. Characterizing and accounting for underlying biases in the measurement model system are needed to improve the robustness of the top-down estimates.

Frequency and Character of Extreme Aerosol Events in the Southwestern United States: A Case Study Analysis in Arizona

This study uses more than a decade’s worth of data across Arizona to characterize the spatiotemporal distribution, frequency, and source of extreme aerosol events, defined as when the concentration of a species on a particular day exceeds that of the average plus two standard deviations for that given month. Depending on which of eight sites studied, between 5% and 7% of the total days exhibited an extreme aerosol event due to either extreme levels of PM10, PM2.5, and/or fine soil. Grand Canyon exhibited the most extreme event days (120, i.e., 7% of its total days). Fine soil is the pollutant type that most frequently impacted multiple sites at once at an extreme level. PM10, PM2.5, fine soil, non-Asian dust, and Elemental Carbon extreme events occurred most frequently in August. Nearly all Asian dust extreme events occurred between March and June. Extreme Elemental Carbon events have decreased as a function of time with statistical significance, while other pollutant categories did not show any significant change. Extreme events were most frequent for the various pollutant categories on either Wednesday or Thursday, but there was no statistically significant difference in the number of events on any particular day or on weekends versus weekdays.

Mercury emissions from global biomass burning: spatialand temporal distribution

This chapter represents a new addition to the UNEP global mercury budget: the mercury emissions from biomass burning, here defined as emissions from wildfires and prescribed burns, and excluding contributions from bio-fuel consumption and charcoal production and use. The results cover the 1997-2006 timeframe. The average annual global mercury emission estimate from biomass burning for 1997-2006 is 675 ± 240 Mg yr-1. This accounts for 8% of all current anthropogenic and natural emissions. The largest Hg emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Our methodology for budget estimation is based on a satellite-constrained bottom-up global carbon fire emission database (GFED version 2), which divides the globe into regions with similar ecosystems and burn behaviour. To estimate mercury emissions, the carbon model output is paired with regional emission factors for Hg, EF(Hg). There are large uncertainties in the budget estimation associated with burned area, fuel mass, and combustion completeness. The discrepancy between the model and traditional ground based assessments (e.g. FRA, 2000) is unacceptably large at this time. Of great urgency is the development and validation of a model for mercury cycling in forests, accounting for the biogeochemistry for each region. This would provide an understanding of the source/sink relationship and thus mercury accumulation or loss in ecosystems. Limiting the burning of tropical and boreal forests would have two beneficial effects: reducing the source of mercury releases to the atmosphere from burning, and maintaining a sink for atmospheric mercury. Restricting the global release mercury would reduce the vegetation/soil pools, and the potential Hg release in case of fire.

Biomass Burning: Observations, Modeling, and Data Assimilation

wHat: Junior faculty with diverse backgrounds in the physical sciences met with senior scientists in the field of biomass burning to discuss current science and near-term research problems in the study of fire emissions. wHEn: 13–15 July 2010 wHErE: Boulder, Colorado F ires affect the Earth system in multiple ways. They are a major source of aerosol particles, greenhouse gases, and other trace constituents in the atmosphere (Crutzen and Andreae 1990; Seiler and Crutzen 1980). They alter the exchanges of matter and energy between the land surface and the atmosphere, with important implications for local, regional, and global environmental patterns. Moreover, fires play a significant role in affecting air quality, the ecosystem, land use, public health, and safety. To understand the role of fires in changing climate conditions and socioeconomic landscapes, recent scientific studies of biomass burning have focused on two goals: i) quantifying the emissions of aerosol particles and trace gases from fires and improving the description of spatial and temporal patterns at mesoscale or finer resolutions and ii) characterizing and understanding the effect of these emissions on atmospheric processes at various scales, ranging from human health and air quality impacts at a local scale to cloud properties and precipitation at a regional scale to interactions with Earth’s climate on a decadal scale. The last decade has seen significant progress toward both goals. Estimates of fire emissions have been greatly improved by better, more comprehensive satellite observations. Global emission inventories are now routinely updated, some in near–real time, with the spatial resolution on the order of kilometers to tens of kilometers and temporal sampling on the order of hourly to a few days (e.g., Reid et al. 2009; van der Werf et al. 2010). Equally dramatic advances have been made in the numerical simulation of the transport and evolution of smoke-related species, which feature both higher resolution and improved descriptions of relevant dynamic and chemical processes. These scientific advances have also benefited from rapid growth in computational power, extensive and detailed laboratory experiments, improved access to ground-based observation networks, and numerous intensive field campaigns. This richness of observations, combined with improvements in atmospheric simulations, has driven broad-based research programs at institutions around the globe aimed at understanding the role of fire in the Earth system. However, large uncertainties remain in our description of the magnitude, patterns, and drivers of AffiliAtions: HyEr—marine meteorology Division, naval research Laboratory, monterey, California; wang— Department of Earth and atmospheric sciences, university of nebraska, Lincoln, nebraska; arEllano—Department of atmospheric sciences, university of arizona, Tucson, arizona Corresponding Author: Edward J. Hyer, naval research Laboratory, 7 grace Hopper avenue, monterey, Ca 93943 E-mail: edward.hyer@nrlmry.navy.mil

Interpolating Fields of Carbon Monoxide Data Using a Hybrid Statistical-Physical Model

Atmospheric Carbon Monoxide (CO) provides a window on the chemistry of the atmosphere since it is one of few chemical constituents that can be remotely sensed, and it can be used to determine budgets of other greenhouse gases such as ozone and OH radicals. Remote sensing platforms in geostationary Earth orbit will soon provide regional observations of CO at several vertical layers with high spatial and temporal resolution. However, cloudy locations cannot be observed and estimates of the complete CO concentration fields have to be estimated based on the cloud-free observations. The current state-of-the-art solution of this interpolation problem is to combine cloud-free observations with prior information, computed by a deterministic physical model, which might introduce uncertainties that do not derive from data. While sharing features with the physical model, this paper suggests a Bayesian hierarchical model to estimate the complete CO concentration fields. The paper also provides a direct comparison to state-of-the-art methods. To our knowledge, such a model and comparison have not been considered before.

Toward a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition

INSU-CNRS (France); Meteo-France; CNES; Universite Paul Sabatier (Toulouse, France); Research Center Julich (FZJ, Julich, Germany); EU; National Aeronautics and Space Administration (NASA); NSF Office of Polar Programs (OPP); Danish Meteorological Institute; Australian Research Council [DP110101948, LE0668470]; European Commission; Max Planck Society; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo; Conselho Nacional de Desenvolvimento Cientifico (Instituto do Milenio LBA); National Science Foundation; National Science Foundation [Computational and Information Systems Laboratory]; Office of Science (BER) of the U.S. Department of Energy; NASA; NASA [NNX13AK24G, NNX14AN47G]

Assessing the impacts of assimilating IASI and MOPITT CO retrievals using CESM-CAM-chem and DART

We show the results and evaluation with independent measurements from assimilating both MOPITT (Measurements Of Pollution In The Troposphere) and IASI (Infrared Atmospheric Sounding Interferometer) retrieved profiles into the Community Earth System Model (CESM). We used the Data Assimilation Research Testbed ensemble Kalman filter technique, with the full atmospheric chemistry CESM component Community Atmospheric Model with Chemistry. We first discuss the methodology and evaluation of the current data assimilation system with coupled meteorology and chemistry data assimilation. The different capabilities of MOPITT and IASI retrievals are highlighted, with particular attention to instrument vertical sensitivity and coverage and how these impact the analyses. MOPITT and IASI CO retrievals mostly constrain the CO fields close to the main anthropogenic, biogenic, and biomass burning CO sources. In the case of IASI CO assimilation, we also observe constraints on CO far from the sources. During the simulation time period (June and July 2008), CO assimilation of both instruments strongly improves the atmospheric CO state as compared to independent observations, with the higher spatial coverage of IASI providing better results on the global scale. However, the enhanced sensitivity of multispectral MOPITT observations to near surface CO over the main source regions provides synergistic effects at regional scales.

The North American Monsoon GPS Transect Experiment 2013

AbstractNorthwestern 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 meteorolo...

Chemical Feedback From Decreasing Carbon Monoxide Emissions

National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Program; National Science Foundation (NSF); U.S. Department of Energy (DOE); NASA [NNX13AK24G]