arXiv subjects

Rasmus E. Benestad

Publications and source records attributed to Rasmus E. Benestad.

4 recordsLinked to original sources

arXiv2026

Artificial intelligence and downscaling global climate model future projections

A critical review of artificial intelligence and deep machine learning (AI/ML) applied to downscaling of global climate model simulations provides some words of caution, based on past experiences and well-established principles. Recent papers tend to ignore more subtle successes with statistics and mathematical based downscaling, and there are examples of inappropriate evaluation strategies and incomplete accounts of the scientific progress when it comes to climate downscaling. An incomplete description state-of-the-art and a dogmatic approach to evaluation may give a deceiving impression that AI/ML is superior to more statistics and mathematics based methods.

physics.geo-ph↗

arXiv2025

A Norwegian Approach to Downscaling

A comprehensive geoscientific downscaling model strategy is presented outlining an approach that has evolved over the last 20 years, together with an explanation for its development, its technical aspects, and evaluation scheme. This effort has resulted in an open-source and free R-based tool, 'esd', for the benefit of sharing and improving the reproducibility of the downscaling results. Furthermore, a set of new metrics was developed as an integral part of the downscaling approach which assesses model performance with an emphasis on regional information for society (RifS). These metrics involve novel ways of comparing model results with observational data and have been developed for downscaling large multi-model global climate model ensembles. This paper presents for the first time an overview of the comprehensive framework adopted by the Norwegian Meteorological Institute for downscaling aimed at supporting climate change adaptation. A literature search suggests that this comprehensive downscaling strategy and evaluation scheme are not widely used within the downscaling community. In addition, this strategy involves a new convention for storing large datasets of ensemble results that provides fast access to information and drastically saves data volume.

physics.geo-ph↗

arXiv2013

Validating a physics-based back-of-the-envelope climate model with state-of-the-art data

An old conceptual physics-based back-of-the-envelope model for greenhouse effect is revisited and validated against state-of-the-art reanalyses. Untraditional diagnostics show a physically consistent picture, for which the state of earth's climate is constrained by well-known physical principles, such as energy balance, flow and, conservation. Greenhouse gas concentrations affect the atmospheric optical depth for infrared radiation, and increased opacity implies higher altitude from which earth's equivalent bulk heat loss takes place without being re-absorbed. Such increase is seen in the reanalyses. There has also been a reduction in the correlation between the spatial structure of outgoing long-wave radiation and surface temperature, consistent with increasingly more processes interfering with the upwelling infrared light before it reaches the top of the atmosphere. State-of-the-art reanalyses further imply increases in the overturning in the troposphere, consistent with a constant and continuous vertical energy flow. The associateion between these aspects can be interpreted as an entanglement between greenhouse effect and the hydrological cycle, where reduced energy transfer associated with increased opacity is compensated by tropospheric overturning activity.

physics.ao-ph↗

arXiv2011

New Evidence of an Enhanced Greenhouse Effect

The state of earth's climate is constrained by well-known physical principles such as energy balance and the conservation of energy. Increased greenhouse gas concentrations affect the atmospheric optical depth, and physical consistency implies that changes in the energy transfer in terms of infra-red light must be compensated by other means of energy flow. Here, a simple heuristic and comprehensive model is used to interpret new aspects of real-world data. It is shown that trends in tropospheric overturning activity and the estimated altitude where earth's bulk heat loss should place are two independent indicators of climate change. There has been increased vertical overturning in the middle and upper parts of the troposphere since 1995 on a global scale. Greater overturning compensates for reduced radiative energy transfer associated with increased optical depth. An increased optical depth is also expected to raise the altitude from where planetary bulk heat loss takes place according to the heuristic model, and an estimated trend of 40m/decade is consistent with a surface warming rate of 0.2K/decade. The simple comprehensive model of the greenhouse effect can also account for feedback processes, changes in the hydrological cycle, and may assist the wider scientific community in understanding of the main principles involved.

physics.ao-ph↗