bluuebunny/crossref_metadata_2025 huggingface dataset:
The Financial Implications of Coverage of Smoking Cessation Treatment by Managed Care Organizations
Authors: Warner Kenneth E. , Mendez David , Smith Dean G.
Published: August 2011

This paper presents results from a simulation of the financial impact and cost effectiveness of smoking cessation in a hypothetical managed care organization (MCO), using data from three large managed care organizations and from existing literature. With base-case assumptions and a market cost of capital, at five years, coverage of cessation services costs an MCO $.61 per member per month (PMPM). In a steady-state situation, net cost is $.41 PMPM. Both values include altered medical expenditures and MCO revenue patterns attributable to coverage-induced cessation. Quitters gain an average of 7.1 years of life, with a direct coverage cost of $3,417 for each life-year saved. Coverage of cost-effective programs by MCOs should be strongly encouraged.
The Check is in the Mail: Determinants of Claims Payable Timing among Health Maintenance Organizations
Authors: Connor Robert , Wholey Douglas R. , Feldman Roger , Riley William
Published: August 2011

This paper used financial data from health maintenance organizations (HMOs) in the United States from the period 1985 to 2001 to examine the determinants of claims payable—the dollar amount of services rendered to enrollees but for which the HMO has not yet paid providers, such as physicians and hospitals. Claims payable management is important because delaying payments to providers can jeopardize provider operations and reduce HMO operational flexibility. The results show that HMOs manage claims payable with a multi-period perspective designed to evoke favorable responses and to avoid unfavorable ones from external parties, and to maintain flexibility for unexpected conditions. Higher HMO profitability, quicker receipt of premiums by the HMO, increased provider involvement, and greater local control of the HMO lead to faster payment to providers. Implications for HMO managers, providers, employers, and regulators are discussed.
The Effect of Managed Care Market Share on Appropriate Use of Coronary Angiography among Traditional Medicare Beneficiaries
Authors: Meara Ellen , Landrum Mary Beth , Ayanian John Z. , McNeil Barbara J. , Guadagnoli Edward
Published: August 2011

Evidence suggests that when managed care market share increases in a geographic area, expenditures in Medicare's fee-for-service sector decrease. But it is unclear how expenditure reductions relate to the quality of medical care for traditional Medicare beneficiaries. We estimated how managed care market share varied with the proportion of fee-for-service Medicare beneficiaries who were admitted for acute myocardial infarction (AMI) and underwent angiography. We classified patients as appropriate, discretionary, and inappropriate, according to guidelines of the American College of Cardiology and the American Heart Association (ACC-AHA). Within all ACC-AHA classes, coronary angiography fell slightly as managed care market share increased.
Managed Care Discounting: Evidence from the MarketScan Database
Authors: Dor Avi , Koroukian Siran M. , Grossman Michael
Published: August 2011

The paper examines price discounting by health maintenance organizations (HMOs) and preferred provider organizations (PPOs) in markets for hospital services. Our empirical analysis focuses on transaction prices for angioplasty, which is a relatively common procedure with well-defined “product” characteristics. After controlling for patient and procedure heterogeneity and market power, we find that on average angioplasty prices are 8% lower for PPOs than for fee-for-service plans, followed by point-of-service HMOs, which capture a 24% discount. Our results are in general agreement with earlier work by Cutler, McClellan, and Newhouse (2000), who show that managed care discounts are “real,” after accounting for case severity and process of care.
Health Plan Disenrollment in a Choice-Based Medicaid Managed Care Program
Authors: Buchmueller Thomas C. , Gilmer Todd , Harris Katherine
Published: August 2011

Consumer decisions to switch health plans have implications for quality of care and risk selection. We examine factors related to time to disenrollment in a Medicaid managed care program where beneficiaries face a menu of plans and can change plans every month. Several findings have direct policy relevance. Families and individuals who make active choices upon entering the program are at substantially lower risk of disenrollment than those who are auto-assigned. Interactions between enrollee ethnicity and provider language proficiency suggest that enrollee satisfaction depends on the cultural competence of providers. Differential disenrollment by risk status results in adverse retention for certain types of plans.
Home and Community-Based Waivers for Disabled Adults: Program versus Selection Effects
Authors: Van Houtven Courtney Harold , Domino Marisa Elena
Published: August 2011

This paper addresses whether changes in expenditures from participation in a Medicaid home and community-based waiver are due to selection effects or true program effects. We examined North Carolina Medicaid claims data (FY1998 to FY2000) for disabled or blind adults likely to need facility-based care using two-part expenditure models for nursing home, inpatient, and total expenditures. Instrumental variables estimation controlled for selection into the program. Although no savings in total costs were found in this sample, significant decreases were found in the level of nursing home and hospital inpatient expenditures for waiver participants, achieving the goals of the home and community-based waiver program.
A Shared Responsibility: U.S. Employers and the Provision of Health Insurance to Employees
Authors: Collins Sara R. , Davis Karen , Ho Alice
Published: August 2011

Employer-based health insurance is the backbone of the U.S. system of health insurance coverage. Yet it has been slowly eroding, and if these trends continue greater numbers of Americans are likely to be uninsured or without affordable coverage. Employer coverage has marked advantages, including benefits to employers and a natural risk pool that offers better benefits at lower cost than individual coverage, and is highly valued by employees. The shift of health care costs from employers who do not cover their workers to other parts of the economy is substantial. Very little attention has been given to policies that might strengthen and expand employer coverage. It will be important to shore up employer coverage both to curb its recent erosion and to build toward a more comprehensive system of health insurance.
Incentives and Physician Specialty Choice: A Case Study of Florida's Program in Medical Sciences
Authors: Fournier Gary M. , Henderson Cheryl
Published: August 2011

The growing shortage of primary care physicians in medically underserved areas of the nation led medical schools and policymakers years ago to design and fund numerous innovative medical education programs to foster the development of a more balanced physician workforce. Florida's Program in Medical Sciences (PIMS) was an example of one such initiative that was established in fall 1971 at Florida State University (FSU). A precursor of the present-day FSU College of Medicine, this program was created specifically to address the growing need for primary care physicians in rural areas of northwest Florida. The results of empirical tests on the career choices of PIMS graduates in the first 20 years provide weak evidence that the program was more effective than the existing channels of medical education in producing additional primary care physicians to rural Florida counties.
Unmet Long-Term Care Needs: An Analysis of Medicare-Medicaid Dual Eligibles
Authors: Komisar Harriet L. , Feder Judith , Kasper Judith D.
Published: August 2011

People who are dually eligible for Medicare and Medicaid are the focus of fiscal struggles between federal and state governments. Drawing on a survey of community-based elderly “dual eligibles,” this paper examines how well their medical and long-term care needs are being met under the current combination of Medicare and Medicaid policies. While few people report difficulty getting medical care, 58% of people needing long-term care (help with activities of daily living) report unmet needs. As a result, many experience serious consequences, such as falls. Although unmet needs are substantial in all six states surveyed, we find the greater the use of paid home care in a state, the lower the likelihood of unmet needs, suggesting states' policies can make a difference.
The Influence of Medicare Home Health Payment Incentives: Does Payer Source Matter?
Authors: Grabowski David C. , Stevenson David G. , Huskamp Haiden A. , Keating Nancy L.
Published: August 2011

During the late 1990s, the U.S. government instituted an interim payment system (IPS) to constrain Medicare home health care expenditures. Previous research has focused largely on the implications of the IPS for Medicare patients; this study broadens the analysis to consider patients with other payer sources. Using the National Home and Hospice Care Survey, we found similar effects of the IPS across payer types. Specifically, the IPS was associated with a decrease in care for the sickest patients, less agency assistance with activities of daily living, and shorter length of use. However, these changes did not translate into worse discharge outcomes.
Do Report Cards Influence Hospital Choice? The Case of Kidney Transplantation
Authors: Howard David H. , Kaplan Bruce
Published: August 2011

The national program to report hospital-level outcomes for transplantation has been in place since 1991, yet it has not been addressed in the existing literature on hospital report cards. We study the impact of reported outcomes on demand at kidney transplant centers. Using a negative binomial regression with hospital fixed effects, we estimate the number of patients choosing each center as a function of reported outcomes. Parameters are identified by the within-hospital variation in outcomes over five successive report cards. We find some evidence that report cards influence younger and college-educated patients, but, overall, report cards do not affect demand.
On the Feasibility of Resolving the Organ Shortage
Authors: Kaserman David L.
Published: August 2011

Debates concerning the feasibility of resolving the organ shortage from the potential pool of deceased donors have suffered from both conceptual and empirical problems. Conceptually, several authors mistakenly have viewed recipient waiting lists as a measure of the magnitude of the shortage. And empirically, the number of deaths that would qualify for potential organ donation has proven difficult to estimate. While the latter problem appears to have been substantially lessened by recent work, the former, definitional, problem remains. This paper offers the economically correct definition of a shortage and applies that definition to the new data on potential supply.
The Wellmark and University of Iowa Partnership: An Innovative Model for Collaboration between Blue Cross-Blue Shield Plans and Colleges
Authors: Prybil Lawrence , Charlton Mary , Roberts Peter
Published: August 2011

Wellmark Blue Cross-Blue Shield and the University of Iowa College of Public Health share a strong commitment to improving the health of communities they serve in Iowa and South Dakota. Beginning in 2002, these organizations forged an innovative partnership through which they annually select several collaborative projects that are congruent with their respective missions and address clearly defined needs. The outcomes of their joint efforts toward the partnership's goals are formally assessed on an annual basis. This cooperative arrangement has proven to be workable and beneficial, and may have applications in other settings.
Insurance Premiums and Insurance Coverage of Near-Poor Children
Authors: Hadley Jack , Reschovsky James D. , Cunningham Peter , Kenney Genevieve , Dubay Lisa
Published: August 2011

States increasingly are using premiums for near-poor children in their public insurance programs (Medicaid/SCHIP) to limit private insurance crowd-out and constrain program costs. Using national data from four rounds of the Community Tracking Study Household Surveys spanning the seven years from 1996 to 2003, this study estimates a multinomial logistic regression model examining how public and private insurance premiums affect insurance coverage outcomes (Medicaid/SCHIP coverage, private coverage, and no coverage). Higher public premiums are significantly associated with a lower probability of public coverage and higher probabilities of private coverage and uninsurance; higher private premiums are significantly related to a lower probability of private coverage and higher probabilities of public coverage and uninsurance. The results imply that uninsurance rates will rise if both public and private premiums increase, and suggest that states that impose or increase public insurance premiums for near-poor children will succeed in discouraging crowd-out of private insurance, but at the expense of higher rates of uninsurance. Sustained increases in private insurance premiums will continue to create enrollment pressures on state insurance programs for children.
Access to Health Insurance, Barriers to Care, and Service Use among Adults with Disabilities
Authors: Sommers Anna S.
Published: August 2011

No studies to date have examined access to insurance coverage or medical care for a broadly defined population of uninsured nonelderly adults with disabilities. This analysis uses the 2002 National Survey of America's Families to examine access to coverage, access to care, and service use for a large sample of adults with disabilities, with a focus on the uninsured. All disabled groups reported unmet need and service use greater than their nondisabled counterparts with the same insured status. Access to coverage was most problematic for low-income adults with work limitations but no other indication of disability, with over one-third uninsured. This group deserves greater policy attention.
Developing Personal Care Programs: National Trends and Interstate Variation, 1992–2002
Authors: Kitchener Martin , Ng Terence , Carrillo Helen , Miller Nancy , Harrington Charlene
Published: August 2011

This paper examines the development of programs delivering personal care to the elderly and disabled. First, we report the latest national participant and expenditure trend data for the three main personal care programs: the Medicaid Personal Care Services (PCS) benefit, Medicaid 1915(c) waivers, and the Older Americans Act Title III. Second, to examine interstate variation revealed in the trend analysis, we present three time-series regression models of personal care development (expenditures, participants, and existence of PCS benefit) that control for state socioeconomic, political, policy, and provider characteristics. Positive predictors of personal care development include: percentages of population aged 85 and older, and nonwhite; per capita income; and liberal state politics. Negative predictors of personal care development include rates of Medicare home health users and hospital beds.
Perverse Incentives in the Medicare Prescription Drug Benefit
Authors: McAdams David , Schwarz Michael
Published: August 2011

This paper analyzes some of the perverse incentives that may arise under the current Medicare prescription drug benefit design. In particular, risk adjustment for a standalone prescription drug benefit creates perverse incentives for prescription drug plans when making coverage decisions and/or for pharmaceutical companies when setting prices. This problem is new in that it does not arise with risk adjustment for other types of health care coverage. For this and other reasons, Medicare's drug benefit requires especially close regulatory oversight, now and in the future. We also consider a relatively minor change in financing the benefit that could lead to significant changes in how the benefit functions. In particular, if all plans were required to charge the same premium, there would be less diversity in quality, but also less need to regulate formulary composition, less budgetary uncertainty, and less upward pressure on drug prices.
Nurse Staffing, Mortality, and Length of Stay in For-Profit and Not-for-Profit Hospitals
Authors: Mark Barbara A. , Harless David W.
Published: August 2011

The issue of differential quality in for-profit (FP) and not-for-profit (NFP) hospitals remains a critical health policy question. With research demonstrating a relationship between nurse staffing and quality, the question arises whether the relationship differs in these hospital types. Using Healthcare Cost and Utilization Project data from the period 1990–1995, we found that case mix-adjusted registered nurse (RN) staffing was significantly lower in FPs than in NFPs, and we found a superior distribution of outcomes (mortality and length of stay) obtained with a lower level of RN staffing. The differences in mortality and length of stay disappeared, however, after controlling for population and market characteristics.
Ownership Form and Consumer Welfare: Evidence from the Nursing Home Industry
Authors: Santerre Rexford E. , Vernon John A.
Published: August 2011

This paper compares the likely consumer benefits of higher quality with the potentially greater production costs that result from increased not-for-profit activity in a nursing home services market area. The comparison of consumer benefits and costs is made possible by observing empirically how an increased market penetration of not-for-profit facilities affects the use of private-pay nursing home care. Increased (decreased) use of nursing home care suggests that the consumer benefits associated with additional not-for-profit nursing homes are greater (less) than consumer costs. The empirical results indicate that, from a consumer's perspective, too few not-for-profit nursing homes may exist in the typical market area of the United States. The policy implication is that more quality of care per dollar might be obtained by attracting a greater percentage of not-for-profit nursing homes into many market areas.
Insurers' Competitive Strategy and Enrollment in Newly Offered Preferred Provider Organizations (PPOs)
Authors: Hirth Richard A. , Grazier Kyle L. , Chernew Michael E. , Okeke Edward N.
Published: August 2011

While early growth in preferred provider organizations (PPOs) coincided with growth of managed care generally, recent expansion has come primarily at the expense of other managed care plans. Little is known about the micro behavior underlying these trends. In 2005, University of Michigan employees were offered PPOs for the first time by vendors who also offered other plans. PPOs helped the offering vendors maintain or increase their total enrollment share. PPOs were most attractive to workers who previously had chosen less managed plans. Because PPOs drew few enrollees from health maintenance organizations (HMOs), there was little evidence of a backlash against managed care in the context of the University of Michigan employee group.
Effects of Diagnosed Dementia on Medicare and Medicaid Program Costs
Authors: Ayyagari Padmaja , Salm Martin , Sloan Frank A.
Published: August 2011

This study examines the impacts of physician-diagnosed Alzheimer's disease and related dementias (ADRD) on Medicare and Medicaid program costs in 1994 and 1999. An innovative method is employed to estimate program payments over the life cycle starting at age 65. Using data from the 1994 and 1999 National Long-Term Care Surveys, merged Medicare claims, and national program data for Medicaid, we find that the share of total Medicare and Medicaid payments attributable to diagnosed ADRD was 5.46% in 1999. Total annual program payments attributable to ADRD decreased between 1994 and 1999, in contrast to an increase implied by a cross-sectional approach.
Research on the Hospital Market: Recent Advances and Continuing Data Needs
Authors: Lindrooth Richard C.
Published: August 2011

Research focused on the hospital market has been instrumental in furthering our understanding of the role of competition in health care. Such research would not have been conducted without the extensive public use data that have been made available to researchers. In particular, path-breaking studies were made possible thanks to access to Medicare and state all-payer discharge data. This paper describes recent advances in our understanding of hospital competition and speculates about what we could learn if additional data were available.
Health Plan Performance Measurement: Does it Affect Quality of Care for Medicare Managed Care Enrollees?
Authors: Bundorf M. Kate , Choudhry Kavita , Baker Laurence
Published: August 2011

Although the objective of provider performance measurement is to improve quality of care, little evidence exists on whether it has this effect. This study examines the implementation of mandatory quality reporting for Medicare managed care (MMC) plans. We compare utilization rates of performance-measured services for Medicare beneficiaries who were and were not enrolled in these plans before and after the program's introduction. We find that the use of measured services increased among both MMC and fee-for-service beneficiaries after the adoption of performance measurement. Our results provide no evidence that performance measurement increased quality of care among MMC enrollees.
Does High-Risk Pool Coverage Meet the Needs of People at Risk for Disability?
Authors: Hall Jean P. , Moore Janice M.
Published: August 2011

State high-risk insurance pools serve people denied coverage because of pre-existing conditions. With benefit plans modeled on the individual market, these pools generally require higher out-of-pocket expenditures and provide fewer benefits than employer-sponsored plans, while their beneficiaries have very intensive needs. We profile 416 working adults enrolled in a state high-risk pool and document their health conditions and health care utilization. High-risk pool and federal employee benefits are compared to assess insurance structure and implications for health and disability outcomes.
Are Adults in Poor Health More Likely to Enroll in Public Insurance?
Authors: Busch Susan H. , Vigdor Elizabeth Richardson
Published: August 2011

Policies to reduce the number of uninsured people are rarely judged by whether they will increase insurance coverage rates among the chronically ill, despite evidence suggesting that the health benefits of coverage are greatest for these individuals. This paper examines the effect of public coverage expansions on insurance take-up and unmet need by low-income mothers in poor health. We find a 14.3-percentage-point reduction in unmet need among mothers reporting fair or poor health status. Our results suggest that some of this reduction is due to individuals moving from inadequate private coverage to public coverage.
Costly Hospital Readmissions and Complex Chronic Illness
Authors: Friedman Bernard , Jiang H. Joanna , Elixhauser Anne
Published: August 2011

People with multiple chronic conditions account for a large and disproportionate share of total health care costs. One aspect of the high cost for such patients is a relatively high number of hospital admissions per year. This study aims to clarify how the rate of hospital readmissions and hospital cost per person in a year depend on a patient's number of different chronic conditions (“complexity”), severity of illness, principal diagnosis at discharge, payer group, and other variables. We use a database of all hospital discharges for adults in six states. The number of different chronic conditions has a smoothly increasing effect on readmissions and cost per year, and there are notable differences by payer group. We offer illustrations of the potential savings from reducing total inpatient cost and readmissions in narrowly targeted populations with the most complex problems. The study's methods and descriptive data potentially could be useful for health plans and their sponsors (employers, government) when they design strategies to address the high cost of complex chronic illness.
Measurement Error in Health Insurance Reporting
Authors: Pascale Joanne
Published: August 2011

In the United States, surveys serve as the only source of data for the number of uninsured people; they also provide rich data for exploring the relationships between health insurance coverage and individuals' life circumstances, such as employment, income, and health status, enabling researchers to assess the effectiveness of various aspects of the health care system. The Current Population Survey (CPS) is one of the most influential surveys measuring health insurance, but it is not without critics. To address outstanding questions about the data quality of the CPS health insurance questions, qualitative testing was conducted to assess various aspects of the questionnaire from the respondent's perspective. A testing protocol was developed largely based on previous health survey methods literature, and test subjects were probed about their comprehension of the questions, particular terms and phrases, and their strategies for formulating an answer. Several design features were identified as problematic, including the overall questionnaire structure, the calendar year reference period, the household-level design, and the wording of questions on public coverage.
Accuracy in Self-Reported Health Insurance Coverage among Medicaid Enrollees
Authors: Call Kathleen Thiede , Davidson Gestur , Davern Michael , Brown E. Richard , Kincheloe Jennifer , Nelson Justine G.
Published: August 2011

The largest portion of the Medicaid undercount is caused by survey reporting error—that is, Medicaid recipients misreport their enrollment in health insurance coverage surveys. In this study, we sampled known Medicaid enrollees to learn how they respond to health insurance questions and to document correlates of accurate and inaccurate reports. We found that Medicaid enrollees are fairly accurate reporters of insurance status and type of coverage, but some do report being uninsured. Multivariate analyses point to the prominent role of program-related factors in the accuracy of reports. Our findings suggest that the Medicaid undercount should not undermine confidence in survey-based estimates of uninsurance.
Data Needs for Policy Research on State-Level Health Insurance Markets
Authors: Simon Kosali
Published: August 2011

Private and public health insurance provision in the United States operates against a backdrop of 50 different regulatory environments in addition to federal rules. Through creative use of available data, a large body of research has contributed to our understanding of public policy in state health insurance markets. This research plays an important role as recent trends suggest states are taking the lead in health care reform. However, several important questions have not been answered due to lack of data. This paper identifies some of these areas, and discusses how the Agency for Healthcare Research and Quality could push the research agenda in state health insurance policy further by augmenting the market-level data available to researchers. As states consider new forms of regulation and assistance for their insurance markets, there is increased need for better warehousing and maintenance of policy databases.
Effect of Medicare Home Health Care Payment on Informal Care
Authors: Golberstein Ezra , Grabowski David C. , Langa Kenneth M. , Chernew Michael E.
Published: August 2011

This paper assesses the effect of payment caps for Medicare home health care on the use of informal care by older adults with functional limitations. We find that individuals exposed to more restrictive payment caps offset reductions in Medicare home health care with increased informal care, although we only observe this effect for lower-income individuals. This suggests that home care payment restrictions may have increased the caregiving burden on some low-income families, but that many higher-income families were able to either forgo the care or finance it privately. Home care payment policies should recognize these effects, balancing costs of the program with the desire to protect families from the burdens associated with providing informal home care.
Access to Health Insurance at Small Establishments: What Can We Learn from Analyzing other Fringe Benefits?
Authors: Abraham Jean Marie , DeLeire Thomas , Royalty Anne Beeson
Published: August 2011

Workers employed at small establishments are less likely to be offered health insurance than workers in larger establishments. They are also paid less and are less likely to be offered pensions, paid sick leave, and paid vacations. Using the Medical Expenditure Panel Survey, we examine the relationship between health insurance and other components of workers' compensation. We also propose an approach for identifying and prioritizing the reasons why workers in small establishments are less likely to be offered employer health insurance by comparing the provision of health insurance and how it changes with establishment size to the provision of these other fringe benefits and how they change with establishment size. We find that workers in larger establishments are not only more likely to be offered health insurance by their employer, but also are more likely to be offered retirement and paid vacation benefits. The results of our benefits comparison analysis suggest an important role for administrative costs as an obstacle to offering health insurance.
Racial and Ethnic Disparities in the Use of High-Volume Hospitals
Authors: Gray Bradford H. , Schlesinger Mark , Siegfried Shannon Mitchell , Horowitz Emily
Published: August 2011

Differences in the source of care could contribute to racial and ethnic disparities in health status. This study looks at a major metropolitan area and examines racial and ethnic differences in the use of high-volume hospitals for 17 services for which there is a documented positive volume-outcome relationship. Focusing on the hospitalizations of New York City area residents in the periods 1995-1996 and 2001–2002, we found, after controlling for socioeconomic characteristics, insurance coverage, proximity of residence to a high-volume hospital, and paths to hospitalization, that minority patients were significantly less likely than whites to be treated at high-volume hospitals for most volume-sensitive services. The largest disparities were between blacks and whites for cancer surgeries and cardiovascular procedures.
Coverage, Utilization, and Health Outcomes of the State Children's Health Insurance Program
Authors: Li Minghua , Baughman Reagan
Published: August 2011

This paper uses data from the National Survey of America's Families (1997–2002) to explore the links between eligibility for the State Children's Health Insurance Program (SCHIP), health insurance coverage, medical care utilization, and health outcomes. We find that SCHIP significantly increased health insurance coverage rates for American children between 1997 and 2002, with most of the gains in coverage for older children. Higher coverage rates translated into increased utilization of the types of medical care that would be expected to improve children's health, such as well-child doctor visits. The effects of SCHIP eligibility expansions on health outcomes, however, are relatively small.
European source and sink areas of CO2 retrieved from Lagrangian transport model interpretation of combined O2 and CO2 measurements at the high alpine research station Jungfraujoch
Authors: Uglietti C. , Leuenberger M. , Brunner D.
Published: August 2011

Abstract. The University of Bern monitors carbon dioxide (CO2) and oxygen (O2) at the High Altitude Research Station Jungfraujoch since the year 2000 by means of flasks sampling and since 2005 using a continuous in situ measurement system. This study investigates the transport of CO2 and O2 towards Jungfraujoch using backward Lagrangian Particle Dispersion Model (LPDM) simulations and utilizes CO2 and O2 signatures to classify air masses. By investigating the simulated transport patterns associated with distinct CO2 concentrations it is possible to decipher different source and sink areas over Europe. The highest CO2 concentrations, for example, were observed in winter during pollution episodes when air was transported from Northeastern Europe towards the Alps, or during south Foehn events with rapid uplift of polluted air from Northern Italy, as demonstrated in two case studies. To study the importance of air-sea exchange for variations in O2 concentrations at Jungfraujoch the correlation between CO2 and APO (Atmospheric Potential Oxygen) deviations from a seasonally varying background was analyzed. Anomalously high APO concentrations were clearly associated with air masses originating from the Atlantic Ocean, whereas low APO concentrations were found in air masses advected either from the east from the Eurasian continent in summer, or from the Eastern Mediterranean in winter. Those air masses with low APO in summer were also strongly depleted in CO2 suggesting a combination of CO2 uptake by vegetation and O2 uptake by dry summer soils. Other subsets of points in the APO-CO2 scatter plot investigated with respect to air mass origin included CO2 and APO background values and points with regular APO but anomalous CO2 concentrations. Background values were associated with free tropospheric air masses with little contact with the boundary layer during the last few days, while high or low CO2 concentrations reflect the various levels of influence of anthropogenic emissions and the biosphere. The pronounced cycles of CO2 and O2 exchanges with the biosphere and the ocean cause clusters of points and lead to a seasonal pattern.
Impact of Po Valley emissions on the highest glacier of the Eastern European Alps
Authors: Gabrieli J. , Carturan L. , Gabrielli P. , Kehrwald N. , Turetta C. , Cozzi G. , Spolaor A. , Dinale R. , Staffler H. , Seppi R. , dalla Fontana G. , Thompson L. , Barbante C.
Published: August 2011

Abstract. In June 2009, we conducted the first extensive glaciological survey of Alto dell'Ortles, the uppermost glacier of Mt. Ortles (3905 m a.s.l.), the highest summit of the Eastern European Alps. This section of the Alps is located in a rain shadow and is characterized by the lowest precipitation rate in the entire Alpine arc. Mt. Ortles offers a unique opportunity to test deposition mechanisms of chemical species that until now were studied only in the climatically-different western sector. We analyzed snow samples collected on Alto dell'Ortles from a 4.5 m snow-pit at 3830 m a.s.l., and we determined a large suite of trace elements and ionic compounds that comprise the atmospheric deposition over the past two years. Trace element concentrations measured in snow samples are extremely low with mean concentrations at pg g−1 levels. Only Al and Fe present median values of 1.8 and 3.3 ng g−1, with maximum concentrations of 21 and 25 ng g−1. The median crustal enrichment factor (EFc) values for Be, Rb, Sr, Ba, U, Li, Al, Ca, Cr, Mn, Fe, Co, Ga and V are lower than 10 suggesting that these elements originated mainly from soil and mineral aerosol. EFc higher than 100 are reported for Zn (118), Ag (135), Bi (185), Sb (401) and Cd (514), demonstrating the predominance of non-crustal depositions and suggesting an anthropogenic origin. Our data show that the physical stratigraphy and the chemical signals of several species were well preserved in the uppermost snow of the Alto dell'Ortles glacier. A clear seasonality emerges from the data as the summer snow is more affected by anthropogenic and marine contributions while the winter aerosol flux is dominated by crustal sources. For trace elements, the largest mean EFc seasonal variations are displayed by V (with a factor of 3.8), Sb (3.3), Cu (3.3), Pb (2.9), Bi (2.8), Cd (2.1), Zn (1.9), Ni (1.8), Ag (1.8), As (1.7) and Co (1.6). When trace species ratios in local and Po Valley emissions are compared with those in Alto dell'Ortles snow, the deposition on Mt. Ortles is clearly linked with Po Valley summer emissions. Despite climatic differences between the Eastern and Western Alps, trace element ratios from Alto dell'Ortles are comparable with those obtained from high-altitude glaciers in the Western Alps, suggesting similar sources and transport processes at seasonal time scales in these two distinct areas. In particular, the large changes in trace element concentrations both in the Eastern and Western Alps appear to be more related to the regional vertical structure of the troposphere rather than the synoptic weather patterns.
Representation of tropical deep convection in atmospheric models – Part 2: Tracer transport
Authors: Hoyle C. R. , Marécal V. , Russo M. R. , Allen G. , Arteta J. , Chemel C. , Chipperfield M. P. , D'Amato F. , Dessens O. , Feng W. , Hamilton J. F. , Harris N. R. P. , Hosking J. S. , Lewis A. C. , Morgenstern O. , Peter T. , Pyle J. A. , Reddmann T. , Richards N. A. D. , Telford P. J. , Tian W. , Viciani S. , Volz-Thomas A. , Wild O. , Yang X. , Zeng G.
Published: August 2011

Abstract. The tropical transport processes of 14 different models or model versions were compared, within the framework of the SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) project. The tested models range from the regional to the global scale, and include numerical weather prediction (NWP), chemical transport, and chemistry-climate models. Idealised tracers were used in order to prevent the model's chemistry schemes from influencing the results substantially, so that the effects of modelled transport could be isolated. We find large differences in the vertical transport of very short-lived tracers (with a lifetime of 6 h) within the tropical troposphere. Peak convective outflow altitudes range from around 300 hPa to almost 100 hPa among the different models, and the upper tropospheric tracer mixing ratios differ by up to an order of magnitude. The timing of convective events is found to be different between the models, even among those which source their forcing data from the same NWP model (ECMWF). The differences are less pronounced for longer lived tracers, however they could have implications for modelling the halogen burden of the lowermost stratosphere through transport of species such as bromoform, or short-lived hydrocarbons into the lowermost stratosphere. The modelled tracer profiles are strongly influenced by the convective transport parameterisations, and different boundary layer mixing parameterisations also have a large impact on the modelled tracer profiles. Preferential locations for rapid transport from the surface into the upper troposphere are similar in all models, and are mostly concentrated over the western Pacific, the Maritime Continent and the Indian Ocean. In contrast, models do not indicate that upward transport is highest over western Africa.
Climate-CH4 feedback from wetlands and its interaction with the climate-CO2 feedback
Authors: Ringeval B. , Friedlingstein P. , Koven C. , Ciais P. , de Noblet-Ducoudré N. , Decharme B. , Cadule P.
Published: August 2011

Abstract. The existence of a feedback between climate and methane (CH4) emissions from wetlands has previously been hypothesized, but both its sign and amplitude remain unknown. Moreover, this feedback could interact with the climate-CO2 cycle feedback, which has not yet been accounted for at the global scale. These interactions relate to (i) the effect of atmospheric CO2 on methanogenic substrates by virtue of its fertilizing effect on plant productivity and (ii) the fact that a climate perturbation due to CO2 (respectively CH4) radiative forcing has an effect on wetland CH4 emissions (respectively CO2 fluxes at the surface/atmosphere interface). We present a theoretical analysis of these interactions, which makes it possible to express the magnitude of the feedback for CO2 and CH4 alone, the additional gain due to interactions between these two feedbacks and the effects of these feedbacks on the difference in atmospheric CH4 and CO2 between 2100 and pre-industrial time (respectively ΔCH4 and ΔCO2). These gains are expressed as functions of different sensitivity terms, which we estimate based on prior studies and from experiments performed with the global terrestrial vegetation model ORCHIDEE. Despite high uncertainties on the sensitivity of wetland CH4 emissions to climate, we found that the absolute value of the gain of the climate-CH4 feedback from wetlands is relatively low (<30 % of climate-CO2 feedback gain), with either negative or positive sign within the range of estimates. Whereas the interactions between the two feedbacks have low influence on ΔCO2, the ΔCH4 could increase by 475 to 1400 ppb based on the sign of the C-CH4 feedback gain. Our study suggests that it is necessary to better constrain the evolution of wetland area under future climate change as well as the local coupling through methanogenesis substrate of the carbon and CH4 cycles – in particular the magnitude of the CO2 fertilization effect on the wetland CH4 emissions – as these are the dominant sources of uncertainty in our model.
Gradients in intact polar diacylglycerolipids across the Mediterranean Sea are related to phosphate availability
Authors: Popendorf K. J. , Tanaka T. , Pujo-Pay M. , Lagaria A. , Courties C. , Conan P. , Oriol L. , Sofen L. E. , Moutin T. , Van Mooy B. A. S.
Published: August 2011

Abstract. Intact polar membrane lipids compose a significant fraction of cellular material in plankton and their synthesis imposes a substantial constraint on planktonic nutrient requirements. As a part of the Biogeochemistry from the Oligotrophic to the Ultraoligtrophic Mediterranean (BOUM) cruise we examined the distribution of several classes of intact polar diacylglycerolipids (IP-DAGs) across the Mediterranean, and found that phospholipid concentration as a percent of total lipids correlated with phosphate concentration. In addition, the ratios of non-phosphorus lipids to phospholipids – sulfoquinovosyldiacylglycerol (SQDG) to phosphatidylglycerol (PG), and betaine lipids to phosphatidylcholine (PC) – were also found to increase from west to east across the Mediterranean. Additionally, microcosm incubations from across the Mediterranean were amended with phosphate and ammonium, and in the course of several days nutrient amendments elicited a shift in the ratios of IP-DAGs. These experiments were used to assess the relative contribution of community shifts and physiological response to the observed change in IP-DAGs across the Mediterranean. The ratio of SQDG to chlorophyll $a$ was also explored as an indicator of phytoplankton response to nitrogen availability. This study is the first to demonstrate the dynamic response of membrane lipid composition to changes in nutrients in a natural, mixed planktonic community.
Contrasting biogeochemistry of nitrogen in the Atlantic and Pacific oxygen minimum zones
Authors: Ryabenko E. , Kock A. , Bange H. W. , Altabet M. A. , Wallace D. W. R.
Published: August 2011

Abstract. We present new data for the stable isotope ratio of inorganic nitrogen species from the contrasting oxygen minimum zones (OMZs) of the Eastern Tropical North Atlantic, south of Cape Verde, and the Eastern Tropical South Pacific off Peru. Differences in minimum oxygen concentration and corresponding N-cycle processes for the two OMZs are reflected in strongly contrasting δ15N distributions. Pacific surface waters are marked by strongly positive values for δ15N-NO3− reflecting fractionation associated with subsurface N-loss and partial NO3− utilization. This contrasts with negative values in NO3− depleted surface waters of the Atlantic which are lower than can be explained by N supply via N2 fixation. We suggest the negative values reflect inputs of nitrate, possibly transient, associated with deposition of Saharan dust. Strong signals of N-loss processes in the subsurface Pacific OMZ are evident in the isotope and N2O data, both of which are compatible with a contribution of canonical denitrification to overall N-loss. However the apparent N isotope fractionation factor observed is relatively low (εd = 11.4 ‰) suggesting an effect of influence from denitrification in sediments. Identical positive correlation of N2O vs. AOU for waters with oxygen concentrations [O2] > 50 μmol l−1 in both regions reflect a nitrification source. Sharp decrease in N2O concentrations is observed in the Pacific OMZ due to denitrification under oxygen concentrations O2 < 5 μmol l−1.
Regional climate model experiments to investigate the Asian monsoon in the Late Miocene
Authors: Tang H. , Micheels A. , Eronen J. , Fortelius M.
Published: August 2011

Abstract. The Late Miocene (11.6–5.3 Ma) is a crucial period in the history of the Asian monsoon. Significant changes in the Asian climate regime have been documented for this period, which saw the formation of the modern Asian monsoon system. However, the spatiotemporal structure of these changes is still ambiguous, and the associated mechanisms are debated. Here, we present a simulation of the average state of the Asian monsoon climate for the Tortonian (11–7 Ma) using the regional climate model CCLM3.2. We employ relatively high spatial resolution (1° × 1°) and adapt the physical boundary conditions such as topography, land-sea distribution and vegetation in the regional model to represent the Late Miocene. As climatological forcing, the output of a Tortonian run with a fully-coupled atmosphere-ocean general circulation model is used. Our regional Tortonian run shows a stronger-than-present East Asian winter monsoon wind as a result of the enhanced mid-latitude westerly wind of our global forcing and the lowered present-day northern Tibetan Plateau in the regional model. The summer monsoon circulation is generally weakened in our regional Tortonian run compared to today. However, the changes of summer monsoon precipitation exhibit major regional differences. Precipitation decreases in northern China and northern India, but increases in southern China, the western coast and the southern tip of India. This can be attributed to the changes in both the regional topography (e.g. the lower northern Tibetan Plateau) and the global climate conditions (e.g. the higher sea surface temperature). The spread of dry summer conditions over northern China and northern Pakistan in our Tortonian run further implies that the monsoonal climate may not have been fully established in these regions in the Tortonian. Compared with the global model, the high resolution regional model highlights the spatial differences of the Asian monsoon climate in the Tortonian, and better characterizes the convective activity and its response to regional topographical changes. It therefore provides a useful and compared to global models, a complementary tool to improve our understanding of the Asian monsoon evolution in the Late Miocene.