Global pressure and temperature 2 wet (GPT2w) is an empirical troposphere delay model providing the mean values plus annual and semiannual amplitudes of pressure, temperature and its lapse rate, water vapor pressure and its decrease factor, weighted mean temperature, as well as hydrostatic and wet mapping function coefficients of the Vienna mapping function 1. All climatological parameters have been derived consistently from monthly mean pressure level data of ERA-Interim fields (European Centre for Medium-Range Weather Forecasts Re-Analysis) with a horizontal resolution of 1°, and the model is suitable to calculate slant hydrostatic and wet delays down to 3°elevation at sites in the vicinity of the earth surface using the date and approximate station coordinates as input. The wet delay estimation builds upon gridded values of the water vapor pressure, the weighted mean temperature, and the water vapor decrease factor, with the latter being tuned to ray-traced zenith wet delays. Comparisons with zenith delays at 341 globally distributed global navigation satellite systems stations show that the mean bias over all stations is below 1 mm and the mean standard deviation is about 3.6 cm. The GPT2w model with the gridded input file is provided at http://ggosatm.hg. tuwien.ac.at/DELAY/SOURCE/GPT2w/.

Up to now, state-of-the-art empirical slant delay modeling for processing observations from radio space geodetic techniques has been provided by a combination of two empirical models. These are GPT (Global Pressure and Temperature) and GMF (Global Mapping Function), both operating on the basis of long-term averages of surface values from numerical weather models. Weaknesses in GPT/GMF, specifically their limited spatial and temporal variability, are largely eradicated by a new, combined model GPT2, which provides pressure, temperature, lapse rate, water vapor pressure, and mapping function coefficients at any site, resting upon a global 5° grid of mean values, annual, and semi-annual variations in all parameters. Built on ERA-Interim data, GPT2 brings forth improved empirical slant delays for geophysical studies. Compared to GPT/GMF, GPT2 yields a 40% reduction of annual and semi-annual amplitude differences in station heights with respect to a solution based on instantaneous local pressure values and the Vienna mapping functions 1, as shown with a series of global VLBI (Very Long Baseline Interferometry) solutions.

Scientists and engineers have observed for some time that tidal amplitudes at many locations are shifting considerably due to nonastronomical factors. Here we review comprehensively these important changes in tidal properties, many of which remain poorly understood. Over long geological time scales, tectonic processes drive variations in basin size, depth, and shape and hence the resonant properties of ocean basins. On shorter geological time scales, changes in oceanic tidal properties are dominated by variations in water depth. A growing number of studies have identified widespread, sometimes regionally coherent, positive, and negative trends in tidal constituents and levels during the 19th, 20th, and early 21st centuries. Determining the causes is challenging because a tide measured at a coastal gauge integrates the effects of local, regional, and oceanic changes. Here, we highlight six main factors that can cause changes in measured tidal statistics on local scales and a further eight possible regional/global driving mechanisms. Since only a few studies have combined observations and models, or modeled at a temporal/spatial resolution capable of resolving both ultralocal and large‐scale global changes, the individual contributions from local and regional mechanisms remain uncertain. Nonetheless, modeling studies project that sea level rise and climate change will continue to alter tides over the next several centuries, with regionally coherent modes of change caused by alterations to coastal morphology and ice sheet extent. Hence, a better understanding of the causes and consequences of tidal variations is needed to help assess the implications for coastal defense, risk assessment, and ecological change.

The link between secular changes in the lunar semidiurnal ocean tide (M 2 ) and relative sea level rise is examined based on numerical tidal modeling and the analysis of long-term sea level records from Europe, Australia, and the North American Atlantic coasts. The study sets itself apart from previous work by using a 1 ∕ 12 ∘ global tide model that incorporates the effects of self-attraction and loading through time-step-wise spherical harmonic transforms instead of iteration. This novel self-attraction and loading implementation incurs moderate computational overheads (some 50%) and facilitates the simulation of shelf sea tides with a global root mean square error of 14.6 cm in depths shallower than 1,000 m. To reproduce measured tidal changes in recent decades, the model is perturbed with realistic water depth changes, compiled from maps of altimetric sea level trends and postglacial crustal rebound. The M 2 response to the adopted sea level rise scenarios exhibits peak sensitivities in the North Atlantic and many marginal seas, with relative magnitudes of 1-5% per century. Comparisons with a collection of 45 tide gauge records reveals that the model reproduces the sign of the observed amplitude trends in 80% of the cases and captures considerable fractions of the absolute M 2 variability, specifically for stations in the Gulf of Mexico and the Chesapeake-Delaware Bay system. While measured-to-model disparities remain large in several key locations, such as the European Shelf, the study is deemed a major step toward credible predictions of secular changes in the main components of the ocean tide. Key Points: • Effects of present-day sea level changes on global tides, primarily M 2 , are studied using a nonlinear barotropic model • The model operates at high accuracy for its horizontal resolution and an explicit treatment of self-attraction and loading • The sign of M 2 long-term trends is correctly simulated at 36 of 45 tide gauge stations Supporting Information: • Supporting Information S1 Correspondence to: M. Schindelegger, schindelegger@igg.uni-bonn.de Citation: Schindelegger, M., Green, J. A. M., Wilmes, S.-B., & Haigh, I. D. (2018). Can we model the effect of observed sea level rise on tides? Journal of Geophysical Research: Oceans, 123, 4593-4609.

Tides and Earth-Moon system evolution are coupled over geological time. Tidal energy dissipation on Earth slows  Earth Es rotation rate, increases obliquity, lunar orbit semi-major axis and eccentricity, and decreases lunar inclination. Tidal and core-mantle boundary dissipation within the Moon decrease inclination, eccentricity and semi-major axis. Here we integrate the Earth-Moon system backwards for 4.5 Ga with orbital dynamics and explicit ocean tide models that are "high-level" (i.e., not idealized). To account for uncertain plate tectonic histories, we employ Monte Carlo simulations, with tidal energy dissipation rates (normalized relative to astronomical forcing parameters) randomly selected from ocean tide simulations with modern ocean basin geometry and with 55, 116, and 252 Ma reconstructed basin paleogeometries. The normalized dissipation rates depend upon basin geometry and  Earth E s rotation rate. Faster Earth rotation generally yields lower normalized dissipation rates. The Monte Carlo results provide a spread of possible early values for the Earth-Moon system parameters. Of consequence for ocean circulation and climate, absolute (un-normalized) ocean tidal energy dissipation rates on the early Earth may have exceeded  today E s rate due to a closer Moon. Prior to  E 3 Ga, evolution of inclination and eccentricity is dominated by tidal and core-mantle boundary dissipation within the Moon, which yield high lunar orbit inclinations in the early Earth-Moon system. A drawback for our results is that the semi-major axis does not collapse to near-zero values at 4.5 Ga, as indicated by most lunar formation models. Additional processes, missing from our current efforts, are discussed as topics for future investigation. Plain Language Summary Tidal dissipation ins oceans and solid body cause the distance to the Moon and the length of day to increase over time. Tides also change the eccentricity and tilt of the lunar orbit, and  Earth E s obliquity (the tilt between the equator plane and the ecliptic plane of our orbit around the Sun). This paper attempts to calculate the evolution of the Earth-Moon system over the whole of  Earth E s history using sophisticated ocean tide and orbit models. Over long time scales, the rate at which tidal energy is being dissipated is affected by the geometrical configuration of the continents, the length of day, and mean sea level, which is affected by plate tectonic forces and the presence or absence of large ice caps. The faster rotating Earth of the past was less efficient at dissipating energy and the present placement of the continents enhances some tides due to resonances. In addition, tidal dissipation in the Moon slows the orbit evolution by absorbing energy from the orbit and there was a time in the distant past when the  Moon s E tidal dissipation was large. The evolution of the Earth-Moon system is complex and uncertain, but it can be addressed with advanced models.