Estimation of potential evapotranspiration from extraterrestrial radiation, air temperature and humidity to assess future climate change effects on the vegetation of the Northern Great Plains, USA

The potential evapotranspiration (PET) that would occur with unlimited plant access to water is a central driver of simulated plant growth in many ecological models. PET is influenced by solar and long wave radiation, temperature, wind speed, and humidity, but it is often modeled as a function of temperature alone. This approach can cause biases in projections of future climate impacts in part because it confounds the effects of warming due to increased greenhouse gases with that which would be caused by increased radiation from the sun. We developed an algorithm for linking PET to extraterrestrial solar radiation (incoming top-of atmosphere solar radiation), as well as temperature and atmospheric water vapor pressure, and incorporated this algorithm into the dynamic global vegetation model MC1. We tested the new algorithm for the Northern Great Plains, USA, whose remaining grasslands are threatened by continuing woody encroachment. Both the new and the standard temperature-dependent MC1 algorithm adequately simulated current PET, as compared to the more rigorous PenPan model of Rotstayn et al. (2006). However, compared to the standard algorithm, the new algorithm projected a much more gradual increase in PET over the 21st century for three contrasting future climates. This difference led to lower simulated drought effects and hence greater woody encroachment with the new algorithm, illustrating the importance of more rigorous calculations of PET in ecological models dealing with climate change

Estimation of potential evapotranspiration from extraterrestrial radiation, air temperature and humidity to assess future climate change effects on the vegetation of the Northern Great Plains, USA

The potential evapotranspiration (PET) that would occur with unlimited plant access to water is a central driver of simulated plant growth in many ecological models. PET is influenced by solar and long wave radiation, temperature, wind speed, and humidity, but it is often modeled as a function of temperature alone. This approach can cause biases in projections of future climate impacts in part because it confounds the effects of warming due to increased greenhouse gases with that which would be caused by increased radiation from the sun. We developed an algorithm for linking PET to extraterrestrial solar radiation (incoming top-of atmosphere solar radiation), as well as temperature and atmospheric water vapor pressure, and incorporated this algorithm into the dynamic global vegetation model MC1. We tested the new algorithm for the Northern Great Plains, USA, whose remaining grasslands are threatened by continuing woody encroachment. Both the new and the standard temperature-dependent MC1 algorithm adequately simulated current PET, as compared to the more rigorous PenPan model of Rotstayn et al. (2006). However, compared to the standard algorithm, the new algorithm projected a much more gradual increase in PET over the 21st century for three contrasting future climates. This difference led to lower simulated drought effects and hence greater woody encroachment with the new algorithm, illustrating the importance of more rigorous calculations of PET in ecological models dealing with climate change

Pre-print -In review for publication in Water Resources Research Trends in Regional Evapotranspiration across the United States under the Complementary Relationship Hypothesis

Abstract The hypothesis of a complementary relationship in regional evapotranspiration allows for estimation of actual evapotranspiration on a regional scale by simple, physically based models that take into account feedbacks in land surface-atmosphere dynamics. A regional, seasonal Advection-Aridity model is used to create a spatially distributed, monthly time-series of actual evapotranspiration for a period of 27 years at a 5-km resolution over the conterminous United States. For the conterminous United States as a whole, a 4.3% increase in annual actual evapotranspiration over the period WY 1962WY -1988 was observed, a trend that was significant at the 90% confidence level according to the Mann-Kendall test. Trends in annual evapotranspiration are analyzed across the spatial scales of the continental United States, a Water Resources Region (WRR), a river basin of 16,000 km 2 , and an individual 5-km square cell. Reducing the spatial scale allowed for clearer identification of areas with significant trends. To establish a base-line for the study of climate change and/or variability, a methodology for rigorous examination of past trends in actual evapotranspiration is proposed, wherein such trends are broken down into the climatic components of actual evapotranspiration in the context of the complementary relationship, and no assumptions are made about the temporal stationarity of the net available energy. Trends in actual evapotranspiration can thus be determined to originate in either the energy budget or the water budget, or both

Estimation of potential evapotranspiration from extraterrestrial radiation, air temperature and humidity to assess future climate change effects on the vegetation of the Northern Great Plains, USA

The potential evapotranspiration (PET) that would occur with unlimited plant access to water is a central driver of simulated plant growth in many ecological models. PET is influenced by solar and longwave radiation, temperature, wind speed, and humidity, but it is often modeled as a function of temperature alone. This approach can cause biases in projections of future climate impacts in part because it confounds the effects of warming due to increased greenhouse gases with that which would be caused by increased radiation from the sun. We developed an algorithm for linking PET to extraterrestrial solar radiation (incoming top-of atmosphere solar radiation), as well as temperature and atmospheric water vapor pressure, and incorporated this algorithm into the dynamic global vegetation model MC1. We tested the new algorithm for the Northern Great Plains, USA, whose remaining grasslands are threatened by continuing woody encroachment. Both the new and the standard temperature-dependent MC1 algorithm adequately simulated current PET, as compared to the more rigorous PenPan model of Rotstayn et al. (2006). However, compared to the standard algorithm, the new algorithm projected a much more gradual increase in PET over the 21st century for three contrasting future climates. This difference led to lower simulated drought effects and hence greater woody encroachment with the new algorithm, illustrating the importance of more rigorous calculations of PET in ecological models dealing with climate change.Keywords: Potential evapotranspiration, Great Plains USA, Climate change, Vegetation dynamics, MC

Effect of the Friendship Bench Intervention on Antiretroviral Therapy Outcomes and Mental Health Symptoms in Rural Zimbabwe: A Cluster Randomized Trial.

IMPORTANCE Common mental disorders (CMD), which include depression and anxiety, are prevalent among people living with HIV and are associated with suboptimal antiretroviral therapy (ART) adherence. OBJECTIVE To assess the effect of a lay health worker-led psychological intervention on ART adherence, virologic suppression, and mental health symptoms. DESIGN, SETTING, AND PARTICIPANTS Open-label pragmatic cluster trial with 1:1 block randomization of 16 health facilities in rural Bikita, Zimbabwe. Recruitment occurred from October 2018 to December 2019, and participants were followed up for 12 months, ending in December 2020. Participants were adults aged 18 years and older, who spoke English or Shona, screened positive for CMD (Shona Symptoms Questionnaire [SSQ]-14 score ≥9), received first-line ART for 6 or more months, had no World Health Organization stage 4 disease, no psychosis, were not pregnant, and provided informed consent. Data were analyzed from March 2021 to February 2022. INTERVENTION The Friendship Bench, consisting of 6 lay health worker-led weekly problem-solving therapy sessions and optional peer-led group support. MAIN OUTCOMES AND MEASURES The primary outcome was mean adherence during 2 to 6 months of follow-up, and the secondary outcomes were mean adherence during 1 to 12 months of follow-up, change in SSQ-14 and Patient Health Questionnaire (PHQ-9) scores (3, 6, 9, and 12 months), and viral load suppression (6 and 12 months). RESULTS A total of 516 participants were recruited (244 in Friendship Bench and 272 in enhanced standard care facilities); 438 (84.9%) were female and the mean (SD) age was 45.6 (10.9) years. Mean (SD) adherence between 2 to 6 months was 89.9% (18.4%) in the Friendship Bench group and 87.2% (20.1%) in the control group. The intervention had no statistically significant effect on adherence between 2 to 6 months (unadjusted mean difference, 1.93 percentage points; 95% CI, -1.20 to 5.06 percentage points; P = .23), between months 1 to 12 (mean difference 0.79 percentage points; 95% CI, -2.14 to 3.71 percentage points; P = .60), or viral suppression. Declines in SSQ-14 scores from baseline to 3 months (difference, -1.65; 95% CI, -3.07 to -0.24), 6 months (difference, -1.57; 95% CI, -2.98 to -0.15), and 9 months (difference, -1.63; 95% CI, -3.05 to -0.22) were greater in the Friendship Bench than the standard care group (P < .05). There were no differences in the decline in the SSQ-14 scores from baseline to 12 months and in declines in PHQ-9 scores from baseline to 3, 6, 9, and 12 months. CONCLUSIONS AND RELEVANCE In this randomized trial of HIV-positive participants with CMD, the Friendship Bench intervention had no effect on adherence and viral suppression, possibly due to the absence of skill-based adherence training and a ceiling effect. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03704805

Hepatitis B infection, viral load and resistance in HIV-infected patients in Mozambique and Zambia

BACKGROUND: Few data on the virological determinants of hepatitis B virus (HBV) infection are available from southern Africa. METHODS: We enrolled consecutive HIV-infected adult patients initiating antiretroviral therapy (ART) at two urban clinics in Zambia and four rural clinics in Northern Mozambique between May 2013 and August 2014. HBsAg screening was performed using the Determine ® rapid test. Quantitative real-time PCR and HBV sequencing were performed in HBsAg-positive patients. Risk factors for HBV infection were evaluated using Chi-square and Mann-Whitney tests and associations between baseline characteristics and high level HBV replication explored in multivariable logistic regression. RESULTS: Seventy-eight of 1,032 participants in Mozambique (7.6%, 95% confidence interval [CI]: 6.1-9.3) and 90 of 797 in Zambia (11.3%, 95% CI: 9.3-13.4) were HBsAg-positive. HBsAg-positive individuals were less likely to be female compared to HBsAg-negative ones (52.3% vs. 66.1%, p20,000 UI/mL). HBsAg-positive individuals had higher levels of ALT and AST compared to HBsAg-negative ones (both p<0.001). In multivariable analyses, male sex (adjusted odds ratio: 2.59, 95% CI: 1.22-5.53) and CD4 cell count below 200/μl (2.58, 1.20-5.54) were associated with high HBV DNA. HBV genotypes A1 (58.8%) and E (38.2%) were most prevalent. Four patients had probable resistance to lamivudine and/or entecavir. CONCLUSION: One half of HBsAg-positive patients demonstrated high HBV viremia, supporting the early initiation of tenofovir-containing ART in HIV/HBV-coinfected adults

Symptoms of common mental disorders and adherence to antiretroviral therapy among adults living with HIV in rural Zimbabwe: a cross-sectional study.

OBJECTIVES: To examine the proportion of people living with HIV who screen positive for common mental disorders (CMD) and the associations between CMD and self-reported adherence to antiretroviral therapy (ART). SETTING: Sixteen government-funded health facilities in the rural Bikita district of Zimbabwe. DESIGN: Cross-sectional study. PARTICIPANTS: HIV-positive non-pregnant adults, aged 18 years or older, who lived in Bikita district and had received ART for at least 6 months. OUTCOME MEASURES: The primary outcome was the proportion of participants screening positive for CMD defined as a Shona Symptoms Questionnaire score of 9 or greater. Secondary outcomes were the proportion of participants reporting suicidal ideation, perceptual symptoms and suboptimal ART adherence and adjusted prevalence ratios (aPR) for factors associated with CMD, suicidal ideation, perceptual symptoms and suboptimal ART adherence. RESULTS: Out of 3480 adults, 18.8% (95% CI 14.8% to 23.7%) screened positive for CMD, 2.7% (95% CI 1.5% to 4.7%) reported suicidal ideations, and 1.5% (95% CI 0.9% to 2.6%) reported perceptual symptoms. Positive CMD screens were more common in women (aPR 1.67, 95% CI 1.19 to 2.35) than in men and were more common in adults aged 40-49 years (aPR 1.47, 95% CI 1.16 to 1.85) or aged 50-59 years (aPR 1.51, 95% CI 1.05 to 2.17) than in those 60 years or older. Positive CMD screen was associated with suboptimal adherence (aPR 1.53; 95% CI 1.37 to 1.70). CONCLUSIONS: A substantial proportion of people living with HIV in rural Zimbabwe are affected by CMD. There is a need to integrate mental health services and HIV programmes in rural Zimbabwe. TRIAL REGISTRATION NUMBER: NCT03704805

Home-based versus mobile clinic HIV testing and counseling in rural Lesotho : a cluster-randomized trial

The success of HIV programs relies on widely accessible HIV testing and counseling (HTC) services at health facilities as well as in the community. Home-based HTC (HB-HTC) is a popular community-based approach to reach persons who do not test at health facilities. Data comparing HB-HTC to other community-based HTC approaches are very limited. This trial compares HB-HTC to mobile clinic HTC (MC-HTC).; The trial was powered to test the hypothesis of higher HTC uptake in HB-HTC campaigns than in MC-HTC campaigns. Twelve clusters were randomly allocated to HB-HTC or MC-HTC. The six clusters in the HB-HTC group received 30 1-d multi-disease campaigns (five villages per cluster) that delivered services by going door-to-door, whereas the six clusters in MC-HTC group received campaigns involving community gatherings in the 30 villages with subsequent service provision in mobile clinics. Time allocation and human resources were standardized and equal in both groups. All individuals accessing the campaigns with unknown HIV status or whose last HIV test was 12 y, HTC uptake was higher in the HB-HTC arm (87.5% versus 58.7%; aOR: 4.91; 95% CI: 2.41-10.0; p>0.001). Out of those who took up HTC, 114 (4.9%) tested HIV-positive, 39 (3.6%) in the HB-HTC arm and 75 (6.2%) in the MC-HTC arm (aOR: 0.64; 95% CI: 0.48-0.86; p = 0.002). Ten (25.6%) and 19 (25.3%) individuals in the HB-HTC and in the MC-HTC arms, respectively, linked to HIV care within 1 mo after testing positive. Findings for secondary outcomes were as follows: HB-HTC reached more first-time testers, particularly among adolescents and young adults, and had a higher proportion of men among participants. However, after adjusting for clustering, the difference in male participation was not significant anymore. Age distribution among participants and immunological and clinical stages among persons newly diagnosed HIV-positive did not differ significantly between the two groups. Major study limitations included the campaigns' restriction to weekdays and a relatively low HIV prevalence among participants, the latter indicating that both arms may have reached an underexposed population.; This study demonstrates that both HB-HTC and MC-HTC can achieve high uptake of HTC. The choice between these two community-based strategies will depend on the objective of the activity: HB-HTC was better in reaching children, individuals who had never tested before, and men, while MC-HTC detected more new HIV infections. The low rate of linkage to care after a positive HIV test warrants future consideration of combining community-based HTC approaches with strategies to improve linkage to care for persons who test HIV-positive.; ClinicalTrials.gov NCT01459120 Please see later in the article for the Editors' Summary

Spatial distribution of water supply in the Coterminous United States

Available water supply across the contiguous 48 states was estimated as precipitation minus evapotranspiration using data for the period 1953-1994. Precipitation estimates were taken from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM). Evapotranspiration was estimated using two models, the Advection-Aridity model and the Zhang model. The evapotranspiration models were calibrated using precipitation and runoff data for 655 hydrologically undisturbed basins, and then tested using estimates of natural runoff for the 18 water resource regions (WRR) of the 48 contiguous states. The final water supply coverage reflects a mixture of outputs from the two evapotranspiration models. Political, administrative, and land cover boundaries were mapped over the coverage of mean annual water supply. Across the entire study area, we find that 53% of the water supply originates on forested land, which covers only 29% of the surface area, and that 24% originates on federal lands, including 18% on national forests and grasslands alone. Forests and federal lands are even more important in the West (the 11 western contiguous states), where 65% of the water supply originates on forested land and 66% on federal lands, with national forests and grasslands contributing 51%

AGU hydrology days 2004

24th annual AGU hydrology days was held at Colorado State University on March 10-12, 2004.Includes bibliographical references.Our aim is to develop a long-term, high resolution net radiation data set that accounts for the effects of local topography that confound simpler analyses of the shortwave radiative balance in rugged terrain; such a dataset may then be used in direct observations of the effects of long-term change and variability in the solar radiation input to the land surface-atmosphere interface, particularly with reference to the estimation of evaporation. Direct and diffuse horizontal solar radiation data are gathered from all reporting stations across the conterminous United States for the period of 1950-1994 and integrated at a monthly time-step. Twelve years of diffuse horizontal radiation data missing from the data sources are replicated based on their historical relationships to coincident and contemporaneous observed direct normal and global radiation. A topographic correction factor is derived to account for the incidence of direct solar radiation on arbitrarily oriented surfaces at any latitude at any moment in any day of the year, and combined with slope and aspect surfaces for the conterminous U.S. derived from a 5-km digital elevation mode. This factor takes into account the solar geometry throughout the seasonal and diurnal cycles by incorporating an hourly weighting in proportion to the diffuse horizontal radiation recorded during the middle day of the month, and is then applied to spatially interpolated surfaces of direct solar radiation and combined with spatially interpolated surfaces of diffuse radiation. Summed, these provide the total incident solar radiation input to an existing energy budget analysis to yield the net surface radiation that may then be applied in models of evaporation. As preliminary uses of this dataset, mean annual and long-term trend surfaces of net surface radiation over the conterminous U.S. for the period WY 1953-1994 are presented