scholarly journals A Comparative Study Between Short Life- Cut off Low and Long Life-Cut off Low Accompanied by Heavy Precipitation Storms Over Iraq: Case Study

2020 ◽  
Vol 31 (2) ◽  
pp. 1
Author(s):  
HADIL JALIL ALSHOUHANI
Keyword(s):  
Comparative Study ◽  
Lower Troposphere ◽  
Heavy Precipitation ◽  
Short Life ◽  
Pressure System ◽  
Upper Troposphere ◽  
Isentropic Surface ◽  
Long Life ◽  
High Potential Vorticity

A comparative study between Short Life Cut Off Low (SL-COL) extended for one day, and Long Life Cut Off Low (LL-COL) extended for ten days associated with successive rain storms over Iraq on 21 to 30 April, 2018. The study tracking the evolution stages of both COLs in different pressure surfaces at troposphere layer, and found that there are many dynamical processes effect on prolong the life of COL. These processes exchanged their roles between different pressure levels. In both cases the high potential vorticity (PV) anomaly at 315ᵒ K isentropic surface is responsible on the emergence COLs, and the convection processes at lower troposphere and latent heat at upper troposphere are responsible on COLs dissipation. The main reasons of long-life COL can be summaries as a high-pressure system below COL at the surface which preventing the convection process, the formation of Omega block that promoting the COL system and preventing its dissipation rapidly in spite of the intense convection processes due to tropical moist system at the surface.

PERSIAN GARDENS IN COLD AND DRY CLIMATE: A CASE STUDY OF TABRIZ’S HISTORICAL GARDENS

2016 ◽  
Vol 10 (3) ◽  
pp. 193
Author(s):  
Ahad Nejad Ebrahimi ◽  
Farnaz Nazarzadeh ◽  
Elnaz Nazarzadeh
Keyword(s):  
Comparative Study ◽  
Water Supply ◽  
Field Study ◽  
Cold Climate ◽  
Natural Substrate ◽  
Garden Design ◽  
Climate Conditions ◽  
North West ◽  
Special Expertise

Throughout history, gardens and garden designing has been in the attention of Persian architects who had special expertise in the construction of gardens. The appearance of Islam and allegories of paradise taken from that in Koran and Saints’ sayings gave spirituality to garden construction. Climate conditions have also had an important role in this respect but little research has been done about it and most of the investigations have referred to spiritual aspects and forms of garden. The cold and dry climate that has enveloped parts of West and North West of Iran has many gardens with different forms and functions, which have not been paid much attention to by studies done so far. The aim of this paper is to identify the features and specifications of cold and dry climate gardens with an emphasis on Tabriz’s Gardens.  Due to its natural and strategic situation, Tabriz has always been in the attention of governments throughout history; travellers and tourists have mentioned Tabriz as a city that has beautiful gardens. But, the earthquakes and wars have left no remains of those beautiful gardens. This investigation, by a comparative study of the climates in Iran and the effect of those climates on the formation of gardens and garden design, tries to identify the features and characteristics of gardens in cold and dry climate. The method of study is interpretive-historical on the basis of written documents and historic features and field study of existing gardens in this climate. The results show that, with respect to natural substrate, vegetation, the form of water supply, and the general form of the garden; gardens in dry and cold climate are different from gardens in other climates.

Towards a taxonomy of intergenerational knowledge transfer practices

2018 ◽  
Vol 25 (2) ◽  
pp. 81-91
Author(s):  
Kerstin Kuyken ◽  
Mehran Ebrahimi ◽  
Anne-Laure Saives
Keyword(s):  
Knowledge Transfer ◽  
Comparative Study ◽  
Design Methodology ◽  
Qualitative Case Study ◽  
High Tech ◽  
Content Type ◽  
Case Study Design ◽  
Younger Workers ◽  
Intergenerational Knowledge

Purpose This paper aims to develop a better understanding of intergenerational knowledge transfer (IKT) practices by adopting a context-related and comparative perspective. Design/methodology/approach A qualitative case study design involving 83 interviews and non-participative observation in German and Quebec organizations has been chosen. Findings Two distinctive archetypes of IKT emerge from both national contexts: “we-individualizing” (Germany) and “I-connecting” (Quebec), leading to an eightfold taxonomy of IKT practices. Research limitations/implications This research is limited to young and senior workers and to high-tech sectors. Originality/value Comparative and inductive study of IKT, adaptation of IKT practices to national contexts, retaining younger workers. This inductive and comparative study allows a better adaptation of IKT practices to national contexts and therefore a better retention of younger workers.

scholarly journals A Case Study of Mass Transport during the East-West Oscillation of the Asian Summer Monsoon Anticyclone

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jiali Luo ◽  
Jiayao Song ◽  
Hongying Tian ◽  
Lei Liu ◽  
Xinlei Liang
Keyword(s):  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Chemical Transport ◽  
Upward Motion ◽  
High Concentration ◽  
Upper Troposphere ◽  
Asian Summer ◽  
Mode Tm ◽  
East West

We use ERA-Interim reanalysis, MLS observations, and a trajectory model to examine the chemical transport and tracers distribution in the Upper Troposphere and Lower Stratosphere (UTLS) associated with an east-west oscillation case of the anticyclone in 2016. The results show that the spatial distribution of water vapor (H2O) was more consistent with the location of the anticyclone than carbon monoxide (CO) at 100 hPa, and an independent relative high concentration center was only found in H2O field. At 215 hPa, although the anticyclone center also migrated from the Tibetan Mode (TM) to the Iranian Mode (IM), the relative high concentration centers of both tracers were always colocated with regions where upward motion was strong in the UTLS. When the anticyclone migrated from the TM, air within the anticyclone over Tibetan Plateau may transport both westward and eastward but was always within the UTLS. The relative high concentration of tropospheric tracers within the anticyclone in the IM was from the east and transported by the westward propagation of the anticyclone rather than being lifted from surface directly. Air within the relative high geopotential height centers over Western Pacific was partly from the main anticyclone and partly from lower levels.

scholarly journals GPS radio occultation with TerraSAR-X and TanDEM-X: sensitivity of lower troposphere sounding to the Open-Loop Doppler model

2014 ◽  
Vol 7 (12) ◽  
pp. 12719-12733 ◽  
Author(s):  
F. Zus ◽  
G. Beyerle ◽  
S. Heise ◽  
T. Schmidt ◽  
J. Wickert
Keyword(s):  
Radio Occultation ◽  
Weather Prediction ◽  
Lower Troposphere ◽  
Systematic Difference ◽  
Open Loop ◽  
Negative Bias ◽  
Upper Troposphere ◽  
Gps Radio Occultation ◽  
Global Positioning ◽  
Data Source

Abstract. The Global Positioning System (GPS) radio occultation (RO) technique provides valuable input for numerical weather prediction and is considered as a data source for climate related research. Numerous studies outline the high precision and accuracy of RO atmospheric soundings in the upper troposphere and lower stratosphere. In this altitude region (8–25 km) RO atmospheric soundings are considered to be free of any systematic error. In the tropical (30° S–30° N) Lower (<8 km) Troposphere (LT), this is not the case; systematic differences with respect to independent data sources exist and are still not completely understood. To date only little attention has been paid to the Open Loop (OL) Doppler model. Here we report on a RO experiment carried out on-board of the twin satellite configuration TerraSAR-X and TanDEM-X which possibly explains to some extent biases in the tropical LT. In two sessions we altered the OL Doppler model aboard TanDEM-X by not more than ±5 Hz with respect to TerraSAR-X and compare collocated atmospheric refractivity profiles. We find a systematic difference in the retrieved refractivity. The bias mainly stems from the tropical LT; there the bias reaches up to ±1%. Hence, we conclude that the negative bias (several Hz) of the OL Doppler model aboard TerraSAR-X introduces a negative bias (in addition to the negative bias which is primarily caused by critical refraction) in our retrieved refractivity in the tropical LT.

scholarly journals Forest fire danger rating in complex topography – results from a case study in the Bavarian Alps in autumn 2011

2013 ◽  
Vol 13 (9) ◽  
pp. 2157-2167 ◽  
Author(s):  
C. Schunk ◽  
C. Wastl ◽  
M. Leuchner ◽  
C. Schuster ◽  
A. Menzel
Keyword(s):  
Forest Fire ◽  
Temperature Inversion ◽  
Fire Danger ◽  
Complex Topography ◽  
Pressure System ◽  
Drought Period ◽  
Bavarian Alps ◽  
Forest Fire Danger ◽  
Fire Danger Indices

Abstract. Forest fire danger rating based on sparse meteorological stations is known to be potentially misleading when assigned to larger areas of complex topography. This case study examines several fire danger indices based on data from two meteorological stations at different elevations during a major drought period. This drought was caused by a persistent high pressure system, inducing a pronounced temperature inversion and its associated thermal belt with much warmer, dryer conditions in intermediate elevations. Thus, a massive drying of fuels, leading to higher fire danger levels, and multiple fire occurrences at mid-slope positions were contrasted by moderate fire danger especially in the valleys. The ability of fire danger indices to resolve this situation was studied based on a comparison with the actual fire danger as determined from expert observations, fire occurrences and fuel moisture measurements. The results revealed that, during temperature inversion, differences in daily cycles of meteorological parameters influence fire danger and that these are not resolved by standard meteorological stations and fire danger indices (calculated on a once-a-day basis). Additional stations in higher locations or high-resolution meteorological models combined with fire danger indices accepting at least hourly input data may allow reasonable fire danger calculations under these circumstances.

scholarly journals Growth of nucleation mode particles in the summertime Arctic: a case study

2016 ◽  
Vol 16 (12) ◽  
pp. 7663-7679 ◽  
Author(s):  
Megan D. Willis ◽  
Julia Burkart ◽  
Jennie L. Thomas ◽  
Franziska Köllner ◽  
Johannes Schneider ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Methanesulfonic Acid ◽  
Lower Troposphere ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Radiative Balance ◽  
Nucleation Mode ◽  
Cloud Properties ◽  
Marine Influence

Abstract. The summertime Arctic lower troposphere is a relatively pristine background aerosol environment dominated by nucleation and Aitken mode particles. Understanding the mechanisms that control the formation and growth of aerosol is crucial for our ability to predict cloud properties and therefore radiative balance and climate. We present an analysis of an aerosol growth event observed in the Canadian Arctic Archipelago during summer as part of the NETCARE project. Under stable and clean atmospheric conditions, with low inversion heights, carbon monoxide less than 80 ppbv, and black carbon less than 5 ng m−3, we observe growth of small particles,  <  20 nm in diameter, into sizes above 50 nm. Aerosol growth was correlated with the presence of organic species, trimethylamine, and methanesulfonic acid (MSA) in particles ∼ 80 nm and larger, where the organics are similar to those previously observed in marine settings. MSA-to-sulfate ratios as high as 0.15 were observed during aerosol growth, suggesting an important marine influence. The organic-rich aerosol contributes significantly to particles active as cloud condensation nuclei (CCN, supersaturation  =  0.6 %), which are elevated in concentration during aerosol growth above background levels of ∼ 100 to ∼ 220 cm−3. Results from this case study highlight the potential importance of secondary organic aerosol formation and its role in growing nucleation mode aerosol into CCN-active sizes in this remote marine environment.

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