Anthony M. DeAngelis

Much of Siberia experienced exceptional warmth during the spring of 2020, which followed an unusually warm winter over the same region. Here, we investigate the drivers of the spring warmth from the perspective of atmospheric dynamics and remote influences, focusing on monthly-time-scale features of the event. We find that the warm anomalies were associated with separate quasi-stationary Rossby wave trains emanating from the North Atlantic in April and May. The wave trains are shown to be extreme manifestations of the dominant modes of spring subseasonal meridional wind variability over the Northern Hemisphere. Using a large ensemble of simulations from NASA’s GEOS atmospheric model, in which the model is constrained to remain close to observations over selected regions, we further elucidate the remote drivers of the unusual spring temperatures in Siberia. In both April and May, the wave trains were likely forced from an upstream region including eastern North America and the western North Atlantic. Analysis with a stationary wave model shows that transient vorticity flux forcing over and downwind of the North Atlantic, which is strongly related to storm activity caused by internal variability, is key to generating the wave trains, suggesting limited subseasonal predictability of the Rossby waves and hence the exceptional Siberian warmth. Our observational and model analyses also suggest that anomalous tropical atmospheric heating contributed to the unusual warmth in Siberia through a teleconnection involving upper-troposphere dynamics and the mean meridional circulation. This tropical–extratropical teleconnection offers a possible physical mechanism by which anthropogenic climate change influenced the extreme Siberian warmth.

Rapid-onset droughts, known as flash droughts, can have devastating impacts on agriculture, water resources, and ecosystems. The ability to predict flash droughts in advance would greatly enhance our preparation for them and potentially mitigate their impacts. Here, we investigate the prediction skill of the extreme 2012 flash drought over the U.S. Great Plains at subseasonal lead times (3 weeks or more in advance) in global forecast systems participating in the Subseasonal Experiment (SubX). An additional comprehensive set of subseasonal hindcasts with NASA’s GEOS model, a SubX model with relatively high prediction skill, was performed to investigate the separate contributions of atmospheric and land initial conditions to flash drought prediction skill. The results show that the prediction skill of the SubX models is quite variable. While skillful predictions are restricted to within the first two forecast weeks in most models, skill is considerably better (3–4 weeks or more) for certain models and initialization dates. The enhanced prediction skill is found to originate from two robust sources: 1) accurate soil moisture initialization once dry soil conditions are established, and 2) the satisfactory representation of quasi-stationary cross-Pacific Rossby wave trains that lead to the rapid intensification of flash droughts. Evidence is provided that the importance of soil moisture initialization applies more generally to central U.S. summer flash droughts. Our results corroborate earlier findings that accurate soil moisture initialization is important for skillful subseasonal forecasts and highlight the need for additional research on the sources and predictability of drought-inducing quasi-stationary atmospheric circulation anomalies.

Assisted reproductive technology (ART) is responsible for 1.7% of births in the United States annually. Despite a large number of studies promoting the efficacy and safety of these practices, there have been reports of imprinting disorders occurring at higher frequencies in children born through ART. Driven by findings in animal studies, it has been postulated that various ART procedures employed at critical points in embryonic development may predispose the genomic imprinting process to errors. Alterations in DNA methylation patterns at imprinting control centers have been reported by some studies to occur more frequently in children with imprinting disorders conceived by ART compared with spontaneous conception, though these findings are not consistently demonstrated and controversy has surrounded the strength of these associations. The rarity of imprinting disorders with a reliance of studies on disease registry cohorts, wide variations in ART protocols, and a lack of proper control groups limit the ability to substantiate associations between imprinting disorders and ART. Large, prospective cohort studies with a focus on molecular etiologies of these conditions are needed to discern whether a true association exists. Based on current evidence, the absolute risk of imprinting disorders after ART is low and screening for imprinting disorders in children conceived by ART is not warranted.

In the current generation of climate models, the projected increase in global precipitation over the 21st century ranges from 2% to 10% under a high‐emission scenario. Some of this uncertainty can be traced to the rapid response to carbon dioxide (CO₂) forcing. We analyze an ensemble of simulations to better understand model spread in this rapid response. A substantial amount is linked to how the land surface partitions a change in latent versus sensible heat flux in response to the CO₂‐induced radiative perturbation; a larger increase in sensible heat results in a larger decrease in global precipitation. Model differences in the land surface response appear to be strongly related to the vegetation response to increased CO₂, specifically, the closure of leaf stomata. Future research should thus focus on evaluation of the vegetation physiological response, including stomatal conductance parameterizations, for the purpose of constraining the fast response of Earth's hydrologic cycle to CO₂ forcing.

Aims Bladder compliance is one expression of the pressure and volume relationship as the bladder fills. In addition to passive elements, autonomous micromotional detrusor activity contributes to this relationship. In the mouse cystometric model, compliance pressure contributes to voiding expulsive pressure. During attempts to isolate the detrusor contractile component of this filling pressurization, we found that compliance reversibly diminishes under conditions which remove central control from the micturition cycle. Methods Ten mature female mice underwent constant infusion pressure/flow cystometry under urethane anesthesia, and five awake mature female mice underwent constant infusion pressure cystometry. Following baseline cystometry, all mice were anesthetized with isoflurane to abolish the micturition reflex, and cystometry conducted with manual emptying of the bladders. Animals were then allowed to recover from isoflurane to re‐establish the micturition reflex, and cystometry again conducted. The urethane group was also studied immediately post‐mortem. Repeated measures comparisons of cystometric parameters were made across conditions. Results Compliance reversibly decreased in all mice with the abolishment of micturition responses by isoflurane anesthesia. A similar decrease was observed immediately post‐mortem in the urethaned mice. Bladder filling and voiding were not different between the intact micturition segments of the testing. Conclusions Enhanced compliance in mice with intact micturition responses suggests that autonomous micromotional activity is suppressed by central processes during normal filling. Since afferent activity during filling is also determined by the relationship between bladder pressure and volume, a feed‐forward afferent signal conditioning mechanism may exist, creating novel therapeutic targets for urinary dysfunctions. Neurourol. Urodynam. 31:30–35, 2012.