Investigating the impacts of agricultural land use change on regional climate processes in the northern North American Great Plains

dc.contributor.advisorChairperson, Graduate Committee: Paul C. Stoy; Jack Brookshire (co-chair)en
dc.contributor.authorBromley, Gabriel Treesen
dc.contributor.otherTobias Gerken, Andreas F. Prein and Paul C. Stoy were co-authors of the article, 'Recent trends in the near-surface climatology of the northern North American Great Plains' in the journal 'Journal of climate' which is contained within this dissertation.en
dc.contributor.otherAndreas F. Prein, Shannon Albeke and Paul C. Stoy were co-authors of the article, 'Simulating the impacts of agricultural land use change on the climate of the northern North American Great Plains: validating a convection-permitting climate model' submitted to the journal 'Climate dynamics' which is contained within this dissertation.en
dc.contributor.otherAndreas F. Prein, Shannon Albeke and Paul C. Stoy were co-authors of the article, 'The decline in summer fallow in the northern plains cooled near-surface climate but had minimal impacts on precipitation' submitted to the journal ' ' which is contained within this dissertation.en
dc.contributor.otherAndreas Prein and Paul C. Stoy were co-authors of the article, 'Recent enhancement of thermodynamic environments in the northern North American Great Plains' submitted to the journal 'Geophysical research letters' which is contained within this dissertation.en
dc.coverage.spatialGreat Plainsen
dc.date.accessioned2022-01-25T03:59:24Z
dc.date.available2022-01-25T03:59:24Z
dc.date.issued2021en
dc.description.abstractThe northern North American Great Plains (NNAGP) is the area defined by the Upper Missouri River Basin and the Canadian Prairies. It is a semi-arid region categorized by large stretches of grassland, pasture, and crops. During the last century and extending to the present day, a standard agricultural practice was to utilize a wheat-summer fallow rotation schedule, where the fields were left unplatted and an herbicide was often applied to keep weeds at bay. Concerns over soil health and profitability have led to the systematic decline of summer fallow, and nearly 116,000 km 2 that used to be fallow during the summer in the 1970s are now planted. An observational analysis discovered that from 1970-2015, during the early warm season, the NNAGP have cooled at -0.18 °C decade -1, nearly the same magnitude as the annual global warming rate. The near-surface atmosphere also moistened, evidenced by a decreasing vapor pressure deficit (VPD) trend, and monthly mean precipitation increased in excess of 8 mm per decade. Monthly mean convective available potential energy (CAPE) increased by 80% at Glasgow, MT and by 35% at Bismarck, ND based on atmospheric sounding observations. To test whether a reduction in summer fallow is responsible for these observed changes, a set of convection-permitting model experiments were performed over the NNAGP. Two sets (4 total) of three-year simulations were driven by ERA5 data with the vegetative fraction adjusted using satellite estimated fallow amounts for 2011 and 1984. The control simulations were extensively validated against an ensemble of observations with large temperature biases in Winter by ~ -3 °C and Summer by ~3°C. The areas where fallow area declined from 1984-2011 were cooler by about 1.5 °C and had a lower VPD by 0.15 kPa compared to where it did not. CAPE increased where fallow declined from 1984-2011 but so did convective inhibition (CIN). These findings insinuate that the observed change to monthly mean precipitation cannot be explained by summer fallow reduction alone. Trends in observed low level moisture transport show that the Great Plains Low Level Jet has been intensifying, bringing increased moisture to the NNAGP and partially responsible for the precipitation increase.en
dc.identifier.urihttps://scholarworks.montana.edu/handle/1/16243en
dc.language.isoenen
dc.publisherMontana State University - Bozeman, College of Agricultureen
dc.rights.holderCopyright 2021 by Gabriel Trees Bromleyen
dc.subject.lcshAgricultureen
dc.subject.lcshLand useen
dc.subject.lcshCrop rotationen
dc.subject.lcshFallowingen
dc.subject.lcshClimatic changesen
dc.titleInvestigating the impacts of agricultural land use change on regional climate processes in the northern North American Great Plainsen
dc.typeDissertationen
mus.data.thumbpage90en
thesis.degree.committeemembersMembers, Graduate Committee: Scott Powell; Ankur R. Desai; Andreas F. Preinen
thesis.degree.departmentLand Resources & Environmental Sciences.en
thesis.degree.genreDissertationen
thesis.degree.namePhDen
thesis.format.extentfirstpage1en
thesis.format.extentlastpage206en

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