Corals record persistent multidecadal SST variability in the Atlantic Warm Pool since 1775 AD

The July–August–September (JAS) seasonal predictability of the Atlantic Warm Pool (AWP) is examined in the extensive set of seasonal hindcasts of the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS). We conduct both deterministic and probabilistic skill analyses of the NCEP CFS Seasonal Hindcasts (SHs). This study reveals that the SHs have a reasonable climatology of the AWP. The presence of robust decadal variability in sea surface temperature (SST) observations, while absent in the SHs, does seem to indicate its influence on the seasonal errors of the AWP in the NCEP CFS. However, after filtering out the observed SST for variability greater than 8 years, there is no systematic relation of AWP seasonal errors in the NCEP CFS with lead time. The signal to noise ratio of the area of the AWP in the SHs decreases with lead time, largely due to increases in the ensemble spread (noise). It is sobering to note that there is barely any probabilistic skill in the NCEP CFS SHs for the prediction of the anomalous AWP events (occurring either in the upper or lower terciles) at nearly all lead times. However if we examine the SHs from 1981–1996, when the observed SST in the AWP region is in one uniform phase of the prevalent decadal variation, then the SHs display useful skill in the prediction of anomalously large AWP events at all lead times. Furthermore, these truncated SHs also show significant probabilistic skill in the prediction of small (lower tercile) and normal (middle tercile) AWP events up to a lead time of 1 month.

A comparison of a Mg/Ca-based sea-surface temperature (SST)-anomaly record from the northern Gulf of Mexico, a calculated index of variability in observed North Atlantic SST known as the Atlantic Multidecadal Oscillation (AMO), and a tree-ring reconstruction of the AMO contain similar patterns of variation over the last 110 years. Thus, the multidecadal variability observed in the instrumental record is present in the tree-ring and Mg/Ca proxy data. Frequency analysis of the Gulf of Mexico SST record and the tree-ring AMO reconstruction from 1550 to 1990 found similar multidecadal-scale periodicities (~30–60 years). This multidecadal periodicity is about half the observed (60–80 years) variability identified in the AMO for the 20th century. The historical records of hurricane landfalls reveal increased landfalls in the Gulf Coast region during time intervals when the AMO index is positive (warmer SST), and decreased landfalls when the AMO index is negative (cooler SST). Thus, we conclude that alternating intervals of high and low hurricane landfall occurrences may continue on multidecadal timescales along the northern Gulf Coast. However, given the short length of the instrumental record, the actual frequency and stability of the AMO are uncertain, and additional AMO proxy records are needed to establish the character of multidecadal-scale SST variability in the North Atlantic.

<p>Observational analysis shows that there is a predominant global-scale multidecadal variability (GMV) of sea surface temperature (SST). Its horizontal pattern resembles that of the Interdecadal Pacific Oscillation (IPO) in the Pacific and the Atlantic multidecadal oscillation (AMO) in the Atlantic Ocean, which could affect global precipitation and temperature over globe. Here, we demonstrate that the GMV could be driven by the Atlantic multidecadal oscillation (AMO) through atmospheric teleconnections and atmosphere-ocean coupling processes. Observations reveal a strong negative correlation when AMO leads GMV by approximately 4–8 yrs. Pacemaker experiments using a climate model driven by observed AMO signals reveal that the tropical Atlantic warm SST anomalies of AMO initiate anomalous cooling in the equatorial central-eastern Pacific through atmospheric teleconnections. Anticyclonic anomalies in the North and South Pacific induce equatorward winds along the coasts of North and South America, contributing to further cooling. The upper ocean dynamics plays a minor role in GMV formation but contributes to a delayed response of the IPO to the AMO forcing. The possible impact of the GMV on AMO was also tested by prescribing only Pacific SST in the model, however, the model could not reproduce the observed phase relationship between the AMO and GMV. These results support the hypothesis that the Atlantic Ocean plays a key role in the multidecadal variability of global SST.</p>

Atlantic Warm Pool (AWP) climate variability is subject to multiple influences of remote and local forcing. However, shortage of observational data before the midtwentieth century and of long‐term sea surface temperature (SST) and climate records has hampered the detection and investigation of decadal‐ and longer‐scale variability. We present new seasonally resolved 125‐year records of coral δ18O and Sr/Ca variations in the Central Caribbean Sea (Little Cayman, Cayman Islands; Diploria strigosa). Both geochemical proxies show decreasing long‐term trends, indicating long‐term warming. Sr/Ca indicates much stronger regional warming than large‐scale grid‐SST data, while δ18O tracks large‐scale SST changes in the Atlantic Warm Pool. Seawater δ18O variations are reconstructed, indicating a drying trend over the past century. High spatial correlation between coral δ18O and SST in the region of the Loop Current and Gulf Stream system suggests that Little Cayman is a sensitive location for detecting past large‐scale temperature variability beyond the Central Caribbean region. More specifically, our δ18O data track changes in North Atlantic Oscillation variability on decadal and multidecadal time scales providing insights into the temporal and spatial nonstationarity of the North Atlantic Oscillation. A combination of our δ18O record with two coral records from different Caribbean sites reveals high spatial correspondence between coral δ18O and SST variability in the North Atlantic subtropical gyre, where few instrumental measurements and proxies are available prior to the twentieth century. Our results clearly demonstrate the potential of combining proxy data to provide information from sparsely sampled areas, helping to reduce uncertainty in model‐based projections.

Few long-term data describe the natural history of hepatic hemangiomas. Because these lesions are frequently imaged repetitively on studies performed for other indications, health care professionals are commonly confronted with the problem of a growing hemangioma. Because the rate and magnitude of normal growth is not well characterized, it is difficult to recognize lesions growing at an abnormal rate, which may require further evaluation or intervention. To establish quantitatively the expected growth rate of hepatic hemangiomas and to define a measure of hemangioma growth that could be used clinically to help identify hemangiomas for which growth is more than expected. Retrospective cohort study at an academic hospital tertiary referral center evaluating the growth rate of hepatic hemangiomas on cross-sectional imaging studies during a 10-year period (1997-2007). The mean (SD) follow-up time was 3.7 (1.9) years. The radiology information system was searched in a 10-year period for hemangioma. Patients with hepatic hemangiomas that were 1 cm or larger as seen on cross-sectional imaging (computed tomography or magnetic resonance imaging), and 1 year or more apart were selected. Images with the longest interval between studies were selected for further review. Each study was rereviewed for diagnostic confirmation and to ensure consistency in measurement technique. Lesions were remeasured in 3 dimensions, and volumes were calculated using 3-dimensional software. Primary outcomes include the fraction of hepatic hemangiomas that demonstrated growth during long-term follow-up and the annual growth rate of those lesions. A total of 163 hemangiomas were identified in 123 patients. The mean (SD) initial size was 3.2 (3.1) cm. During follow-up, 39.3% of hemangiomas grew 5% or more in mean linear dimension. The mean (SD) annual linear growth rate was 0.03 (0.21) cm for all lesions and 0.19 (0.23) cm for those that grew 5% or more. By volume, 44.7% of lesions grew 5% or more. The mean (SD) annual volumetric growth rate was 2.8% (21.0%) for all lesions and 17.7% (22.8%) in those that grew 5% or more. The initial size predicted the growth in linear dimension and volume (P < .001). There was no significant change in growth rate over time, indicating uniform growth (R = 0.00843; P = .92). Nearly 40% of hepatic hemangiomas grow over time. Although the overall rate of growth is slow, hemangiomas that exhibit growth do so at a modest rate (2 mm/y in linear dimension and 17.4% per year in volume). Further research is needed to determine how patients with more rapidly growing hemangiomas should be treated.

Previous studies suggested that Atlantic Multidecadal Variability (AMV) modulations on pan‐Pacific sea surface temperature (SST) variability and prediction are model‐dependent. These results were mainly based on SST forcing experiments in which AMV‐related Atlantic SST anomalies were prescribed. However, the AMV itself is also model‐dependent, but its influences on the Pacific remain unclear. Here, we use multi‐model fully coupled experiments from the Coupled Model Intercomparison Project Phase 6 (CMIP6), along with observations, to study the model‐dependent AMV trans‐basin effects. We found that AMV strength is a key factor: Stronger (Weaker) model AMV than observations overestimates (underestimates) SST response and decadal prediction skills, mainly in the North Pacific. The reason is that stronger positive phased AMV, for example, leads to higher sea level pressure anomalies over the North Pacific, which lifts sea surface height and deepens thermocline to warm SST. Our study highlights the necessity to improve simulations of AMV strength.

Idealized model experiments using the NCAR CESM1.0.5 under equinox conditions are designed and performed to address two fundamental questions about the effects of the sea surface temperature (SST) variation associated with the Atlantic multidecadal oscillation (AMO) on circulation and precipitation in North America and Europe: 1) Is the observed relationship between the AMO SST and the warm-season precipitation in North America a statistical coincidence? and 2) Why is the response of negative precipitation anomaly to warm SST in the AMO fairly uniform across most of North America, whereas the positive precipitation anomaly in the cold SST rather spotty? Model experiments are done with either a warm or cold SST anomaly in an aquaplanet, a planet with idealized continents, and a planet with both idealized continents and orography. Major results show that the atmospheric response to warm SST anomaly in the North Atlantic is fairly similar among the three sets of experiments. In the lower troposphere, the response has a significant negative geopotential anomaly from the SST anomaly center to the east and a positive geopotential anomaly in upstream North America. However, the response to the cold SST anomaly changes considerably among these experiments, particularly in North America. These results provide a foundation to answer the abovementioned two questions. First, they show that there is physical connection of the AMO SST and atmospheric circulation anomalies in North America. Moreover, the rather stable atmospheric response to the warm SST may explain the observed largely consistent response to the warm SST anomaly. The varying responses of the atmosphere to the cold SST indicate a strong sensitivity of the atmosphere to other forcings during the cold SST anomaly in the North Atlantic. This sensitivity could explain the varying and less stable response of the atmosphere to the cold SST during the AMO.

Substance and opioid misuse are growing public health concerns. This study's objectives were to evaluate trends in substance and opioid misuse-related emergency department (ED) visits in Alberta, Canada. This is a cross-sectional time-series analysis utilizing National Ambulatory Care Reporting System ED data from Alberta, Canada. All substance and opioid misuse-related visits made by adults (≥ 18years) from 2010/11 to 2014/15 were analyzed. Acuity was measured by the Canadian Triage and Acuity Scale (CTAS). Relevant visits were identified by ICD-10 diagnostic coding. Substance and opioid visits over 60months were compared to all ED visits per 100,000 adult population using regression analysis, while controlling for temporal and seasonal variation. Trends among age and sex subgroups were also evaluated. From 2010/11 to 2014/15, substance and opioid misuse-related visits increased by 38.0% and 57.3% to 1119 and 118 visits per 100,000 population, respectively. Annual growth rates for substance and opioid visits were 4.4% higher (95% CI: 2.2, 6.7) and 10.6% higher (95% CI: 6.8, 14.6) than all ED visits. The 18-29year-old category experienced the highest annual growth rate of all age groups, and the annual opioid visit growth rate was 5.6% higher among males than females. Compared to all visits, substance misuse-related visits arrived more frequently by ambulance, were higher acuity, and were hospitalized more often. Substance and opioid misuse-related ED visits increased significantly from 2010 to 2015, especially among younger patients. Future research should elaborate causes and evaluate interventions to curb the growth of this issue.

A researcher used censuses and surveys to analyze 1966-1976 and 1976-1986 population data to compare population growth and fertility of Iran under the Shah with those of theocratic Iran. Between 1966-1976 the government introduced policies which improved the legal and social status of women and promoted fertility control. These resulted in a reduction in the annual population growth rate from 3.1-2.7%. In fact the crude birth rate fell from 49-42.7. Yet the rural birth rate (49.1) was still 1 of the highest in the world. A rising age at marriage contributed to the fall in fertility. For example in 1966 46.5% of 15-19 year old women were married compared to 34.2% in 1976. In fact the singulate mean age of marriage increased from 18.4-19.7. Further the percentage of women of reproductive age who were married decreased 81-75% between 1966-1976. Moreover age specific fertility rates fell for all 20-40 year old women. Indeed total fertility declined from 7.7-6.3. This was more pronounced in urban areas (6.9-4.4). As a result of the Iranian Revolution and the Iran-Iraq war population size increased rapidly from 33.7-49.4 million (1976-1986)--3.8% annual growth rate. Further the crude birth rate increased 12% (1986 47.6). In addition at least 1.8 million people from Afghanistan sought refuge in Iran. Moreover the age at 1st marriage was not any higher than in 1986 than it was in 1976. In fact the government reduced the legal age to 9 for females and 14 for males. Further it abolished the family planning council. In addition the proportion of 15-59 year old married women only decreased 3% between 1976-1986 compared to 6% between 1976-1986. Age specific fertility rates increased significantly especially for 40-44 year olds (32%). Further total fertility rose to 7 and the increase was especially high in urban areas (16% increase compared to 8% in rural areas). As of the end of 1991 there were indications that the government recognized the population problem and had taken steps to promote family planning.

Arabian Sea (AS) warming has been significantly accelerated since the 1990s, in particular in the spring season. Here we link the AS warming changes to the Atlantic multidecadal oscillation (AMO). A set of Atlantic pacemaker experiments with a slab mixed‐layer ocean model successfully reproduces the AS spring multidecadal variability and its connection with the AMO. An atmospheric teleconnection from the Atlantic to the AS in the preceding winter and associated thermodynamic air‐sea feedback is found to be important. The teleconnection can be reestablished by the atmospheric model when the AMO sea surface temperature (SST) and its trans‐basin footprint over the western Pacific are prescribed simultaneously. The western Pacific SST warming associated with the AMO positive phase induces a Gill‐type Rossby wave over the AS, showing anomalously low pressures and converging southerlies that weaken winter northerlies. Thus, the wind‐evaporation‐SST feedback results in and maintains the AS warm SST anomalies to the subsequent spring.

In this paper it is proposed that the stochastic excitation of a multidecadal internal ocean mode is at the origin of the multidecadal sea surface temperature variability in the North Atlantic. The excitation processes of the spatial sea surface temperature pattern associated with this multidecadal mode within an idealized three-dimensional model are studied by adding noise to the surface heat flux forcing. In the regime where the internal mode is damped, the amplitude of its sea surface temperature pattern depends on the type of noise forcing applied. While the mode is weakly excited by white noise, only the introduction of spatial and temporal coherence in the forcing, with characteristics of the North Atlantic Oscillation in particular, causes the amplitude of the variability to increase to levels comparable to those observed. Within this idealized model the physical mechanism of the excitation can be determined: the presence of the noise rectifies the background state and consequently changes the growth factor of the internal mode.

Assessment of TFP change at provincial level in Vietnam: New evidence using Färe–Primont productivity index

Interannual to Decadal Rainfall Variability over Greater Horn of Africa: Non-Stationary Teleconnections, Physical Mechanisms, and Predictability

Variation in skeletal extension, density and calcification of the Scleractinian coral Porites lobate across the northern Persian Gulf

Population cycles in voles are often thought to be generated by one-year delayed density dependence on the annual population growth rate. In common voles, however, it has been suggested by Turchin (2003) that some populations exhibit first-order cycles, resulting from strong overcompensation (i.e. carrying capacity overshoots in peak years, with only an effect of the current year abundance on annual growth rates). We focus on a common vole (Microtus arvalis) population from western France that exhibits 3-year cycles. Several overcompensating nonlinear models for populations dynamics are fitted to the data, notably those of Hassell, and Maynard-Smith and Slatkin. Overcompensating direct density dependence (DD) provides a satisfactory description of winter crashes, and one-year delayed density dependence is not responsible for the crashes, thus these are not classical second-order cycles. A phase-driven modulation of direct density dependence maintains a low-phase, explaining why the cycles last three years instead of two. Our analyses suggest that some of this phase dependence can be expressed as one-year delayed DD, but phase dependence provides a better description. Hence, modelling suggests that cycles in this population are first-order cycles with a low phase after peaks, rather than fully second-order cycles. However, based on the popular log-linear second-order autoregressive model, we would conclude only that negative delayed density dependence exists. The additive structure of this model cannot show when delayed DD occurs (here, during lows rather than peaks). Our analyses thus call into question the automated use of second-order log-linear models, and suggests that more attention should be given to non-(log)linear models when studying cyclic populations. From a biological viewpoint, the fast crashes through overcompensation that we found suggest they might be caused by parasites or food rather than predators, though predators might have a role in maintaining the low phase and spatial synchrony.