Inﬂuence of Mineral Dust Aerosol on the Chemical Composition of the Atmosphere PI: Charles S. Zender University of California at Irvine Department of Earth System Science University of California Irvine, CA 92697-3100 zender@uci.edu Voice: (949) 824-2987 Fax: (949) 824-3256

Abstract This proposal outlines a program of scientiﬁc research and educational development focused on mineral dust aerosol, atmospheric chemistry, and curricular use of satellite data. Mineral dust impacts the chemical composition of the atmosphere by providing a surface for heterogeneous chemistry, and for light scattering and absorption at photolytic wavelengths. We propose to assess the current and potential future inﬂuence of mineral dust on the chemical composition of the atmosphere by perfoming simulations of these processes within a global Chemical Transport Model (CTM). Research will focus on reducing uncertainties of the role of mineral dust on atmospheric NOy , SOx , and O3 cycles. Mineral dust provides a surface for heterogeneous removal of H2 O2 , HNO3 , HO2 , N2 O5 , NO3 , O3 , and SO2 from the atmosphere. This research will ﬁrst quantify the impact of these processes relative to the impact of other externally mixed aerosols (carbonaceous, sulfate). Second, we will study the inﬂuence of mineral dust on photochemistry and assess its regional and seasonal patterns and importance relative to these other aerosols. Although largely of natural origin, emissions of mineral dust are also highly susceptible to enchancement by anthropogenic disturbance such as land use change. Thus the satellite record of the last 20 years will provide crucial insights and constraints on the potential future impacts of mineral dust on the chemistry/climate system. The educational component of the proposal focuses on enhancing undergraduate and graduate exposure to, and experience with, remotely-sensed data. Graduate students will learn to obtain and use remotely-sensed data from the AVHRR, TOMS, and/or SeaWiFs satellites as their term project in my new course, Radiative Processes and Remote Sensing Our department’s large undergraduate survey courses will all be enhanced to present students with new satellite data that illustrates each week’s academic theme.

CONTENTS

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Contents
1 Introduction 2 Enhancing Curricula with Satellite Data 2.1 Undergraduate Curriculum . . . . . . . . . . . . . . . . . 2.2 Graduate Curriculum . . . . . . . . . . . . . . . . . . . . 2.3 Work Plan for Educational Component . . . . . . . . . . 2.4 Evaluation and Expansion of Educational Component . . 2.5 Signiﬁcance to Professional Goals and Responsibilities . . 2.6 Prior Education, Outreach, and Service Accomplishments 3 Mineral Dust Aerosol and Atmospheric Chemistry 3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 Heterogeneous Chemistry on Mineral Dust . . . 3.1.2 Dust Distribution, Mineralogy, and Atmospheric 3.1.3 Photochemical Impact of Mineral Dust Aerosol 3.2 Objectives and Hypotheses . . . . . . . . . . . . . . . . 3.3 Research Plans . . . . . . . . . . . . . . . . . . . . . . 3.4 Methods and Procedures . . . . . . . . . . . . . . . . . 3.4.1 In Situ Data . . . . . . . . . . . . . . . . . . . . 3.4.2 Satellite Data . . . . . . . . . . . . . . . . . . . 3.5 Expected Signiﬁcance of Results . . . . . . . . . . . . . 3.6 Synergies with Existing Research Eﬀorts . . . . . . . . 3.7 Beneﬁts to Community . . . . . . . . . . . . . . . . . . 3.8 Signiﬁcance to Professional Goals and Responsibilities . 3.9 Work Plan for Research . . . . . . . . . . . . . . . . . 3.10 Prior Research Accomplishments . . . . . . . . . . . . 3.11 References . . . . . . . . . . . . . . . . . . . . . . . . . 4 Management of the Project 5 Personnel 6 Current Support 7 Budget Justiﬁcation 8 Curriculum Vitae 1 1 1 2 2 3 3 4 4 4 6 6 8 9 10 11 11 12 12 13 13 13 13 14 14 17 17 17 17 19

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1

Introduction

This proposal outlines a three year program of research and educational development concerning the impact of aerosols on chemical composition of the atmosphere. The research employs a hierarchy of models to simulate physical processes involving mineral dust aerosol in the climate system. A central component of this research, however, is the evaluation and improvement of model predictions through the use of satellite and in situ observations. The ﬁrst portion of this proposal describes the integration of satellite data into the curriculum of our academic department. Existing undergraduate courses and a new graduate level course will draw in distinct but beneﬁcial ways from the satellite datasets used in the research component of this project. The second portion of this proposal outlines the scientiﬁc research into the inﬂuence of mineral dust aerosol on the chemical composition of the atmosphere. This research area hinges on the use of global satellite datasets which are the pedagogical toolbox for the educational project. The third part of the proposal summarizes my past research experience and accomplishments.

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Enhancing Curricula with Satellite Data

Our knowledge of Earth’s chemical, biological, and physical cycles is increasingly derived (using radiative transfer theory) from observations made by remote sensing instruments such as satellite-borne radiometers. No course at UC Irvine currently oﬀers instruction in formal radiative transfer theory or its application to the remote sensing of the environment.

2.1

Undergraduate Curriculum

The Earth System Science (ESS) department, hitherto a graduate department only, is introducing a new undergraduate degree to campus, a B.S. in Earth and Environmental Sciences (EES). ESS faculty are now motivated to help develop recruit highly interested undergraduate students into the major. Many of these students are likely to be drawn from our four large survey courses (The Physical Environment; Atmospheric Pollution, Ozone, and Climate; The Atmosphere; Oceanography). Although we Earth scientists ﬁnd the material in these courses intrinsically interesting, many students are skeptical of the value of studying the environment, especially when compared to studying technological ﬁelds which promise an advantage in today’s hot job market. A teaching approach which uses data from spaceborne sensors to illustrate environmental processes and change will alert bright students to the increasing convergence of the environment and technology. One way to stimulate interest in the EES major among undergraduates is to illustrate the curriculum of these survey courses with the exciting images produced by satellite sensors. Developing the material for our largest survey course, “The Atmosphere”, I was struck by how infrequently satellite data appear in undergraduate texts. Partially this is due to the long tradition of favoring hand-drawn illustrations in textbooks that developed before satellite-derived data was widely available. Another barrier between students and remotelysensed data is frequently the instructor who may not use satellite data very often and thus is unlikely to employ it in the classroom.

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2.2

Graduate Curriculum

No course at UC Irvine currently oﬀers instruction in formal radiative transfer theory or its application to the remote sensing of the environment. To ﬁll this gap I proposed a new course, ESS 111/211: “Radiative Processes and Remote Sensing”, which has been accepted and is scheduled to meet during Winter quarters beginning in 2001. The course will develop a theoretical understanding of radiative processes necessary to understand remote sensing techniques, and then apply these techniques to important environmental properties. This proposal will support a new component for this course: integration of satellite data into the required graduate student term project. The ﬁrst 6 weeks of the course (not shown) are devoted largely to the radiative transfer theory which underlies remote sensing technology. The ﬁnal four weeks of the course introduce remote sensing technology (week 7), speciﬁc remotely-sensed ﬁelds (weeks 8 and 9), and climate change potentially observable from space. 1. 2. 3. 4. 5. 6. 7. 8. Week Week Week Week Week Week Week Week 7a: Optical Instrumentation I: Radiometers, LIDAR 7b: Optical Instrumentation II: DOAS, Limb scanning, Inversion methods 8a: Remote Sensing I, Ocean: Color/Productivity, Altimetry, SST 8b: Remote Sensing II, Land: Vegetation, BDRF, PAR 9a: Remote Sensing III, Atmosphere: Water vapor, Ozone, Wind 9b: Remote Sensing IV, Atmosphere: Reﬂecting and absorbing aerosols 10a: Environmental Impacts I: Radiative forcing by CO2 , O3 , CH4 , N2 O, CFCs 10b: Environmental Impacts II: UV Radiation, Photolysis, PAR

During these intensive four weeks the students will be introduced to techniques and data from AVHRR, TOMS, TOPEX, ERBE, and SeaWiFs. Students will learn, for example, how total O3 and Chlorophyll concentrations are inferred from radiance measurements. At the same time, graduate students will write an original paper about 10–20 pages in length which includes numerical model of a radiative process currently used in remote sensing techniques.

2.3

Work Plan for Educational Component

This proposal provides partial funds to support a programmer/analyst whose responsibilities will include disseminating satellite imagery to ESS faculty teaching survey courses. This highly qualiﬁed (Master’s or PhD) person will help organize, statistically analyze, and graphically visualize multiple remote sensing and model datasets. She will become familiar with, initially, AVHRR, TOMS, ERBE, and SeaWiFs satellite products (eventually Terra and Aqua as well) in support for the mineral dust research. During Year 1 the programmer/analyst will concentrate on learning, developing and enhancing tools to extract and visualize ﬁelds relevant to the PI’s research and teaching. Introducing satellite data into graduate curricula is fraught with pitfalls. Data must be made available to students who employ a variety of computing platforms and the students have a limited timeframe to extract and manipulate the data in order to answer a meaningful question. Every Winter quarter the programmer/analyst to be funded by this proposal will provide necessary support to students working on term projects in the Remote Sensing course. This will include providing necessary scripts and support to prevent students from

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stumbling over the practicalities of integrating satellite data into their term projects. During Spring quarters the programmer will assemble satellite-derived material in support of the PI’s survey course on the atmosphere. In Years 2 and 3, we will expand the program by providing satellite data at the request of ESS faculty who teach the other Earth System Science undergraduate survey courses. These faculty will receive lists from me of the satellite ﬁelds at our disposal before each term commences. They will give me their syllabi and identify satellite data they would like to illustrate their lectures. These data could range from simple updates of their current material, to data not in any textbooks but of special relevance, to new syntheses of satellite material that the faculty member has not the time or familiarity to visualize themselves. The responses to this plan from faculty who teach these courses has been uniformly positive and all are eager to integrate appropriate remote sensing data into the ESS curriculum.

2.4

Evaluation and Expansion of Educational Component

The educational component of the proposal will impact approximately 400 undergraduates in four courses and 4–8 graduate students in one course per year. All UC Irvine courses are evaluated by the students at the end of the term. The evaluations are conﬁdential, and contain room for four optional questions. We will use these questions to speciﬁcally isolate the success or failure of the remotely-sensed data presented during the course. Undergraduates will be asked to rank their agreement with the statements 1. The satellite imagery stimulated my interest in the subject 2. The satellite imagery complemented the text and lectures 3. The satellite imagery helped to clarify important topics Additionally, the surveys will ask an open-ended question, such as, “How could satellite data be used to improve the course?” These evaluations should provide an objective indicator of our success or failure at meeting our educational objectives. Moreover, the ﬁrst-year feedback will provide information crucial to improving the expansion of the program to all undergraduate survey courses in Years 2 and 3. After Year 3 it may be possible discern signiﬁcant trends in student satisfaction with the satellite component of the courses from the 3-year timeseries of student evaluations and enrollment.

2.5

Signiﬁcance to Professional Goals and Responsibilities

As an educator I seek to present students with the most vivid, compelling, and persuasive material possible to illustrate the often drier, but equally necessary, fundamental theory taught in any course. With the rapid improvement in educational technology and growing competition of high-tech industries for motivated students, Earth science educators are wise to introduce sophisticated, digital education technologies into the classroom. Increasing use of satellite datasets in our department’s classes contributes to both of these professional goals. Our department is responsible for objectively educating students to the potential impacts of human activity (their activity) on the Earth system. The global nature of satellite data

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keep both the instructor and the students from focusing too much on locally important but globally less signiﬁcant environmental issues (and the reverse). Increased exposure to satellite data not only expands students’ horizons beyond processes in their immediate vicinity, it also instills an appreciation for the many mechanisms by which humans and the Earth system interact on a global scale. Since this educational plan integrates my research interests with my educational goals and philosophy, its likelihood of success is enhanced.

2.6

Prior Education, Outreach, and Service Accomplishments

1. Development of Widely Distributed Geophysical Software: I write and manage the netCDF Operators (NCO) toolset (NCO works with HDF4, too). NCO is an Open Source software project (http://nco.sourceforge.net) developing free tools to manipulate geophysical datasets. NCO is one of two components of the CSM Component Model Processing Suite and is used daily by hundreds of geoscientists. 2. Undergraduate Teaching: I teach ESS 20E: “The Atmosphere”, a large (150 students) undergraduate survey course. All course material is placed on the web (http://eee. uci.edu/00s/42020), and the course includes web-based learning exercises. 3. Mentoring of Undergraduates: At the University of Colorado I founded and directed the Astrophysical, Planetary, Atmospheric Sciences Departmental Help Center, a free tutoring center which assisted dozens of undergraduates in the physical sciences every semester. My role included securing funding, tutoring, and managing a group of about 10 paid graduate student tutors. This activity occurred under my direction from 1992–1995, and continued after my departure. Throughout this period I contributed to secondary school teaching by answering calls for to the Math and Science Teachers Hotline (1-800-866-MAST) organized by the University of Northern Colorado.

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3.1

Mineral Dust Aerosol and Atmospheric Chemistry
Overview

Mineral dust is the dominant aerosol by mass and surface area in the atmosphere, and it plays important roles in heterogeneous and photochemical reactions. Wind erosion lifts about 1– 3 GT yr−1 of silt and clay-sized particles (D < 10 µm) from the topsoil [Andreae, 1996]. These small particles, usually called mineral dust aerosol, are in the aerosol accumulation mode and so may undergo long range, high altitude transport. During its mean atmospheric lifetime of about 10 days, dust aerosol may take up water through a variety of processes such as swelling, deposition of hygroscopic coatings, and cloud processing [e.g., H¨nel , 1976]. a A signiﬁcant fraction of the northern hemisphere from is susceptible to large dust events, and thus to chemical processes inﬂuenced by dust. Figure 1 shows the Absorbing Aerosol Index (AAI) [Herman et al., 1997] derived from the TOMS measurements for July, 1998. The exact relationship between AAI and aerosol optical depth (AOD) and mass path depends on regional and seasonal characteristics of the aerosol [Hsu et al., 1999]. Nevertheless, AAI product currently provides perhaps the best observational proxy for the global distribution of absorbing aerosols including mineral dust. In concert with surface observations, these

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Figure 1: Absorbing aerosol index measured by TOMS in July, 1998. satellite data tell us that mineral dust is a dominant or signiﬁcant component of aerosol carried from North Africa across the subtropical north Paciﬁc, over the Arabian Peninsula and Sea, interior to central and East Asia (especially during spring) [e.g., Li et al., 1996; Husar et al., 1997; Guelle et al., 2000]. Recent regional and global studies show that mineral dust in these plumes substantially alters heterogeneous chemistry and photochemistry [Zhang et al., 1994; Dentener et al., 1996; Dickerson et al., 1997; Zhang and Carmichael , 1999]. Previous three-dimensional chemical transport simulations have focused on the impact of only a few types of aerosol, in isolation, upon atmospheric composition, or upon more complete aerosol species but over a smaller region and timescale. All suggest that aerosol-aerosol interactions and long-range transport are important, even decisive, factors that should not be neglected. Indeed, it is better to consider long-lived aerosols as internally mixed multi-component aerosols rather than as externally mixed aerosols [Meng et al., 1998]. Thus a global CTM with an integrated suite of aerosols is necessary to address questions of global air quality, emissions-impacts, and, ultimately, radiative forcing of climate. We propose to integrate the inﬂuence of mineral dust on the global chemical composition of the atmosphere into an existing CTM that will allow simultaneous heterogeneous and photochemical interactions by dust, sulfate, carbon, and sea salt.

3 MINERAL DUST AEROSOL AND ATMOSPHERIC CHEMISTRY Table 1: Uptake Coeﬃcients for Mineral Dust Used in MOZART Reaction H2 O2 + Dust −→ Products HNO3 + Dust −→ Products HO2 + Dust −→ Products N2 O5 + Dust −→ Products NO3 + Dust −→ Products O3 + Dust −→ Products OH + Dust −→ Products SO2 + Dust −→ Products
a

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Uptake coeﬃcient 1.0 × 10−4 0.005 0.1 0.001 0.1 5.0 × 10−5 0.1 3.0 × 10−4

Referencesa 1 1, 2 1, 4 1, 2 3, 4 1, 2, 4 4 1, 4

References: 1, Dentener et al. [1996]; 2, DeMore et al. [1997]; 3, Seinfeld and Pandis [1997]; 4, Zhang and Carmichael [1999];

3.1.1

Heterogeneous Chemistry on Mineral Dust

Convincing evidence that heterogeneous chemistry on mineral dust particles signiﬁcantly alters the concentration and deposition of important atmospheric oxidants has been ﬁrmly established by Zhang et al. [1994]; Carmichael et al. [1995]; Zhang and Carmichael [1999]. Once sequestered on mineral dust particles, oxidants such as SO2 and HNO3 appear to undergo fast neutralization reactions with alkaline material (e.g., CaCO3 ) in mineral dust. Dentener et al. [1996] estimate that as much as half of total column particulate sulfate and nitrate are in sequestered on mineral dust aerosol in and downwind of dust source regions. Zhang and Carmichael [1999] found 10–40% reductions in O3 during dusty conditions in East Asia. A combination of laboratory measurements and ﬁeld studies suggest at least eight important members of the NOy , SOx , and O3 cycles undergo direct uptake on mineral dust: H2 O2 , HNO3 , HO2 , N2 O5 , NO3 , O3 , and SO2 [Zhang and Carmichael , 1999]. The uptake (γ) coeﬃcients which drive these heterogeneous processes are thought to range from the very large (γ = 0.1 for HO2 , NO3 , OH) to relatively small (γ = 5.0 × 10−5 for O3 ). Table 1 lists the uptake processes to be integrated into our CTM. Since the exact chemical pathways and products are poorly known and the mineralolgical composition of dust is highly variable [Claquin et al., 1999], the uncertainty in the uptake coeﬃcients is large. One foreseeable outcome of our studies is that the combined heterogeneous processes operating on all aerosols will scavenge these trace gases too eﬃciently, leading to signiﬁcant biases. will provide an opportunity to constrain uptake coeﬃcients 3.1.2 Dust Distribution, Mineralogy, and Atmospheric Chemistry

Empirical studies show very strong stoichiometric relationships between an alkaline constituent of dust, CaCO3 , and particulate SO2− and NO− [Carmichael et al., 1995; Dentener 4 3 et al., 1996]. This suggests that uptake and oxidation SOx and NOy on mineral dust is limited by CaCO3 availability. The global distributions of CaCO3 , as well as other impor-

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Figure 2: Simulated 1998 annual mean mass deposition ﬂux (mg cm−2 ka−1 ) of (a) dust and (b) CaCO3 (NB: 20070602 Original CaCO3 simulations and ﬁgures lost, substituted duplicate of (a) for posterity). tant crustal minerals, must be obtained from in situ soil samples. The IGBP global soil dataset [Carter and Scholes, 1998] has assembled many thousand soil proﬁles (pedons), into one quality-controlled dataset. The global distribution of CaCO3 peaks strongly around the Arabian Pensinsula and Iran, where CaCO3 accounts for up to 15% of topsoil mass. We have implemented the IGBP soil CaCO3 content into our prognostic mineral dust distribution model, using the size resolved partitioning approach of Claquin et al. [1999]. Figure 2 shows our simulated annual mean mass deposition ﬂux of total dust and of CaCO3 for 1998. CaCO3 is a much larger mass fraction of deposited dust over central Asia than over the subtropical North Atlantic. The global mean continental CaCO3 topsoil content is about 2.5%, but Figure 2 shows that the distribution of CaCO3 as a fraction of total dust mass, is highly non-linear. The usefulness of global chemical studies of mineral dust depends on the adequacy of the prediction of dust emission, transport, and deposition processes, i.e., on the ﬁdelity of the simulated dust distribution to observations. Dust emissions are highly sensitive to wind

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Figure 3: Measured (black) and simulated (green) surface mass concentration of mineral dust (µg m−3 ) in Barbados during 1998. Annual means are 22 and 21 µg m−3 , respectively. (NB: 20070602 Original proposal submitted with 1998 daily mean simulations. These simulations and ﬁgures were lost, substituted 1990s monthly timeseries for posterity). speed, surface roughness, vegetation, and soil moisture. Transport and deposition depend on adequate representation of size distributions, convection, and washout. Our model [Collins et al., 2001] represents the most important spatial and temporal characteristics of dust distribution. Figure 3 shows the simulated surface mass concentration of mineral dust in Barbados during 1998. The model reproduces the mean and the temporal variability of the long-range transported dust quite adequately. 3.1.3 Photochemical Impact of Mineral Dust Aerosol

Aerosols of disparate compositions, optical properties, and vertical distributions are now recognized to play complex roles in modifying atmospheric photochemistry [e.g., Madronich, 1989]. Aerosols scatter and absorb sunlight and thus alter the actinic ﬂux available to drive atmospheric photochemistry. Through these mechanisms, aerosols signiﬁcantly alter tropospheric concentrations of many important oxidants such as O3 , NOy , and HOx [Dickerson et al., 1997] in turbid conditions. The radiative transfer model of Zender et al. [1997] was used in Figure 4 to simulate the impact of a 1 km thick, 1 km high aerosol layer on the photodissociation rate coeﬃcient JNO2 , the key determinant in the relative abundance NO2 and NO during daylight. The scattering aerosol (sulfate) increases JNO2 by 20–25% in the lower troposphere. The absorbing aerosol (dust) reduces JNO2 by as much as 40%. These eﬀects extend into the stratosphere and are highly sensitive to aerosol optical properties [He and Carmichael , 1999; Sokolik and Toon, 1999]. Accounting for the photochemical forc-

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Figure 4: Vertical proﬁle of relative impacts of mineral dust (green) and of sulfate (blue) aerosol on JNO2 . Both aerosols have a speciﬁed visible optical depth of 1.0 and are uniformly distributed in the lowest 1 km of the atmosphere. The black line represents JNO2 in a clean, aerosol-free atmosphere. Simulations are for a solar zenith angle of 30◦ in a standard, cloud-free mid-latitude summer atmosphere. ing by aerosols signiﬁcantly improves predicted tropospheric oxidant levels in turbid regions [Dickerson et al., 1997]. Single column demonstrations such as Figure 4 bely the diﬃculty of simulating aerosol impact on global photochemistry. To our knowledge no global CTM currently has both an adequate J-rate scheme and a comprehensive aerosol treatement. The diﬃculty stems from the computational expense of accurately integrating J values with strong spectral variation (e.g., JO3 ) in global models [Madronich, 1989]. Many CTMs [e.g., Brasseur et al., 1998] employ multi-dimensional (5–7 dimensions is typical) lookup tables to determine a clear sky J-values, and then apply highly-parameterized cloud corrections when applicable [Chang et al., 1987]. This simple approach is suitable for pristine (non-turbid) skies and for single layer liquid cloud decks, but inadequate for extension to more complex scattering geometries or to aerosol scattering. Wild et al. [2000] and Landgraf and Crutzen [1998] present methods more suitable for studying aerosols, clouds, and chemistry in CTMs. These studies suggest that the changes in the chemical composition of the atmosphere due to improved photolysis alone are quite interesting, even without an integrated aerosol suite.

3.2

Objectives and Hypotheses

These objectives are important to our understanding and representation of aerosol-cloudchemistry-climate interactions. Each objective is followed by a sample hypothesis which can be explored in a framework of modeling validated by measurements. 1. Objective: Identify regions where absorbing and scattering aerosols strongly interact Hypothesis: Dust has more frequent and stronger interactions with sulfate near East Asia than near Africa.

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The eﬀects of absorbing (e.g., dust, carbon) and scattering (e.g., sulfate) aerosol on photolysis rates are opposite (Figure 4), and non-linear interactions are expected in regions and seasons where the two coexist. Dust from East Asia and the Arabian peninsula has more opportunity to interact with strong anthropogenic emissions than dust from North Africa which travels over the subtropical North Atlantic. 2. Objective: Understand inﬂuence of aerosol layer structure on ozone production Hypothesis: Higher mineral dust layers have more impact on column ozone. Absorbing aerosol layers above brighter aerosols and above clouds will have a greater impact on photolysis (Figure 4). Zonal gradients of dust concentration slope downward from the source region as dust settles gravitationally (Figure 1). We will compare simulations and measurements of strong dust events for evidence of a zonal gradient of dust impact on O3 . 3. Objective: Examine interaction of dust, clouds, and atmospheric chemistry Hypothesis: The heterogeneous impacts of dust will increase relative to the photochemical impacts in the presence of clouds. Although the subtropics are not generally very cloudy, wet deposition remains the dominant removal mechanism for dust in the accumulation mode. Cloud scattering and cloud screening impact photochemistry so strongly [Madronich, 1989] that scattering and absorption by dust, which is usually beneath clouds, will have little eﬀect on photochemistry (Figure 4) in the presence of clouds. The reverse will occur when clouds form beneath dust layers. 4. Objective: Understand importance of dust mineralogy on heterogeneous chemistry Hypothesis: Oxidant uptake by dust particles over the Atlantic is less (per unit mass of dust) than over Asia because of greater soil CaCO3 content in Asia Dentener et al. [1996] showed that oxidant uptake on East Asian mineral aerosol obeys the empirical stoichiometric relationship [NO− ] + 2[SO2− ] < 2[Ca2+ ]. Figure 2 shows 3 4 that dust Ca content varies regionally but is generally low over the Atlantic. If this constraint does not hold over the Atlantic (which may be testable at Bermuda), more complex mineralogical and heterogeneous chemistry schemes may need to be adopted. 5. Objective: Elucidate the relative sensitivity of aerosols to natural climate variability Hypothesis: Mineral dust emission is more sensitive to climate variability on most timescales than other aerosols. Due to their strong sensitivity to wet deposition, virtually all tropospheric aerosol is sensitive to climatic shifts in precipitation (e.g., ENSO). Mineral dust emissions, moreover, are also sensitive to precipitation. Thus we expect mineral dust emissions (Figure 3) and chemistry downwind to respond uniquely to climate variability on many timescales.

3.3

Research Plans

We will study the eﬀects of mineral aerosols on atmospheric chemistry and climate in a framework of global modeling evaluated against data from satellite and other platforms.

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Simulations will be performed with a 3-D global chemical transport model (CTM). The ﬁrst three of our objectives (§3.2) will be met by analyzing the results of full CTM simulations of recent years, probably 1998 and 1999. The CTM will be driven by NCEP meteorology so that simulations may be evaluated against recent high quality datasets like INDOEX [e.g., Collins et al., 2001]. These three objectives will be our highest priority. Meeting these objectives fully will require simulations with and without mineral dust heterogenous chemistry, photochemistry, and both. Objective 4 (mineralogical eﬀects) will require an ensemble of simulations to test the eﬃcacy of various assumptions about mineralogy-chemistry interactions. These simulations may be of shorter duration (e.g., three months). Objective 5 (sensitivity to natural variability) requires expensive simulations in order to answer questions of variability on timescales longer than seasonal. These objectives will be accomplished if resources permit.

3.4

Methods and Procedures

The mineral dust aerosol scheme has already been implemented in MATCH [e.g., Collins et al., 2001] which is the meteorological driver for the MOZART CTM [Brasseur et al., 1998]. Thus our initial choice for the CTM is MOZART, but other suitable options include the UCI CTM, IMPACT from LLNL, or other MATCH-based models. Mineral dust emisssions are based on a combination of land surface properties and meteorological ﬁelds [Marticorena and Bergametti , 1995]. A comprehensive evaluation of our simulated mineral dust distribution is currently in progress. Our representation of heterogeneous chemistry on mineral dust is based on Zhang et al. [1994] and Zhang and Carmichael [1999] and is summarized in Table 1. The dust physics and chemistry will be integrated with the existing aerosol suite within the CTM. A major component of this proposal is to account for the eﬀects of clouds and aerosols on tropospheric photochemistry. An accurate representation of particulate interactions with actinic ﬂux will require a forward radiative transfer scheme applicable to multiple scattering, vertically inhomogeneous atmospheres at all zenith angles. We will use the method of Wild et al. [2000] or Landgraf and Crutzen [1998] and carefully evaluate our implementation of sensitive J-values such as JO3 against accurate, multi-stream, high resolution radiative transfer models [Zender et al., 1997]. With these modiﬁcations we believe the physical and chemical parameterizations will be state-of-the-art for in nearly all aspects of global aerosol-chemistry modeling. The modeling component of this proposal centers on integrating and evaluating the impacts of a uniﬁed suite of aerosols on tropospheric chemistry. This requires that the suite of aerosols in the CTM be evaluated against comprehensive aerosol climatologies inferred from a combination of ground-based, aircraft, and satellite data. 3.4.1 In Situ Data

Simulations will be compared to collocated measurements of dust concentration, and particulate NO3 , SO4 , and other species at Barbados, Bermuda, Iza˜a, Kaashidhoo, and, evenn tually, ACE Asia sites [e.g., Savoie et al., 1992]. Measurements of Ca and non-sea-salt Ca at Bermuda will be crucial in determining whether to determining whether Ca mineral dust

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crossing the Atlantic constrains acid uptake as strongly as East Asian dust [Dentener et al., 1996] (Objective 4). Ozonesonde climatologies [Logan, 1999] will provide crucial vertical and seasonal constraints on the chemical inﬂuence of mineral dust. Data composites of aircraft and ground based measurements of O3 , NO, NOx , HNO3 , PAN, H2 O2 and other species [Emmons et al., 2000] will be extremely valueable for more comprehensive regional assessments. 3.4.2 Satellite Data

Our use of satellite data will take place in two parallel eﬀorts. First, we will compare the aerosol optical depth predicted by the CTM directly to long term satellite datasets. The two long term satellite climatologies which presently exist are the optical depth products from the AVHRR Pathﬁnder instruments [Stowe et al., 1997] and the aerosol residuals from TOMS instruments [Herman et al., 1997]. Although these satellite optical depth products include many model assumptions about aerosol size distribution, optical properties, and vertical distribution, they are complementary and represent the best global climatology of aerosol distribution presently available. TOMS, for example, is best for evaluating absorbing material such as mineral dust and carbonaceous aerosols while the AVHRR data is better suited for evaluating highly scattering aerosols such as sulfate. The high spatial resolution of SeaWiFS makes it particularly well suited for evaluation of individual aerosol events. These and future (MODIS, PICASSO) satellite products will help guide the development and evaluation of chemical transport models to become more capable of simulating aerosol eﬀects in current and future climate scenarios. The second approach is to compare predictions from the CTM against the “best guess” global estimates of aerosol concentration predicted by a global aerosol assimilation model that assimlates AVHRR-inferred aerosol optical depth [Collins et al., 2001]. The CTM and the assimilation model use the same meteorology and mineral dust physics so the mineral dust comparison will be direct. We note that these models produce aerosol concentrations that can drive the NCAR Column Radiation Model (CRM) which has been modiﬁed to include optical properties for sulfate [Kiehl et al., 2000], dust [Zender et al., 1997], sea-salt and carbon [Haywood and Ramaswamy, 1998] aerosols. This approach will, time-permitting, allow us to study aerosol impacts on radiative forcing.

3.5

Expected Signiﬁcance of Results

It is already known that mineral dust aerosol does have signiﬁcant eﬀects on atmospheric chemistry downwind from certain source regions [e.g., Dentener et al., 1996; Dickerson et al., 1997]. This project will extend previous studies to account for both heterogeneous and photochemical impacts of dust on global scales in the framework of an integrated tropospheric aerosol suite. Our objectives (§3.2) will substantially increase our understanding of the sensitivity of air quality to aerosols in general, and especially to mineral dust. Since mineral dust emissions respond strongly to land use change and long term climate variability, these results will reduce uncertainty as to the past and potential future chemical composition of the atmosphere.

3 MINERAL DUST AEROSOL AND ATMOSPHERIC CHEMISTRY

13

3.6

Synergies with Existing Research Eﬀorts

The dust physics use the NCAR Land Surface Model (LSM) to provide the biogeophysical surface properties needed to predict mobilization and deposition. PI Zender is working on a NASA project with G. Bonan of NCAR to couple the dust emission processes within the LSM and investigate dust emission changes due to land-use change. At the same time, G. Brasseur and D. Hauglustaine of MPI are working to fully couple the LSM and chemistry to MOZART. All of these existing projects will beneﬁt from the proposed studies of chemistry and mineralology of dust.

3.7

Beneﬁts to Community

The mineral dust aerosol physics package is also a component of the aerosol suite in the next generation NCAR Community Climate Model (CCM) and is used in the Model for Atmospheric Transport and Chemistry (MATCH) aerosol assimilation project of W. Collins [Collins et al., 2001] and P. Rasch of NCAR. Improvements to the mineral dust physics, mineralogy, optics and chemistry which arise from this MOZART proposal will be folded very quickly into both the MATCH aerosol assimilation model, and the NCAR CCM where they will beneﬁt the larger community of aerosol, biogeochemistry, and paleoclimate scientists. Once mineral dust chemistry is integrated into a global CTM, we will be well-placed to collaborate on studies of the “indirect eﬀect” of mineral dust aerosol on cloud droplet nucleation, precipitation, and albedo [e.g., Wurzler et al., 2000]. Reducing uncertainties in these areas is a high priority for climate assessments such as IPCC.

3.8

Signiﬁcance to Professional Goals and Responsibilities

This plan ﬁrmly advances my career goal of improving our ability to predict climate and climate change. Until recently computational limitations have required that, on global scales, chemistry and climate be studied separately (in CTMs and GCMs, respectively). As the newest member of the Earth System Science department and a young scientist with experience in both subjects, my goal is to help these ﬁelds merge in fully coupled Earth System models. This proposed work is a signiﬁcant stride towards this uniﬁcation.

3.9

Work Plan for Research

In Year 1 Dr. Zender will integrate heterogeneous chemistry with the existing aerosol suite within the CTM. The postdoc to be hired will work to replace the table-lookup scheme in the CTM with a forward radiative transfer code optimized for computing photolysis [Wild et al., 2000]. Simulations of 1998 and 1999 will commence, and we will evaluate and adjust free parameters to ensure the mineral dust aerosol chemistry produces reasonable and wellunderstood results when coupled to the CTM. In Year 2 we will analyze the full seasonal climatologies of atmospheric response to mineral dust in support of our primary objectives (§3.2). Available computer time will be used to run ensembles of particular events and months (e.g. INDOEX) in order to better understand the sensitivity of the simulations to, e.g., dust optical properties. In Year 3 we intend to work on

14 our remaining two objectives, dust mineralogy and natural climate variability. Results from our experiments will be published and made available online for interested collaborators and assessment purposes as soon as possible.

3.10

Prior Research Accomplishments

1. Radiative Eﬀects of Tropical Cirrus Anvil on Climate: My dissertation research at the University of Colorado, in collaboration with J. Kiehl of NCAR, examined the role of tropical cirrus anvil on climate. We ﬁrst documented the eﬀect of ice crystal size and habit on anvil formation and radiative properties [Zender and Kiehl , 1994]. An important conclusion from this study was that shortwave radiative properties of tropical cirrus anvils are very sensitive to the presence of small (3 < L < 20 µm) ice crystals which account for less than 2% of cloud mass. This prediction is still controversial since accurate observations of crystals in this size range have only recently become available. On a global scale, these anvil physics contribute to teleconnections between tropical anvil heating and the extratropical circulation [Zender and Kiehl , 1997]. 2. Enhanced Shortwave Absorption in Clouds: The discrepancy between models and observations of Earth’s atmospheric energy budget is about 20 W m−2 , globally annually averaged. The ARESE experiment attempted measured the energy budget in clear and cloudy conditions using stacked aircraft observations. Detailed spectral analysis of the results shows signiﬁcant evidence of enhanced shortwave absorption in cloudy atmospheres [Zender et al., 1997]. Successive experiments have not resolved the intense controversy over these measurements, which have enormous implications for climate prediction. 3. Radiative Forcing by Oxygen Collision Complexes: Scrutiny of the magnitude and causes of enhanced shortwave absorption has led to many interesting discoveries, including the recognition that absorption by collision complexes of oxygen is signiﬁcant globally (about 1 W m−2 ). Zender [1999] produced the ﬁrst climatology of collision complexes and their absorption and illustrated many unique features of collision complex absorption. This study refuted the notion that O2 ·X contributes to enhanced cloudy absorption (globally).

3.11

References

Andreae, M. O., Climatic eﬀects of changing atmospheric aerosol levels, in Future Climates of the World: A Modelling Perspective, World Survey of Climatology, vol. 16, edited by A. Henderson-Sellers, pp. 347–398, Elsevier, Amsterdam, 1996. 3.1 Brasseur, G. P., D. A. Hauglustaine, S. Walters, P. J. Rasch, J.-F. M¨ller, C. Granier, and u X. X. Tie, MOZART, a global chemical transport model for ozone and related chemical tracers 1. Model description, J. Geophys. Res., 103 (D21), 28,265–28,289, 1998. 3.1.3, 3.4 Carmichael, G., Y. Zhang, L. Chen, M. Hong, and H. Ueda, Seasonal variation of aerosol composition at Cheju Island, Korea, Atmos. Environ., 30, 2407–2416, 1995. 3.1.1, 3.1.2 Carter, R., and R. Scholes, Generating a global database of soil properties, 1998. 3.1.2

15 Chang, J. S., R. A. Brost, I. S. A. Isaksen, S. Madronich, P. Middleton, W. R. Stockwell, and C. J. Walcek, A three-dimensional Eulerian acid deposition model: Physical concepts and formulation, J. Geophys. Res., 92, 14,681–14,700, 1987. 3.1.3 Claquin, T., M. Schulz, and Y. J. Balkanski, Modeling the mineralogy of atmospheric dust sources, J. Geophys. Res., 104 (D18), 22,243–22,256, 1999. 3.1.1, 3.1.2 Collins, W. D., P. J. Rasch, B. E. Eaton, B. Khattatov, J.-F. Lamarque, and C. S. Zender, Forecasting aerosols using a chemical transport model with assimilation of satellite aerosol retrievals: Methodology for INDOEX, J. Geophys. Res., 106 (D7), 7313–7336, 2001. 3.1.2, 3.3, 3.4, 3.4.2, 3.7 DeMore, W. B., S. P. Sander, D. M. Golden, R. F. Hampson, M. J. Kurylo, C. J. Howard, A. R. Ravishankara, C. E. Kolb, and M. J. Molina, Chemical kinetics and photochemical data for use in stratospheric modeling, Evaluation Number 12 97-4, Jet Propulsion Laboratory, Pasadena Calif., 1997. 2 Dentener, F. J., G. R. Carmichael, Y. Zhang, J. Lelieveld, and P. J. Crutzen, Role of mineral aerosol as a reactive surface in the global troposphere, J. Geophys. Res., 101 (D17), 22,869– 22,889, 1996. 3.1, 1, 3.1.1, 3.1.2, 4, 3.4.1, 3.5 Dickerson, R. R., S. Kondragunta, G. Stenchikov, K. L. Civerolo, B. G. Doddridge, and B. N. Holben, The impact of aerosols on solar ultraviolet radiation and photochemical smog, Science, 278, 827–830, 1997. 3.1, 3.1.3, 3.1.3, 3.5 Emmons, L. K., D. A. Hauglustaine, J.-F. Muller, M. A. Carroll, G. P. Brasseur, D. Brunner, J. Stahelin, V. Thouret, and A. Marenco, Data composites of airborne observations of tropospheric ozone and its precursors, In press in J. Geophys. Res., 2000. 3.4.1 Guelle, W., Y. J. Balkanski, M. Schulz, B. Marticorena, G. Bergametti, C. Moulin, R. Arimoto, and K. D. Perry, Modeling the atmospheric distribution of mineral aerosol: Comparison with ground measurements and satellite observations for yearly and synoptic timescales over the North Atlantic, J. Geophys. Res., 105 (D2), 1997–2012, 2000. 3.1 H¨nel, G., The properties of atmospheric aerosol particles as functions of the relative hua midity at thermodynamic equilibrium with the surrounding moist air, Adv. Geophys., 19, 73–188, 1976. 3.1 Haywood, J. M., and V. Ramaswamy, Global sensitivity studies of the direct radiative forcing due to anthropogenic sulfate and black carbon aerosols, J. Geophys. Res., 103 (D6), 6043– 6058, 1998. 3.4.2 He, S., and G. R. Carmichael, Sensitivity of photolysis rates and ozone production in the troposphere to aerosol properties, J. Geophys. Res., 104 (7), 26,307–26,324, 1999. 3.1.3 Herman, J. R., P. K. Bhartia, O. Torres, C. Hsu, C. Seftor, and E. Celarier, Global distribution of UV-absorbing aerosols from Nimbus 7/TOMS data, J. Geophys. Res., 102 (D14), 16,911–16,922, 1997. 3.1, 3.4.2 Hsu, N. C., J. R. Herman, O. Torres, B. N. Holben, D. Tanr´, T. F. Eck, A. Smirnov, e B. Chatenet, and F. Lavenu, Comparisons of the TOMS aerosol index with Sunphotometer aerosol optical thickness: Results and applications, J. Geophys. Res., 104 (D6), 6269–6279, 1999. 3.1 Husar, R. B., J. M. Prospero, and L. L. Stowe, Characterization of tropospheric aerosols over the oceans with the NOAA advanced very high resolution radiometer optical thickness operational product, J. Geophys. Res., 102 (D14), 16,889–16,909, 1997. 3.1 Kiehl, J. T., T. L. Schneider, P. J. Rasch, M. C. Barth, and J. Wong, Radiative forcing due to sulfate aerosols from simulations with the National Center for Atmospheric Research Community Climate Model, Version 3, J. Geophys. Res., 105 (D1), 1441–1458, 2000. 3.4.2 Landgraf, J., and P. J. Crutzen, An eﬃcient method for online calculations of photolysis and heating rates, J. Atmos. Sci., 55 (5), 863–878, 1998. 3.1.3, 3.4

16 Li, X., H. Maring, D. Savoie, K. Voss, and J. M. Prospero, Dominance of mineral dust in aerosol light-scattering in the north Atlantic trade winds, Nature, 380, 416–419, 1996. 3.1 Logan, J. A., An analysis of ozonesonde data for the troposphere: Recommendations for testing 3-d models and development of a gridded climatology for tropospheric ozone, J. Geophys. Res., 104, 16,115–16,140, 1999. 3.4.1 Madronich, S., Numerical integration errors in calculated tropospheric photodissociation rate coeﬃcients, J. Atmos. Chem., 10, 289–300, 1989. 3.1.3, 3.1.3, 3 Marticorena, B., and G. Bergametti, Modeling the atmospheric dust cycle: 1. Design of a soil-derived dust emission scheme, J. Geophys. Res., 100 (D8), doi:10.1029/95JD00,690, 16,415–16,430, 1995. 3.4 Meng, Z., D. Dabdub, and J. H. Seinfeld, Size-resolved and chemically resolved model of atmospheric aerosol dynamics, J. Geophys. Res., 103, 3419–3436, 1998. 3.1 Savoie, D. L., J. M. Prospero, S. J. Oltmans, W. C. Graustein, K. K. Turekian, J. T. Merrill, and H. Levy II, Sources of nitrate and ozone in the marine boundary layer of the tropical North Atlantic, J. Geophys. Res., 97 (D11), 11,575–11,589, 1992. 3.4.1 Seinfeld, J. H., and S. N. Pandis, Atmospheric Chemistry and Physics, 1326 pp., John Wiley & Sons, New York, NY, 1997. 3 Sokolik, I. N., and O. B. Toon, Incorporation of mineralogical composition into models of the radiative properties of mineral aerosol from UV to IR wavelengths, J. Geophys. Res., 104 (D8), 9423–9444, 1999. 3.1.3 Stowe, L. L., A. M. Ignatov, and R. R. Singh, Development, validation, and potential enhancements to the second-generation operational aerosol product at the National Environmental Satellite, Data, and Information Service of the National Oceanic and Atmospheric Administration, J. Geophys. Res., 102 (D14), 16,923–16,934, 1997. 3.4.2 Wild, O., X. Zhu, and M. Prather, Fast-J: Accurate simulation of in- and below-cloud photolysis in tropospheric chemical models, J. Atmos. Chem., 37, 245–282, 2000. 3.1.3, 3.4, 3.9 Wurzler, S., T. G. Reisin, and Z. Levin, Modiﬁcation of mineral dust particles by cloud processing and subsequent eﬀects on drop size distributions, J. Geophys. Res., 105 (D5), 4501–4512, 2000. 3.7 Zender, C. S., Global climatology of abundance and solar absorption of oxygen collision complexes, J. Geophys. Res., 104 (D20), 24,471–24,484, 1999. 3 Zender, C. S., and J. T. Kiehl, Radiative sensitivities of tropical anvils to small ice crystals, J. Geophys. Res., 99 (D12), 25,869–25,880, 1994. 1 Zender, C. S., and J. T. Kiehl, Tropical climate sensitivity to representation of cirrus anvil lifecycle, in Proceedings of the Ninth AMS Conference on Atmospheric Radiation, pp. 111–114, American Meteorological Society, AMS Press, Boston, MA, February 2–5, Long Beach, CA, 1997. 1 Zender, C. S., B. Bush, S. K. Pope, A. Bucholtz, W. D. Collins, J. T. Kiehl, F. P. J. Valero, and J. Vitko, Jr., Atmospheric absorption during the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE), J. Geophys. Res., 102 (D25), 29,901– 29,915, 1997. 3.1.3, 3.4, 3.4.2, 2 Zhang, Y., and G. R. Carmichael, The role of mineral aerosol in tropospheric chemistry in East Asia—a model study, J. Appl. Meteorol., 38 (3), 353–366, 1999. 3.1, 4, 3.1.1, 3.4 Zhang, Y., Y. Sunwoo, V. Kotamarthi, and G. R. Carmichael, Photochemical oxidant processes in the presence of dust: An evaluation of the impact of dust on particulate nitrate and ozone formation, J. Appl. Meteorol., 33, 813–824, 1994. 3.1, 3.1.1, 3.4

4 MANAGEMENT OF THE PROJECT

17

4

Management of the Project

The project will be directed by Dr. Zender. Development of chemical parameterizations for the mineral dust model will take place at UC Irvine. Development and initial model integrations will take place on the School of Physical Sciences’ SGI O2000 supercomputer. Additional computer resources for long term integrations of the CTM are required and will be requested from outside supercomputing facilities (e.g., NCAR and MPI Hamburg) pending funding of this proposal. Collaboration on integration of mineral dust aerosol with existing aerosol components of the CTM and evaluation of the results will occur during annual summer visits to NCAR and one visit to Germany by UCI personnel.

5

Personnel

C. Zender is an Assistant Professor at the University of California at Irvine. He has improved aerosol, cloud, and trace gas representations in global climate models. His research focuses on Cloud and Aerosol Microphysics, Terrigenic Aerosol, and Radiative Transfer and Radiative Forcing. He is an aﬃliate scientists at NCAR and an active member of the CCSM Atmospheric and Biogeochemistry Model Working Groups. The postdoc at UCI will be an expert in atmospheric photochemistry and have signiﬁcant experience with integrated aerosol-chemistry models and evaluation. Dr. Zender and the postdoc will interact with UCI personnel (M. Prather’s group and D. Dabdub’s group) on issues regarding tropospheric chemistry and multicomponent aerosols. The programmer/analyst at UCI will write and manage model code, perform runs, and interface with outside personnel on computational issues of the CTM. Other scientists likely to be involved in the project are: X. X. Tie, NCAR, Global aerosol impacts, G. P. Brasseur, MPI Hamburg, Atmospheric oxidants.

6

Current Support

Dr. Zender is a Co-investigator on NASA grant, “Eﬀects of land-use on climate and water resources: application of a land surface model for land-use management”, PI: G. B. Bonan, 1/1/00–1/1/03. His responsibilities include dust model development and investigation of dust response to land surface change. This grant funds Dr. Zender with summer salary for two months.

7

Budget Justiﬁcation

PI Zender requests funds for one month of summer salary. Funds are requested for one full time postdoc. The postdoc will have strong command of photochemistry, aerosols, and the NOy , SOx , and O3 cycles. The postdoc will focus on perturbation of atmospheric chemical cycles by the mineral dust aerosol.

7 BUDGET JUSTIFICATION

18

Funds are requested for 1/3 of a Programmer/Analyst. The balance of the programmer’s salary is requested in other grants. Up to 1/3 of this salary will be provided from startup funds by PI Zender. The programmer/analyst will help Dr. Zender fulﬁll both the educational and research components of the project. To do this, the programmer must be comfortable with statistics, Fortran90, scripting, and massively parallel computing. It is anticipated that the programmer will have a Master’s degree or equivalent in geophysical or computer sciences.

8 CURRICULUM VITAE

19

8

Curriculum Vitae
Curriculum Vitae CHARLES S. ZENDER

Department of Earth System Science University of California Irvine, CA 92697-3100 EDUCATION

zender@uci.edu Voice: (949) 824-2987 Fax: (949) 824-3256

Ph.D. (1996) Atmospheric Sciences, University of Colorado, Boulder. “Representation of tropical cirrus anvil in climate models”, Advisors: Jeﬀrey Kiehl and Gary Thomas M.S. (1993) Atmospheric Sciences, University of Colorado, Boulder. B.A. (1990) Physics, Harvard University SPECIALTIES AND INTERESTS Atmospheric Physics, Cloud and Aerosol Microphysics and Chemistry, Terrigenic Aerosol, Particle Composition and Optical Properties, Radiative Transfer and Radiative Forcing, Global Climate and Climate Change PROFESSIONAL APPOINTMENTS 1999–now University of California at Irvine – Assistant Professor of Earth System Science 2000–2003 National Center for Atmospheric Research (NCAR), Boulder, CO – Aﬃliate Scientist of the Climate and Global Dynamics (CGD) Division 1998–1999 NCAR – Visiting Scientist in Atmospheric Chemistry and CGD Divisions 1996–1998 NCAR – Postdoctoral fellow in Advanced Study Program 1991–1996 University of Colorado at Boulder and NCAR CGD – Graduate research assistant 1991 College of the Atlantic, Bar Harbor, ME – Visiting Faculty in Physical Sciences 1989–1990 Smithsonian Astrophysical Observatory, Cambridge, MA – Programmer, Technician REFEREED PUBLICATIONS Zender, C. S. and J. T. Kiehl, Radiative sensitivities of tropical anvils to small ice crystals, J. Geophys. Res., 99, 25869–25880, 1994. Zender, C. S., B. Bush, S. K. Pope, A. Bucholtz, W. D. Collins, J. T. Kiehl, F. P. J. Valero, and J. Vitko Jr., Atmospheric absorption during the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE), J. Geophys. Res., 102, 29901–29915, 1997. Zender, C. S. and J. T. Kiehl, Sensitivity of climate simulations to radiative eﬀects of tropical anvil structure, J. Geophys. Res., 102, 23793–23803, 1997. Cess, R. D., M. Zhang, F. P. J. Valero, S. K. Pope, A. Bucholtz, B. Bush, C. S. Zender, and J. Vitko Jr., Absorption of solar radiation by the cloudy atmosphere: Further interpretations of collocated aircraft measurements, J. Geophys. Res., 104, 2059–2066, 1999. Zender, C. S., Global climatology of abundance and solar absorption of oxygen collision complexes, J. Geophys. Res., 104, 24471–24484, 1999.

8 CURRICULUM VITAE

20

Collins, W. D., P. J. Rasch, B. E. Eaton, B. Khattatov, J.-F. Lamarque, and C. S. Zender, Forecasting aerosols using a chemical transport model with assimilation of satellite aerosol retrievals: Methodology for INDOEX, In Press in J. Geophys. Res., 2000. Yu, S., C. S. Zender, and V. K. Saxena, Direct radiative forcing and atmospheric absorption by boundary layer aerosol in the southeastern US: new observational estimates and model results, Submitted to Atmos. Environ., 2000. FUNDING Co-I on NASA grant “Eﬀects of land-use on climate and water resources: application of a land surface model for land-use management”, PI: G. B. Bonan, 1/1/2000–1/1/2003 SERVICE • Peer-review for Geophys. Res. Lett., J. Geophys. Res., J. Atmos. Sci., Mon. Weather Rev., Nature, Q. J. R. Meteorol. Soc., Tellus, NSF, NASA, USGCRP • Maintainer of NCAR CCM Column Radiation Model (http://www.cgd.ucar.edu/ cms/crm). 1996–present. • Author and administrator of NCO netCDF Operators (http://nco.sourceforge. net/nco), a freely available geophysical data manipulation toolkit. 1995–present. • Author and maintainer of Enhanced Absorption Bibliography (http://www.ess.uci. edu/∼zender/bib aca.ps.gz). 1997–present. • Contributor to the University of Northern Colorado Mathematics and Science Teachers Hotline (MAST) (800 866-MAST). 1995–present. • University of Colorado, Boulder, CO – Founder and director of the APAS Help Center, a free tutoring center which assisted dozens of diverse undergraduates in the physical sciences every year. My role included securing funding, tutoring, and managing a group of about 10 paid graduate student tutors. 1992–1995. HONORS Outstanding Student Presentation in Atmospheric Sciences Section, Fall AGU Meeting, San Francisco CA, 1995 COURSES TAUGHT Earth System Science 20E: The Atmosphere Earth System Science 111/211: Radiative Processes and Remote Sensing COLLABORATORS C. A. Ammann (U. Massachusetts Amherst), G. B. Bonan (NCAR), G. P. Brasseur (MPI Hamburg), R. D. Cess (SUNY Stonybrook), P. Ch´lek (Dalhousie), W. D. Collins y (NCAR), J. T. Kiehl (NCAR), N. M. Mahowald (UC Santa Barbara), G. McFarquhar (NCAR) K. Oleson (NCAR), P. J. Rasch (NCAR), X. X. Tie (NCAR), F. P. J. Valero (Scripps), S. Yu (Duke)