Observational Needs for Improving Ocean and Coupled Reanalysis, S2S Prediction, and Decadal Prediction.

Developments in observing system technologies and ocean data assimilation (DA) are symbiotic. New observation types lead to new DA methods and new DA methods, such as coupled DA, can change the value of existing observations or indicate where new observations can have greater utility for monitoring and prediction. Practitioners of DA are encouraged to make better use of observations that are already available, for example, taking advantage of strongly coupled DA so that ocean observations can be used to improve atmospheric analyses and vice versa. Ocean reanalyses are useful for the analysis of climate as well as the initialization of operational long-range prediction models. There are many remaining challenges for ocean reanalyses due to biases and abrupt changes in the ocean-observing system throughout its history, the presence of biases and drifts in models, and the simplifying assumptions made in DA solution methods. From a governance point of view, more support is needed to bring the ocean-observing and DA communities together. For prediction applications, there is wide agreement that protocols are needed for rapid communication of ocean-observing data on numerical weather prediction (NWP) timescales. There is potential for new observation types to enhance the observing system by supporting prediction on multiple timescales, ranging from the typical timescale of NWP, covering hours to weeks, out to multiple decades. Better communication between DA and observation communities is encouraged in order to allow operational prediction centers the ability to provide guidance for the design of a sustained and adaptive observing network.

Data Assimilation in the Solar Wind: Challenges and First Results.

Data assimilation (DA) is used extensively in numerical weather prediction (NWP) to improve forecast skill. Indeed, improvements in forecast skill in NWP models over the past 30 years have directly coincided with improvements in DA schemes. At present, due to data availability and technical challenges, DA is underused in space weather applications, particularly for solar wind prediction. This paper investigates the potential of advanced DA methods currently used in operational NWP centers to improve solar wind prediction. To develop the technical capability, as well as quantify the potential benefit, twin experiments are conducted to assess the performance of the Local Ensemble Transform Kalman Filter (LETKF) in the solar wind model ENLIL. Boundary conditions are provided by the Wang-Sheeley-Arge coronal model and synthetic observations of density, temperature, and momentum generated every 4.5 h at 0.6 AU. While in situ spacecraft observations are unlikely to be routinely available at 0.6 AU, these techniques can be applied to remote sensing of the solar wind, such as with Heliospheric Imagers or interplanetary scintillation. The LETKF can be seen to improve the state at the observation location and advect that improvement toward the Earth, leading to an improvement in forecast skill in near-Earth space for both the observed and unobserved variables. However, sharp gradients caused by the analysis of a single observation in space resulted in artificial wavelike structures being advected toward Earth. This paper is the first attempt to apply DA to solar wind prediction and provides the first in-depth analysis of the challenges and potential solutions.

Physical activity for bone health in inactive teenage girls: is a supervised, teacher-led program or self-led program best?

PURPOSE: To investigate the effect of a six-month teacher-led osteogenic physical activity program, vs. a self-led activity program, on ultrasound measurements of bone in inactive teenage girls. METHODS: Ninety sedentary girls [mean (SD) age 16.3 (.6) years] were identified from 300 assessed for physical activity across five schools in southeast Ireland. Schools were matched and randomly assigned to a teacher-led physical activity (TLPA) program, a self-led physical activity (SLPA) program, or a control group. Broadband ultrasound attenuation (BUA), speed of sound (SOS), and os calcis stiffness index (OCSI) were measured using a portable ultrasound machine. Anthropometry, aerobic fitness, calcium intake, and physical activity were assessed, and focus groups held one month after program completion. Descriptive statistics, paired t-tests, and analysis of variance were used to analyze the data. RESULTS: Both intervention groups demonstrated significant improvements (p < .05) in BUA, SOS, OCSI and aerobic fitness, i.e., TLPA: +14.9%, +21.9%, + 15.9%, and +8.5%, respectively, and SLPA: +10.6%, +30.3%, + 15.6%, and +5.1%, respectively, with no change in controls. Differences between intervention groups and controls were significant for BUA and OCSI (p < .05). TLPA and SLPA groups engaged in an average of 4.5 and 3.4 hours/week of physical activity, respectively, over the intervention period. The SLPA group continued to exercise after the intervention had ceased, whereas the TLPA group did not. CONCLUSIONS: Previously inactive teenage girls can adhere to an osteogenic activity program whether supervised or directing their own activity. Longer-term, sustainable initiatives with this age group are needed and might focus on developing personal skills for physical activity.