عنوان

Global simulation of lakes and river transport in climate models, and investigations of lake/climate feedbacks during the middle Holocene

شماره

TLpq304380260

زبان متن نوشتاري يا گفتاري و مانند آن

انگلیسی

عنوان اصلي

Global simulation of lakes and river transport in climate models, and investigations of lake/climate feedbacks during the middle Holocene

نام عام مواد

[Thesis]

نام نخستين پديدآور

M. T. Coe

نام ساير پديدآوران

J. E. Kutzbach

نام ناشر، پخش کننده و غيره

The University of Wisconsin - Madison

تاریخ نشرو بخش و غیره

1997

نام خاص و کميت اثر

133

جزئيات پايان نامه و نوع درجه آن

Ph.D.

کسي که مدرک را اعطا کرده

The University of Wisconsin - Madison

امتياز متن

1997

متن يادداشت

The goal of this study is to investigate the sensitivity of climate to changes in the area and location of surface waters (lakes and wetlands). A model (SWAM) is developed to predict surface water area and river transport globally. SWAM is based on a linear reservoir hydrologic model and requires, as input, climatic estimates of runoff, precipitation, and evaporation from either observations or climate simulations, and estimates of topography from digital terrain models. SWAM is first applied on a usd2\sp\circusd x usd2\sp\circusd resolution to modern and middle Holocene climates of northern Africa. The middle Holocene simulation (6000 years before present), using climate input from the GENESIS climate model experiment, illustrates the potential sensitivity of surface water area to climatic change. SWAM simulates an increase in surface water area of northern Africa from about 1% coverage (modern) to about 3% (6000 yr BP). The increase is primarily a result of a greatly expanded Lake Chad and increased waters to the north of the Niger bend. The second part of this study examined whether expanded middle Holocene surface waters may have had an impact on the strength of the summer monsoon of northern Africa. Three experiments with the National Center for Atmospheric Research Community Climate Model version 3 are analyzed: (1) a modern simulation, (2) a middle Holocene simulation with 6000 yr BP orbital forcing, and (3) a middle Holocene simulation with 6000 yr BP orbital forcing and prescribed expanded surface water. The expanded surface waters in northern Africa result in significant changes in the simulated climate especially in northern summer. Net surface radiation and evaporation increase due to expanded surface waters by amounts which are comparable to changes due to orbital forcing alone. Precipitation increases regionally, but decreases to the south of the lakes. The geographic distribution of precipitation in the experiment with increased surface water area is in better agreement with observations than the simulation without surface water changes. This result demonstrates the need for including interactive lake models within climate models. In the third part of the study, SWAM is applied on a higher resolution usd(5\sp\primeusd x usd5\sp\primeusd) to simulate present-day lakes and river transport for all continents (except Antarctica and Greenland). The model develops its own river transport directions based on elevation. Subjective and objective techniques are developed to reduce the digital terrain model bias of overestimating surface water. The model simulates the large scale modern surface water features and river transport in fair agreement with observations. The simulated modern lake area (about 3% of the land area) is somewhat larger than the observed area (about 2%). Wetlands are poorly simulated by the model due to the coarse resolution of the digital terrain models. The results obtained from SWAM indicate that present-day terrain models are adequate for including interactive lakes and rivers in climate simulations. (Abstract shortened by UMI.)

موضوع مستند نشده

Atmosphere

موضوع مستند نشده

climate

موضوع مستند نشده

Earth sciences

موضوع مستند نشده

Hydrology

موضوع مستند نشده

Pure sciences

مستند نام اشخاص تاييد نشده

J. E. Kutzbach

مستند نام اشخاص تاييد نشده

M. T. Coe

نام الکترونيکي

فرمت انتشار

p

نوع ماده

[Thesis]

کد کاربرگه

276903

سطح دسترسي

a

تكميل شده

Y