Abstract
High spatial/temporal resolution mobile transects were used to examine the thermal and moisture structure of the sea-breeze front (SBF) along the Mississippi coast during August 2014 and 2015. Compared to most similar studies, conditions were much warmer and more humid. Results show a 1-2 g/kg increase in mixing ratio across the mature SBF zone, and up to a 2.5°C temperature decrease. When SBF radar fine lines are identifiable, their position agrees very well with surface thermodynamic changes. Although temperatures were cooler at the coast, microscale offsets in location of thermal, moisture, and radiative features are noted in the vicinity of the SBF, particularly when the sea-breeze system is relatively weak or immature. At times, it seems that strong solar insolation causes the temperature to rise temporarily within the transition zone behind the kinematic SBF. These results are at variance with most other diagnostic studies. Some thermodynamic variations are noted within the marine air mass in connection to minor water bodies such as Biloxi Bay. The potential for passage of the SBF to at least temporarily increase human heat stress as described by heat index is also noted.
Highlights
High spatial/temporal resolution mobile transects were used to examine the thermal and moisture structure of the sea-breeze front (SBF) along the Mississippi coast during August 2014 and 2015
It seems that strong solar insolation causes the temperature to rise temporarily within the transition zone behind the kinematic SBF. ese results are at variance with most other diagnostic studies
It should be noted that not all coastal air mass contrasts necessarily meet these criteria. e sea-breeze front (SBF) is the boundary or transitional zone between the marine and terrestrial air masses once the sea breeze is Advances in Meteorology established. is transition may be described or inferred with reference to temperature, water vapor content, threedimensional wind patterns, atmospheric chemistry, or radar/lidar backscatter. e sea-breeze system or circulation encompasses a broader view of the sea breeze, SBF, associated convective systems, upper return flow, and peripheral aspects of the larger-scale atmospheric conditions (e.g., Figure 2 of Sills et al [7] for lake breeze), as well as the physical processes associated with the diurnal sea/land breeze cycle
Summary
A strengthening air mass contrast (of temperature and dewpoint) and difference in cloud patterns (cumulus inland vs mostly clear offshore) (Figure 11) were documented in close vicinity to the coast, which could reasonably be interpreted as a “passive” or “nonprogressive” sea-breeze pattern. Collecting data northward about an hour later, a very similar temperature pattern is noted at a slightly more southerly position (in spite of generally onshore winds) At this time (around 1630 UTC; 1130 CDT), diurnal heating of the land area has effectively reversed the general temperature gradient between the coast and Saucier, so that θv increases nearly 2 C northward to about 30.47 N and remains approximately constant (Figure 13). Over a distance of tens of meters, the surface temperature went from 34 C in the water to 35.5 C in wet sand to 41–46 C over dry sand and 52 C on concrete
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