Improving operational drought definitions—taking them to basin scale

Keyword(s):  
2019 ◽  
Author(s):  
Hamed D. Ibrahim

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.


1999 ◽  
Vol 40 (10) ◽  
pp. 103-110
Author(s):  
Carlo De Marchi ◽  
Pavel Ivanov ◽  
Ari Jolma ◽  
Ilia Masliev ◽  
Mark Griffin Smith ◽  
...  

This paper presents the major features of two decision support systems (DSS) for river water quality modeling and policy analysis recently developed at the International Institute of Applied Systems Analysis (IIASA), DESERT and STREAMPLAN. DESERT integrates in a single package data management, model calibration, simulation, optimization and presentation of results. DESERT has the flexibility to allow the specification of both alternative water quality models and flow hydraulics for different branches of the same river basin. Specification of these models can be done interactively through Microsoft® Windows commands and menus and an easy to use interpreted language. Detailed analysis of the effects of parameter uncertainty on water quality results is integrated into DESERT. STREAMPLAN, on the other hand, is an integrated, easy-to-use software system for analyzing alternative water quality management policies on a river basin level. These policies include uniform emission reduction and effluent standard based strategies, ambient water quality and least-cost strategies, total emission reduction under minimized costs, mixed strategies, local and regional policies, and strategies with economic instruments. A distinctive feature of STREAMPLAN is the integration of a detailed model of municipal wastewater generation with a water quality model and policy analysis tools on a river basin scale.


1996 ◽  
Vol 33 (4-5) ◽  
pp. 63-72
Author(s):  
Federico Preti

Monitoring and modelling are two complementary instruments necessary for the analysis of pollution phenomena, such as groundwater contamination and lakes eutrophication, often generated by diffuse (nonpoint) sources (NPS). A review of scientific literature has been conducted to obtain the information necessary to develop a correct methodology relative to environmental field monitoring and modelling agricultural nonpoint pollution. A questionnaire has been handed out to several researchers who are involved in this research field in order to learn of other pertinent activities being undertaken and to facilitate the exchange of information. Testing and verification of a methodology for the analysis of contamination caused by the use of agrochemicals, based on field monitoring studies and the application of a distributed nonpoint pollution model, have been conducted in Italy. Based on the research developed and practical experience, some of the main guidelines for conducting studies of pollution processes caused by agriculture as well as a summary of theoretical and practical aspects encountered in the design of field and basin scale model validation studies and in the use of published experimental results to test models can be proposed.


Author(s):  
N. Penny Holliday ◽  
Stephanie Henson

The growth, distribution, and variability of phytoplankton populations in the North Atlantic are primarily controlled by the physical environment. This chapter provides an overview of the regional circulation of the North Atlantic, and an introduction to the key physical features and processes that affect ecosystems, and especially plankton, via the availability of light and nutrients. There is a natural seasonal cycle in primary production driven by physical processes that determine the light and nutrient levels, but the pattern has strong regional variations. The variations are determined by persistent features on the basin scale (e.g. the main currents and mixed layer regimes of the subtropical and subpolar gyres), as well as transient mesoscale features such as eddies and meanders of fronts.


Meccanica ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 59-72 ◽  
Author(s):  
O. Bolognani ◽  
M. Mancini ◽  
R. Rosso

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