Frequency of extreme Sahelian storms tripled since 1982 in satellite observations.

The hydrological cycle is expected to intensify under global warming, with studies reporting more frequent extreme rain events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall. A globally important group of intense storms-mesoscale convective systems (MCSs)-poses a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet, and rain gauges in this region have recorded a rise in 'extreme' daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming, and challenges conventional projections made by general circulation models.

Novel formulations of oral bisphosphonates in the treatment of osteoporosis.

Oral bisphosphonates are a key intervention in the treatment of osteoporosis and in reducing the risk of fragility fractures. Their use is supported by over 3 decades of evidence; however, patient adherence to oral bisphosphonates remains poor in part due to complex dosing instructions and adverse events, including upper gastrointestinal symptoms. This problem has led to the development of novel oral bisphosphonate formulations. Buffered, effervescent alendronate is dissolved in water and so seeks to reduce upper gastro-intestinal adverse events, and gastro-resistant risedronate aims to reduce the complexity of dosing procedure (e.g. fasting prior to consumption) whilst still maintaining the efficacy of fracture risk reduction. Clinical trials and real-world data have been employed to demonstrate some benefits in terms of reduced upper gastro-intestinal adverse events, adherence, persistence and health economic outcomes. This report describes the result of an ESCEO (European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis) expert working group, which explores where oral bisphosphonates sit in current clinical practice guidelines, review their risk-benefit profile and the consequences of poor adherence before exploring novel oral bisphosphonate formulations and their potential clinical and health economic impact. Further research is required but there are signs that these novel, oral bisphosphonate formulations may lead to improved tolerance of oral bisphosphonates and thus, improved adherence and fracture outcomes.

Study of the statistics of water vapor mixing ratio determined from Raman lidar measurements.

The statistical properties of atmospheric water vapor mixing ratio (WVMR) determined as the ratio of Raman lidar signals backscattered from water vapor and nitrogen molecules are studied. It is shown that WVMR estimates can be biased by a small percentage at low signal photon-counting rates due to fluctuations in the nitrogen signal in the denominator of the ratio, the magnitude of the bias being linked to the signal-to-noise ratio of the nitrogen signal. This is particularly important when unbiased estimates are required as in the case of climate studies and global positioning system (GPS) signal calibration. Different bias corrections and a modified ratio formulation are proposed in order to correct or eliminate this bias. The method is successfully applied in processing signals obtained with an experimental Raman lidar system devoted to calibrate GPS signals for slant path delays. It is shown to reduce biases into negligible values in both WVMR and wet path delay estimates in the range interval of 0-7 km.