Assessment of the onset, cessation, and duration of rainfall season over Botswana

2021 ◽  
Author(s):  
P. B. Maruatona ◽  
O. Moses
Keyword(s):  
Rainfall Season

Investigation of 18 physiologically dormant Australian native species: germination response, environmental correlations and the implications for conservation

2020 ◽  
pp. 1-9
Author(s):  
Justin C. Collette ◽  
Mark K.J. Ooi
Keyword(s):  
Native Species ◽  
Strong Dependence ◽  
Ex Situ ◽  
Source Population ◽  
Seasonal Temperature ◽  
Environmental Correlations ◽  
Rainfall Season ◽  
Germination Response ◽  
Rainfall Seasonality ◽  
Germination Experiments

Abstract For physiologically dormant (PD) species in fire-prone environments, dormancy can be both complex due to the interaction between fire and seasonal cues, and extremely deep due to long intervals between recruitment events. Due to this complexity, there are knowledge gaps particularly surrounding the dormancy depth and cues of long-lived perennial PD species. This can be problematic for both in situ and ex situ species management. We used germination experiments that tested seasonal temperature, smoke, dark and heat for 18 PD shrub species distributed across temperate fire-prone Australia and assessed how germination was correlated with environmental factors associated with their home environments. We found extremely high levels of dormancy, with only eight species germinating above 10% and three species producing no germination at all. Seven of these eight species had quite specific seasonal temperature requirements and/or very strong responses to smoke cues. The maximum germination for each species was positively correlated with the mean temperature of the source population but negatively correlated with rainfall seasonality and driest months. The strong dependence on a smoke cue for some of the study species, along with examples from other studies, provides evidence that an obligate smoke response could be a fire-adapted germination cue. Germination response correlated with rainfall season of the source populations is a pattern which has often been assumed but little comparative data across sites with different rainfall seasonality exists. Further investigation of a broader range of species from different rainfall season environments would help to elucidate this knowledge gap.

scholarly journals Assessing Prone Areas to Heavy Rainfall and the Impaction of the Upper Warm Temperature Anomaly during March–May Rainfall Season in Tanzania

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Kantamla Biseke Mafuru ◽  
Tan Guirong
Keyword(s):  
Heavy Rainfall ◽  
Temperature Anomaly ◽  
Temporal Distribution ◽  
Warning System ◽  
Congo Basin ◽  
Horizontal Wind ◽  
Warm Temperature ◽  
Rainfall Season ◽  
Key Factor ◽  
Upper Level

This study analyses the spatial and temporal distribution of heavy rainfall events (HREs) and its associated circulation anomalies over Tanzania during March to May (MAM) rainfall season of 1980–2010. A total of 822 HREs were revealed, concentrated over the northern sector (NS) of the country. Years with anomalous HREs are associated with low-level westerly convergence, advection of moisture from both the Indian Ocean and Congo basin, an upper warm temperature anomaly (UWTA), intensified and well-positioned Intertropical Convergence Zone (ITCZ), and pronounced rising motion since the ascending limb of the Walker type of circulation is centered over Tanzania. The analysis of the UWTA in this study has brought a key factor in exploring the possible likely cause and improved early warning system for the HREs during the MAM rainfall season in Tanzania. Making use of the thermal wind equation and the velocity divergent form of the continuity equation (DFCE), we found that the UWTA results into an upper-level horizontal wind divergence which significantly accelerates vertical ascent, deepening the surface low pressure for an enhanced convective process and HREs formation.

scholarly journals Variations in the Summertime Atmospheric Hydrologic Cycle Associated with Seasonal Precipitation Anomalies over the Southwestern United States

2006 ◽  
Vol 7 (4) ◽  
pp. 788-807 ◽  
Author(s):  
Bruce T. Anderson ◽  
Hideki Kanamaru ◽  
John O. Roads
Keyword(s):  
New Mexico ◽  
Large Scale ◽  
Moisture Flux ◽  
Hydrologic Cycle ◽  
Seasonal Precipitation ◽  
Model Simulations ◽  
Moisture Flux Convergence ◽  
Rainfall Season ◽  
Rainfall Anomalies ◽  
The Mean

Abstract This paper examines year-to-year variations in the large-scale summertime hydrologic cycle over the southwestern United States using a suite of regional model simulations and surface- and upper-air-based observations. In agreement with previous results, it is found that observed interannual precipitation variations in this region can be subdivided into two spatiotemporal regimes—one associated with rainfall variability over the southwestern portion of the domain centered on Arizona and the other associated with variations over the southeastern portion centered on western Texas and eastern New Mexico. Because of the limited duration of the model simulation data, it is possible to only investigate one positive rainfall season over the Arizona region and one negative rainfall season over the New Mexico region. From these investigations it appears that for the positive rainfall anomalies over Arizona excess seasonal precipitation is balanced by both enhanced evaporation and vertically integrated large-scale moisture flux convergence. Vertical profiles of these terms indicate that the anomalous large-scale moisture flux convergence is actually related to a decrease in the mean large-scale moisture flux divergence aloft; below 800 mb there is a decrease in the mean moisture flux convergence typically found at these levels, which in turn produces anomalous moisture divergence from the region. For the negative rainfall anomalies over New Mexico similar results, but of opposite sign, are found; one exception is that at the lowest levels there is an additional (negative) contribution to the vertically integrated moisture flux convergence anomaly related to a weakening of the mean low-level moisture flux convergence during the low-rainfall year. Further studies using two different model simulations with the same large-scale dynamic forcing but differing initial soil moisture values indicate that similar balances are also found for rainfall anomalies related to surface soil moisture changes within the domain, suggesting that the changes in large-scale moisture flux convergence described above can be attributed to both year-to-year variations in the regional land–atmosphere interactions as well as variations in the large-scale circulation patterns.

scholarly journals Rainfed farming prospects in the low rainfall zone of northern Iraq based on meteorological and soil moisture measurements

2017 ◽  
Vol 3 ◽  
Author(s):  
Mohammad Hasan Hussein
Keyword(s):  
Soil Moisture ◽  
Moisture Distribution ◽  
Seasonal Rainfall ◽  
Tillage Systems ◽  
Northern Iraq ◽  
Rainfall Season ◽  
Rainfed Farming ◽  
Soil Moisture Conservation ◽  
Soil Moisture Distribution ◽  
Runoff Plots

<p dir="RTL" align="right"> </p><p dir="RTL" align="right">More than 50% of the rainfed region in northernIraqfalls within the low rainfall zone receiving between 300 and 400 mm of mean seasonal rainfall. Several natural runoff plots with access tubes were used to measure soil moisture distribution in depth and time. Measurements during two consecutive rainfall seasons were used to forecast the rainfed farming prospects in the low rainfall zone. The first season is considered wet because it received 568 mm of mean seasonal rainfall; the second rainfall season is considered dry because it received 256 of mean seasonal rainfall. The prospects of tillage systems, fertilization and soil moisture conservation for a successful rainfed farming (wheat and barley crops) venture in the low rainfall zone were explored and  a rainfed farming guide for this zone was suggested. </p><p dir="RTL" align="right"><strong><br /></strong></p><p dir="RTL" align="right"> </p>

scholarly journals Evaluation of Sesame Yield and Yield Component under Different NPSZnB Fertilizer Rates in Western Tigray, Ethiopia

2020 ◽  
pp. 7-16
Author(s):  
Teame Shimgabr ◽  
Negasi Gebereslasie ◽  
Welesenbet Haftu ◽  
Haile Alene
Keyword(s):  
Grain Yield ◽  
Sesamum Indicum ◽  
Yield Component ◽  
Control Analysis ◽  
Nutrient Deficiencies ◽  
Yield Attributes ◽  
Site Specific ◽  
Rainfall Season ◽  
Oil Crops ◽  
Fertilizer Rates

Sesame is one of the most popular oil crops in the Western Tigray Ethiopia. Blended fertilizers containing N, P, S, Zn and B have been recommended to ameliorate site specific nutrient deficiencies in different districts of Tigray. Field experiment was conducted during rainfall season of 2018 and 2019 to study the effect of NPSZnB fertilizer on sesame (Sesamum indicum L.) in vertisols of Western Tigray at the Humera station, Banat and Kebabo Kafta Humera and Tsegede Wereda’s. The treatments consisted of six levels of NPSZnB 0, 50, 100, 150, 200 and 250 kg ha-1 and one blanket recommendation NP was applied. Data were recorded on sesame yield and yield components. The results revealed that addition of graded rate of NPSZnB significantly increased yield and yield attributes over the control. Analysis of variances showed that grain yield, number of capsule per plant, number of seeds per capsule and number of branching per plant was significant differences at (P< 0.001). Grain yield increases from 421 kg ha-1 to 630.1 kg ha-1 as NPSZnB increases from 0 (control) to 150 kg ha-1 and 421 kg ha-1 to 626.2 kg ha-1 as NP increases from 0 (control) to 41 N kg and 46 P205 kg ha-1 respectively. But NPSZnB was not significant with blanket recommendation of NP (41 kg N and 46 kg P205 ha-1), this indicates that either the blend or blanket NP can be used but not one to replace the other.

scholarly journals Assessing the Variability of Heavy Rainfall during October to December Rainfall Season in Tanzania

2021 ◽  
Vol 11 (02) ◽  
pp. 267-283
Author(s):  
Lovina Peter Japheth ◽  
Guirong Tan ◽  
Ladislaus Benedict Chang’a ◽  
Agnes Lawrence Kijazi ◽  
Kantamla Biseke Mafuru ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Rainfall Season

scholarly journals Geographical Variability of Drought in Northern South Africa

2017 ◽  
Vol 9 (1) ◽  
pp. 53
Author(s):  
Tibangayuka A Kabanda
Keyword(s):  
South Africa ◽  
Seasonal Rainfall ◽  
Dense Network ◽  
Rainfall Characteristics ◽  
Rainfall Season ◽  
Geographical Variability ◽  
Dry Spells ◽  
Source Data ◽  
Precipitation Indices ◽  
Drought Occurrence

This study focuses on the geographical variation of drought in northern South Africa (hereafter NSA). It assesses seasonal rainfall characteristics to determine drought occurrence and persistence in NSA. Seasonal rainfall data for the period 1960-2009 is used and was obtained from the South Africa Weather Service (SAWS). Rainfall stations in NSA are well distributed, forming a dense network of point-source data samples. Standardised Precipitation Indices (SPIs) are employed to detect drought occurrence and intensity at different locations. Analysis of SPIs with respect to time suggests that the severity of drought results from the accumulation of consecutive dry spells within a rainfall season and sometimes even consecutive dry rainfall seasons. It also shows the intensity and frequency of drought has increased in recent years.  The trend towards worsening drought conditions has significant socioeconomic implications for the region and other areas with similar geographical settings.

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