Interseasonal Storage Research Articles

Climate, interseasonal storage of soil water, and the annual water balance

The effects of annual totals and seasonal variations of precipitation and potential evaporation on the annual water balance are explored. It is assumed that the only other factor of significance to annual water balance is a simple process of water storage, and that the relevant storage capacity is the plant-available water-holding capacity of the soil. Under the assumption that precipitation and potential evaporation vary sinusoidally through the year, it is possible to derive an analytic solution of the storage problem, and this yields an expression for the fraction of precipitation that evaporates (and the fraction that runs off) as a function of three dimensionless numbers: the ratio of annual potential evaporation to annual precipitation (index of dryness); an index of the seasonality of the difference between precipitation and potential evaporation; and the ratio of plant-available water-holding capacity to annual precipitation. The solution is applied to the area of the United States east of 105°W, using published information on precipitation, potential evaporation, and plant-available water-holding capacity as inputs, and using an independent analysis of observed river runoff for model evaluation. The model generates an areal mean annual runoff of only 187 mm, which is about 30% less than the observed runoff (263 mm). The discrepancy is suggestive of the importance of runoff-generating mechanisms neglected in the model. These include intraseasonal variability (storminess) of precipitation, spatial variability of storage capacity, and finite infiltration capacity of land.

The Organization of a West African Grain Market

In this study I reconsider some widespread views on African grain marketing by providing a description of Burkina Faso on the basis of extended field observations and interviews. The collection and distribution of grain are largely achieved by a network of agents working for major merchants and by a large number of independent smaller traders. The complex mechanisms involved reveal that competition is severely restricted both at village and national levels. Most traders operate with very small funds while most farmers have little withholding capacity. Despite the large number of actors involved interseasonal storage of market grain is concentrated. High urban grain prices do not benefit most producers because linkages are seasonal. Existing institutions such as Village Groups may benefit some farmers when they are properly funded. Their impact shows that greater access by farmers to national capital resources may improve marketing structures.

Estimating the Meridional Energy Transports in the Atmosphere and Ocean

Abstract The poleward energy transports in the atmosphere–ocean system are estimated for the annual mean and the four seasons based on satellite measurements of the net radiation balance at the top of the atmosphere, atmospheric transports of energy at the north or south poles various types of corrections had to be made, so that the global balances are maintained. This also enabled us to estimate the uncertainties in the procedures used. The uncertainties found are similar to those reported by Hastenrath based on different satellite data sets but using the same correction method. Finally, oceanic heat transports are computed for the annual mean and seasons. One of the crucial terms in the heat budget, the interseasonal storage of energy in the oceans, is estimated for three different layers 0–112, 0–552 and 0–550 m, enabling a further error estimate in the inferred oceanic heat transports. The present results confirm the presence of a strong annual cycle in the transport of energy by the oceans.

Performance characteristics of solar ponds operating at different latitudes

The results of a comparative study of the performance of solar ponds operating at different latitudes are presented in this paper. A mathematical tool was developed to study the behaviour of solar ponds operating under different physical and operational conditions. The hourly meteorological data of Kew and Singapore were used. The pond operating at higher latitudes, i.e. Kew, where seasonal variations are significant, must be deeper than a pond operating near the equator. The deeper pond can also act as an interseasonal storage device. A pond operating at a location in Singapore attains a fairly high temperature but the temperature requirements are also high for the desired applications such as space cooling in conjunction with a refrigeration cycle. Although a pond at Kew attains a lower temperature compared with a pond at Singapore, it can supply considerable amounts of thermal energy to support a space heating load. Both the ponds require auxiliary heating, the magnitude being dependent upon the nature of the load.

Stockage couplé de calories et de frigories en aquifère par doublet de forages

The doublet system (a pair of wells) is applied to sensible heat storage in an aquifer. It avoids several problems inherent in single-well storage: water supply and removal, and maintenance of groundwater pressure. Two systems are studied by mathematical models: the sweep system (successive warm and cold waves through the aquifer) and the warm well-cold well system (two separate zones of storage). The models were first checked by simulation of in situ experiments. The thermal behavior of both systems is evaluated by comparing the operating conditions in functions of the reservoir physical parameters and the exploitation conditions. Constraints imposed on the operating rules by the optimization of thermal efficiency are determined. Finally, these results are applied to a coupled interseasonal storage: hot and cold water are successively stored in an aquifer in order to improve alternative heating and air conditioning of buildings by heat pumps using groundwater. Several solutions are studied.