Progress 07/01/08 to 06/30/13
Outputs
Target Audience: Target audiences were : (a) public agencies and private organizations providing emergency food assistance to drought-stricken countries of sub-saharan Africa, (b) scientists and policy makers in these countries, and (c) scientists worldwide trying to better understand the climate of the sub-saharan, semi-arid ecotone. This was achieved by (a) publication of results in anopen access, online journal, and (b) a public-access website (still under construction) with 1349 years of decadal rainfall records for 30 rainfall stations in Burkina Faso and Niger with coordinates ranging from 9.88 to 18.5 degree north latitude and -4.77 to 13.2 degree longitude. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? We developed linkages withscientists at (a) the Natural Resources Conservation Service, Lincoln, Nebraska, (b) Dept., of Agricultural and Biosystems Engineering, Iowa State University, Ames, Iowa,and (c) the Institute for Water Saving Agriculture, North-West Agricultural and Forestry University, Yangling, China How have the results been disseminated to communities of interest? Results were disseminated via: (a) publication in open access, online journal, and (b) a public-access website (still under construction). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Rainfall over semi-arid sub-saharan West Africa did not return to its pre-1969 levels following the disastrous famine due to the unprecedented rainfall failure in consecutive years from 1969 through 1974 across the entire region. Consequently, many countries annually plan for delivering emergency humanitarian food aid (most provided by the US) to mitigate famine in this region. If failure of the rains at a given location can be reliably predicted ex-ante, it would help planners to respond in a timelier and more targeted manner. A good indicator would be a characteristic of the seasonal rainfall distribution that can be shown to be reasonably invariant over time and space. The question is: can we find such an indicator given the highlyvariable and unreliable inter-seasonal and intra-seasonal distribution of the mono-modal, monsoonal rainfall across the semi-arid ecotone of sub-Saharan of West Africa?We investigated whether such invariance existed for the seasonal median date (meaning the date when 50% of the seasonal total occurs). Weposted such invariancemay exist since the sun’s cyclic declination forces the advance and retreat of the Inter-tropical Front over West Africa. To test this, we examined the statistical properties of the seasonal median date for 1349 station-years of rainfall records for 30 point rainfallgauges in Burkina Faso and Niger with coordinates ranging from 9.88° to 18.5° north latitude and −4.77° to 13.2° longitude.Our resultsshowed the median date was quite narrowly distributed, and therefore can be used as a reasonable rainfall predictor. Our analysescan be extended for the entire network of point rainfall stations over semi-arid West Africa. The results can be used to generate near real-time GIS- based maps for the entire region pinpointinglikely areas of food security vulnerability as the current rainy season progresses. This would assist humanitarian and famine relief and assistance planners to respond in a more timely and targeted manner topotential failure of the rains in this region. Finally, the techniques that have been developed will be universally applicable and potentially very beneficial in terms of cost and time effectiveness to all types of environmental monitoring, data analysis, experimental design, and management in the United States and internationally.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
N. Persaud. 2013. Invariance in the seasonal median dates for mono-modal monsoonal rainfall distribution over the semi-srid ecotone of sub-saharan West Africa. International Journal of Geosciences, 2013, 4, 1-7. (open access online at http://www.scirp.org/journal/ijg)
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: We completed further analyses that confirmed our hypothesis that (a) the sun's declination can be directly related to the advance and retreat of the Inter-tropical Front over the food-insecure semi-arid ecotone of sub-saharan West Africa and therefore (b) the median date for mono-modal monsoonal rainfall over this region would exhibit invariant behanvior. We demonstrated strong invariance in the median date by examining its statistical properties for 1349 years of rainfall records for 30 rainfall stations in Burkina Faso and Niger with coordinates ranging from 9.88 to 18.5 degree north latitude and minus 4.77 to 13.2 degree longitude. The results showed that the median date can be used as a reasonable predictor that would enable humanitarian assistance planners to intervene in a timely manner to drought and crop failure in this region. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Emergency and humanitarian food aid agencies PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Rainfall over semi-arid sub-saharan West Africa did not return to its pre-1969 levels following the disastrous famine due to the unprecedented rainfall failure in consecutive years from 1969 through 1974 from across the entire region. Many countries annually plan for delivering emergency humanitarian food aid (most provided by the US) to mitigate famine in this region. If failure of the rains can be reliably predicted, it would help planners to respond in a more timely manner. Many past attempts, to reliably predict future rainfall based on analysis of statistical patterns of historical point rainfall data have not been remarkably successful. As a result, planners have increasingly relied on costly modeling using real time data from weather observation satellites to better understand and predict the meso-scale rainfall regime over this region vis-a-vis the in-place traditional observations from synoptic stations. Our results show that the median date can be used as a reasonably reliable predictor. The algorithms and analyses developed can be expanded to generate near real-time GIS- based maps that will enable humanitarian and assistance planners to pinpoint likely areas of food security vulnerability as the rainy season progresses. More broadly, This work is relevant to US agriculture because the findings contribute directly to the scientific body of knowledge on applications of nonlinear science in semi-arid agricultural environments enabling more effective determinants of climate change.
Publications
- No publications reported this period
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: We have completed 3 studies that analyzed long duration time series of available point rainfall data over Burkina Faso and Niger (between 9 to 23 degrees north latitude) in the sudano-sahelian zone of West Africa. We are summarizing our findings for publication. These studies are: (1) Latitudinal effect on statistical parameters of point rainfall distribution over the sudano-sahelian zone. (2) Quantifying intensification of drought across the sudano-sahelian zone based on harmonic analysis of point rainfall records. (3) Latitudinal effect on the mid-point of the rainy season over the sudano-sahelian zone. These findings contribute directly to the scientific body of knowledge on applications nonlinear science in semi-arid agricultural environments. The techniques developed are directly applicable to US semi-arid, dryland agri-climates West of the Mississippi enabling more effective determinants of climate change. PARTICIPANTS: We received assistance and input from the Scientific Director, Institut National de la Recherche Agronomique du Niger (INRAN), B.P. 429, Niamey, Niger TARGET AUDIENCES: Scientific Community PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In their entirety, these studies supported our project hypothesis that the observed point rainfall distribution pattern over this zone results from the superimposition of shorter term, non-periodic stochastic influences on the more stable, periodic behavior of the Inter-tropical Convergence Zone over West Africa. These results would help policy makers better understand and respond to the long-term eco-geographical effects of climate change. Also, since the approaches enable better signalling of rainfall deficits, they could make US food assistance planning and decision making for this drought-prone region more timely and targeted. The findings contribute directly to the scientific body of knowledge on applications nonlinear science in semi-arid agricultural environments. The techniques developed are directly applicable to US semi-arid, dryland agri-climates West of the Mississippi enabling more effective determinants of climate change.
Publications
- No publications reported this period
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: We continued the rather difficult task to develop a non-linear spatio-temporal model to adequately describe the spatio-temporal latitudinal effect on point rainfall records from all staions in Niger and Burkina Faso in West Africa. We have compiled the results of calculations on (a) the annual and semi-annual harmonics from the rainfall series for all synoptic stations with 20 or more years of record from these two countries, and (b)the calculated mid-point dates of the monomodal rainy season for each year of record for the same synoptic stations. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
These results provide an approach to better quantify the reported intensification of drought across the sudano-sahelian zone based on the amplitude and phase shifts of the harmonic components. This would help policy makers better understand and respond to the long-term eco-geographical effects of climate change. The results would also make planning and decision making for food assistance more timely since the approach of the midpoint dates would signal that rainfall before would be equal to the rainfall after with a known degree of confidence.
Publications
- No publications reported this period
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: 1. We examined the non-linear patterns in the residuals obtained by removing the calculated annual and semi-annual harmonics from the rainfall series for all synoptic stations with 20 or more years of record in Burkina Faso and Niger, West Africa. The results showed that the latitudinal effect in space and time on point rainfall over these countries (that span the West African sudano-sahelian zone) can be described by the interplay of deterministic and stochastic factors. We are in the process of developing a non-linear spatio-temporal model to describe the latitudinal effect. 2. We examined the summary statistics and the parametric distributions for the calculated mid-point dates of the monomodal rainy season for each year of record for the same synoptic stations. The results showed that the variabilty of the mid-point dates increased with increasing latitude. On the other hand the occurrence of the midpoint date could be predicted with reasonable confidence. We are preparing three manuscripts that document these findings. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
These results provide an approach to better quantify the reported intensification of drought across the sudano-sahelian zone based on the amplitude and phase shifts of the harmonic components. This would help policy makers better understand and respond to the long-term eco-geographical effects of climate change. The results would also make planning and decision making for food assistance more timely since the approach of the midpoint dates would signal that rainfall before would be equal to the rainfall after with a known degree of confidence.
Publications
- No publications reported this period
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Progress 07/01/08 to 12/13/08
Outputs
OUTPUTS: In the 6 months since the inception of this project we have requested,assembled, and reformatted the digitized rainfall records for all synoptic stations in Burkina Faso and Niger, West Africa. These neighboring West African countries entirely straddle the soudano-sahelian zone. We have checked all the records received for errors and have calculated the mid-point dates of the rainy season for each year of record for all stations. We have calcuated the annual and semi-annual harmonic components of the annual rainfall distribution for each year for all stations with 20 or more years of record. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We found: (a) A strong latitudinal effect on the occurrence and variabilty of the midpoint of the rainy season over the sudano-sahelian zone, and (b) Initial indications that we would be able to better quantify the reported intensification of drought across the sudano-sahelian zone based on the amplitude and phase shifts of the harmonic components we have thus far extracted.
Publications
- No publications reported this period
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