Innovative Orbital Design (United States)

Anthropogenic activities drive 55% of Australasia's CH budget, natural sources 45%, with wetlands contributing 42%, though uncertain. Natural sources dominate 82% of Australasia's NO budget, anthropogenic 18%, with Australia contributing 92% of total NO emissions.Australia's CH and NO top-down and bottom-up budgets align within uncertainties, while New Zealand shows major discrepancies.

Abstract What would a world without tropical cyclones look like? Although such a world is unrealistic, addressing this question would reveal the role tropical cyclones (TCs) play in modulating the climate system. In this study, we begin to address this question by introducing a novel algorithm for reducing TC activity in TC‐permitting global climate models (GCMs) through suppression of wind‐induced surface heat exchange (WISHE) at grid points where TC‐like conditions are detected. This algorithm, abbreviated as “SWISHE,” was implemented in a suite of GCM simulations developed by NOAA's Geophysical Fluid Dynamics Laboratory and compared to a control suite of simulations with no perturbations. Application of SWISHE resulted in a model‐mean 44% reduction of TC frequency compared to control simulations, with TCs of hurricane‐strength reduced by approximately 90%. Aggregate analysis of TCs reveals that TCs in the SWISHE simulations are weaker, as peak 10‐m horizontal wind speeds decrease by a model‐mean of 3.9 m s−1 and minimum sea‐level pressures increase by a model‐mean of 4.7 hPa. Composite analysis is used to confirm that SWISHE effectively suppressed latent heat fluxes in grid cells with TC‐like conditions. The results presented herein are intended to provide a first step in establishing methodology to understand upscale impacts of TCs on the climate system.

Abstract Hurricane storm surge represents a significant threat to coastal communities around the world. Here, we use artificial neural network (ANN) models to predict storm surge levels using hurricane characteristics along the US Gulf and East Coasts. The ANN models are trained with storm surge levels from a hydrodynamic model and physical characteristics of synthetic hurricanes which are downscaled from National Centers for Environmental Prediction (NCEP) reanalysis using a statistical‐deterministic hurricane model. The ANN models are able to accurately predict storm surge levels with root‐mean‐square errors (RMSE) below 0.2 m and correlation coefficients > 0.85. The ANN models trained with the NCEP data also show satisfactory accuracy (RMSE below 0.7 m; correlation > 0.7) in predicting storm surge levels for hurricanes downscaled from future climate projections. Once trained, we use the ANN models to assess the sensitivity of storm surge levels to variations in hurricane characteristics and local geophysical features. Progressively stronger maximum wind speeds and larger outer radius sizes independently increase storm surge levels at all locations along the US East and Gulf Coasts. The response of storm surge levels to changes in hurricane translation speed, however, is found to be sensitive to coastal configuration, with increases in hurricane translation speed amplifying (reducing) storm surge levels in open ocean (semi‐enclosed) regions.

A proposed mechanism responsible for causing certain resonant motions in the Kuiper belt is described. It is the so called ’hop’ with Neptune where an object dramatically moves from one resonance to another. This implies, among other things, that in the distant past, the currently resonant Kuiper belt objects, including Pluto, may have been weakly captured by Neptune. In another result, it is indicated why the 2:3 resonance is prevalent over all other being a minimum of a special energy relation. This paper can be viewed in part as an extension of a recent paper by Belbruno and Marsden(1997).