The most effective scheme in improving the performance of the WRF model for precipitation over northwest Iran
Shaghayegh
Moradi
Atmospheric Science and Meteorological Research Institute
author
Sohaila
Javanmard
Faculty member of physical meteorology and weather modification, Atmospheric Science and Meteorological research Center,
author
Sarmad
Ghader
Faculty member of Atmospheric Science and Meteorological Research Institute
author
Majid
Azadi
Faculty member of Atmospheric Science and Meteorological Research Institute
author
Maryam
Gharayloo
Faculty member of Geophysics Institute, Tehran University, Tehran, Iran
author
text
article
2020
per
Evaluation of the performance of the parameterization schemes used in the WRF model is assessed for precipitation over northwest Iran at a 5 km by 5 km grid. Simulations are performed for a winter day. A step-wise decision approach is followed, beginning with seven simulations for the various Cumulus schemes and then four microphysics schemes; after that, 36 different configurations of the model’s PBL, Long-wave, Short-wave, and Land Surface schemes were tested. Root-Mean-Squared-Error chooses the best performing scheme at each step. The concluding scheme set consists of the Lin et al. microphysics scheme, the MYJ PBL scheme, the Dudhia scheme for shortwave, the RRTM for longwave radiation, Eta Similarity option for the Land Surface scheme, and without cumulus scheme. In this study, combinations of schemas that have the most and least effect on the distribution of simulated precipitation data were also identified. For this purpose, 36 configurations are adopted for longwave radiation, shortwave radiation, and boundary layer schemes in 12 groups of three with rotation of shortwave radiation and 12 groups of three with rotation of longwave schema, and in 9 groups of 4 with rotation of the boundary layer scheme was divided, and simulated precipitation variance and sd was calculated for these 33 groups. Thus, among the configurations created, the configurations that have the most and the least effect in estimating the six-hour rainfall and their scattering were identified. The results of the scatter study of each group of precipitation estimated data calculated by variance showed that the change in the choice of the boundary layer scheme when longwave radiation scheme is the RRTM scheme and short wave radiation scheme is the Goddard scheme, can bring the results closer to observation. Changes in the choice of shortwave radiation when longwave radiation is CAM and boundary layer scheme is the MYJ scheme has the least effect on precipitation estimation. This indicates the variability of selecting the most effective schema in precipitation prediction and can be influential in choosing the configuration in ensemble precipitation.
Journal of Meteorology and Atmospheric Science
Iran Meteorology Society (IMS)
2645-7261
3
v.
3
no.
2020
188
200
https://www.ims-jmas.net/article_132634_99a6e01dfe80f96145b4b85ba3e1f61d.pdf
dx.doi.org/10.22034/jmas.2021.286905.1138
Investigation of climatological changes in height of freezing level in some Mehrabad, Mashhad, and Kermanshah airports
sakineh
khansalari
Assistant professor, Atmospheric Science and Meteorological Research Center,Tehran, Iran
author
text
article
2020
per
Identifying and studying freezing level is an important issue in aviation weather science. Due to the global warming climate, the altitude of freezing level, especially in the subtropical, is increasing, which has attracted the attention of many meteorological and climatological researchers, and many studies have been conducted in this field. To quantify these changes, it is necessary to statistically study the changes in freezing level elevation due to climate change and global warming. In this study, in order to identify the freezing level at each point, temperature information was used at different levels of the atmosphere above that point. The oldest and most common method for determining freezing level is the use of radio-sounding data, and this method is performed twice a day at 00 and 12 UTC. Therefore, due to the dispersion of this data in the period under study (if available), this information was collected at three stations of Mehrabad, Mashhad, and Kermanshah airports. Analysis of freezing level changes in selected airports of the country, in different months, seasons, and years using the Mann-Kendall test, does not show an upward or downward trend. In other words, monthly and seasonal changes in the height of this level in different years are not dependent on climate change. Synoptic investigating indicate that changes in the altitude of the freezing level at different years depend on atmospheric systems and the synoptic conditions of the studied month or season.
Journal of Meteorology and Atmospheric Science
Iran Meteorology Society (IMS)
2645-7261
3
v.
3
no.
2020
201
223
https://www.ims-jmas.net/article_139807_93a04f778b45ce3b9b6176d2043100bb.pdf
dx.doi.org/10.22034/jmas.2021.290442.1142
Synoptic and dynamical analysis of the cyclonic occurrence of heavy rains during the cold period of western Iran
rastegar
mohammadi
Kharazmi University
author
mohammad
saligheh
kharazmi University
author
Mohammad Hossein
Naserzadeh
Kharazmi University
author
Mehri
Akbari
Kharazmi University
author
text
article
2020
per
Cyclonic systems are generally unstable conditions messenger that result from the spread of significant disturbances that occur in atmospheric currents. In this study, daily rainfall data of 4 catchments and gridded data (ECMWF) with 6-hour time steps and spatial separation of 0.25 * 0.25 from 1979 to 2004 were used. using with the cluster analysis method 3 atmospheric patterns were extracted. where the center of the trough in 500 and 700 hPa Stacking on top of each other, the geopotential height is the minimum and the geopotential gradient will be the maximum and will lead to the occurrence of the most cyclogenesis, Which occurred in the first pattern these conditions and resulted in average heavy rainfall of 38.6 mm. In the second pattern, none of the conditions of stacking on top of each other and deeping of the trough, and this has led to the lowest average heavy rainfall of 32.7 mm. In the third pattern, the condition of matching of the two centers of the troughs is established, but they do not condition of deeping trough And have led to heavy rainfall of 36/1 mm which is less than the first pattern. Also, the most cyclogeneses location in the eastern Mediterranean to Iraq, heavy rains caused by cyclones are born in this region. The results also showed that most of the moisture comes from the Red Sea. the subtropical jet stream plays a role in strengthening and ascending, in the north of Saudi Arabia and the Persian Gulf.
Journal of Meteorology and Atmospheric Science
Iran Meteorology Society (IMS)
2645-7261
3
v.
3
no.
2020
224
241
https://www.ims-jmas.net/article_139808_8c7d8b87698b32ed74a8d7d13995352d.pdf
dx.doi.org/10.22034/jmas.2021.272997.1123
Investigation of synoptic mechanism on formation of leeward cyclogenisis in iran
hassan
haji mohamadi
author
reza
doostan
Assistant Professor of climatology at Ferdowsi University of Mashhad
author
majid
habibi nokhandan
Member of the Faculty of Climatology and Head of the National Center for Climatology and Climatology
author
text
article
2020
per
To investigate the mechanism governing the formation of cyclones in Iran over a period of 18 years (2017-2000) using the National Geological Survey's Center for Environmental Prediction / Atmospheric Sciences (NCEP / NCAR) 2.5 Geographic Resolution And the European Center for Medium Term Forecasting (ECMWF), with a resolution of 0.125 °, identified the phenomenon in the Zagros Mountains. Two potential equilibrium parameters on the convective surfaces and relative equilibrium advection were also used to investigate the dynamic structure. The results showed that during this 18 year period, only three examples of the above mentioned phenomenon occurred in Iran. The major mechanism governing the formation of these cyclones in the windward part of the mountain with the formation of a high-pressure core and an increase in relative relative tropics at the ground level and the positioning of a quasi-stationary stack in the troposphere mid-level as a major condition of the mountainous winds and the presence of a dune. With the strong geopotential rotations over the mountainous altitudes that continue from the middle to upper troposphere, these conditions are accompanied by a positive torrential flow. Thus, the first and foremost condition for the occurrence of windsurfing is the existence of these two conditions on the windward and mountainous slopes. At the level of 500 hPa in central Iran, the relative tropical advection values increase, indicating a positive relative tropical increase both in time and location in the region.
Journal of Meteorology and Atmospheric Science
Iran Meteorology Society (IMS)
2645-7261
3
v.
3
no.
2020
242
254
https://www.ims-jmas.net/article_139809_b5cbf9aef4d44c111f60984ee60596d9.pdf
dx.doi.org/10.22034/jmas.2021.212037.1089
Modified patterns of diurnal temperature and relative humidity in Mountainous regions of Iran and Sample Stations
bahareh
Mirkamandar
Water engineering- Agriculture college- Ferdowsi university of Mashhad
author
Mahboobeh
Farzandi
Water engineering- Agriculture college-Ferdowsi university of Mashhad
author
text
article
2020
per
Estimation of the daily average of temperature and relative humidity with common methods is the average of the three standard hours (3, 9 and 15) Greenwich Mean Time. The curve of these two variables on a normal day is a skewed curve to the right. Climatic conditions of the meteorological stations are also another parameter to be considered. Daily average of relative humidity patterns shows only half of a daily value. Therefore, the equal coefficients could be used only as approximation for estimating daily average of relative humidity. This research presents a new method for estimating daily average of temperature and relative humidity in Mountainous regions of Iran. The Patterns for the sample stations in each climatic region were presented separately. Therefore, we used from three clustering of Iran and Systematic sampling to select sample stations. The best models were presented by reviewing the required statistics and analyzing the residuals. The coefficient of determination (R2) and the Fisher statistics show that the patterns have a good ability to estimate the daily average of temperature and relative humidity. The mean squares errors are a measure of the applicability of patterns. The accuracy of the estimating daily average of temperature and relative humidity recommended models in Mountainous regions and its sample stations was confirmed by calculating the mean squared errors. Proposed patterns of this study have less error than the common patterns.
Journal of Meteorology and Atmospheric Science
Iran Meteorology Society (IMS)
2645-7261
3
v.
3
no.
2020
255
274
https://www.ims-jmas.net/article_139805_4bc86eb37aed802f94cc78a71df1f15c.pdf
dx.doi.org/10.22034/jmas.2021.296291.1147
Predicting Flood Flow with Gene Expression Model and Estimating Hydrograph
Using Gary and Gamma Models
(Case study: Qarasu watershed of Kermanshah)
erfan
bahrami
university of birjand water engineer science
author
hossein
khozeymehnezhad
Associate professor, Department of Water Engineering, Faculty of Agriculture, University of Birjand, Birjand, Iran.
author
text
article
2020
per
Good performance of intelligent models has increased their use in predicting different hydrological phenomena.so it is necessary to evaluate the performance of models developed in different regions of the world with different climatic, hydrological and physiographic features in order to comment on their performance in different regions.Hence, to predict the flood discharge of the basin, the data of the region have been collected for a period of 10 years with the length of the statistical period (2010-2020) using the intelligent model of gene expression planning.After analyzing the model's evaluation criteria, the results showed the good and high performance of the model in predicting flood discharge.Using both synthetic hydrograph Gary and Gamma models, the significant runoff parameters (flood peak discharge error), (Time to reach flood peak discharge error), and (flow volume error) and three criteria (Root mean square error, mean absolute error and determination of coefficient ) were evaluated to determine the shape of the flood hydrograph. Also, using the scoring and ranking method for each of the errors and the best model in estimating each of the flood characteristics was determined. based on the results, the values of the expressed domains for the gamma model are (9.50, -12.9), (20.09, -40.1), (75, -100), (0.42, 1.66), (3.20, 1.03) and (0.94, 0.87) The results showed the superiority of the gamma model Gary model and the selected model was able to appropriately estimate the characteristics of the flood hydrograph. It is also recommended to study this model in flood modeling in other ungauged watershed
Journal of Meteorology and Atmospheric Science
Iran Meteorology Society (IMS)
2645-7261
3
v.
3
no.
2020
275
293
https://www.ims-jmas.net/article_139806_f2d680f5abb5a6866a37e969c27975d8.pdf
dx.doi.org/10.22034/jmas.2021.293305.1145