Publication Date



Open access

Embargo Period


Degree Name

Master of Science (MS)


Meteorology and Physical Oceanography (Marine)

Date of Defense


First Committee Member

Peter Minnett

Second Committee Member

Brian Haus

Third Committee Member

Goshka Szczodrak


Ship-based measurements of the air-sea temperature difference (air-sea ΔT) are analyzed and presented with a focus on the temperature difference probability distribution and causes of its stability and variability. By taking the measurements with a hyperspectral infrared radiometer, temperatures of both the lower atmosphere and the skin layer of the ocean are acquired by a single, well-calibrated instrument. Consider that for each radiometric cruise deployment, when the air-sea ΔT measurements are plotted in a histogram, a mean air-sea ΔT peak at about -1 K becomes apparent regardless of measurement location or time of year. The large amount of air-sea ΔT data centered around -1 K suggests that there is a ‘feedback’ loop involving oceanic and atmospheric variables that stabilizes the air-sea ΔT around -1 K. Within a system, “feedback” is defined as the process in which a part of the output of the system is returned to its input to influence or regulate its further output. A feedback loop may be characterized as positive or negative. Following an initial disturbance, a positive feedback loop will lead to a growth in the initial perturbation, and could push a previously stable system past a critical condition and into another state. A negative feedback loop will act to lessen the initial disturbance, keeping the system within a stable state. When describing climate systems, there are a number of variables that allow for the formation of both positive and negative feedback loops. Data from the multiple cruises point to the negative ‘tail’ of the air-skin ΔT being caused by a combination of low wind speeds (less than 3 m/s) and intense solar radiation. Wind speeds from 3 m/s to 9 m/s cause an increase in sensible and latent heat fluxes that serve as negative feedbacks that stabilize the air-sea ΔT around its -1 K mean. At wind speeds above 10 m/s and low humidity levels, the latent heat flux acts as a positive feedback, and depending on the strength of other oceanic and atmospheric heat fluxes, may cause the air-skin ΔT to become more negative. A flow diagram of initial disturbances and the resulting feedbacks is presented, demonstrating the necessary conditions and consequences of the negative and positive feedback loops with regard to the air-skin ΔT.


oceanography; air sea temperature difference; remote sensing