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 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.

scholarly journals Non-linear statistical downscaling of present and LGM precipitation and temperatures over Europe

2007 ◽  
Vol 3 (4) ◽  
pp. 899-933 ◽  
Author(s):  
M. Vrac ◽  
D. Paillard ◽  
P. Naveau
Keyword(s):  
Statistical Downscaling ◽  
Large Scale ◽  
Western Europe ◽  
Generalized Additive Models ◽  
Circulation Model ◽  
Additive Models ◽  
Future Climate Change ◽  
Small Scale ◽  
Global Circulation Model ◽  
Non Linear

Abstract. The needs of small-scale climate information have become prevalent to study the impacts of future climate change as well as for paleoclimate researches where the reconstructions from proxies are obviously local. In this study we develop a non-linear statistical downscaling method to generate local temperatures and precipitation values from large-scale variables (e.g. Global Circulation Model – GCM – outputs), through Generalized Additive Models (GAMs) calibrated on the present Western Europe climate. First, various monthly GAMs (i.e. one model for each month) are tested for preliminary analysis. Then, annual GAMs (i.e. one model for the 12 months altogether) are developed and tailored for two sets of predictors (geographical and physical) to downscale local temperatures and precipitation. As an evaluation of our approach under large-scale conditions different from present Western Europe, projections are realized (1) for present North America and Northern Europe and compared to local observations (spatial test); and (2) for the Last Glacial Maximum (LGM) period, and compared to local reconstructions and GCMs outputs (temporal test). In general, both spatial and temporal evaluations indicate that the GAMs are flexible and efficient tools to capture and downscale non-linearities between large- and local-scale variables. More precisely, the results emphasize that, while physical predictors alone are not capable of downscaling realistic values when applied to climate strongly different from the one used for calibration, the inclusion of geographical-type variables – such as altitude, advective continentality and W-slope – into GAM predictors brings robustness and improvement to the method and its local projections.

scholarly journals Utility of daily vs. monthly large-scale climate data: an intercomparison of two statistical downscaling methods

2007 ◽  
Vol 4 (5) ◽  
pp. 3413-3440 ◽  
Author(s):  
E. P. Maurer ◽  
H. G. Hidalgo
Keyword(s):  
Statistical Downscaling ◽  
General Circulation ◽  
Large Scale ◽  
Impact Analysis ◽  
Climate Model ◽  
Daily Precipitation ◽  
Circulation Model ◽  
Reanalysis Data ◽  
Temperature Extremes ◽  
Daily Data

Abstract. Downscaling of climate model data is essential to most impact analysis. We compare two methods of statistical downscaling to produce continuous, gridded time series of precipitation and surface air temperature at a 1/8-degree (approximately 140 km² per grid cell) resolution over the western U.S. We use NCEP/NCAR Reanalysis data from 1950–1999 as a surrogate General Circulation Model (GCM). The two methods included are constructed analogues (CA) and a bias correction and spatial downscaling (BCSD), both of which have been shown to be skillful in different settings, and BCSD has been used extensively in hydrologic impact analysis. Both methods use the coarse scale Reanalysis fields of precipitation and temperature as predictors of the corresponding fine scale fields. CA downscales daily large-scale data directly and BCSD downscales monthly data, with a random resampling technique to generate daily values. The methods produce comparable skill in producing downscaled, gridded fields of precipitation and temperatures at a monthly and seasonal level. For daily precipitation, both methods exhibit some skill in reproducing both observed wet and dry extremes and the difference between the methods is not significant, reflecting the general low skill in daily precipitation variability in the reanalysis data. For low temperature extremes, the CA method produces greater downscaling skill than BCSD for fall and winter seasons. For high temperature extremes, CA demonstrates higher skill than BCSD in summer. We find that the choice of most appropriate downscaling technique depends on the variables, seasons, and regions of interest, on the availability of daily data, and whether the day to day correspondence of weather from the GCM needs to be reproduced for some applications. The ability to produce skillful downscaled daily data depends primarily on the ability of the climate model to show daily skill.

Gridded Statistical Downscaling Based on Interpolation of Parameters and Predictor Locations for Summer Daily Precipitation in North China

2019 ◽  
Vol 58 (10) ◽  
pp. 2295-2311
Author(s):  
Yonghe Liu ◽  
Jinming Feng ◽  
Zongliang Yang ◽  
Yonghong Hu ◽  
Jianlin Li
Keyword(s):  
Distance Function ◽  
Statistical Downscaling ◽  
Spatial Dependence ◽  
Large Scale ◽  
North China ◽  
Dynamical Downscaling ◽  
Daily Precipitation ◽  
Summer Precipitation ◽  
Single Station ◽  
Dense Grid

AbstractFew statistical downscaling applications have provided gridded products that can provide downscaled values for a no-gauge area as is done by dynamical downscaling. In this study, a gridded statistical downscaling scheme is presented to downscale summer precipitation to a dense grid that covers North China. The main innovation of this scheme is interpolating the parameters of single-station models to this dense grid and assigning optimal predictor values according to an interpolated predictand–predictor distance function. This method can produce spatial dependence (spatial autocorrelation) and transmit the spatial heterogeneity of predictor values from the large-scale predictors to the downscaled outputs. Such gridded output at no-gauge stations shows performances comparable to that at the gauged stations. The area mean precipitation of the downscaled results is comparable to other products. The main value of the downscaling scheme is that it can obtain reasonable outputs for no-gauge stations.

Retrievals of dust and ozone from NOMAD-UVIS

2020 ◽  
Author(s):  
Arianna Piccialli ◽  
Ann Carine Vandaele ◽  
Yannick Willame ◽  
Cedric Depiesse ◽  
Loic Trompet ◽  
...  
Keyword(s):  
Dust Storm ◽  
Circulation Model ◽  
Dust Storms ◽  
Atmospheric Composition ◽  
Trace Gas ◽  
Global Circulation Model ◽  
Global Circulation ◽  
Solar Occultation ◽  
Composition And Structure ◽  
Hydrogen Radicals

<p>We will present two years of observation of <strong>dust</strong> and <strong>ozone</strong> vertical distribution obtained from <strong>NOMAD-UVIS solar occultations</strong>.</p><p>Atmospheric <strong>aerosols</strong> are ubiquitous in the Martian atmosphere and they strongly affect the Martian climate [1]. This is particularly true during dust storms. In June 2018, after a pause of 11 years, a planet-encircling dust storm took place on Mars that lasted two months.</p><p><strong>Ozone</strong>, on the other hand, is a species with a short chemical lifetime and characterized by sharp gradients at the day-night terminator due to photolysis [2]. Odd hydrogen radicals play an important role in the destruction of ozone. This results in a strong anti-correlation between O<sub>3</sub> and H<sub>2</sub>O [2].</p><p>The <strong>NOMAD</strong> (Nadir and Occultation for MArs Discovery) – operating onboard the ExoMars 2016 Trace Gas Orbiter satellite – started to acquire the first scientific measurements on 21 April 2018.</p><p>It is a spectrometer composed of 3 channels: 1) a solar occultation channel (SO) operating in the infrared (2.3-4.3 μm); 2) a second infrared channel LNO (2.3-3.8 μm) capable of doing nadir, as well as solar occultation and limb; and 3) an ultraviolet/visible channel UVIS (200-650 nm) that can work in the three observation modes [3,4]. The UVIS channel has a spectral resolution <1.5 nm. In the solar occultation mode it is mainly devoted to study the climatology of ozone and aerosols content [5].</p><p>Since the beginning of operations, on 21 April 2018, NOMAD-UVIS acquired more than <strong>3000 solar occultations</strong> with a complete coverage of the planet. NOMAD-UVIS spectra are simulated using the line-by-line radiative transfer code ASIMUT-ALVL developed at IASB-BIRA [6]. In a preliminary study based on SPICAM-UV solar occultations (see [7]), ASIMUT was modified to take into account the atmospheric composition and structure at the day-night terminator. As input for ASIMUT, we used gradients predicted by the 3D GEM-Mars v4 Global Circulation Model (GCM) [8,9].</p><p>NOMAD will help us improve our knowledge of the climatology of ozone and aerosols. In particular, we will have the rare opportunity to analyze the distribution of aerosols during a dust storm.</p><p>References:</p><p>[1] Määttänen, A., Listowski, C., Montmessin, F., Maltagliati, L., Reberac, A., Joly, L., Bertaux, J.L., Apr. 2013. Icarus 223, 892–941.</p><p>[2] Lefèvre, F., et al., Aug. 2008. Nature 454, 971–975.</p><p>[3] Vandaele, A.C., et al., Planetary and Space Science, Vol. 119,  pp. 233–249, 2015.</p><p>[4] Neefs, E., et al., Applied Optics, Vol. 54 (28),  pp. 8494-8520, 2015.</p><p>[5] M.R. Patel et al., In: Appl. Opt. 56.10 (2017), pp. 2771–2782. DOI: 10.1364/AO.56.002771.</p><p>[6] Vandaele, A.C., et al., JGR, 2008. 113 doi:10.1029/2008JE003140.</p><p>[7] Piccialli, A., Icarus, in press, https://doi.org/10.1016/j.icarus.2019.113598.</p><p>[8] Neary, L., and F. Daerden (2018), Icarus, 300, 458–476, doi:10.1016/j.icarus.2017.09.028.</p><p>[9] Daerden et al., 2019, Icarus 326, https://doi.org/10.1016/j.icarus.2019.02.030</p>

Impact of gradients at the Martian terminator on the retrieval of ozone from TGO/NOMAD-UVIS

2020 ◽  
Author(s):  
Arianna Piccialli ◽  
Ann Carine Vandaele ◽  
Yannick Willame ◽  
Shohei Aoki ◽  
Cedric Depiesse ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Circulation Model ◽  
Atmospheric Composition ◽  
Global Circulation Model ◽  
Model Calculations ◽  
Global Circulation ◽  
Retrieval Technique ◽  
Solar Occultation ◽  
Composition And Structure ◽  
The Impact

<p><strong>1. Introduction</strong></p><p>Rapid variations in species concentration at the terminator have the potential to cause asymmetries in the species distributions along the line of sight (LOS) of a solar occultation experiment. Ozone, in particular, displays steep gradients across the terminator of Mars due to photolysis [1]. Nowadays, most of the retrieval algorithms for solar and stellar occultations rely on the assumption of a spherically symmetrical atmosphere. However, photochemically induced variations near sunrise/sunset conditions need to be taken into account in the retrieval process in order to prevent inaccuracies.</p><p>Here, we investigated the impact of gradients along the LOS of the solar occultation experiment TGO/NOMAD-UVIS for the retrieval of ozone under sunrise/sunset conditions. We used the diurnal variations in the ozone concentration obtained from photochemical model calculations together with an adapted radiative transfer code.</p><p><strong>2. The NOMAD UVIS channel</strong></p><p>NOMAD is a spectrometer composed of 3 channels: 1) a solar occultation channel (SO) operating in the infrared (2.3-4.3 μm); 2) a second infrared channel LNO (2.3-3.8 μm) capable of doing nadir, as well as solar occultation and limb; and 3) an ultraviolet/visible channel <strong>UVIS</strong> (200-650 nm) that can work in the three observation modes [2,3].</p><p>The UVIS channel has a spectral resolution <1.5 nm. In the solar occultation mode it is mainly devoted to study the climatology of <strong>ozone</strong> and <strong>aerosols</strong> content [4].</p><p>Since the beginning of operations, on 21 April 2018, NOMAD UVIS acquired more than 3000 solar occultations with an almost complete coverage of the planet.</p><p><strong>3. Retrieval technique</strong></p><p>NOMAD-UVIS spectra are simulated using the line-by-line radiative transfer code <strong>ASIMUT-ALVL</strong> developed at IASB-BIRA [5]. In a preliminary study based on SPICAM-UV solar occultations (see [6]), ASIMUT was modified to take into account the atmospheric composition and structure at the day-night terminator. As input for ASIMUT, we used gradients predicted by the 3D GEM-Mars v4 Global Circulation Model (GCM) [7,8]. UVIS ozone profiles will also be compared to SPICAM-UV retrievals.</p><p><strong> 4. Summary and future work</strong></p><p>We will present ozone vertical profiles retrieved from the first Martian year of observations from TGO/NOMAD-UVIS. In addition, we plan to compare our retrievals to SPICAM-UV observations. As first step, we will retrieve O<sub>3</sub> profiles without taking in account gradients. Then, we will investigate the effects of ozone density gradients on the retrieval of ozone.</p><p><strong>References</strong></p><p>[1] Lefèvre, F., Bertaux, J.L., Clancy, R. T., Encrenaz, T., Fast, K., Forget, F., Lebonnois, S., Montmessin, F., Perrier, S., Aug. 2008. Heterogeneous chemistry in the atmosphere of Mars. Nature 454, 971–975.</p><p>[2] Vandaele, A.C., et al., Planetary and Space Science, Vol. 119, pp. 233–249, 2015.</p><p>[3] Neefs, E., et al., Applied Optics, Vol. 54 (28), pp. 8494-8520, 2015.</p><p>[4] M.R. Patel et al., In: Appl. Opt. 56.10 (2017), pp. 2771–2782. DOI: 10.1364/AO.56.002771.</p><p>[5] Vandaele, A.C., et al., JGR, 2008. 113 doi:10.1029/2008JE003140.</p><p>[6] Piccialli, A., Icarus, 2019, </p><p>[7] Neary, L., and F. Daerden (2018), Icarus, 300, 458–476, doi:10.1016/j.icarus.2017.09.028.</p><p>[8] Daerden et al., 2019, Icarus 326, https://doi.org/10.1016/j.icarus.2019.02.030</p><!-- COMO-HTML-CONTENT-END --> <p class="co_mto_htmlabstract-citationHeader"> <strong class="co_mto_htmlabstract-citationHeader-intro">How to cite:</strong> Piccialli, A., Vandaele, A. C., Willame, Y., Aoki, S., Depiesse, C., Trompet, L., Neary, L., Viscardy, S., Daerden, F., Erwin, J., Thomas, I. R., Ristic, B., Mason, J. P., Patel, M., Bellucci, G., and Lopez-Moreno, J.-J.: Impact of gradients at the Martian terminator on the retrieval of ozone from TGO/NOMAD-UVIS, Europlanet Science Congress 2020, online, 21 September–9 Oct 2020, EPSC2020-670, 2020 </p>

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.

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