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Summer Regional United States Diurnal Temperature Range Variability With Soil Moisture Conditions

Brewer, Robert Wayne
http://rave.ohiolink.edu/etdc/view?acc_num=osu1428939308

Abstract Details

2015, Master of Science, Ohio State University, Atmospheric Sciences.
Long-term (1895-2012) soil moisture proxy data are collected and analyzed for its spatial and temporal variability across the United States in conjunction with air temperature and diurnal temperature range (DTR) variations over the same period. Palmer Drought Severity Index (PDSI) summer data were subjected to a Rotated Principle Component Analysis (RPCA) that identified 10 regions (components) having unique patterns of PDSI spatial and temporal variability. Four of those regions (RPC1: Ohio River Valley; RPC2: upper Midwest and eastern Northern Plains; RPC3: southeastern United States; RPC5: Southern Plains) are analyzed further with regard to DTR variations. In conjunction to the summer PDSI time series scores produced by the RPCA, mean DTR, T-max, and T-min (maximum and minimum temperatures) were obtained using GHCNM station data within each of the regions of interest and analyzed for trends. The twelve wettest and driest summers were also identified for each of the 4 regions based on the rank of their PDSI time series scores. The average temperature/DTR for each of these cases (wet or dry) were then compared. Soil moisture in the Ohio River Valley (RPC1) has an increasing trend throughout the 20th-21st centuries. T-max shows a downtrend of 0.5°C while T-min has increased ~ 0.7°C producing a downward trend in DTR throughout the period of record. The upper Midwest and eastern Northern Plains (RPC2) produced similar behavior as the Ohio River Valley with more moist soil conditions at the end of the 20th and early 21st century. DTR trends downward in this region due to a very clear upward trend in T-min coupled with a negligible downtrend in T-max. PDSI in the southeastern United States (RPC3) does not have a strong trend but does show a slight increase. T-max produces a trivial, but slight increasing trend while T-min shows a stronger increase in temperatures. This outcome produces a decreasing trend in DTR. Soil moisture in the Southern Plains (RPC5) shows an overall decline in PDSI. T-max produced a long-term increase of ~ 0.6°C. T-min produces an increasing trend slightly larger than that of T-max causing a very small decreasing DTR trend. The long-term DTR trends in each region seemed to be mostly influenced by the larger long-term increasing trends of T-min as compared to the smaller trends in T-max. However, DTR during the most extreme soil moisture summers (wet or dry) seemed to be influenced more by the variability in T-max, as T-min did not fluctuate as much. The 2012 summer drought was used as a case study to evaluate month-to-month DTR variations in the context of variations in precipitation and drought conditions. On a statewide and month-to-month basis, 2012 DTR variations almost always declined (increased) in response to increases (decreases) in rainfall. This variability agrees with that shown in the DTR soil-moisture portion of the analyses.
Jeffery Rogers, Dr. (Advisor)
Jay Stanley Hobgood, Dr. (Committee Member)
Jialin Lin, Dr. (Committee Member)
113 p.
Atmospheric Sciences; Climate Change; Meteorology
Diurnal Temperature Range; Soil Moisture; PDSI; Trends; Variability; T-max; T-min; 2012; Drought

Recommended Citations

Citations

  • Brewer, R. W. (2015). Summer Regional United States Diurnal Temperature Range Variability With Soil Moisture Conditions [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428939308

    APA Style (7th edition)

  • Brewer, Robert. Summer Regional United States Diurnal Temperature Range Variability With Soil Moisture Conditions. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1428939308.

    MLA Style (8th edition)

  • Brewer, Robert. "Summer Regional United States Diurnal Temperature Range Variability With Soil Moisture Conditions." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428939308

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.