Final Report Summary - MODES (Modal analysis of atmospheric balance, predictability and climate)
Numerical weather prediction (NWP) models stand for the fundamental input to the society on a daily basis. Climate models provide input for the planning of future of our life on the Earth at many time scales. Increasing complexity of weather and climate models aims at a more accurate representation of the spatial and temporal features of a multitude of processes taking place in our living atmosphere. Their understanding and validation is crucial for the models’ improvement. At this end, the MODES project produced a novel tool for the scale-dependent introspective of the global weather and climate models. The MODES software has been made available to the atmospheric research community. Selected outputs of the modal analysis are published on a daily basis at the MODES web site http://meteo.fmf.uni-lj.si/MODES.
MODES has provided a global perspective of the limits of the useful prediction skill of the NWP models. A scale-dependent analysis of global predictability suggests that “the devil” lies at the large scales. MODES showed that the larger the spatial scale, the greater the amplitude of uncertainties in the initial conditions (analyses) for the global prediction systems. A large part of these uncertainties is found in the tropical region in relation to the lack of wind observations and challenges of the tropical data assimilation and NWP modelling. The growth of forecast uncertainties takes place at all spatial scales from the beginning of forecasts, suggesting that the errors in the initial state at large scales are very important for the loss of useful predictability in the 10-day forecast range. The modal perspective points out the role of the tropics and the need to reduce the large-scale tropical analysis uncertainties in order for the practical predictability to converge towards the theoretical limit.
MODES has quantified the level of inertio-gravity (IG) wave energy across many scales. Although the IG waves constitute a small portion of the global atmospheric wave energy, it is crucial to validate their spectrum in the NWP and climate models as it reflects the fundamental dynamical processes developing in response to nonhomogeneous forcings.
Discussed three regimes of the IG energy spectrum consist of a component associated with the large-scale unbalanced circulations that resides mainly in the tropics, a synoptic-scale IG range approximately between 3000 km and 500 km that is represented well by the models, and the mesoscale range where global models are characterized by an insufficient variability.
MODES has provided a global perspective of the limits of the useful prediction skill of the NWP models. A scale-dependent analysis of global predictability suggests that “the devil” lies at the large scales. MODES showed that the larger the spatial scale, the greater the amplitude of uncertainties in the initial conditions (analyses) for the global prediction systems. A large part of these uncertainties is found in the tropical region in relation to the lack of wind observations and challenges of the tropical data assimilation and NWP modelling. The growth of forecast uncertainties takes place at all spatial scales from the beginning of forecasts, suggesting that the errors in the initial state at large scales are very important for the loss of useful predictability in the 10-day forecast range. The modal perspective points out the role of the tropics and the need to reduce the large-scale tropical analysis uncertainties in order for the practical predictability to converge towards the theoretical limit.
MODES has quantified the level of inertio-gravity (IG) wave energy across many scales. Although the IG waves constitute a small portion of the global atmospheric wave energy, it is crucial to validate their spectrum in the NWP and climate models as it reflects the fundamental dynamical processes developing in response to nonhomogeneous forcings.
Discussed three regimes of the IG energy spectrum consist of a component associated with the large-scale unbalanced circulations that resides mainly in the tropics, a synoptic-scale IG range approximately between 3000 km and 500 km that is represented well by the models, and the mesoscale range where global models are characterized by an insufficient variability.