Determination of Cloud-top Height through Three-dimensional Cloud Reconstruction using DIWATA-1 Data.

Cloud-top height is a useful parameter with which to elucidate cloud vertical growth, which often indicates severe weather such as torrential rainfall and thunderstorms; it is widely used in meteorological research. However, general cloud-top height estimation methods are hindered by observational and analytical constraints. This study used data from DIWATA-1, the Philippines' first microsatellite, to overcome these limitations and successfully produce sophisticated three-dimensional cloud models via stereo-photogrammetry. High-temporal snapshot 200-ms-interval imaging of clouds over Iloilo, Philippines, is performed. Two types of telescopes were used to capture 30 stereoscopic cloud images at ~60- and ~3-m ground sampling resolutions; these were used to construct three-dimensional cloud models with 40- and 2-m vertical resolutions, respectively. The imaged clouds have heights of 2.0 to 4.8 km, which is below freezing level for the Philippines and typical of stratocumulus and cumulus clouds. The results are validated using cloud-edge heights determined by measuring the distance from the clouds to their ground shadows. An RMSE of 0.32 km and a maximum difference of 0.03 km are found for the low- and high-resolution telescopes, respectively. For further validation, the results are compared with cloud-top heights estimated from HIMAWARI-8 images captured on the same day, yielding an average vertical difference of 0.15 km and a maximum difference of 1.7 km.

Prior individual training and self-organized queuing during group emergency escape of mice from water pool.

We study the impact of prior individual training during group emergency evacuation using mice that escape from an enclosed water pool to a dry platform via any of two possible exits. Experimenting with mice avoids serious ethical and legal issues that arise when dealing with unwitting human participants while minimizing concerns regarding the reliability of results obtained from simulated experiments using 'actors'. First, mice were trained separately and their individual escape times measured over several trials. Mice learned quickly to swim towards an exit-they achieved their fastest escape times within the first four trials. The trained mice were then placed together in the pool and allowed to escape. No two mice were permitted in the pool beforehand and only one could pass through an exit opening at any given time. At first trial, groups of trained mice escaped seven and five times faster than their corresponding control groups of untrained mice at pool occupancy rate ρ of 11.9% and 4%, respectively. Faster evacuation happened because trained mice: (a) had better recognition of the available pool space and took shorter escape routes to an exit, (b) were less likely to form arches that blocked an exit opening, and (c) utilized the two exits efficiently without preference. Trained groups achieved continuous egress without an apparent leader-coordinator (self-organized queuing)-a collective behavior not experienced during individual training. Queuing was unobserved in untrained groups where mice were prone to wall seeking, aimless swimming and/or blind copying that produced circuitous escape routes, biased exit use and clogging. The experiments also reveal that faster and less costly group training at ρ = 4%, yielded an average individual escape time that is comparable with individualized training. However, group training in a more crowded pool (ρ = 11.9%) produced a longer average individual escape time.

Self-organized queuing and scale-free behavior in real escape panic.

Numerical investigations of escape panic of confined pedestrians have revealed interesting dynamical features such as pedestrian arch formation around an exit, disruptive interference, self-organized queuing, and scale-free behavior. However, these predictions have remained unverified because escape panic experiments with real systems are difficult to perform. For mice escaping out of a water pool, we found that for a critical sampling rate the escape behavior exhibits the predicted features even at short observation times. The mice escaped via an exit in bursts of different sizes that obey exponential and (truncated) power-law distributions depending on exit width. Oversampling or undersampling the mouse escape rate prevents the observation of the predicted features. Real systems are normally subject to unavoidable constraints arising from occupancy rate, pedestrian exhaustion, and nonrigidity of pedestrian bodies. The effect of these constraints on the dynamics of real escape panic is also studied.