Simulations of the Effects of Water Vapor, Cloud Liquid Water, and Ice on AMSU Moisture Channel Brightness Temperatures

Radiative transfer simulations are performed to determine how water vapor and nonprecipitating cloud liquid water and ice particles within typical midlatitude atmospheres affect brightness temperatures T-B\u27s of moisture sounding channels used in the Advanced Microwave Sounding Unit (AMSU) and AMSU-like instruments. The purpose is to promote a general understanding of passive top-of-atmosphere T-B\u27s for window frequencies at 23.8, 89.0, and 157.0 GHz, and water vapor frequencies at 176.31, 180.31, and 182.31 GHz by documenting specific examples. This is accomplished through detailed analyses of T-B\u27s for idealized atmospheres, mostly representing temperate conditions over land. Cloud effects are considered in terms of five basic properties: droplet size distribution phase, liquid or ice water content, altitude, and thickness. Effects on T-B of changing surface emissivity also are addressed. The brightness temperature contribution functions are presented as an aid to physically interpreting AMSU T-B\u27s. Both liquid and ice clouds impact the T-B\u27s in a variety of ways. The T-B\u27s at 23.8 and 89 GHz are more strongly affected by altostratus liquid clouds than by cirms clouds for equivalent water paths. In contrast, channels near 157 and 183 GHz are more strongly affected by ice clouds. Higher clouds have a greater impact on 157- and 183-GHz T-B\u27s than do lower clouds. Clouds depress T-B\u27s of the higher-frequency channels by suppressing, but not necessarily obscuring, radiance contributions from below. Thus, T-B\u27s are less closely associated with cloud-top temperatures than are IR radiometric temperatures. Water vapor alone accounts for up to 89% of the total attenuation by a midtropospheric liquid cloud for channels near 183 GHz. The Rayleigh approximation is found to be adequate for typical droplet size distributions; however, Mie scattering effects from liquid droplets become important for droplet size distribution functions with modal radii greater than 20 mu m near 157 and 183 GHz, and greater than 30-40 mu m at 89 GHz. This is due mainly to the relatively small concentrations of droplets much larger than the mode radius. Orographic clouds and tropical cumuli have been observed to contain droplet size distributions with mode radii in the 30-40-mu m range. Thus, as new instruments bridge the gap between microwave and infrared to frequencies even higher than 183 GHz, radiative transfer modelers are cautioned to explicitly address scattering characteristics of such clouds

Motor Vehicle Fatalities During Memorial Day Weekends, 1981-2016

OBJECTIVE: Motor vehicle crashes are a leading cause of injury death in the United States, and Memorial Day weekend is one of six holiday periods with an increased number of motor vehicle fatalities in the United States. However, few motor vehicle fatality comparisons were made between Memorial Day weekend and non-holiday periods. Our aims were to determine which day(s) during the holiday had highest motor vehicle fatality risk compared to non-holiday travel and to identify potential risk factors. RESULTS: Of 43,457 traffic fatalities studied, 15,292 (35%) occurred during the holiday, with Saturday being deadliest but Monday having highest odds of traffic fatality. Both sexes, all years, age \u3c 65, drivers and passengers, rural and urban, and all regions in the United States were at increased risk during the holiday versus non-holiday periods

The modifying role of pregnancy on ophthalmological and neuro-ophthalmological diseases

The female visual system experiences a series of physiological modifications during pregnancy, and these changes have profound implications on many general ophthalmological and neuro-ophthalmological disorders, exacerbating some conditions while alleviating others. Patients with open-angle glaucoma experience improved disease states, with accompanying normal visual fields. Uveitis and MS-induced optic neuritis exhibit decreased rates of occurrence. Non-proliferative diabetic retinopathy initially worsens with gestation, eventually improving in the postpartum state with only 5% of cases progressing into the proliferative stage. As for idiopathic intracranial hypertension, existing symptoms worsen during pregnancy. Therapeutic interventions such as immunosuppressants, anti-neoplastic drugs, and steroids administered prophylactically during fetal development may lead to potential teratogenic outcomes manifesting in devastating birth defects and should be administered with caution.  Résumé Le système visuel féminin subit une série de modifications physiologiques pendant la grossesse, et ces changements ont des implications profondes sur de nombreux troubles ophtalmologiques et neuro-ophtalmologiques généraux, exacerbant certaines conditions tout en soulageant d’autres. Les patients atteints de glaucome à angle ouvert ont une amélioration des états pathologiques, accompagnés de champs visuels normaux. L’uvéite et la névrite optique induite par la SEP présentent des taux d’occurrence réduits. La rétinopathie diabétique non proliférative s’aggrave au début avec la gestation, s’améliorant finalement dans l’état postpartum avec seulement 5% des cas progressant dans le stade prolifératif. En ce qui concerne l’hypertension intracrânienne idiopathique, les symptômes existants s’aggravent pendant la grossesse. Les interventions thérapeutiques comme les immunosuppresseurs, les médicaments antinéoplasiques et les stéroïdes administrés de façon prophylactique pendant le développement du fœtus peuvent entraîner des effets tératogènes potentiels se manifestant par des malformations congénitales dévastatrices et doivent être administrés avec prudence.