scholarly journals Numerical simulation of rainfall with assimilation of conventional and GPS observations over north of Iran

2016 ◽  
Vol 59 (3) ◽  
Author(s):  
Mohammad Ali Sharifi ◽  
Majid Azadi ◽  
Ali Sam Khaniani
Keyword(s):  
Relative Humidity ◽  
Caspian Sea ◽  
Model Simulation ◽  
Global Analysis ◽  
Three Dimensional ◽  
Wrf Model ◽  
Precipitable Water ◽  
Absolute Error ◽  
The Caspian Sea ◽  
North Of Iran

<p>In this work, the effect of assimilation of synoptic, radiosonde and ground-based GPS precipitable water vapor (PWV) data has been investigated on the short-term prediction of precipitation, vertical relative humidity and PWV fields over north of Iran. We selected two rainfall events (i.e. February 1, 2014, and September 17, 2014) caused by synoptic systems affecting the southern coasts of the Caspian Sea. These systems are often associated with a shallow and cold high pressure located over Russia that extends towards the southern Caspian Sea. The three dimensional variational (3DVAR) data assimilation system of the weather research and forecasting (WRF) model is used in two rainfall cases. In each case, three numerical experiments, namely CTRL, CONVDA and GPSCONVDA, are performed. The CTRL experiment uses the global analysis as the initial and boundary conditions of the model. In the second experiment, surface and radiosonde observations are inserted into the model. Finally, the GPSCONVDA experiment uses the GPS PWV data in the assimilation process in addition to the conventional observations. It is found that in CONVDA experiment, the mean absolute error (MAE) of the accumulated precipitation is reduced about 5 and 13 percent in 24h model simulation of February and September cases, respectively, when compared to CTRL. Also, the results in both cases suggest that the assimilation of GPS data has the greatest impact on model PWV simulations, with maximum root mean squares error (RMSE) reduction of 0.7 mm. In the GPSCONVDA experiment, comparison of the vertical profiles of 12h simulated relative humidity with the corresponding radiosonde observations shows a slight improvement in the lower levels.</p>

scholarly journals Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction

Ocean Science ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 311-329 ◽  
Author(s):  
R. A. Ibrayev ◽  
E. Özsoy ◽  
C. Schrum ◽  
H. İ. Sur
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Caspian Sea ◽  
Seasonal Cycle ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Coastal Currents ◽  
The Caspian Sea ◽  
Sea Surface Topography

Abstract. A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. The model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.

scholarly journals A Numerical Simulation of Extratropical Storm Surge and Hydrodynamic Response in the Bohai Sea

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yumei Ding ◽  
Lei Ding
Keyword(s):  
Storm Surge ◽  
Bohai Sea ◽  
Model Simulation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Ocean Model ◽  
Tidal Currents ◽  
The Bohai Sea ◽  
Hydrodynamic Response ◽  
Coastal Ocean Model

A hindcast of typical extratropical storm surge occurring in the Bohai Sea in October 2003 is performed using a three-dimensional (3D) Finite Volume Coastal Ocean Model (FVCOM). The storm surge model is forced by 10 m winds obtained from the Weather Research Forecasting (WRF) model simulation. It is shown that the simulated storm surge and tides agree well with the observations. The nonlinear interaction between the surge and astronomical tides, the spatial distribution of the maximum surge level, and the hydrodynamic response to the storm surge are studied. The storm surge is the interaction of the surge and the astronomical tides. The currents change rapidly during the storm surge and turn to be the unidirectional at some places where the tidal currents are usually rectilinear. The results show that the local surge current velocity in each depth, with a magnitude of the same order as the astronomic tidal currents, increases or decreases rapidly depending on the relationship between the winds and current directions. Furthermore, the current pattern gets more complicated under the influence of the direction of the winds, which might affect sand movement in the coastal water of the Bohai Sea.

Verbascum shahsavarensis (Scrophulariaceae), a new species for Flora of Iran

Phytotaxa ◽  
2015 ◽  
Vol 203 (1) ◽  
pp. 76 ◽  
Author(s):  
Arash SOTOODEH ◽  
Laure Civeyrel ◽  
Farideh Attar
Keyword(s):  
New Species ◽  
Endemic Species ◽  
Caspian Sea ◽  
The Other ◽  
Distribution Map ◽  
Flora Of Iran ◽  
The Caspian Sea ◽  
Coastal City ◽  
North Of Iran ◽  
A New Species

A new endemic species, Verbascum shahsavarensis, is described from north of Iran. Based on two unique characters of this species, these being two anterior longitudinally obliquely inserted anthers and an ebracteolate pedicel, we compared it to species described by Murbeck in 1933. The new species can be easily distinguished from the other Iranian species by having bi-colored hairs on the stamen filaments and the unique anther and pedicel characters. A distribution map is provided. The name of new species comes from Shahsavar, the ancient name of Tonekabon, an old coastal city on the Caspian Sea.

scholarly journals Evaluation of squared timber and log products in the Hyrcanian Forests of Iran

2011 ◽  
Vol 57 (No. 2) ◽  
pp. 64-69 ◽  
Author(s):  
M. Hosseini S ◽  
B. Majnounian ◽  
A. Skoupý
Keyword(s):  
Linear Equation ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Hyrcanian Forests ◽  
The North ◽  
Northern Areas ◽  
North Of Iran ◽  
Timber Products

The forests located in the northern areas of Iran are known as Hyrcanian Forests and are distributed across three provinces, namely Gilan, Maznadarn and Golestan. These provinces are situated in the north of Iran near the Caspian Sea. Timber products in the said forests during the last two decades were markedly different so that the total timber harvested in the first decade was 1.6 million m3 on average, however, in the second decade it nearly amounted to 1 million m<sup>3</sup>. Two major timber products of Iran are studied and compared in this research, namely logs and squared timber. Squared timber products averaged 10.7% during the first decade, but they fell to 7.3% over the second decade. Apropos of log products, they reached 20.9% and 29.2% over the first and the second decade, respectively. Analyses of the data indicate the following converse linear equation between squared timber products and log products during the 20 years of study: Y =&ndash;0.359X + 18.065 (Y = log products, X = squared timber, R<sup>2</sup> = 0.768).Accordingly, any increase in log products at a time caused the squared timber products to decrease at the same time.

scholarly journals Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction

2009 ◽  
Vol 6 (3) ◽  
pp. 1913-1970 ◽  
Author(s):  
R. A. Ibrayev ◽  
E. Özsoy ◽  
C. Schrum ◽  
H. İ. Sur
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Caspian Sea ◽  
Seasonal Cycle ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Coastal Currents ◽  
The Caspian Sea ◽  
Sea Surface Topography

Abstract. A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. Model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.

scholarly journals Impacts of Biomass Burning Emission Inventories and Atmospheric Reanalyses on Simulated PM10 over Indochina

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 160
Author(s):  
Kyohei Takami ◽  
Hikari Shimadera ◽  
Katsushige Uranishi ◽  
Akira Kondo
Keyword(s):  
Air Quality ◽  
Biomass Burning ◽  
Model Simulation ◽  
Global Analysis ◽  
Wrf Model ◽  
The United States ◽  
Emission Inventories ◽  
Fire Emissions ◽  
Percentage Difference ◽  
Environmental Prediction

Biomass burning (BB) is a major source of atmospheric particles over Indochina during the dry season. Moreover, Indochina has convoluted meteorological scales, and regional meteorological conditions dominate the transport patterns of pollutants. This study focused on the impacts of BB emission inventories and atmospheric reanalyses on simulated PM10 over Indochina in 2014 using the Community Multiscale Air Quality (CMAQ) model. Meteorological fields to input to CMAQ were produced by using the Weather Research and Forecasting (WRF) model simulation with the United States National Centers for Environmental Prediction Final (NCEP FNL) Operational Global Analysis or European Centre for Medium Range Weather Forecasts Interim Reanalysis (ERA-interim). The Fire INventory from NCAR (FINN) v1.5 or the Global Fire Emissions Database including small fires (GFED v4.1s) was selected for BB emissions for the air quality simulation. The simulation case with NCEP FNL and FINN v1.5 (FNL + FINN) performed best throughout 2014, including the season when BB activities were intensified. The normalized percentage difference for maximum daily mean PM10 concentrations at Chiang Mai for FNL + FINN and the two simulation cases applying GFED v4.1s for BB emissions (−53% to −27%) was much larger than that between the FNL + FINN and ERA + FINN cases (10%). BB emission inventories more strongly impacted PM10 simulation than atmospheric reanalyses in highly polluted areas by BB over Indochina in 2014.

scholarly journals Investigation of observational error sources in multi-Doppler-radar three-dimensional variational vertical air motion retrievals

2019 ◽  
Vol 12 (3) ◽  
pp. 1999-2018 ◽  
Author(s):  
Mariko Oue ◽  
Pavlos Kollias ◽  
Alan Shapiro ◽  
Aleksandra Tatarevic ◽  
Toshihisa Matsui
Keyword(s):  
Doppler Radar ◽  
Model Simulation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Sampling Time ◽  
Added Value ◽  
Limiting Factors ◽  
Convective Systems ◽  
Air Motion ◽  
Wind Retrievals

Abstract. Multi-Doppler-radar network observations have been used in different configurations over the last several decades to conduct three-dimensional wind retrievals in mesoscale convective systems. Here, the impacts of the selected radar volume coverage pattern (VCP), the sampling time for the VCP, the number of radars used, and the added value of advection correction on the retrieval of the vertical air motion in the upper part of convective clouds are examined using the Weather Research and Forecasting (WRF) model simulation, the Cloud Resolving Model Radar SIMulator (CR-SIM), and a three-dimensional variational multi-Doppler-radar retrieval technique. Comparisons between the model truth (i.e., WRF kinematic fields) and updraft properties (updraft fraction, updraft magnitude, and mass flux) retrieved from the CR-SIM-generated multi-Doppler-radar field are used to investigate these impacts. The findings are that (1) the VCP elevation strategy and sampling time have a significant effect on the retrieved updraft properties above 6 km in altitude; (2) 2 min or shorter VCPs have small impacts on the retrievals, and the errors are comparable to retrievals using a snapshot cloud field; (3) increasing the density of elevation angles in the VCP appears to be more effective to reduce the uncertainty than an addition of data from one more radar, if the VCP is performed in 2 min; and (4) the use of dense elevation angles combined with an advection correction applied to the 2 min VCPs can effectively improve the updraft retrievals, but for longer VCP sampling periods (5 min) the value of advection correction is challenging. This study highlights several limiting factors in the retrieval of upper-level vertical velocity from multi-Doppler-radar networks and suggests that the use of rapid-scan radars can substantially improve the quality of wind retrievals if conducted in a limited spatial domain.

scholarly journals Obesity in the north of Iran (South-East of the Caspian Sea)

2011 ◽  
Vol 36 (3) ◽  
pp. 100-101 ◽  
Author(s):  
Gholamreza Veghari ◽  
Hamidreza Joshaghani ◽  
Farhad Niknezhad ◽  
Mehdi Sedaghat ◽  
Ahmad Hoseini ◽  
...  
Keyword(s):  
Caspian Sea ◽  
The Caspian Sea ◽  
The North ◽  
North Of Iran

DOI: 10.3329/bmrcb.v36i3.6167Bangladesh Med Res Counc Bull 2010; 36: 100-101

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