On the relationship of orography with extreme dry spells in Greece

Abstract. The objective of this study is to investigate the relationship of orography over Greece with prolonged dry spells, as represented by the maximum number consecutive dry days (CDD index) during an extremely dry summer. For this purpose a simulation experiment was conducted with the aid of the regional climate model RegCM3.1 using a spatial resolution of 10 km. It was shown that a significant precipitation regime formed over the mountainous areas of continental Greece and Crete during this dry summer, due to orographically forced precipitation, consequently influencing the length of dry spells. Furthermore, the CDD appears spatial variations over the maritime areas, despite the zero or insignificant precipitation. The sensitivity test that was performed with the elimination of orography demonstrated the important role that orography plays in the distribution of CDD, since significant lengthening of extreme dry spells was found over the mountainous areas.

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Implementation of an Urban Parameterization Scheme into the Regional Climate Model COSMO-CLM

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-12-0209.1 ◽

2013 ◽

Vol 52 (10) ◽

pp. 2296-2311 ◽

Cited By ~ 28

Author(s):

Kristina Trusilova ◽

Barbara Früh ◽

Susanne Brienen ◽

Andreas Walter ◽

Valéry Masson ◽

...

Keyword(s):

Spatial Resolution ◽

Climate Model ◽

Spatial Scales ◽

Regional Climate ◽

Coupled Model ◽

Urban Land ◽

Urban Land Use ◽

Small Scale ◽

Model Simulations ◽

Scale Modelling

AbstractAs the nonhydrostatic regional model of the Consortium for Small-Scale Modelling in Climate Mode (COSMO-CLM) is increasingly employed for studying the effects of urbanization on the environment, the authors extend its surface-layer parameterization by the Town Energy Budget (TEB) parameterization using the “tile approach” for a single urban class. The new implementation COSMO-CLM+TEB is used for a 1-yr reanalysis-driven simulation over Europe at a spatial resolution of 0.11° (~12 km) and over the area of Berlin at a spatial resolution of 0.025° (~2.8 km) for evaluating the new coupled model. The results on the coarse spatial resolution of 0.11° show that the standard and the new models provide 2-m temperature and daily precipitation fields that differ only slightly by from −0.1 to +0.2 K per season and ±0.1 mm day−1, respectively, with very similar statistical distributions. This indicates only a negligibly small effect of the urban parameterization on the model's climatology. Therefore, it is suggested that an urban parameterization may be omitted in model simulations on this scale. On the spatial resolution of 0.025° the model COSMO-CLM+TEB is able to better represent the magnitude of the urban heat island in Berlin than the standard model COSMO-CLM. This finding shows the importance of using the parameterization for urban land in the model simulations on fine spatial scales. It is also suggested that models could benefit from resolving multiple urban land use classes to better simulate the spatial variability of urban temperatures for large metropolitan areas on spatial scales below ~3 km.

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A Preliminary Study on the Relationship between Vegetation Cover and Regional Climate Change in Jiangsu Area of China

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.916 ◽

2013 ◽

Vol 448-453 ◽

pp. 916-922

Author(s):

Yan Rong Yang ◽

Zhe Kong ◽

Chun Ming Liu

Keyword(s):

Climate Change ◽

Vegetation Cover ◽

Vegetation Index ◽

Climate Model ◽

Regional Climate ◽

Precipitation Amount ◽

Regional Climate Change ◽

Research Field ◽

Research Fields ◽

The Relationship

The relationship between vegetation cover and climate change is one of the most important research fields in global change. Herein Jiangsu province and thereabout in China is chosen to be the research field. Under the support of observations from normalized differential vegetation index (NDVI) during years from 1998 to 2008 and corresponding benchmark weather stations, the relationship between vegetation and climate change had been analyzed combined with simulations from regional climate model RegCM3, in perspectives of point vegetation cover amount and area vegetation cover type respectively. Conclusions are: (1) Points observations showed that NDVI had positive correlation with annual total precipitation and negative correlation with annual average temperature. (2) Area simulations showed that two different vegetation types in south and north Jiangsu almost had same 8warming value, but the incremental annual precipitation amount is more significant in south Jiangsu.

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Impact of RCM Spatial Resolution on the Reproduction of Local, Subdaily Precipitation

Journal of Hydrometeorology ◽

10.1175/jhm-d-14-0007.1 ◽

2015 ◽

Vol 16 (2) ◽

pp. 534-547 ◽

Cited By ~ 20

Author(s):

Jonas Olsson ◽

Peter Berg ◽

Akira Kawamura

Keyword(s):

Spatial Resolution ◽

Climate Model ◽

Positive Impact ◽

Regional Climate ◽

Low Frequency ◽

Small Scale ◽

Hydrological Hazards ◽

Change Impact ◽

Urban Catchments ◽

Intensity Duration Frequency

Abstract Many hydrological hazards are closely connected to local precipitation (extremes), especially in small and urban catchments. The use of regional climate model (RCM) data for small-scale hydrological climate change impact assessment has long been nearly unfeasible because of the low spatial resolution. The RCM resolution is, however, rapidly increasing, approaching the size of small catchments and thus potentially increasing the applicability of RCM data for this purpose. The objective of this study is to explore to what degree subhourly temporal precipitation statistics in an RCM converge to observed point statistics when gradually increasing the resolution from 50 to 6 km. This study uses precipitation simulated by RCA3 at seven locations in southern Sweden during 1995–2008. A positive impact of higher resolution was most clearly manifested in 10-yr intensity–duration–frequency (IDF) curves. At 50 km the intensities are underestimated by 50%–90%, but at 6 km they are nearly unbiased, when averaged over all locations and durations. Thus, at 6 km, RCA3 apparently generates low-frequency subdaily extremes that resemble the values found in point observations. Also, the reproduction of short-term variability and less extreme maxima were overall improved with increasing resolution. For monthly totals, a slightly increased overestimation with increasing resolution was found. The bias in terms of wet fraction and wet spell characteristics was overall not strongly dependent on resolution. These metrics are, however, influenced by the cutoff threshold used to separate between wet and dry time steps as well as the wet spell definition.

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Influence of spatial resolution on regional climate model derived wind climates

Journal of Geophysical Research Atmospheres ◽

10.1029/2011jd016822 ◽

2012 ◽

Vol 117 (D3) ◽

pp. n/a-n/a ◽

Cited By ~ 38

Author(s):

S. C. Pryor ◽

G. Nikulin ◽

C. Jones

Keyword(s):

Regional Climate Model ◽

Spatial Resolution ◽

Climate Model ◽

Regional Climate

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Highway Alignment Parameters Design and Capacity Analysis on Two-Lane Highway

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.539.860 ◽

2014 ◽

Vol 539 ◽

pp. 860-866

Author(s):

Jiang Liu

Keyword(s):

Capacity Analysis ◽

Horizontal Curve ◽

Mountainous Areas ◽

Key Factors ◽

Horizontal Curves ◽

Percent Time ◽

Simulation Results ◽

Relationship Of ◽

Highway Alignment ◽

The Relationship

A two-lane highway is an undivided highway with only one lane of traffic in each direction. Two-lane highways are one of the most common roadways at mountainous areas in China. Due to the wider range to choose the horizontal and vertical curves in the design of two-lane highways, the combination of both leads to larger differences on two-lane highway capacities. Thus, the highway alignments are one of the key factors which affect the two-lane highway capacities. According to the empirical data and existing studies, it is regarded that there is no impacts on the capacity for horizontal curves with a radius more than 400m and vertical curves with the gradient less than 3%. Two concepts are defined as effective bending and effective gradient which represent the extent the horizontal curve bends and the steepness of vertical curve respectively. The method to calculate effective bending of horizontal curve and steepness of vertical curve is given and its relevant properties are also discussed. According to the simulation results and the principle of speed differences, the effective bending and effective gradient have been classified into 7 and 6 levels, separately. As a result, there will be 42 combinations of different highway alignments of two-lane highways based on the different combinations of the effective bending and effective gradient. Under this circumstance, the relationship of speed-volume and volume-PTSF (percent time spend following) are obtained from the simulation results. Finally, the capacity of two-lane highway is given under different highway alignments of two-lane highway at mountainous areas in China.

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Applying an isotope-enabled regional climate model over the Greenland ice sheet: effect of spatial resolution on model bias

Climate of the Past ◽

10.5194/cp-17-1685-2021 ◽

2021 ◽

Vol 17 (4) ◽

pp. 1685-1699

Author(s):

Marcus Breil ◽

Emanuel Christner ◽

Alexandre Cauquoin ◽

Martin Werner ◽

Melanie Karremann ◽

...

Keyword(s):

Spatial Resolution ◽

General Circulation ◽

Climate Model ◽

Regional Climate ◽

Circulation Model ◽

Ice Cores ◽

Arctic Region ◽

The Arctic ◽

Simulation Results ◽

The Arctic Region

Abstract. In order to investigate the impact of spatial resolution on the discrepancy between simulated δ18O and observed δ18O in Greenland ice cores, regional climate simulations are performed with the isotope-enabled regional climate model (RCM) COSMO_iso. For this purpose, isotope-enabled general circulation model (GCM) simulations with the ECHAM5-wiso general circulation model (GCM) under present-day conditions and the MPI-ESM-wiso GCM under mid-Holocene conditions are dynamically downscaled with COSMO_iso for the Arctic region. The capability of COSMO_iso to reproduce observed isotopic ratios in Greenland ice cores for these two periods is investigated by comparing the simulation results to measured δ18O ratios from snow pit samples, Global Network of Isotopes in Precipitation (GNIP) stations and ice cores. To our knowledge, this is the first time that a mid-Holocene isotope-enabled RCM simulation is performed for the Arctic region. Under present-day conditions, a dynamical downscaling of ECHAM5-wiso (1.1∘×1.1∘) with COSMO_iso to a spatial resolution of 50 km improves the agreement with the measured δ18O ratios for 14 of 19 observational data sets. A further increase in the spatial resolution to 7 km does not yield substantial improvements except for the coastal areas with its complex terrain. For the mid-Holocene, a fully coupled MPI-ESM-wiso time slice simulation is downscaled with COSMO_iso to a spatial resolution of 50 km. In the mid-Holocene, MPI-ESM-wiso already agrees well with observations in Greenland and a downscaling with COSMO_iso does not further improve the model–data agreement. Despite this lack of improvement in model biases, the study shows that in both periods, observed δ18O values at measurement sites constitute isotope ratios which are mainly within the subgrid-scale variability of the global ECHAM5-wiso and MPI-ESM-wiso simulation results. The correct δ18O ratios are consequently not resolved in the GCM simulation results and need to be extracted by a refinement with an RCM. In this context, the RCM simulations provide a spatial δ18O distribution by which the effects of local uncertainties can be taken into account in the comparison between point measurements and model outputs. Thus, an isotope-enabled GCM–RCM model chain with realistically implemented fractionating processes constitutes a useful supplement to reconstruct regional paleo-climate conditions during the mid-Holocene in Greenland. Such model chains might also be applied to reveal the full potential of GCMs in other regions and climate periods, in which large deviations relative to observed isotope ratios are simulated.

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Spatial Correlation between Altitude & other Climatic Variables : A Climatic Model of Kashmir Region using Regression Analysis

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.f9391.038620 ◽

2020 ◽

Vol 8 (6) ◽

pp. 4388-4391

Keyword(s):

Spatial Resolution ◽

Climate Model ◽

Climatic Variables ◽

Regression Equations ◽

Climate Data ◽

Annual Average ◽

Average Wind Speed ◽

Significance Level ◽

Elevation Model ◽

The Relationship

Kashmir has been encountering expanded temperature and change in precipitation system, which may antagonistically influence the significant environments in the nation differentially. In this study a effort has been put forward to deduce a relationship between altitude & other climatic variables such as Annual average temperature, Annual average precipitation, Annual average wind speed, Annual average solar radiation, Annual average max temperature, Annual average min temperature & Annual average vapor pressure. The data used for this study was provided by worldclim (version2.0), the spatial resolution of the data was about 1 km². The large study area & fine spatial resolution produced a vast amount of data points, which were analyzed with a significance level of the tests at 5%. Further for analysis the data was divided into zones categorized according to the elevation zones, this was mainly done to ease the work flow as the observation points were vast and also to reduce the standard error for each of the variables during analysis. Based on the climate data and the DEM (Digital Elevation Model) used for this study we deduced four multiple linear regression equations for four elevation zones, which describe the relationship between altitude & climatic variables. Although deducing a climate model which can precisely define relationship between the climatic variables & altitude is a challenge although an effort has been made to describe the relationship between elevation and climatic variables.

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Impact of spatial resolution on the modelling of the Greenland ice sheet surface mass balance between 1990–2010, using the regional climate model MAR

The Cryosphere ◽

10.5194/tc-6-695-2012 ◽

2012 ◽

Vol 6 (3) ◽

pp. 695-711 ◽

Cited By ~ 58

Author(s):

B. Franco ◽

X. Fettweis ◽

C. Lang ◽

M. Erpicum

Keyword(s):

Regional Climate Model ◽

Mass Balance ◽

Spatial Resolution ◽

Climate Model ◽

Regional Climate ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Dynamical Model ◽

Surface Mass Balance ◽

Surface Mass

Abstract. With the aim to force an ice dynamical model, the Greenland ice sheet (GrIS) surface mass balance (SMB) was modelled at different spatial resolutions (15–50 km) for the period 1990–2010, using the regional climate model MAR (Modèle Atmosphérique Régional) forced by the ERA-INTERIM reanalysis. This comparison revealed that (i) the inter-annual variability of the SMB components is consistent within the different spatial resolutions investigated, (ii) the MAR model simulates heavier precipitation on average over the GrIS with decreasing spatial resolution, and (iii) the SMB components (except precipitation) can be derived from a simulation at lower resolution with an "intelligent" interpolation. This interpolation can also be used to approximate the SMB components over another topography/ice sheet mask of the GrIS. These results are important for the forcing of an ice dynamical model needed to enable future projections of the GrIS contribution to sea level rise over the coming centuries.

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Dynamical Downscaling Luaran Global Climate Model (GCM) Menggunakan Model REGCM3 untuk Proyeksi Curah Hujan di Kabupaten Indramayu

Agromet ◽

10.29244/j.agromet.28.1.9-16 ◽

2018 ◽

Vol 28 (1) ◽

pp. 9

Author(s):

Syamsu Dwi Jadmiko ◽

Akhmad Faqih

Keyword(s):

Regional Climate Model ◽

Spatial Resolution ◽

Climate Model ◽

Dynamical Downscaling ◽

High Spatial Resolution ◽

Global Climate ◽

Global Climate Model ◽

Regional Climate ◽

Equations Of Motion ◽

Daily Rainfall

Future rainfall projection can be predicted by using Global Climate Model (GCM). In spite of low resolution, we are not able specifically to describe a local or regional information. Therefore, we applied downscaling technique of GCM output using Regional Climate Model (RCM). In this case, Regional Climate Model version 3 (RegCM3) is used to accomplish this purpose. RegCM3 is regional climate model which atmospheric properties are calculated by solving equations of motion and thermodynamics. Thus, RegCM3 is also called as dynamic downscaling model. RegCM3 has reliable capability to evaluate local or regional climate in high spatial resolution up to 10 × 10 km. In this study, dynamically downscaling techniques was applied to produce high spatial resolution (20 × 20 km) from GCM EH5OM output which commonly has rough spatial resolution (1.875<sup>o</sup> × 1.875<sup>o</sup>). Simulation show that future rainfall in Indramayu is relatively decreased compared to the baseline condition. Decreased rainfall generally occurs during the dry season (July-June-August/JJA) in a range 10-20%. Study of extreme daily rainfall indicates that there is no significant increase or decrease value.

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