“Drought Research Initiative”的意思、由来-开放百科全书

The Drought Research Initiative(DRI) was established to better understand the physical characteristics of and processes influencing Canadian Prairie droughts, and to contribute to their better prediction, through a focus on the recent severe drought that began in 1999 and largely ended in 2005. It is an interdisciplinary effort that involves 15 funded investigators from 6 Canadian universities and more than 20 collaborators from other universities and federal laboratories as well as partners from three provincial governments (Alberta, Manitoba and Saskatchewan). DRI is achieving its objective by focusing on five complementary research themes, including quantification, understanding, prediction, comparisons with other droughts, and implications for society. Details beyond the scope of this entry can be found in Stewart et al. (2008)^[1] or on the DRI website

Background

DRI addresses a multi-year drought that began in 1999 with cessation of its atmospheric component in 2004/2005 and many of its hydrological components in 2005. It was the worst drought for at least a hundred years in parts of the Canadian Prairies. According to Phillips (2002),^[2] for the western and central Canadian Prairies during 2001 and 2002, “… it was the worst of times. Even in the dust bowl of the 1930s, no single year between Medicine Hat, Kindersley and Saskatoon was drier than in 2001”. The drought affected agriculture, recreation, tourism, health, hydro-electricity, and forestry in the Prairies. Gross Domestic Product fell some $5.8 billion and employment losses exceeded 41,000 jobs for 2001 and 2002. This drought also contributed to a negative or zero net farm income for several provinces for the first time in 25 years (Statistics Canada, 2003^[3]) with agricultural production over Canada dropping an estimated $3.6 billion in 2001/2002. Previously reliable water supplies such as streams, wetlands, dugouts, reservoirs, and groundwater were placed under stress and often failed. More details are available in Wheaton (2005).^[4]

Despite the enormous economic, environmental, and societal impacts of droughts, DRI is undertaking the first integrated drought research program of its kind in Canada with the hope being that the occurrence and nature of drought can be better anticipated on short and long term scales. From a longer-term perspective, this 5-year Network represents an essential step in better predicting droughts over Canada, their detailed structure and their impacts with increasing confidence and better assessing whether there will be a ‘drying of the continental interior’ in the future

Research Themes

DRI is achieving its objective by focusing on five complementary research themes, including quantification, understanding, and better prediction of a particular drought with funding primarily from the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS). Comparisons with other droughts, and implications for society have been funded with additional direct and in-kind support coming from Environment Canada, Agriculture and Agri-Food Canada, Natural Resources Canada, Prairie Farm Rehabilitation Administration (PFRA), Saskatchewan Watershed Authority, Saskatchewan Research Council, Manitoba Water Stewardship and Manitoba Hydro.

1: Characterizing Drought

To characterize the drought of 1999-2005 DRI has been quantifying its atmospheric, hydrologic, and land-surface physical features at a variety of spatial and temporal scales. This analysis will be realized by addressing three focused questions:

The analysis has involved the development of a four-dimensional assessment of the atmosphere during the drought over various temporal scales using a knowledge of temperature, humidity, geopotential height, wind, clouds, precipitation amount, and current weather. At the surface, the spatial and temporal characteristics of vegetative state (in terms of water stress) for major vegetation types (crops and boreal zones), soil moisture, stream network, river flows, lake levels, wetlands, depression storage, groundwater and sub-surface flows be assessed to determine when and where drought is occurring. Although this is a difficult task due to data gaps, and the complexity of the shallow undulations in the prairies topography, an analysis of in-situ data, satellite data and model output now provides a comprehensive overview of the evolution of the drought.

2: Drought Processes

DRI is also focusing on the understanding of the processes and feedbacks governing the formation, evolution, cessation and structure of the drought. This theme addresses the following questions:

There are many ways in which drought, basically a sustained precipitation deficit, can be initiated and prolonged. Some processes that reduce precipitation include, large scale circulation anomalies, lack of moisture advected into a region, reduction of local moisture supplies, production of virga as opposed to precipitation, and possibly even the role of aerosols in the dusty environment acting to reduce precipitation. Over the five years of this drought, these processes and numerous other factors were operating at various times and locations to preclude substantial precipitation from being produced over large regions of the Prairies.

While prairie drought processes have characteristic spatial and temporal scales, land surface hydrological/biophysical processes generally operate at small spatial scales (and with larger inherent spatial variability) while atmospheric process have a hierarchy of scales ranging from planetary to local turbulence. DRI is addressing the cascade of energy and movement of moisture through atmospheric processes and the horizontal scale link between land surface and groundwater processes during drought events.

3: Drought Prediction

Drought prediction research in DRI is directed at assessing and reducing uncertainties in the prediction of drought and its structure. In particular, prediction research has focused on the evaluation and improvement of prediction models. The modelling tools used are global and regional climate models (GCMs and RCMs), and hydrological models. The hydrological models are driven by output from the atmospheric models, data from ongoing research sites and reanalysis products. DRI modeling studies address the following questions:

Use is being made of archived historical model outputs and new simulations to address many of these issues. DRI focuses on many facets of a particular extreme and consequently many more variables beyond the traditional temperature and precipitation need to be examined. For example, experiments carried out within DRI are helping to assess the role of soil moisture and snow cover on seasonal prediction.

4: Drought Comparisons

Theme 4 provides comparisons of the recent drought and previous droughts over this region and those in other regions, in the context of climate variability and change. For many users there is a need to understand a current or recent drought event in the context of historical droughts. These comparisons are guided by the following research questions:

Comparisons between the 1999-2004/05 drought have focused on the internal structure of drought, as well as its presence over a particular region. Many droughts, including the 1999-2005 event have a complex internal structure for their precipitation patterns which often changed dramatically during the drought. More details on these comparisons are available in Bonsal (2008).^[5]

5: Drought Impacts

Theme 5 applies our progress in drought characterization and prediction to critical issues of importance to society during times of drought. These efforts are linked to the following questions:

In order to advance this theme, DRI has carried out an extensive consultative process with the users; has launched a set of simulation exercises to test how users may adapt new DRI products to make better decisions through an exercise known as DEWS (Drought Early Warning System test), and formed a Partners Advisory Committee composed of experts from user agencies and groups to give advice on their needs for DRI research and information. More details are available in Lawford et al. (2008).^[6]

Program Structure and Linkages

DRI is led by two Principal Investigators, Drs. Ronald Stewart and John Pomeroy. A Board of Directors, chaired by Jim Bruce oversees the program strategy and a Science Committee takes the day-to-day decisions about the implementation of the project. In addition, the operational details are implemented by a Secretariat consisting of a Network Manager, a Financial Manager and two Data Managers. A Partners Advisory Committee, chaired by Harvey Hill, also meets and reports on the user needs to the Board of Directors. The program have also established strong linkages and collaborations with research initiatives and departments and on provincial, federal and international levels. The detailed program structure and linkages can be found in Stewart et al., (2008).^[1]

The DRI Legacy

DRI has brought together an unprecedented amount of information on Canadian drought. On its web site, one can find many links to various datasets that describe elements of drought in the atmosphere, at the surface or below the surface. Compiling a Prairie-wide database of provincial groundwater and water levels is part of this effort. The data are being brought together in an integrated information system. Synthesis articles, special issue of Atmosphere-Ocean and a public information document about the 1999-2005 drought are in preparation. In addition, new techniques of archiving and making available datasets are being explored as one other legacy of DRI. Undoubtedly, the greatest legacy of DRI will be the young people who have been trained at the PhD, Masters and early scientist level who carried out much of this research and are now pursuing lifetime careers in disciplines related to DRI.

References

1. ^¹Stewart, R., J. Pomeroy and R. Lawford, 2008: A Drought Research Initiative for the Canadian Prairies, CMOS Bulletin, Vol. 36, No. 3, 97-102.
2. ^Phillips, D.W., 2002: The top ten Canadian weather stories for 2001. CMOS Bulletin, 30, 19-23.
3. ^Statistics Canada, 2003: Net Farm Income. Catalogue No. 21-010-XIE, Volume 2. Ottawa, Ontario.
4. ^Wheaton, E, Wittrock V, Kulshreshtha S, Koshida G, Grant C,Chipanshi A, Bonsal BR (2005) Lessons learned from thedrought years of 2001 and 2002: synthesis report. Agricultureand Agri-Food Canada, Saskatchewan ResearchCouncil Publ No. 11602–46E03, Saskatoon
5. ^Bonsal, B., 2008: Droughts in Canada: an overview. CMOS Bulletin, Vol. 36, No. 3, 79-86.
6. ^Lawford, R., H. Hill, E. Wheaton, I. Hanuta, A. Warkentin, B. Girling and R. Stewart, 2008: A review of some requirements for drought information on the Canadian Prairies. CMOS Bulletin, Vol. 36, No. 3, 97-102.