scholarly journals Study of Some Patterns for Severe Rainfalls Over Iraq

2020 ◽  
Vol 31 (4) ◽  
pp. 9
Author(s):  
Yaser Ali Shaghati
Keyword(s):  
Relative Humidity ◽  
Sea Level ◽  
Vertical Velocity ◽  
Geopotential Height ◽  
Cloud Cover ◽  
Heavy Rain ◽  
Relative Vorticity ◽  
Sea Level Pressure ◽  
First Case ◽  
Heavy Rainfalls

Study of rain received particularly great importance in the areas described as semi-arid, which is on the other hand are not well prepared for the drainage of rain that may turned into flash floods. The pressure systems, especially those passing through the country in the winter rainy season and spring also autumn have a role in determining the amount of rainfall falling in the region In addition to climate change and its effects in terms of climate cycles and climate extremes and thus required determine the size of rainfall Whether it is beneficial or harmful. In this study to determine of heavy rainfalls, two important cases of heavy rainfalls were studied in 24, Dec, 2016 and 24, Nov, 2018, which exceeded 50 mm on the Iraq, from one country to another in this account , rainfalls rate, divider from the World Meteorological Organization (WMO) in which the rain intensity is determined according to the schedule and limits (light precipitation I≤2 mm / hour), (moderate precipitation 2<I≤10 mm / Hour), (heavy precipitation 10 <I≤50 mm / hour), (torrential precipitation I> 50 mm / hour). Each case was Analyzed and visualized by using the data analysis and display system (GrADS) The data were obtained from Tropical Rainfall Measuring Mission (TRMM). Show maps results of the first case in (24 December, 2016) in the northeastern region, the central region and the western region of the country the abundant rain condition through maps of rainfall rates on these areas as well as by maps of mean sea level pressure and dense cloud cover, maps showed a decrease the temperature accompanying the low pressure also streamlines, geopotential height, relative vorticity show this. And show the vertical velocity (omega), relative humidity, geopotential height, relative vorticity, and show support of air decline in terms of streamlines, relative humidity, geopotential height and relative vorticity over the country. Maps 700 hPa the vertical velocity (omega), relative humidity, geopotential height and relative vorticity, maps 500 hPa, results of second case, (24 November, 2018) that occurred in the northeastern and eastern part and southeastern part of the country, also appear clear through maps of falling rainfall rates, as well as maps of sea level pressure and the dense cloud cover accompanying the heavy rain situation. maps 850 hPa it shows the low temperature accompanying the atmospheric decline, also streamlines, geopotential height and relative vorticity also maps 700 hPa and 500 hPa lik first case, in differential patterns all of this shows clear support for the atmospheric decline in terms of streamlines, relative humidity, geopotential height, and relative vorticity, and explain the causes of heavy rain situation over Iraq.

scholarly journals Studying Recorded lightning over Iraq for Period 1998-2011

2018 ◽  
Vol 28 (3) ◽  
pp. 1
Author(s):  
Lena Mohammed Abbas
Keyword(s):  
Relative Humidity ◽  
Sea Level ◽  
Vertical Velocity ◽  
Mean Value ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Mean Values ◽  
Level Pressure ◽  
Special Cases ◽  
The Hours

This research studies distribution of thunderstorm in Iraq for the period (1998-2011), the result showed that  the largest regions which had been hit by lightning stroke were between latitude (35-36◦)E and longitude (45-46◦)N, and April was the most frequent of lightning occurrence, also the results showed  that the number of flashes of most lightning cases were between (50-100) with higher number of flashes for some special cases. The studying of meteorological parameters which accompanied thunderstorm formation such as (Mean sea level pressure, Lifting index, relative humidity and Vertical velocity) illustrates the values of mean sea level pressure were increased during the hours after lightning occurrence comparing with their values before and at the time of lightning occurrence and their monthly mean value much greater than that recorded at the time of lightning occurrence, in addition the values of lifting index were negative at the time of lightning occurrence that refer to instability whereas their monthly average showed positive values. The values of relative humidity were greater at lightning recorded time at the three levels (500, 700, 1000)mb and also through the hours before and after this time comparing with their monthly mean. Vertical velocity values were negative for the three levels at the time of lightning occurrence that is referring to upward motion which is necessary for thundercloud initiation, and their monthly mean values were mostly negative at (500, 700)mb whereas were positive at the surface level

scholarly journals Recent atmospheric changes and future projections along the Saudi Arabian Red Sea Coast

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Abdulhakim Bawadekji ◽  
Kareem Tonbol ◽  
Nejib Ghazouani ◽  
Nidhal Becheikh ◽  
Mohamed Shaltout
Keyword(s):  
Relative Humidity ◽  
Sea Level ◽  
Air Temperature ◽  
Surface Wind ◽  
Surface Air Temperature ◽  
Saudi Arabian ◽  
Sea Level Pressure ◽  
Ensemble Mean ◽  
Red Sea Coast ◽  
Sea Coast

AbstractRecent and future climate diagrams (surface air temperature, surface relative humidity, surface wind, and mean sea level pressure) for the Saudi Arabian Red Sea Coast are analysed based on hourly observations (2016–2020) and hourly ERA5 data (1979–2020) with daily GFDL mini-ensemble means (2006–2100). Moreover, GFDL mini-ensemble means are calculated based on the results of three GFDL simulations (GFDL-CM3, GFDL-ESM2M, and GFDL-ESM2G). Observation data are employed to describe the short-term current weather variability. However, ERA5 data are considered to study the long-term current weather variability after bias removal via a comparison to observations. Finally, a bias correction statistical model was developed by matching the cumulative distribution functions (CDFs) of corrected ERA5 and mini-ensemble mean data over 15 years (2006–2020). The obtained local statistic were used to statically downscale GFDL mini-ensemble means to study the future uncertainty in the atmospheric parameters studied. There occurred significant spatial variability across the study area, especially regarding the surface air temperature and relative humidity, based on monthly analysis of both observation and ERA5 data. Moreover, the results indicated that the ERA5 data suitably describe Tabuk, Jeddah and Jizan weather conditions with a marked spatial variability. The best performance of ERA5 surface air temperature and relative humidity (surface wind speed and sea level pressure) data was detected in Tabuk (Jeddah). These data for the Saudi Arabian Red Sea coast, 1979–2020, exhibit significant positive trends of the surface air temperature and surface wind speed and significant negative trends of the relative humidity and sea level pressure. The GFDL mini-ensemble mean projection result, up to 2100, contains a significant bias in the studied weather parameters. This is partly attributed to the coarse GFDL resolution (2° × 2°). After bias removal, the statistically downscaled simulations based on the GFDL mini-ensemble mean indicate that the climate in the study area will experience significant changes with a large range of uncertainty according to the considered scenario and regional variations.

scholarly journals Comments on “Incorporating the Effects of Moisture into a Dynamical Parameter: Moist Vorticity and Moist Divergence”

2016 ◽  
Vol 31 (4) ◽  
pp. 1393-1396 ◽  
Author(s):  
David M. Schultz ◽  
Thomas Spengler
Keyword(s):  
Relative Humidity ◽  
Potential Vorticity ◽  
Single Case ◽  
Heavy Rain ◽  
Relative Vorticity ◽  
Dynamical Parameter ◽  
Accumulated Rainfall ◽  
Moist Potential Vorticity ◽  
Model Precipitation

Abstract In a recent article, Qian et al. introduced the quantities moist vorticity and moist divergence to diagnose locations of heavy rain. These quantities are constructed by multiplying the relative vorticity and divergence by relative humidity to the power k, where k = 10 in their article. Their approach is similar to that for the previously constructed quantity generalized moist potential vorticity. This comment critiques the approach of Qian et al., demonstrating that the moist vorticity, moist divergence, and by extension generalized moist potential vorticity are flawed mathematically and meteorologically. Raising relative humidity to the 10th power is poorly justified and is based on a single case study at a single time. No meteorological evidence is presented for why areas of moist vorticity and moist divergence should overlap with regions of 24-h accumulated rainfall. All three quantities have not been verified against the output of precipitation directly from the model nor is the approach of combining meteorological quantities into a single parameter appropriate in an ingredients-based forecasting approach. Researchers and forecasters are advised to plot the model precipitation directly and employ an ingredients-based approach, rather than rely on these flawed quantities.

DETERMINATION OF THE CORRELATION BETWEEN INDIVIDUAL METEOROLOGICAL VALUES AT THE BEGINNING OF THE DEPOSITION OF ICE ON THE TERRITORY OF UKRAINE BY THE MONTHS OF THE COLD PERIOD OF THE YEAR DURING 2001-2013 AND THEIR SPATIAL DISTRIBUTION

2019 ◽  
pp. 140-151
Author(s):  
S.I. Pyasetska ◽  
N.P. Grebenyuk ◽  
S.V. Savchuk
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Sea Level ◽  
Meteorological Parameters ◽  
Cold Period ◽  
Sea Level Pressure ◽  
Average Maximum ◽  
Average Relative Humidity ◽  
Maximum Minimum

The article presents the results of the study of the determination of the correlation connection between a number of meteorological values at the beginning of the deposition of ice on the wires of a standard ice-cream machine in certain months of the cold period of the year on the territory of Ukraine during 2001-2013. The research was conducted for 3 winter months, as well as for March and November. The pair of meteorological parameters have been determined at the beginning of the deposition of ice that have a statistically significant correlation coefficient and a spatial-temporal distribution of the distribution in certain months across the territory of Ukraine has been obtained. The most common variant of the statistically significant connection between individual meteorological parameters was the connection between the temperature of the water column (average, maximum, minimum) and relative humidity of air (average, maximum). Thus, for almost all months studied, a statistically significant correlation between the temperature of the vapor (average, maximum, minimum) and relative humidity of air (average, maximum) was established. For the winter months, the correlation coefficient of this connection was positive, and for March and November, it was negative. A widespread version of a statistically significant connection was the relationship between the air temperature (average, maximum, minimum) and the height of the snow cover. This connection for the months studied turned out to be negative. The variants of negative statistically significant connection between average wind speed and average relative humidity of air (January-February, December), average and maximum wind speed and sea-level pressure (November), and also between daily amount precipitation and snow (March), daily rainfall and wind speed (average, maximum), and pressure at sea level (November). During the months of the cold period of the year, statistically significant connections between the air temperature (average, maximum) and pressure at sea level (November), wind speed (average, maximum) and average humidity (January, December), pressure on sea levels and average relative humidity (March). Also, there were isolated cases of statistically significant correlation between snow and sea level pressure (December). The most frequently statistically significant connections between meteorological values at the dates of deposition of ice on the wires of a standard icing machine were observed at stations in the central, northeastern, eastern and separate southern regions.

The North Pacific Oscillation–West Pacific Teleconnection Pattern: Mature-Phase Structure and Winter Impacts

2008 ◽  
Vol 21 (9) ◽  
pp. 1979-1997 ◽  
Author(s):  
Megan E. Linkin ◽  
Sumant Nigam
Keyword(s):  
Sea Level ◽  
Pacific Northwest ◽  
Geopotential Height ◽  
Storm Track ◽  
Teleconnection Pattern ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Mature Phase ◽  
The Pacific

Abstract The North Pacific Oscillation (NPO) in sea level pressure and its upper-air geopotential height signature, the west Pacific (WP) teleconnection pattern, constitute a prominent mode of winter midlatitude variability, the NPO/WP. Its mature-phase expression is identified from principal component analysis of monthly sea level pressure variability as the second leading mode just behind the Pacific–North American variability pattern. NPO/WP variability, primarily on subseasonal time scales, is characterized by a large-scale meridional dipole in SLP and geopotential height over the Pacific and is linked to meridional movements of the Asian–Pacific jet and Pacific storm track modulation. The hemispheric height anomalies at upper levels resemble the climatological stationary wave pattern attributed to transient eddy forcing. The NPO/WP divergent circulation is thermal wind restoring, pointing to independent forcing of jet fluctuations. Intercomparison of sea level pressure, geopotential height, and zonal wind anomaly structure reveals that NPO/WP is a basin analog of the NAO, which is not surprising given strong links to storm track variability in both cases. The NPO/WP variability is influential: its impact on Alaskan, Pacific Northwest, Canadian, and U.S. winter surface air temperatures is substantial—more than that of PNA or ENSO. It is likewise more influential on the Pacific Northwest, western Mexico, and south-central Great Plains winter precipitation. Finally, and perhaps, most importantly, NPO/WP is strongly linked to marginal ice zone variability of the Arctic seas with an influence that surpasses that of other Pacific modes. Although NPO/WP variability and impacts have not been as extensively analyzed as its Pacific cousins (PNA, ENSO), it is shown to be more consequential for Arctic sea ice and North American winter hydroclimate.

A Characterization of the Present-Day Arctic Atmosphere in CCSM4

2012 ◽  
Vol 25 (8) ◽  
pp. 2676-2695 ◽  
Author(s):  
Gijs de Boer ◽  
William Chapman ◽  
Jennifer E. Kay ◽  
Brian Medeiros ◽  
Matthew D. Shupe ◽  
...  
Keyword(s):  
Sea Level ◽  
Energy Budget ◽  
Cloud Cover ◽  
Lower Troposphere ◽  
Surface Fluxes ◽  
The Arctic ◽  
Sea Level Pressure ◽  
Climate System Model ◽  
Level Pressure ◽  
Arctic Atmosphere

Abstract Simulation of key features of the Arctic atmosphere in the Community Climate System Model, version 4 (CCSM4) is evaluated against observational and reanalysis datasets for the present-day (1981–2005). Surface air temperature, sea level pressure, cloud cover and phase, precipitation and evaporation, the atmospheric energy budget, and lower-tropospheric stability are evaluated. Simulated surface air temperatures are found to be slightly too cold when compared with the 40-yr ECMWF Re-Analysis (ERA-40). Spatial patterns and temporal variability are well simulated. Evaluation of the sea level pressure demonstrates some large biases, most noticeably an under simulation of the Beaufort High during spring and autumn. Monthly Arctic-wide biases of up to 13 mb are reported. Cloud cover is underpredicted for all but summer months, and cloud phase is demonstrated to be different from observations. Despite low cloud cover, simulated all-sky liquid water paths are too high, while ice water path was generally too low. Precipitation is found to be excessive over much of the Arctic compared to ERA-40 and the Global Precipitation Climatology Project (GPCP) estimates. With some exceptions, evaporation is well captured by CCSM4, resulting in P − E estimates that are too high. CCSM4 energy budget terms show promising agreement with estimates from several sources. The most noticeable exception to this is the top of the atmosphere (TOA) fluxes that are found to be too low while surface fluxes are found to be too high during summer months. Finally, the lower troposphere is found to be too stable when compared to ERA-40 during all times of year but particularly during spring and summer months.

scholarly journals Wet-Bulb Temperature from Relative Humidity and Air Temperature

2011 ◽  
Vol 50 (11) ◽  
pp. 2267-2269 ◽  
Author(s):  
Roland Stull
Keyword(s):  
Gene Expression ◽  
Relative Humidity ◽  
Sea Level ◽  
Air Temperature ◽  
Mean Absolute Error ◽  
Gene Expression Programming ◽  
Absolute Error ◽  
Sea Level Pressure ◽  
Air Temperatures ◽  
Low Humidity

AbstractAn equation is presented for wet-bulb temperature as a function of air temperature and relative humidity at standard sea level pressure. It was found as an empirical fit using gene-expression programming. This equation is valid for relative humidities between 5% and 99% and for air temperatures between −20° and 50°C, except for situations having both low humidity and cold temperature. Over the valid range, errors in wet-bulb temperature range from −1° to +0.65°C, with mean absolute error of less than 0.3°C.

scholarly journals A new framework for probabilistic seasonal forecasts based on circulation type classifications and driven by an ensemble global model

2018 ◽  
Vol 15 ◽  
pp. 183-190 ◽  
Author(s):  
Gianni Messeri ◽  
Riccardo Benedetti ◽  
Alfonso Crisci ◽  
Bernardo Gozzini ◽  
Matteo Rossi ◽  
...  
Keyword(s):  
Sea Level ◽  
Geopotential Height ◽  
Circulation Type ◽  
Seasonal Forecasts ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Circulation Types ◽  
Temperature And Precipitation ◽  
Medium Range ◽  
New Framework

Abstract. In the last years coupled atmospheric ocean climate models have remarkably improved medium range seasonal forecasts, especially on middle latitude areas such as Europe and the Mediterranean basin. In this study a new framework for medium range seasonal forecasts is proposed. It is based on circulation types extracted from long range global ensemble models and it aims at two goals: (i) an easier use of the information contained in the complex system of atmospheric circulations, through their reduction to a limited number of circulation types and (ii) the computation of high spatial resolution probabilistic forecasts for temperature and precipitation. The proposed framework could be also useful to lead predictions of weather-derived parameters, such as the risk of heavy rainfall, drought or heat waves, with important impacts on agriculture, water management and severe weather risk assessment. Operatively, starting from the ensemble predictions of mean sea level pressure and geopotential height at 500 hPa of the NCEP – CFSv2 long range forecasts, the third-quantiles probabilistic maps of 2 m temperature and precipitation are computed through a Bayesian approach by using E-OBS 0.25∘ gridded datasets. Two different classification schemes with nine classes were used: (i) Principal Component Transversal (PCT9), computed on mean sea level pressure and (ii) Simulated Annealing Clustering (SAN9), computed on geopotential height at 500 hPa. Both were chosen for their best fit concerning the ground-level precipitation and temperature stratification for the Italian peninsula. Following this approach an operative chain based on a very flexible and exportable method was implemented, applicable wherever spatially and temporally consistent datasets of weather observations are available. In this paper the model operative chain, some output examples and a first attempt of qualitative verification are shown. In particular three case studies (June 2003, February 2012 and July 2014) were examined, assuming that the ensemble seasonal model correctly predicts the circulation type occurrences. At least on this base, the framework here proposed has shown promising performance.

scholarly journals Logistic Model as a Statistical Downscaling Approach for Forecasting a Wet or Dry Day in the Bagmati River Basin

2015 ◽  
Vol 9 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Rajendra Man Shrestha ◽  
Srijan Lal Shrestha ◽  
Azaya Bikram Sthapit
Keyword(s):  
Relative Humidity ◽  
Sea Level ◽  
Principal Components ◽  
Logistic Model ◽  
Roc Analysis ◽  
Principal Component ◽  
Predictor Variables ◽  
Validation Period ◽  
Sea Level Pressure ◽  
Bagmati River

A binary logistic model is developed for probabilistic prediction of a wet or dry day based upon daily rainfall data from 1981 to 2008 taken from 25 stations of Bagmati River basin. The predictor variables included in the model are daily relative humidity, air surface temperature, sea level pressure, v-wind which are expressed as principal components of 9 grids of the National Centers for Environmental Protection (NCEP)/National Center for Atmospheric Research (NCAR) Reanalysis data with resolution of 2.50×2.50. Principal component analysis is used to reduce the dimension of the predictors in the presence of spatial correlations between grids and thus reduce their multicollinearity effect. The result depicts that the model has 86.4 percent predictive capability in the analysis period (1981-2000) and 86.1 in the validation period (2001-2008) along with support of receiver operating characteristic (ROC) analysis. The results demonstrate that the first two principal components of relative humidity are the key predictor variables with respective odds ratios (ORs) of 4.18 and 3.61, respectively. The other statistically significant predictors are the second principal component of v-wind with OR 1.43, the second and first principal components of air surface temperature with ORs 1.38 and 0.76, respectively and the first principal component of sea level pressure with OR 0.44. Goodness-of-fit test, ROC analysis and other main diagnostic tests showed that the fitted logistic model is characterized by good fits for analysis as well as validation period.

scholarly journals An Inter-Comparison of Arctic Synoptic Scale Storms between Four Global Reanalysis Datasets

2020 ◽  
Author(s):  
Alexander Vessey ◽  
Kevin Hodges ◽  
Len Shaffrey ◽  
Jonathan Day
Keyword(s):  
Sea Level ◽  
Relative Vorticity ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Tracking Method ◽  
Level Pressure ◽  
Storm Tracking ◽  
Storm Characteristics

&lt;p&gt;Arctic sea ice has reduced significantly over recent decades and is projected to reduce further over this century. This has made the Arctic more accessible and increased opportunities for the expansion of business and industrial activities.&amp;#160; As a result, the exposure and risk of humans and infrastructure to extreme storms will increase in the Arctic.&lt;/p&gt;&lt;p&gt;Our understanding of the current risk from storms comes from analysing the past, for example, by using storm tracking algorithms to detect storms in reanalysis datasets. &amp;#160;However, there are multiple reanalysis datasets available from different institutions and there are multiple storm tracking methods.&amp;#160; Previous studies have found that there can be differences between reanalysis datasets and between storm tracking methods in the climatology of storms, particularly in mid-latitude regions rather than the Arctic.&amp;#160; In this study, we aimed to improve the understanding of Arctic storms by assessing their characteristics in multiple global reanalyses, the ECMWF-Interim Reanalysis (ERA-Interim), the 55-Year Japanese Reanalysis (JRA-55), the NASA-Modern Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2), and the NCEP-Climate Forecast System Reanalysis (NCEP-CFSR), using the same storm tracking method based on 850 hPa relative vorticity and mean sea level pressure.&lt;/p&gt;&lt;p&gt;The results from this study show that there are no significant trends in Arctic storm characteristics between 1980-2017, even though the Arctic has undergone rapid change. &amp;#160;Although some similar Arctic storm characteristics are found between the reanalysis datasets, there are generally higher differences between the reanalyses in winter (DJF) than in summer (JJA).&amp;#160; In addition, substantial differences can arise between using the same storm tracking method based on 850 hPa relative vorticity or mean sea level pressure, which adds to the uncertainty associated with current Arctic storm characteristics.&lt;/p&gt;

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