Most borehole paleoclimate studies have been based on the assumption that the exchange of temperature between the air and ground surface remains constant. However, secular changes in boundary-layer factors can generate anomalous ground temperatures. This dissertation is an investigation of factors that cause separation of air and ground temperatures on a seasonal to inter-annual time scale, including snow cover duration, latent energy of ground freezing, daily sunlight, precipitation, and vegetation.
Continual records of surface air and near-surface ground temperatures from five sites in North Dakota show similar trends in seasonal air-ground temperature separation. Statistical regressions of mean annual ground temperatures from Fargo and Bottineau sites indicate respective warming trends of 0.93±.09°C / 9 years and 1.17±.15°C / 6 years. Mean annual air temperatures and ground temperatures calculated with a conduction model assuming direct air-ground coupling do not display any significant trends.
The effect of snow cover duration on air-ground temperature exchange was tested by comparing average winter air-ground temperature differences (T5cm - Tair) with annual duration of snow cover. The correlation coefficients between these variables are: Bottineau: r2 = .84 (6 years), Fargo: r2 = .71 (9 years), Langdon: r2 = .56 (6 years), Minot: r2 = .79 (6 years), and Streeter: r2 = .87 (6 years). Best-fit latent energy of ground freezing values were determined with a conduction model and compared with total fall precipitation. The correlation coefficients between these variables are: Bottineau: r2= .38, Fargo r2= .66, Langdon: r2= .69, Minot: r2= .95, and Streeter: r2= .01.
A least-squares linear regression of mean annual air temperatures recorded in northwestern North Dakota from 1895 to 1995 indicates a warming magnitude of 1.57±.23°C per century. This temperature time series was forced into the ground with direct coupling to generate a synthetic temperature-depth profile. Inversion of this profile yielded a ground-surface warming magnitude of 1.7°C per century. Total fall precipitation is used as a proxy for latent energy of ground freezing. Latent energy effects were modeled with direct coupling of the regional air temperature record and a temperature dependent constraint for snow cover insulation. This generated a 0.4°C per century signal.
","abstract_html":"<p>Most borehole paleoclimate studies have been based on the assumption that the exchange of temperature between the air and ground surface remains constant. However, secular changes in boundary-layer factors can generate anomalous ground temperatures. This dissertation is an investigation of factors that cause separation of air and ground temperatures on a seasonal to inter-annual time scale, including snow cover duration, latent energy of ground freezing, daily sunlight, precipitation, and vegetation. </p><p>Continual records of surface air and near-surface ground temperatures from five sites in North Dakota show similar trends in seasonal air-ground temperature separation. Statistical regressions of mean annual ground temperatures from Fargo and Bottineau sites indicate respective warming trends of 0.93±.09°C / 9 years and 1.17±.15°C / 6 years. Mean annual air temperatures and ground temperatures calculated with a conduction model assuming direct air-ground coupling do not display any significant trends. </p><p>The effect of snow cover duration on air-ground temperature exchange was tested by comparing average winter air-ground temperature differences (T5cm - Tair) with annual duration of snow cover. The correlation coefficients between these variables are: Bottineau: r2 = .84 (6 years), Fargo: r2 = .71 (9 years), Langdon: r2 = .56 (6 years), Minot: r2 = .79 (6 years), and Streeter: r2 = .87 (6 years). Best-fit latent energy of ground freezing values were determined with a conduction model and compared with total fall precipitation. The correlation coefficients between these variables are: Bottineau: r2= .38, Fargo r2= .66, Langdon: r2= .69, Minot: r2= .95, and Streeter: r2= .01. </p><p>A least-squares linear regression of mean annual air temperatures recorded in northwestern North Dakota from 1895 to 1995 indicates a warming magnitude of 1.57±.23°C per century. This temperature time series was forced into the ground with direct coupling to generate a synthetic temperature-depth profile. Inversion of this profile yielded a ground-surface warming magnitude of 1.7°C per century. Total fall precipitation is used as a proxy for latent energy of ground freezing. Latent energy effects were modeled with direct coupling of the regional air temperature record and a temperature dependent constraint for snow cover insulation. This generated a 0.4°C per century signal. </p>","abstract_has_math":false,"creators":["Schmidt, William L."],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["W.D. Gosnold Jr."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2000,"date_issued":"2000-01-01T08:00:00Z","date_published":"2000-01-01T08:00:00Z","updated_at":"2026-07-24T03:24:58Z","subjects":["Earth temperature--North Dakota; Soil temperature--North Dakota; Climatic changes--North Dakota; Global warming","Geology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://commons.und.edu/theses/264","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["W.D. Gosnold Jr."]},{"key":"dc:creator","label":"Author","values":["Schmidt, William L."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Earth temperature--North Dakota; Soil temperature--North Dakota; Climatic changes--North Dakota; Global warming","Geology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://commons.und.edu/theses/264"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Most borehole paleoclimate studies have been based on the assumption that the exchange of temperature between the air and ground surface remains constant. However, secular changes in boundary-layer factors can generate anomalous ground temperatures. This dissertation is an investigation of factors that cause separation of air and ground temperatures on a seasonal to inter-annual time scale, including snow cover duration, latent energy of ground freezing, daily sunlight, precipitation, and vegetation.
Continual records of surface air and near-surface ground temperatures from five sites in North Dakota show similar trends in seasonal air-ground temperature separation. Statistical regressions of mean annual ground temperatures from Fargo and Bottineau sites indicate respective warming trends of 0.93±.09°C / 9 years and 1.17±.15°C / 6 years. Mean annual air temperatures and ground temperatures calculated with a conduction model assuming direct air-ground coupling do not display any significant trends.
The effect of snow cover duration on air-ground temperature exchange was tested by comparing average winter air-ground temperature differences (T5cm - Tair) with annual duration of snow cover. The correlation coefficients between these variables are: Bottineau: r2 = .84 (6 years), Fargo: r2 = .71 (9 years), Langdon: r2 = .56 (6 years), Minot: r2 = .79 (6 years), and Streeter: r2 = .87 (6 years). Best-fit latent energy of ground freezing values were determined with a conduction model and compared with total fall precipitation. The correlation coefficients between these variables are: Bottineau: r2= .38, Fargo r2= .66, Langdon: r2= .69, Minot: r2= .95, and Streeter: r2= .01.
A least-squares linear regression of mean annual air temperatures recorded in northwestern North Dakota from 1895 to 1995 indicates a warming magnitude of 1.57±.23°C per century. This temperature time series was forced into the ground with direct coupling to generate a synthetic temperature-depth profile. Inversion of this profile yielded a ground-surface warming magnitude of 1.7°C per century. Total fall precipitation is used as a proxy for latent energy of ground freezing. Latent energy effects were modeled with direct coupling of the regional air temperature record and a temperature dependent constraint for snow cover insulation. This generated a 0.4°C per century signal.
"]},{"key":"dc:title","label":"Title","values":["Air-ground temperature exchange"]}]}],"canonical_facts":{"dc:contributor":["W.D. Gosnold Jr."],"dc:creator":["Schmidt, William L."],"dc:description.abstract":["Most borehole paleoclimate studies have been based on the assumption that the exchange of temperature between the air and ground surface remains constant. However, secular changes in boundary-layer factors can generate anomalous ground temperatures. This dissertation is an investigation of factors that cause separation of air and ground temperatures on a seasonal to inter-annual time scale, including snow cover duration, latent energy of ground freezing, daily sunlight, precipitation, and vegetation.
Continual records of surface air and near-surface ground temperatures from five sites in North Dakota show similar trends in seasonal air-ground temperature separation. Statistical regressions of mean annual ground temperatures from Fargo and Bottineau sites indicate respective warming trends of 0.93±.09°C / 9 years and 1.17±.15°C / 6 years. Mean annual air temperatures and ground temperatures calculated with a conduction model assuming direct air-ground coupling do not display any significant trends.
The effect of snow cover duration on air-ground temperature exchange was tested by comparing average winter air-ground temperature differences (T5cm - Tair) with annual duration of snow cover. The correlation coefficients between these variables are: Bottineau: r2 = .84 (6 years), Fargo: r2 = .71 (9 years), Langdon: r2 = .56 (6 years), Minot: r2 = .79 (6 years), and Streeter: r2 = .87 (6 years). Best-fit latent energy of ground freezing values were determined with a conduction model and compared with total fall precipitation. The correlation coefficients between these variables are: Bottineau: r2= .38, Fargo r2= .66, Langdon: r2= .69, Minot: r2= .95, and Streeter: r2= .01.
A least-squares linear regression of mean annual air temperatures recorded in northwestern North Dakota from 1895 to 1995 indicates a warming magnitude of 1.57±.23°C per century. This temperature time series was forced into the ground with direct coupling to generate a synthetic temperature-depth profile. Inversion of this profile yielded a ground-surface warming magnitude of 1.7°C per century. Total fall precipitation is used as a proxy for latent energy of ground freezing. Latent energy effects were modeled with direct coupling of the regional air temperature record and a temperature dependent constraint for snow cover insulation. This generated a 0.4°C per century signal.
"],"dc:identifier":["https://commons.und.edu/theses/264"],"dc:subject":["Earth temperature--North Dakota; Soil temperature--North Dakota; Climatic changes--North Dakota; Global warming","Geology"],"dc:title":["Air-ground temperature exchange"],"thesis:degree_discipline":["Geology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T03:24:58Z"}