scholarly journals Seasonal Surface Air Temperature and Precipitation in the FSU Climate Model Coupled to the CLM2

2005 ◽  
Vol 18 (16) ◽  
pp. 3217-3228 ◽  
Author(s):  
D. W. Shin ◽  
S. Cocke ◽  
T. E. LaRow ◽  
James J. O’Brien
Keyword(s):  
Heat Flux ◽  
Air Temperature ◽  
Climate Model ◽  
Initial Conditions ◽  
Sensible Heat Flux ◽  
Surface Air Temperature ◽  
Community Land Model ◽  
Temperature And Precipitation ◽  
The Impact ◽  
Convective Scheme

Abstract The current Florida State University (FSU) climate model is upgraded by coupling the National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) as its land component in order to make a better simulation of surface air temperature and precipitation on the seasonal time scale, which is important for crop model application. Climatological and seasonal simulations with the FSU climate model coupled to the CLM2 (hereafter FSUCLM) are compared to those of the control (the FSU model with the original simple land surface treatment). The current version of the FSU model is known to have a cold bias in the temperature field and a wet bias in precipitation. The implementation of FSUCLM has reduced or eliminated this bias due to reduced latent heat flux and increased sensible heat flux. The role of the land model in seasonal simulations is shown to be more important during summertime than wintertime. An additional experiment that assimilates atmospheric forcings produces improved land-model initial conditions, which in turn reduces the biases further. The impact of various deep convective parameterizations is examined as well to further assess model performance. The land scheme plays a more important role than the convective scheme in simulations of surface air temperature. However, each convective scheme shows its own advantage over different geophysical locations in precipitation simulations.

scholarly journals Panama’s Current Climate Replicability in a Non-Hydrostatic Regional Climate Model Nested in an Atmospheric General Circulation Model

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1543
Author(s):  
Reinhardt Pinzón ◽  
Noriko N. Ishizaki ◽  
Hidetaka Sasaki ◽  
Tosiyuki Nakaegawa
Keyword(s):  
Regional Climate Model ◽  
Air Temperature ◽  
General Circulation ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Air Temperature ◽  
Circulation Model ◽  
Horizontal Resolution ◽  
Temperature And Precipitation ◽  
Current Climate

To simulate the current climate, a 20-year integration of a non-hydrostatic regional climate model (NHRCM) with grid spacing of 5 and 2 km (NHRCM05 and NHRCM02, respectively) was nested within the AGCM. The three models did a similarly good job of simulating surface air temperature, and the spatial horizontal resolution did not affect these statistics. NHRCM02 did a good job of reproducing seasonal variations in surface air temperature. NHRCM05 overestimated annual mean precipitation in the western part of Panama and eastern part of the Pacific Ocean. NHRCM05 is responsible for this overestimation because it is not seen in MRI-AGCM. NHRCM02 simulated annual mean precipitation better than NHRCM05, probably due to a convection-permitting model without a convection scheme, such as the Kain and Fritsch scheme. Therefore, the finer horizontal resolution of NHRCM02 did a better job of replicating the current climatological mean geographical distributions and seasonal changes of surface air temperature and precipitation.

scholarly journals Evaluation of nature-based solutions implementation scenarios, using urban surface modelling

2021 ◽  
pp. 1-42
Author(s):  
Emmanuel Panagiotakis ◽  
Dionysia Kolokotsa ◽  
Nektarios Chrysoulakis
Keyword(s):  
Heat Flux ◽  
Relative Humidity ◽  
Urban Environment ◽  
Air Temperature ◽  
Green Infrastructure ◽  
Model Simulation ◽  
Meteorological Data ◽  
Sensible Heat Flux ◽  
The Impact ◽  
The City

The present paper aims to study the impact of Nature Based Solutions (NBS) on the urban environment. The Surface Urban Energy and Water balance Scheme (SUEWS) is used to quantify the impact of NBS in the city of Heraklion, Crete, Greece, a densely built urban area. Local meteorological data and data from an Eddy Covariance flux tower installed in the city center are used for the model simulation and evaluation. Five different scenarios are tested by replacing the city’s roofs and pavements with green infrastructure, i.e., trees and grass, and water bodies. The NBS impact evaluation is based on the changes of air temperature above 2m from the ground, relative humidity and energy fluxes. A decrease of the air temperature is revealed with the highest reduction (2.3%) occurring when the pavements are replaced with grass for all scenarios. The reduction of the air temperature is followed by a decrease in turbulent sensible heat flux. For almost all cases, an increase of the relative humidity is noticed, accompanied by a considerable increase of the turbulent latent heat flux. Therefore, NBS in cities change the energy balance significantly and modify the urban environment for the citizens' benefit.

scholarly journals An assessment of climate state reconstructions obtained using particle filtering methods

2013 ◽  
Vol 9 (1) ◽  
pp. 43-74
Author(s):  
S. Dubinkina ◽  
H. Goosse
Keyword(s):  
Data Assimilation ◽  
Particle Filter ◽  
Air Temperature ◽  
Particle Filtering ◽  
Climate Model ◽  
Initial Conditions ◽  
Surface Air Temperature ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity

Abstract. In an idealized framework, we assess reconstructions of the climate state of the Southern Hemisphere during the past 150 yr using the climate model of intermediate complexity LOVECLIM and three data-assimilation methods: a nudging, a particle filter with sequential importance resampling, and an extremely efficient particle filter. The methods constrain the model by pseudo-observations of surface air temperature anomalies obtained from a twin experiment using the same model but different initial conditions. The net of the pseudo-observations is chosen to be either dense (when the pseudo-observations are given at every grid cell of the model) or sparse (when the pseudo-observations are given at the same locations as the dataset of instrumental surface temperature records HADCRUT3). All three data-assimilation methods provide with good estimations of surface air temperature and of sea ice concentration, with the extremely efficient particle filter having the best performance. When reconstructing variables that are not directly linked to the pseudo-observations of surface air temperature as atmospheric circulation and sea surface salinity, the performance of the particle filters is weaker but still satisfactory for many applications. Sea surface salinity reconstructed by the nudging, however, exhibits a patterns opposite to the pseudo-observations, which is due to a spurious impact of the nudging on the ocean mixing.

scholarly journals Amplification of the Impact of Assimilating ATOVS Radiances on Simulated Surface Air Temperatures over Canterbury by the Southern Alps, New Zealand

2012 ◽  
Vol 140 (4) ◽  
pp. 1367-1384 ◽  
Author(s):  
Yang Yang ◽  
M. Uddstrom ◽  
M. Revell ◽  
P. Andrews ◽  
R. Turner
Keyword(s):  
New Zealand ◽  
Air Temperature ◽  
Cold Front ◽  
Initial Conditions ◽  
Surface Air Temperature ◽  
Southern Alps ◽  
Limited Area ◽  
Infrared Observation ◽  
Simulated Surface ◽  
The Impact

The New Zealand Limited Area Model is used to investigate the impact of assimilating NOAA-15 and -16 Advanced Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (ATOVS) radiances on surface air temperature over Canterbury, New Zealand, for two föehn cases in January 2004. For both cases, the simulated westerly-northwesterly wind crossing the Southern Alps and descending in the lee (i.e., a föehn) was stronger with ATOVS data (pass 2) than without ATOVS data (pass 1). Also, for one case, the timing of the passage of a cold front over Canterbury was more accurately forecast in pass 2. The associated differences in the potential height ΔH and winds ΔV over South Island between pass 1 and pass 2 for both cases developed from small differences in the initial conditions. It is suggested the dynamical forcing of the Southern Alps contributes to the amplification of ΔH and ΔV. The enhanced ΔV led to stronger adiabatic descent in the lee (or a stronger föehn) with stronger adiabatic warming and surface diabatic heating in pass 2. Additionally, the later passage of the cold front in pass 2 during one case allowed a longer period of heating of the surface air ahead of the cold front. As a result, large well-organized differences in surface air temperature between pass 1 and pass 2 (ΔT of 4–10 K) occurred over Canterbury. Thus, the Southern Alps acted to amplify the impact of assimilating ATOVS radiances on simulated surface air temperature over Canterbury under föehn conditions. Verification with surface observations at five climate stations over Canterbury showed a positive impact of ATOVS radiance assimilation for the two cases.

scholarly journals Validation of the ALARO-0 model within the EURO-CORDEX framework

2016 ◽  
Vol 9 (3) ◽  
pp. 1143-1152 ◽  
Author(s):  
Olivier Giot ◽  
Piet Termonia ◽  
Daan Degrauwe ◽  
Rozemien De Troch ◽  
Steven Caluwaerts ◽  
...  
Keyword(s):  
Air Temperature ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Air Temperature ◽  
Convective Precipitation ◽  
Microphysics Scheme ◽  
Near Surface ◽  
Temperature And Precipitation ◽  
European Climate ◽  
Jackknife Procedure

Abstract. Using the regional climate model ALARO-0, the Royal Meteorological Institute of Belgium and Ghent University have performed two simulations of the past observed climate within the framework of the Coordinated Regional Climate Downscaling Experiment (CORDEX). The ERA-Interim reanalysis was used to drive the model for the period 1979–2010 on the EURO-CORDEX domain with two horizontal resolutions, 0.11 and 0.44°. ALARO-0 is characterised by the new microphysics scheme 3MT, which allows for a better representation of convective precipitation. In Kotlarski et al. (2014) several metrics assessing the performance in representing seasonal mean near-surface air temperature and precipitation are defined and the corresponding scores are calculated for an ensemble of models for different regions and seasons for the period 1989–2008. Of special interest within this ensemble is the ARPEGE model by the Centre National de Recherches Météorologiques (CNRM), which shares a large amount of core code with ALARO-0. Results show that ALARO-0 is capable of representing the European climate in an acceptable way as most of the ALARO-0 scores lie within the existing ensemble. However, for near-surface air temperature, some large biases, which are often also found in the ARPEGE results, persist. For precipitation, on the other hand, the ALARO-0 model produces some of the best scores within the ensemble and no clear resemblance to ARPEGE is found, which is attributed to the inclusion of 3MT. Additionally, a jackknife procedure is applied to the ALARO-0 results in order to test whether the scores are robust, meaning independent of the period used to calculate them. Periods of 20 years are sampled from the 32-year simulation and used to construct the 95 % confidence interval for each score. For most scores, these intervals are very small compared to the total ensemble spread, implying that model differences in the scores are significant.

Horizontal heat impacts of a bare facade on air temperature in an adjacent green plot within pedestrian heights in Beijing

2019 ◽  
pp. 1420326X1989267
Author(s):  
Hongxuan Zhou ◽  
Guan Wang ◽  
Dan Hu ◽  
Jing Sun
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Atmospheric Environment ◽  
Dominant Factor ◽  
Sensible Heat ◽  
Significance Level ◽  
The Impact

This study focuses on the horizontal heat impact of facades on the surrounding atmospheric environment at pedestrian heights. The results show that (1) the horizontal heat impact of a facade on the surrounding atmosphere was relatively uniform due to the homogeneous energy flux near the facade; (2) the significance of horizontal heat impacts gradually weakened with height, and the average significance was 48.74% in the spring and 47.81% in the summer; (3) energy factors, such as net radiation, soil heat flux, sensible heat flux, latent heat flux, and ground radiation, influenced the significance of the air temperature difference between the two observation sites where the investigation was conducted; one site was near the facade (distance = 0.30 m), the other one was far from the wall (distance = 10 m), and no dominant factor was found; and (4) the sensible heat flux was higher at the site near the facade than at the site far from the facade at the 0.05 significance level in the summer, which could be attributed to the strong horizontal heat impact from the facade. In contrast, the impact of the facade on the latent heat flux was not significant at the 0.05 significance level in the summer.

scholarly journals An assessment of particle filtering methods and nudging for climate state reconstructions

2013 ◽  
Vol 9 (3) ◽  
pp. 1141-1152 ◽  
Author(s):  
S. Dubinkina ◽  
H. Goosse
Keyword(s):  
Data Assimilation ◽  
Particle Filter ◽  
Air Temperature ◽  
Particle Filtering ◽  
Climate Model ◽  
Initial Conditions ◽  
Surface Air Temperature ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity

Abstract. Using the climate model of intermediate complexity LOVECLIM in an idealised framework, we assess three data-assimilation methods for reconstructing the climate state. The methods are a nudging, a particle filter with sequential importance resampling, and a nudging proposal particle filter and the test case corresponds to the climate of the high latitudes of the Southern Hemisphere during the past 150 yr. The data-assimilation methods constrain the model by pseudo-observations of surface air temperature anomalies obtained from the same model, but different initial conditions. All three data-assimilation methods provide with good estimations of surface air temperature and of sea ice concentration, with the nudging proposal particle filter obtaining the highest correlations with the pseudo-observations. When reconstructing variables that are not directly linked to the pseudo-observations such as atmospheric circulation and sea surface salinity, the particle filters have equivalent performance and their correlations are smaller than for surface air temperature reconstructions but still satisfactory for many applications. The nudging, on the contrary, obtains sea surface salinity patterns that are opposite to the pseudo-observations, which is due to a spurious impact of the nudging on vertical exchanges in the ocean.

scholarly journals Numerical simulations of the impact of the 20 March 2015 eclipse on UK weather

2016 ◽  
Vol 374 (2077) ◽  
pp. 20150218 ◽  
Author(s):  
P. A. Clark
Keyword(s):  
Boundary Layer ◽  
Air Temperature ◽  
Urban Areas ◽  
Weather Prediction ◽  
Sensible Heat Flux ◽  
Thermal Inertia ◽  
Surface Air Temperature ◽  
Atmospheric Effects ◽  
Near Surface ◽  
The Impact

Short lead-time forecasts using the operational United Kingdom variable-resolution (UKV) configuration of the Met Office’s numerical weather prediction model, with horizontal grid-length 1.5 km over the UK, with and without a representation of the 20 March 2015 eclipse, have been used to simulate the impact of the eclipse on UK weather. The major impact was surface-driven through changes to surface heat and moisture fluxes that changed the boundary-layer development. In cloud-free areas, the nocturnal stable boundary layer persisted or quickly re-established during the eclipse. Surface temperatures were reduced by 7–8°C, near-surface air temperature by 1–3°C, and near-surface winds were backed, typically by 20°. Impacts on wind speed were small and variable, and would have been very difficult to detect. Smaller impacts occurred beneath cloud. However, the impact was enhanced because most of the incoming radiation that reached the surface was driving surface sensible heat flux rather than moisture flux, and the near-surface air temperature impact (0.5–1° C ) agrees reasonably well with observations. The modelled impact of the eclipse was substantially reduced in urban areas due to their large thermal inertia. Experience from other assessments of the model suggests that this lack of response may be exaggerated. Surface impacts propagated upwards and downstream with time, resulting in a complex pattern of response, though generally near-surface temperature differences persisted for many hours after the eclipse. The impact on atmospheric pressure fields was insufficient to account for any significant perturbations to the wind field when compared with the direct impacts of surface stress and boundary-layer mixing. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’.

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