scholarly journals Atmospheric dynamics on tidally locked Earth-like planets in the habitable zone of an M dwarf star

2013 ◽  
Vol 8 (S299) ◽  
pp. 376-377 ◽  
Author(s):  
Ludmila Carone ◽  
Rony Keppens ◽  
Leen Decin
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Rotation Period ◽  
Circulation Model ◽  
Return Flow ◽  
Parameter Study ◽  
Global Circulation Model ◽  
Dwarf Star ◽  
Global Circulation ◽  
M Dwarf

AbstractWe investigated the large scale atmospheric circulation of Gl581g, a potentially habitable planet around an M dwarf star, using an idealized dry global circulation model (GCM) with simplified thermal forcing as a first step towards a systematic extended parameter study. The results are compared with the work of Joshi et al. (1997) who investigated a tidally-locked habitable Earth analogue with less than half the rotation period of Gl581g. The extent, form and strength of the atmospheric circulation in each model generally agree with each other, even though the models differ in key parameters such as planetary radius, surface gravity, forcing scheme and rotation period. The substellar point is associated with an uprising direct circulation-branch of a Hadley-like cell with return flow over the poles. It is compelling to assume that the substellar point of a tidally locked terrestrial exoplanet behaves dynamically like the Earth's tropic associated with clouds and precipitation, making it an ideal target for habitability.

Downscaling of GCM forecasts to streamflow over Scandinavia

2008 ◽  
Vol 39 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Patrik Nilsson ◽  
Cintia B. Uvo ◽  
Willem A. Landman ◽  
Tinh D. Nguyen
Keyword(s):  
Large Scale ◽  
Circulation Model ◽  
Model Output ◽  
Northern Sweden ◽  
Global Circulation Model ◽  
Global Circulation ◽  
Principal Source ◽  
Streamflow Forecasts ◽  
Linear Neural Network ◽  
Model Output Statistics

A seasonal forecasting technique to produce probabilistic and deterministic streamflow forecasts for 23 basins in Norway and northern Sweden is developed in this work. Large scale circulation and moisture fields, forecasted by the ECHAM4.5 model 4 months in advance, are used to forecast spring flows. The technique includes model output statistics (MOS) based on a non-linear Neural Network (NN) approach. Results show that streamflow forecasts from Global Circulation Model (GCM) predictions, for the Scandinavia region are viable and highest skill values were found for basins located in south-western Norway. The physical interpretation of the forecasting skill is that stations close to the Norwegian coast are directly exposed to prevailing winds from the Atlantic Ocean, which constitute the principal source of predictive information from the atmosphere on the seasonal timescale.

scholarly journals Statistical downscaling and scenario construction of precipitation in Scania, southern Sweden

2004 ◽  
Vol 35 (3) ◽  
pp. 261-278 ◽  
Author(s):  
Maj-Lena Linderson ◽  
Christine Achberger ◽  
Deliang Chen
Keyword(s):  
Atmospheric Circulation ◽  
Statistical Downscaling ◽  
Large Scale ◽  
Circulation Model ◽  
Summer Precipitation ◽  
Atmospheric Composition ◽  
Global Circulation Model ◽  
Southern Sweden ◽  
Monthly Basis ◽  
Projected Changes

Statistical downscaling models for precipitation in Scania, southern Sweden, have been developed and applied to calculate the changes in the future Scanian precipitation climate due to projected changes in the atmospheric composition. The models are based on multiple linear regression, linking large-scale predictors at monthly time resolution to regional statistics of daily precipitation on a monthly basis. To account for spatial precipitation variability within the area, the precipitation statistics were derived for different regions in Scania. The final downscaling models, developed for different regions and seasons, use atmospheric circulation, large-scale humidity and precipitation as predictors. Among the precipitation statistics examined, only the models for estimating the mean precipitation and the frequency of wet days were skilful. Based on the Canadian Global Circulation Model 1 (CGCM1), a future scenario of these two statistics was created. The downscaled scenario shows a significant increase of the annual mean precipitation by about 10% and a slight decrease in the frequency of wet days, indicating an increase in the precipitation amounts as well as in the precipitation intensity. The main increase of precipitation amounts and intensity occur during winter, while the summer precipitation amounts decrease slightly. The seasonal changes found in precipitation are likely attributed to changes in the westerly flow of the atmospheric circulation.

scholarly journals Using the UM dynamical cores to reproduce idealised 3-D flows

2014 ◽  
Vol 7 (6) ◽  
pp. 3059-3087 ◽  
Author(s):  
N. J. Mayne ◽  
I. Baraffe ◽  
D. M. Acreman ◽  
C. Smith ◽  
N. Wood ◽  
...  
Keyword(s):  
Large Scale ◽  
Circulation Model ◽  
Simplified Model ◽  
Global Circulation Model ◽  
Dynamical Equations ◽  
Present Evidence ◽  
Global Circulation ◽  
The Uk ◽  
Tidally Locked Earth

Abstract. We demonstrate that both the current (New Dynamics), and next generation (ENDGame) dynamical cores of the UK Met Office global circulation model, the UM, reproduce consistently, the long-term, large-scale flows found in several published idealised tests. The cases presented are the Held–Suarez test, a simplified model of Earth (including a stratosphere), and a hypothetical tidally locked Earth. Furthermore, we show that using simplifications to the dynamical equations, which are expected to be justified for the physical domains and flow regimes we have studied, and which are supported by the ENDGame dynamical core, also produces matching long-term, large-scale flows. Finally, we present evidence for differences in the detail of the planetary flows and circulations resulting from improvements in the ENDGame formulation over New Dynamics.

scholarly journals Using the UM dynamical cores to reproduce idealised 3-D flows

2013 ◽  
Vol 6 (3) ◽  
pp. 3681-3741 ◽  
Author(s):  
N. J. Mayne ◽  
I. Baraffe ◽  
D. M. Acreman ◽  
C. Smith ◽  
N. Wood ◽  
...  
Keyword(s):  
Large Scale ◽  
Circulation Model ◽  
Test Case ◽  
Global Circulation Model ◽  
Dynamical Equations ◽  
Present Evidence ◽  
Global Circulation ◽  
The Uk ◽  
Tidally Locked Earth

Abstract. We demonstrate that both the current (New Dynamics), and next generation (ENDGame) dynamical cores of the UK Met Office global circulation model, the UM, reproduce consistently, the long-term, large-scale flows found in several published idealised tests. The cases presented are the Held–Suarez test, a simplified model of Earth (including a stratosphere), and a model of a hypothetical Tidally Locked Earth (TLE). Furthermore, we show that using simplifications to the dynamical equations, which are expected to be justified for the physical domains and flow regimes we have studied, and which are supported by the ENDGame dynamical core, also produces matching long-term, large-scale flows. Finally, we present evidence for differences in the detail of the planetary (meridional) flows and circulations resulting from improvements in the ENDGame formulation over New Dynamics. Specifically, we find greater symmetry in the meridional circulations of the Tidally Locked Earth test case using the ENDGame formulation, which is a better match to our physical expectations of the flow for such a slowly rotating Earth-like system.

scholarly journals Indirect downscaling of global circulation model data based on atmospheric circulation and temperature for projections of future precipitation in hourly resolution

2013 ◽  
Vol 10 (7) ◽  
pp. 8841-8874 ◽  
Author(s):  
F. Beck ◽  
A. Bárdossy
Keyword(s):  
Atmospheric Circulation ◽  
Regional Distribution ◽  
Circulation Model ◽  
High Temporal Resolution ◽  
Global Circulation Model ◽  
Hourly Precipitation ◽  
Atmospheric Circulation Patterns ◽  
Urban Sewage ◽  
Empirical Distributions ◽  
Global Circulation

Abstract. Many hydraulic applications like the design of urban sewage systems require projections of future precipitation in high temporal resolution. We developed a method to predict the regional distribution of hourly precipitation sums based on daily mean sea level pressure and temperature data from a Global Circulation Model. It is an indirect downscaling method avoiding uncertain precipitation data from the model. It is based on a fuzzy-logic classification of atmospheric circulation patterns (CPs) that is further subdivided by means of the average daily temperature. The observed empirical distributions at 30 rain gauges to each CP-temperature class are assumed as constant and used for projections of the hourly precipitation sums in the future. The method was applied to the CP-temperature sequence derived from the 20th century run and the scenario A1B run of ECHAM5. According to ECHAM5, the summers in southwest Germany will become progressively drier. Nevertheless, the frequency of the highest hourly precipitation sums will increase. According to the predictions, estival water stress and the risk of extreme hourly precipitation will both increase simultaneously during the next decades.

How well does a 1/4° global circulation model simulate large-scale oceanic observations?

1996 ◽  
Vol 101 (C11) ◽  
pp. 25779-25811 ◽  
Author(s):  
Detlef Stammer ◽  
Robin Tokmakian ◽  
Albert Semtner ◽  
Carl Wunsch
Keyword(s):  
Large Scale ◽  
Circulation Model ◽  
Global Circulation Model ◽  
Global Circulation

scholarly journals Seasonal predictability of the 2010 Russian heat wave

2013 ◽  
Vol 1 (5) ◽  
pp. 5057-5086 ◽  
Author(s):  
P. Katsafados ◽  
A. Papadopoulos ◽  
G. Varlas ◽  
E. Papadopoulou ◽  
E. Mavromatidis
Keyword(s):  
Heat Wave ◽  
Large Scale ◽  
Initial Conditions ◽  
Circulation Model ◽  
Global Circulation Model ◽  
Atmospheric Blocking ◽  
Seasonal Predictability ◽  
Global Circulation ◽  
Seasonal Time Scale ◽  
The Impact

Abstract. The prevailed atmospheric blocking over Eastern Europe and Western Russia during July and August 2010 led in the development of the devastating Russian heat wave. Therefore the question whether the event was predictable or not is highly important. The principal aim of this study is to examine the predictability of this high-impact atmospheric event on a seasonal time scale. To this end, a set of dynamical seasonal simulations have been carried out using an Atmospheric Global Circulation Model (AGCM). The impact of various model initializations on the predictability of this large scale event and its sensitivity to the initial conditions has been also investigated. Ensemble seasonal simulations indicated that only a few individual members reproduced the main features of the blocking system 3 months ahead. Most members missed the phase space and the velocity of the system setting limitations in the predictability of the event.

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