A Long-Term Study of Sea-Breeze Characteristics: A Case Study of the Coastal City of Adelaide

Zahra Pazandeh Masouleh School of Civil, Environmental and Mining Engineering, University of Adelaide, South Australia, Australia

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David John Walker School of Civil, Environmental and Mining Engineering, University of Adelaide, South Australia, Australia

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John McCauley Crowther School of Civil, Environmental and Mining Engineering, University of Adelaide, South Australia, Australia

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Abstract

The sea-breeze characteristics of the Adelaide, Australia, coastline have been studied by applying a sea-breeze detection algorithm to 3- and 6-hourly meteorological records of near-surface and upper-air data at Adelaide Airport from 1955 to 2007. The sea breeze is typically a westerly gulf breeze combined with a later-occurring southerly ocean breeze. Regression analysis showed a significant increasing trend in the intensity of sea breezes but not in their frequency. Over the 52-yr period, there was an average increase of 1 m s−1 in zonal and 0.7 m s−1 in meridional sea-breeze wind speed components. The annually and seasonally averaged maximum wind speeds on sea-breeze days increased significantly over the 52-yr period of the study by 0.65 m s−1 for the whole year, 0.48 m s−1 in spring, 1.02 m s−1 in summer, and 1.10 m s−1 in autumn. A comparison of hourly data for 1985–95 with those for 1996–2007 showed frequencies of sea-breeze onset times less than 4 h from sunrise increasing from 29% to 36%, durations greater than 8 h increasing from 51% to 59%, and times of maximum sea breeze between 2 and 6 h after sunrise increasing from 44% to 50%. The monthly frequency of sea breezes was found to increase by 2.8 percentage points for each degree Celsius rise in monthly average maximum air temperature at Adelaide Airport. The meridional ocean-breeze wind speed, unlike the gulf-breeze wind speed, is also correlated with maximum air temperature at Adelaide Airport.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Zahra Pazandeh Masouleh, zahra.pazandehmasouleh@adelaide.edu.au

Abstract

The sea-breeze characteristics of the Adelaide, Australia, coastline have been studied by applying a sea-breeze detection algorithm to 3- and 6-hourly meteorological records of near-surface and upper-air data at Adelaide Airport from 1955 to 2007. The sea breeze is typically a westerly gulf breeze combined with a later-occurring southerly ocean breeze. Regression analysis showed a significant increasing trend in the intensity of sea breezes but not in their frequency. Over the 52-yr period, there was an average increase of 1 m s−1 in zonal and 0.7 m s−1 in meridional sea-breeze wind speed components. The annually and seasonally averaged maximum wind speeds on sea-breeze days increased significantly over the 52-yr period of the study by 0.65 m s−1 for the whole year, 0.48 m s−1 in spring, 1.02 m s−1 in summer, and 1.10 m s−1 in autumn. A comparison of hourly data for 1985–95 with those for 1996–2007 showed frequencies of sea-breeze onset times less than 4 h from sunrise increasing from 29% to 36%, durations greater than 8 h increasing from 51% to 59%, and times of maximum sea breeze between 2 and 6 h after sunrise increasing from 44% to 50%. The monthly frequency of sea breezes was found to increase by 2.8 percentage points for each degree Celsius rise in monthly average maximum air temperature at Adelaide Airport. The meridional ocean-breeze wind speed, unlike the gulf-breeze wind speed, is also correlated with maximum air temperature at Adelaide Airport.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Zahra Pazandeh Masouleh, zahra.pazandehmasouleh@adelaide.edu.au

1. Introduction

The difference between the thermal and radiative properties of the sea and land surfaces can produce an unstable temperature gradient at low levels of the atmosphere that initiates a sea breeze. Several environmental parameters affect the formation and characteristics of these circulations and these may change over long periods of time, for example, surface aerodynamic roughness and land surface heat flux (Crosman and Horel 2010).

Development of cities along the coast has led to a change in land surface cover, which modifies the near-surface wind regime by increasing the land surface frictional drag force. Furthermore, the urban heat island (UHI) effect can interact with the sea-breeze circulation and may cause an increase in sea-breeze intensity and its frequency of occurrence (Yoshikado 1992).

The effect of sea breeze on precipitation (Baker et al. 2001), air pollution (Grossi et al. 2000), and coastal processes (Masselink and Pattiaratchi 1998; Masselink and Pattiaratchi 2001) has been extensively studied and its impact on locally generated waves and consequently on the general sedimentation pattern has been observed (Psuty 2005).

The city of Adelaide (Fig. 1) is located on a coastal plain in South Australia, bounded on the west by Gulf St. Vincent and on the east by the Mount Lofty ranges (of which the highest point is 726 m above mean sea level). Adelaide (34°55′43″S, 138°35′55″E, elevation 59 m above Australian Height Datum) has a Mediterranean climate (Köppen classification Csa) with warm to hot, dry summers and cool to mild winters. Sea breezes in Adelaide occur frequently: 30% of days in spring, 42% in summer, 24% in autumn, and 10% in winter (Pazandeh Masouleh et al. 2016). The sea breezes typically start from an easterly overnight land breeze, which reverses in the early morning to a westerly sea breeze. During the midafternoon, the wind direction becomes southwesterly and the wind speed reaches its maximum. During late afternoon and early evening, the wind speed abates and its direction backs to southerly and finally becomes an easterly land breeze in late evening. The climate of South Australia is controlled by several climate drivers: the southern annular mode, the Indian Ocean dipole, the El Niño–Southern Oscillation, and the “subtropical ridge” (Australian Bureau of Meteorology 2010). A study by Hendon et al. (2007) showed that the southern annular mode has an indirect impact on maximum surface temperatures of Australia through increased rainfall during the high index polarity of the southern annular mode, which reduces the maximum temperature across southern and eastern Australia. Additionally, the latitudinal position and the intensity (mean maximum pressure) of the Subtropical Ridge in Australia has been shown to affect rainfall as well as air temperature and zonal and meridional winds (Larsen and Nicholls 2009; Williams and Stone 2009). The potential impact of other climate drivers is mostly on rainfall of the inland areas (Pazandeh Masouleh 2015).

Fig. 1.
Fig. 1.

Map of the study area showing the two measurement stations of Adelaide Airport and Edithburgh. The two components of the sea breeze and the resultant are also shown. (Source: Google Earth.)

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

The establishment of the city of Adelaide in 1836 began the change from a natural habitat to an urban habitat on the Adelaide plain. Since then, the city has expanded vastly so that greater Adelaide currently covers over 1800 km2 and, as of the 2016 census, had a population of almost 1.3 million. The sea breeze from Gulf St. Vincent is an important factor for the generation of the local wave climate and this in turn drives the coastal processes, including the storms that damage beaches and coastal infrastructure. Therefore, any change in wind climate is significant in the long-term planning of coastal management, which was the main motivation for this study.

Previous studies of the Adelaide metropolitan thermal characteristics were mainly focused on the architectural effects of street canyons and energy consumption on the climate of the central business district (CBD), suggesting the presence of a nighttime UHI and a daytime cool island, with the maximum intensity occurring approximately 2 h after midday. The arrival of a sea breeze in the afternoon of summer months cools the temperature of the coastal area significantly. However, the UHI intensity increases as air heated above the western suburbs reaches the CBD, leaving the city warmer than the suburbs and surrounding parklands (Erell and Williamson 2007; Guan et al. 2013). Note that the UHI in the work by Erell and Williamson (2007) has been considered as a temperature difference between the CBD and the surrounding suburbs.

The Adelaide shoreline has been observed to experience an interaction of two sea-breeze systems: one is generated over Gulf St. Vincent, bringing warm moist air, and the other arrives later in the day and is generated over the Southern Ocean. The Southern Ocean component is referred to as a continental sea breeze and its arrival is characterized by a cooler and drier air mass. With continuous surface observation of the weather, the arrival of the two breezes can be observed through changes in temperature and relative humidity (Physick and Byron-Scott 1977). A southerly shift in the afternoon sea-breeze direction was also noted in a study in Western Australia (Masselink and Pattiaratchi 2001) and is regarded as the effect of synoptic weather patterns and Coriolis forces on what is referred to as a “pure sea breeze.”

2. Method for the detection of sea breezes

The method was previously described in Pazandeh Masouleh et al. (2016). Parts of the methods are repeated here for the readers’ convenience. Sea-breeze detection has been widely studied, but the criteria used have varied according to the availability of the local meteorological records (Borne et al. 1998; Furberg et al. 2002; Bigot and Planchon 2003; Dunsmuir et al. 2003). Topography and the local climate may also influence the accuracy of the selection method (Azorin-Molina et al. 2011). For example, Perez and Silva Diaz (2017) discussed the occurrence and time of passage of sea breezes in São Paulo, Brazil, from 1960 to 2009 and explained 95% of the variance in terms of local variables such as air temperature and sea surface temperature.

A sea-breeze day can be detected either thorough its commencement features, such as an abrupt change in the surface climatic observation (e.g., a sudden decrease in temperature plus increase in humidity or a sudden increase in onshore wind velocity; Physick and Byron-Scott 1977; Sumner 1977), or it can be recognized using a continuous characteristic of the day such as a gradual shift in the wind to an onshore direction (Steyn and Faulkner 1986; Pattiaratchi et al. 1997; Borne et al. 1998; Tijm et al. 1999; Furberg et al. 2002; Miller and Keim 2003; Azorin-Molina and Chen 2009).

The main objective of this study was to apply the authors’ detection algorithm (Pazandeh Masouleh et al. 2016) to consistent meteorological observations for the longest period with the highest possible temporal resolution. The Adelaide Airport station observations proved to be the best choice, and the data, supplied by the Australian Bureau of Meteorology, included 3-hourly surface readings of the temperature, wind speed, and wind direction and 6-hourly upper-air wind speed and direction. Corresponding records of the surface temperature of Gulf St. Vincent were obtained from the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer data as described by Townshend (1994) and Pazandeh Masouleh (2015).

In this study, the first sea-breeze selection criterion was to select days with a positive difference between Adelaide Airport air temperature (1.2 m above ground level) and average sea surface temperature in Gulf St. Vincent. This establishes the potential for sea-breeze occurrence. The next three criteria detect the surface wind characteristics of a fully developed sea breeze. The second criterion was an offshore wind speed at the 700-hPa level of less than 7.5 m s−1 between 1200 and 1400 Australian central standard time (ACST). The third criterion was either 1) calm conditions or an offshore wind in the early morning, followed by a rotation to the sea-breeze sector in the afternoon, followed by a calm or offshore wind in the night or 2) an afternoon wind speed exceeding 1.5 m s−1 on days for which morning or evening winds are predominantly a light onshore breeze. The fourth criterion was that the afternoon wind direction was within the sea-breeze sector for at least two successive readings (i.e., at least 3-h duration).

Previous studies tried to use characteristics of a sea-breeze day to distinguish them from synoptic-scale flows, mostly using available near-surface or upper-level air records of meteorological stations. The selection criteria in this study were adapted to the available long-term record of data and included the sea surface temperatures, inland air temperature at 1.2 m, upper-level wind velocity, and afternoon wind velocity characteristics.

There were some short periods of missing data in the observational records, and for these days the detection algorithm could not be applied. Accordingly, the sea-breeze cases for each time period are presented as the percentage of sea-breeze occurrence.

3. Results

For the period of study, August 1955–June 2008, with 95% data availability for both surface and upper-air-level observations, 4893 sea-breeze days were identified (26.6% of the days analyzed).

a. Long-term trends in wind speeds

Over the 52-yr period of the study there were some changes in weather observation practice, which makes it more difficult to determine the long-term changes in the surface wind observations. For example, in 1988, as part of an improvement to the observing instruments, the Dines pressure-tube anemometers at the Adelaide Airport station were replaced by Synchrotac cup anemometers. To homogenize the wind records, an adjustment, introduced by Logue (1986), was applied to the mean wind speed records of the Dines pressure-tube anemometer.

The implementation of daylight saving and a change in the frequency of observation can have a potential effect on the time series analysis of the observations. Because the data at the Adelaide Airport weather station were taken at 3-hourly intervals, the change to daylight saving time in 1971 shifted the observation timing from 0000, 0300, 0600 ACST, and so on during the non-daylight-saving days to 2300, 0200, 0500 ACST, and so on during the daylight-saving days. This change in observation time was adopted from 1972 to 1985.

Furthermore, daylight saving time in South Australia started from early October each year and ended in early March of the following year. However, this clashes with seasonal averaging of the data: summer (December–February), autumn (March–May), winter (June–August), and spring (September–November). Because changes to the local time would affect spring and summer observations, a comparison of changes in the intensity of wind components was made between the entire period of observation and the same period excluding the observations of 1972–85. The results are shown in Figs. 2 and 3 and will be discussed later. The analyses of wind intensity will be discussed on a seasonal basis, excluding winter months because of the lower number of sea-breeze cases.

Fig. 2.
Fig. 2.

Summer sea-breeze, average U component at 1500 local time for (a) the entire period and (b) excluding 1972–84 when observation times were changed by an hour for daylight saving.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

Fig. 3.
Fig. 3.

Summer average U component at (left) 1200 and (right) 2100 local time for (a),(c) the entire period and (b),(d) excluding 1972–84, when observation times were changed by an hour for daylight saving.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

The two components of the afternoon sea breezes at Adelaide, as demonstrated by Physick and Byron-Scott (1977), are a southerly ocean breeze and a westerly gulf breeze. To assess individually the alteration of each of the breezes, the south-to-north, meridional component V and the west-to-east, zonal component U of the wind were examined separately.

The arrival of the locally generated sea breeze, the gulf breeze, has been observed to be as early as 1000 ACST (Physick and Byron-Scott 1977), and so the wind components at 1200, 1500, 1800, and 2100 ACST were examined. The linear least squares regression results are presented in Tables 16 for summer, autumn, and spring and for sea-breeze and non-sea-breeze days. The second and third columns in each table contain the gradient of the fitted trend line and its standard error. The fourth column contains the coefficient of variation R2, and the fifth and sixth columns relate to testing the null hypothesis that the gradient of the trend line is zero. The statistical analysis program calculates the t statistic and then determines the p value as the probability of a more extreme result than was observed, assuming the null hypothesis of a zero trend gradient. The rows with a p value of 0.025 or less are printed in boldface, indicating rejection of the null hypothesis. The seventh column contains the normalized root-mean-square error (NRMSE), which is a nondimensional form of root-mean-square error (RMSE) and is calculated by dividing RMSE by the average observed values. The critical value for a two-tailed t test for a sample size of 52 at the 5% significance level is 2.01, and therefore a higher t statistic, along with a significantly low p value (<0.025), indicates a significant trend at the 5% level in the strength of the mentioned afternoon wind of sea-breeze days. Moreover, the values of the standard error of regression and NRSME of residuals of the afternoon wind components are comparatively lower than at other times.

Table 1.

Regression analysis of the U component of seasonally averaged wind speed in summer. Here and in subsequent tables, rows with a p value of 0.025 or less are in boldface, indicating rejection of the null hypothesis.

Table 1.
Table 2.

As in Table 1, but for the V component.

Table 2.
Table 3.

As in Table 1, but for autumn.

Table 3.
Table 4.

As in Table 2, but for autumn.

Table 4.
Table 5.

As in Table 1, but for spring.

Table 5.
Table 6.

As in Table 2, but for spring.

Table 6.

1) Results for summer

The three months of December–February are regarded as summer months for this study. To avoid any misinterpretation of data resulting from the reduction in the number of records as a result of daylight saving, plots are shown of the zonal wind component U of averaged sea-breeze days at 1500 ACST for the entire observation set (Fig. 2a) and with the 1972–84 observations excluded (Fig. 2b).

The change in data-collection time from 1500 to 1400 ACST for 13 yr of the observational record does not make any significant impact on the trend of the 1500 ACST wind intensity on sea-breeze days: the linear regression gradients of Figs. 2a and 2b are 0.0198 and 0.0195 m s−1 yr−1, respectively. There was a similar pattern of behavior for other observational records, as shown in Fig. 3, and therefore the period of daylight saving has been included in this study to maximize the number of data points in the regressions.

The regression results for the zonal component (Table 1) indicate that the trend gradient parameter is significantly different from zero at the 5% level for afternoon winds of sea-breeze days at 1200, 1500, and 2100 ACST, suggesting an increase in the wind intensity over time. By contrast, the afternoon winds on non-sea-breeze days do not show any significant changes to the wind strength.

Figure 4 illustrates the meridional component of averaged summer wind at 1800 and 2100 ACST on sea-breeze days and 2100 ACST on non-sea-breeze days. The regression analysis (Table 2) shows that the 1800 and 2100 ACST meridional winds on sea-breeze days have increased significantly over the 52-yr period. However, the meridional components of the 2100 ACST wind on non-sea-breeze days show an increase similar to that on the 1800 ACST sea-breeze days. This suggests that generally the afternoon southeasterly wind at 2100 is increasing, which might be associated with continental-scale changes to the wind regime.

Fig. 4.
Fig. 4.

Summer average V component of (a) 1800 and (b) 2100 ACST wind for sea-breeze days and (c) 2100 ACST wind for non-sea-breeze days.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

2) Results for autumn

Results for the autumn months of March–May for the period from 1956 to 2007 are given in Tables 3 and 4. The zonal component of averaged summer winds at 1800 and 2100 ACST of sea-breeze days and 2100 ACST of non-sea-breeze days is plotted in Fig. 5.

Fig. 5.
Fig. 5.

Autumn average U component of (a) 1500 and (b) 2100 ACST wind for sea-breeze days and (c) 2100 ACST wind for non-sea-breeze days. The 5-yr moving averages are also plotted.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

The regression analysis results in Table 3 show a significant increase in intensity of the zonal component on sea-breeze days at 1500 and 2100 ACST, as in summer. However, there is a similar intensification on non-sea-breeze days at 2100 ACST. It is clear from the results in Table 4 that the sea-breeze meridional components at 1500, 1800, and 2100 ACST have an increasing trend for both sea-breeze and non-sea-breeze days. In Fig. 6 the meridional component winds at 1500, 1800, and 2100 ACST for both cases are plotted.

Fig. 6.
Fig. 6.

Autumn average V component of (left) sea breeze and (right) non–sea breeze at (a),(b) 1500, (c),(d) 1800, and (e),(f) 2100 ACST. The 5-yr moving averages are also plotted.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

3) Results for spring

For the three spring months of September–November, the results are listed in Tables 5 and 6. Note, however, that, because of data unavailability in 1992, this year was omitted from the analysis.

The averaged afternoon zonal components of wind on sea-breeze days are plotted in Fig. 7 and analyzed in Table 5. There is a significant increase in velocity at 1500, 1800, and 2100 ACST on selected sea-breeze days but no significant changes otherwise. For 1200 ACST, the p value of 0.03 implies that the regression coefficient is not significant at the preferred level of 5% but is significant at the 6% level.

Fig. 7.
Fig. 7.

Spring average U component of wind on sea-breeze days at (a) 1200, (b) 1500, (c) 1800, and (d) 2100 ACST.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

In the case of the meridional wind component (Table 6), there is no significant change in the wind velocity on non-sea-breeze days but there is a significant increase at 1800 and 2100 ACST in wind on sea-breeze days. Despite the presence of a positive trend in the intensity of 1500 ACST meridional wind on sea-breeze days, shown in Fig. 8a, the t test shows that it is not significant at the 5% level.

Fig. 8.
Fig. 8.

Spring average V component of wind on sea-breeze days at (a) 1500, (b) 1800, and (c) 2100 ACST.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

4) Trends in maximum wind speed

The maximum wind speeds (resultant of U and V) on sea-breeze days over the study period (1955–2007) were averaged annually and seasonally and the results plotted in Fig. 9. This indicates an average increase of 0.0125 m s−1 yr−1 in the speed of maximum wind speed over spring, summer, and autumn combined. The maximum increase observed between seasons was in autumn with an average rate of 0.0213 m s−1 yr−1 increase in the wind speed. A more detailed analysis of the trends is given in Table 7.

Fig. 9.
Fig. 9.

Maximum speed of sea breeze averaged (a) annually and seasonally over (b) summer, (c) autumn, and (d) spring.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

Table 7.

Regression analysis of maximum wind speeds (m s−1) vs year on sea-breeze days.

Table 7.

b. Analysis and discussion

The annual frequency of sea-breeze occurrences for the period of 1955–2007 is shown in Fig. 10. Analysis shows that there is no significant trend in the frequency of sea-breeze events for the period of the study; however, the number of selected sea-breeze days does fluctuate markedly from year to year.

Fig. 10.
Fig. 10.

Annual frequency of sea-breeze events for the period of 1956–2007, with the line showing the 5-yr moving average.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

On the other hand, the intensity of the afternoon wind has shown a distinctive trend for the same time period. Table 8 summarizes the times when significant changes were observed, with blank cells denoting no significant change. Where change is significant at the 5% level, the average wind speed increase or decrease (negative sign) over the 52-yr period is given in meters per second and as a percentage of the mean. The statistically significant increases in wind speed on sea-breeze days over the full period of 52 yr have an average increase in intensity of 0.98 m s−1 for U and 1.00 m s−1 for V, which is on average about 55% of the mean value for both U and V.

Table 8.

The time of observed significant increase of the component of afternoon winds during sea-breeze and non-sea-breeze days in spring, summer, and autumn. Here, ΔU and ΔV are the changes in mean zonal and meridional wind speed over the entire 52-yr period, expressed in meters per second and as a percentage of the mean. Note that the asterisk signifies an unrealistic value because of low mean U.

Table 8.

Irrespective of the season, the intensity of the 1500 and 2100 ACST zonal wind speeds in the set of identified sea-breeze days is progressively increasing over time, whereas for non-sea-breeze days there has not been any significant change, except during autumn. Moreover, the zonal wind speeds on sea-breeze days at 1200 ACST in summer show an increasing trend in intensity.

For the meridional wind direction, there is a greater intensification in the late-afternoon southerly wind speed. This is the time that has been documented for the arrival of the Southern Ocean breeze across the Adelaide region, normally with some delays from the nearshore observations (Physick and Byron-Scott 1977). The growth of the 1500 ACST westerly wind followed by the growth of the 1800 ACST southerly wind and then the increase of the 2100 easterly wind show a progressive intensification of the sea breeze.

The correlations between the average intensity of the wind component for each subsequent reading are summarized in Table 9. The high correlation factors shown for the V readings (0.86–0.96) demonstrate that the southerly winds (V) are generally caused by synoptic-scale flows that are steady over the whole afternoon. This is similar for the non-sea-breeze days’ westerly winds (U), for which the correlations vary between 0.84 and 0.87. On the other hand, because the sea-breeze days’ westerly components are considered to result from locally generated winds, they vary independently and have much lower correlation coefficients (0.32–0.44). Examples of the correlation are plotted in Fig. 11.

Table 9.

The correlation between each afternoon wind component and the next reading (ACST).

Table 9.
Fig. 11.
Fig. 11.

The 1800 ACST wind component (X axes) against 1500 ACST wind component (Y axes) for (top) sea-breeze and (bottom) non-sea-breeze days for the (a),(b) U and (c),(d) V components (m s−1).

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

c. Effect of changes in land surface temperature

The temperature difference between the land and sea is the essential causal factor for a sea-breeze circulation. However, the diurnal variation in sea surface temperature is much smaller than that of the land surface. Therefore, the increase in intensity of the afternoon wind on sea-breeze days should be related to an increase in the temperature and, more specifically, the maximum temperature of the land surface. To test this hypothesis, the data from Adelaide Airport station were used. Because land surface temperatures were not available, the air temperature at 1.2-m height was used instead, with the assumption that the two temperatures will be closely similar during strong convective conditions on sea-breeze days. The anomalies of the 1.2-m-height maximum and minimum temperatures of the station are plotted in Fig. 12. The anomalies are the departure of temperature from the long-term average of 1956–2007.

Fig. 12.
Fig. 12.

Anomalies (bars), 5-yr moving average (thick curve), and linear-trend line of 1.2-m (a) maximum and (b) minimum temperatures at Adelaide Airport.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

Apparently, there are upward trends in both maximum and minimum temperatures. However, as indicated in Fig. 12, the rate of increase in minimum temperature is considerably higher than that of the daily maximum. To examine the role of increasing temperature in afternoon wind intensity, the monthly averaged maximum temperatures of sea-breeze and non-sea-breeze days were compared with the afternoon components of south–north and west–east winds, as shown in Table 10. Regardless of the day’s categorization as sea breeze or non–sea breeze, the afternoon southerly wind intensity is significantly correlated (0.63–0.81) with the maximum daily temperature.

Table 10.

Correlation coefficient between monthly averaged U or V components of wind and maximum temperature for afternoons (ACST) on sea-breeze and non-sea-breeze days.

Table 10.

Given that the V component of afternoon wind is mainly associated with the arrival of the ocean breeze whereas the U component is mainly attributed to the locally generated gulf breeze, distinctly higher correlation suggests the role of land surface temperature on increased ocean-breeze intensity. Note that the Adelaide Airport station is near the shoreline and is constantly exposed to the cooling effect of onshore winds, and thus its air temperature may be lower than the surface temperature of the Adelaide metropolitan areas, which are farther inland. The ocean-breeze intensity is probably related to the larger temperature differences between the Southern Ocean and the continental interior and influenced by the latitudinal position of the Subtropical Ridge, which lies to the south of Adelaide in summer and to the north in winter.

Because the detrended maximum daily temperature has a strong correlation with the detrended afternoon V component of the wind for cases of both sea-breeze and non-sea-breeze days, as plotted in Fig. 13, the increase in the surface temperature of the continental interior is likely to be the major causal factor of the increase in southerly wind components.

Fig. 13.
Fig. 13.

Plots of monthly averaged detrended V component of wind against detrended maximum temperature on (left) sea-breeze and (right) non-sea-breeze days at (a),(c) 1800 and (b),(d) 2100 ACST.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

Since the warmer months are shown to have a higher percentage of sea-breeze events, the values of maximum temperature were compared with the frequency of sea-breeze occurrence to identify any correlation. Figure 14 shows the frequency of observed sea-breeze days against the mean maximum monthly temperature at Adelaide Airport. The correlation suggests an increase of 2.8 percentage points in the frequency of sea breeze in a month for a rise of 1°C in the mean maximum temperature of the month.

Fig. 14.
Fig. 14.

Plot of monthly averaged maximum temperature (°C) vs the percentage of selected sea-breeze days.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

d. Recent changes in sea-breeze onset, duration, and time of maximum wind speed

For the period of 1985 onward (a total of 22 yr), where the hourly record of meteorological data was available, the onset time, duration, and time of the maximum sea breeze were analyzed. The data have been annually averaged over the first 11 yr (black bars in Fig. 14) and the last 11 yr (gray bars in Fig. 15) of the observation period. As shown in Fig. 15, in comparing 1996–2007 with 1985–1995, it is seen that there is a rise of 7 percentage points in the frequency of sea breezes arriving within 4 h after sunrise and a drop of 6 percentage points in those arriving from 4 to 8 h after sunrise. The time to reach a maximum wind speed has become more concentrated between 2–4 and 4–6 h after sunrise, with increases of 3 percentage points and corresponding reductions in the extremes of less than 2 or more than 6 h. Moreover, with an increase of 5 percentage points, 59% of the sea breezes were observed to have a duration of more than 8 h in the period of 1996–2007. The seasonal variation in the duration of the sea breeze for the period of 1985–2007 is plotted in Fig. 16, which indicates that the duration of the sea breeze in summer is significantly longer than in spring and autumn.

Fig. 15.
Fig. 15.

Annually averaged time of (top) sea-breeze onset, (middle) time of sea-breeze maximum, and (bottom) sea-breeze duration for the two periods of 1985–95 (black) and 1996–2007 (gray).

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

Fig. 16.
Fig. 16.

Seasonally averaged sea-breeze duration for the period of 1985–2007.

Citation: Journal of Applied Meteorology and Climatology 58, 2; 10.1175/JAMC-D-17-0251.1

4. Summary and conclusions

Sea-breeze days have been identified on the basis of the observational record of surface and upper-air-level meteorological data and the behavior of afternoon winds. No significant trend has been detected in the frequency of sea-breeze days. However, regression analysis of the zonal components of winds on sea-breeze and non-sea-breeze days shows that the intensity of the 1500 onshore and 2100 ACST offshore U component on spring, summer, and autumn sea-breeze days is progressively increasing over time, whereas, except for autumn’s 2100 ACST offshore wind, there is no significant change to the intensity of non-sea-breeze day winds. Similarly, the 1800 and 2100 ACST meridional wind components of sea-breeze days have shown a growth in intensity over the period of study, whereas for non-sea-breeze days, it is more evident in autumn and late nights of summer. The correlation between the average intensity of the wind component for each subsequent reading demonstrates that, except for the zonal wind component of sea-breeze days, which is considered to be locally generated, the afternoon meridional components of non-sea-breeze days and sea-breeze days are highly correlated between successive time steps. This result suggests that these winds are potentially caused by more persistent synoptic-scale flows rather than by locally developed, changeable winds.

Over the study period, the maximum resultant wind speeds on sea-breeze days have increased significantly in summer by 1.02 m s−1 and in autumn by 1.10 m s−1. Following this result, the monthly averages of maximum air temperature at 1.2-m heights at the Adelaide airport station, which have shown a noticeable increase over time, were compared with the afternoon wind components of both sea-breeze and non-sea-breeze days. The results, as shown in Table 10, indicate higher correlation between the meridional component and the maximum temperature, suggesting the role of land surface temperature on the intensity of southerly wind, known as the ocean breeze. On the other hand, the slight negative correlation between the 2100 ACST meridional component of sea-breeze days and air temperature indicates the greater likelihood of a land breeze (offshore wind) to occur on days with higher land temperatures.

Although an explanation using near-surface air temperature has been suggested for the presence of an increasing intensity of the meridional component of afternoon winds on sea-breeze and non-sea-breeze days, the reason behind the significant growth of 1500 ACST westerly and 2100 ACST easterly wind components of sea-breeze days (related to the sea breeze and land breeze, respectively) has not been identified. Pazandeh Masouleh (2015) investigated the possible influence of the major climatic influences (Southern Oscillation index, Antarctic Oscillation index, and Indian Ocean dipole index) but found no significant relationships. It is possible that the sea breezes are being affected by the UHI effect. Previous studies have highlighted the interaction of UHI circulation with sea breezes for cities located in the neighborhood of the coast (Yoshikado 1994; Ohashi and Kida 2002; Cenedese and Monti 2003; Freitas et al. 2007). Because the most noticeable change to the Adelaide plain is the development of the metropolitan area and growth of the population, this urban-modified climate of the area can play an important role in the characteristics of the afternoon winds. Analysis of this possible interaction is, however, beyond the scope of this article and requires further study.

REFERENCES

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    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dunsmuir, W. T. M., E. Spark, S. K. Kim, and S. Chen, 2003: Statistical prediction of sea breezes in Sydney Harbour. Aust. Meteor. Mag., 52, 117126.

    • Search Google Scholar
    • Export Citation
  • Erell, E., and T. Williamson, 2007: Intra-urban differences in canopy layer air temperature at a mid-latitude city. Int. J. Climatol., 27, 12431255, https://doi.org/10.1002/joc.1469.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Freitas, E., C. Rozoff, W. Cotton, and P. S. Dias, 2007: Interactions of an urban heat island and sea-breeze circulations during winter over the metropolitan area of São Paulo, Brazil. Bound.-Layer Meteor., 122, 4365, https://doi.org/10.1007/s10546-006-9091-3.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Furberg, M., D. G. Steyn, and M. Baldi, 2002: The climatology of sea breezes on Sardinia. Int. J. Climatol., 22, 917932, https://doi.org/10.1002/joc.780.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Grossi, P., P. Thunis, A. Martilli, and A. Clappier, 2000: Effect of sea breeze on air pollution in the greater Athens area. Part II: Analysis of different emission scenarios. J. Appl. Meteor., 39, 563575, https://doi.org/10.1175/1520-0450(2000)039<0563:EOSBOA>2.0.CO;2.

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  • Guan, H., J. M. Bennet, C. M. Ewenz, S. N. Benger, and Vinodkumar, S. Zhu, R. Clay, and V. Soebarto, 2013: Characterisation, interpretation and implications of the Adelaide urban heat island. Flinders University Dept. of Planning and Local Government Rep., 141 pp., https://hdl.handle.net/2328/26839.

  • Hendon, H. H., D. W. Thompson, and M. C. Wheeler, 2007: Australian rainfall and surface temperature variations associated with the Southern Hemisphere annular mode. J. Climate, 20, 24522467, https://doi.org/10.1175/JCLI4134.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Larsen, S. H., and N. Nicholls, 2009: Southern Australian rainfall and the subtropical ridge: Variations, interrelationships, and trends. Geophys. Res. Lett., 36, L08708, https://doi.org/10.1029/2009GL037786.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Logue, J., 1986: Comparison of wind speeds recorded simultaneously by a pressure-tube anemograph and a cup-generator anemograph. Meteor. Mag., 115, 178185.

    • Search Google Scholar
    • Export Citation
  • Masselink, G., and C. Pattiaratchi, 1998: Morphodynamic impact of sea breeze activity on a beach with beach cusp morphology. J. Coastal Res., 14, 393406.

    • Search Google Scholar
    • Export Citation
  • Masselink, G., and C. Pattiaratchi, 2001: Characteristics of the sea breeze system in Perth, Western Australia, and its effect on the nearshore wave climate. J. Coastal Res., 17, 173187.

    • Search Google Scholar
    • Export Citation
  • Miller, S. T. K., and B. D. Keim, 2003: Synoptic-scale controls on the sea breeze of the central New England coast. Wea. Forecasting, 18, 236248, https://doi.org/10.1175/1520-0434(2003)018<0236:SCOTSB>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ohashi, Y., and H. Kida, 2002: Local circulations developed in the vicinity of both coastal and inland urban areas: A numerical study with a mesoscale atmospheric model. J. Appl. Meteor., 41, 3045, https://doi.org/10.1175/1520-0450(2002)041<0030:LCDITV>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pattiaratchi, C., B. Hegge, J. Gould, and I. Eliot, 1997: Impact of sea-breeze activity on nearshore and foreshore processes in southwestern Australia. Cont. Shelf Res., 17, 15391560, https://doi.org/10.1016/S0278-4343(97)00016-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pazandeh Masouleh, Z., 2015: Identification of sea breezes, their climatic trends and causation, with application to the Adelaide coast. Ph.D. thesis, University of Adelaide, 200 pp., https://hdl.handle.net/2440/95317.

  • Pazandeh Masouleh, Z., D. Walker, and J. M. Crowther, 2016: Sea breeze characteristics on two sides of a shallow gulf: Study of the Gulf St Vincent in South Australia. Meteor. Appl., 23, 222229, https://doi.org/10.1002/met.1547.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Perez, G. M. P., and M. A. F. Silva Diaz, 2017: Long-term study of the occurrence and time of passage of sea breeze in São Paulo, 1960–2009. Int. J. Climatol., 37, 12101220, https://doi.org/10.1002/joc.5077.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Physick, W. L., and R. A. D. Byron-Scott, 1977: Observations of the sea breeze in the vicinity of a gulf. Weather, 32, 373381, https://doi.org/10.1002/j.1477-8696.1977.tb04481.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Psuty, N. P., 2005: Coastal foredune development under a diurnal wind regime, Paracas, Peru. J. Coastal Res., Special Issue 42, 68–73, available from cerf.jcr@gmail.com.

  • Steyn, D. G., and D. A. Faulkner, 1986: The climatology of sea breezes in the lower Fraser Valley, B.C. Climatol. Bull., 20, 2139.

  • Sumner, G. N., 1977: Sea breeze occurrence in hilly terrain. Weather, 32, 200208, https://doi.org/10.1002/j.1477-8696.1977.tb04556.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tijm, A. B. C., A. A. M. Holtslag, and A. J. Van Delden, 1999: Observations and modeling of the sea breeze with the return current. Mon. Wea. Rev., 127, 625640, https://doi.org/10.1175/1520-0493(1999)127<0625:OAMOTS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Townshend, J. R. G., 1994: Global data sets for land applications from the Advanced Very High Resolution Radiometer. Int. J. Remote Sens., 15, 33193332, https://doi.org/10.1080/01431169408954333.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Williams, A. A., and R. C. Stone, 2009: An assessment of relationships between the Australian subtropical ridge, rainfall variability, and high-latitude circulation patterns. Int. J. Climatol., 29, 691709, https://doi.org/10.1002/joc.1732.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yoshikado, H., 1992: Numerical study of the daytime urban effect and its interaction with the sea breeze. J. Appl. Meteor., 31, 11461164, https://doi.org/10.1175/1520-0450(1992)031<1146:NSOTDU>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yoshikado, H., 1994: Interaction of the sea breeze with urban heat islands of different sizes and locations. J. Meteor. Soc. Japan, 72B, 139143, https://doi.org/10.2151/jmsj1965.72.1_139.

    • Crossref
    • Search Google Scholar
    • Export Citation
Save
  • Australian Bureau of Meteorology, 2010: Australian climate influences. Accessed 15 April 2014, http://www.bom.gov.au/watl/about-weather-and-climate/australian-climate-influences.shtml.

  • Azorin-Molina, C., and D. Chen, 2009: A climatological study of the influence of synoptic-scale flows on sea breeze evolution in the Bay of Alicante (Spain). Theor. Appl. Climatol., 96, 249260, https://doi.org/10.1007/s00704-008-0028-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Azorin-Molina, C., S. Tijm, and D. Chen, 2011: Development of selection algorithms and databases for sea breeze studies. Theor. Appl. Climatol., 106, 531546, https://doi.org/10.1007/s00704-011-0454-4.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Baker, R. D., B. H. Lynn, A. Boone, W. K. Tao, and J. Simpson, 2001: The influence of soil moisture, coastline curvature, and land-breeze circulations on sea-breeze-initiated precipitation. J. Hydrometeor., 2, 193209, https://doi.org/10.1175/1525-7541(2001)002<0193:TIOSMC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bigot, S., and O. Planchon, 2003: Identification and characterization of sea breeze days in northern France using singular value decomposition. Int. J. Climatol., 23, 13971405, https://doi.org/10.1002/joc.940.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Borne, K., D. Chen, and M. Nunez, 1998: A method for finding sea breeze days under stable synoptic conditions and its application to the Swedish west coast. Int. J. Climatol., 18, 901914, https://doi.org/10.1002/(SICI)1097-0088(19980630)18:8<901::AID-JOC295>3.0.CO;2-F.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cenedese, A., and P. Monti, 2003: Interaction between an inland urban heat island and a sea-breeze flow: A laboratory study. J. Appl. Meteor., 42, 15691583, https://doi.org/10.1175/1520-0450(2003)042<1569:IBAIUH>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Crosman, E., and J. Horel, 2010: Sea and lake breezes: A review of numerical studies. Bound.-Layer Meteor., 137, 129, https://doi.org/10.1007/s10546-010-9517-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dunsmuir, W. T. M., E. Spark, S. K. Kim, and S. Chen, 2003: Statistical prediction of sea breezes in Sydney Harbour. Aust. Meteor. Mag., 52, 117126.

    • Search Google Scholar
    • Export Citation
  • Erell, E., and T. Williamson, 2007: Intra-urban differences in canopy layer air temperature at a mid-latitude city. Int. J. Climatol., 27, 12431255, https://doi.org/10.1002/joc.1469.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Freitas, E., C. Rozoff, W. Cotton, and P. S. Dias, 2007: Interactions of an urban heat island and sea-breeze circulations during winter over the metropolitan area of São Paulo, Brazil. Bound.-Layer Meteor., 122, 4365, https://doi.org/10.1007/s10546-006-9091-3.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Furberg, M., D. G. Steyn, and M. Baldi, 2002: The climatology of sea breezes on Sardinia. Int. J. Climatol., 22, 917932, https://doi.org/10.1002/joc.780.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Grossi, P., P. Thunis, A. Martilli, and A. Clappier, 2000: Effect of sea breeze on air pollution in the greater Athens area. Part II: Analysis of different emission scenarios. J. Appl. Meteor., 39, 563575, https://doi.org/10.1175/1520-0450(2000)039<0563:EOSBOA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Guan, H., J. M. Bennet, C. M. Ewenz, S. N. Benger, and Vinodkumar, S. Zhu, R. Clay, and V. Soebarto, 2013: Characterisation, interpretation and implications of the Adelaide urban heat island. Flinders University Dept. of Planning and Local Government Rep., 141 pp., https://hdl.handle.net/2328/26839.

  • Hendon, H. H., D. W. Thompson, and M. C. Wheeler, 2007: Australian rainfall and surface temperature variations associated with the Southern Hemisphere annular mode. J. Climate, 20, 24522467, https://doi.org/10.1175/JCLI4134.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Larsen, S. H., and N. Nicholls, 2009: Southern Australian rainfall and the subtropical ridge: Variations, interrelationships, and trends. Geophys. Res. Lett., 36, L08708, https://doi.org/10.1029/2009GL037786.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Logue, J., 1986: Comparison of wind speeds recorded simultaneously by a pressure-tube anemograph and a cup-generator anemograph. Meteor. Mag., 115, 178185.

    • Search Google Scholar
    • Export Citation
  • Masselink, G., and C. Pattiaratchi, 1998: Morphodynamic impact of sea breeze activity on a beach with beach cusp morphology. J. Coastal Res., 14, 393406.

    • Search Google Scholar
    • Export Citation
  • Masselink, G., and C. Pattiaratchi, 2001: Characteristics of the sea breeze system in Perth, Western Australia, and its effect on the nearshore wave climate. J. Coastal Res., 17, 173187.

    • Search Google Scholar
    • Export Citation
  • Miller, S. T. K., and B. D. Keim, 2003: Synoptic-scale controls on the sea breeze of the central New England coast. Wea. Forecasting, 18, 236248, https://doi.org/10.1175/1520-0434(2003)018<0236:SCOTSB>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ohashi, Y., and H. Kida, 2002: Local circulations developed in the vicinity of both coastal and inland urban areas: A numerical study with a mesoscale atmospheric model. J. Appl. Meteor., 41, 3045, https://doi.org/10.1175/1520-0450(2002)041<0030:LCDITV>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pattiaratchi, C., B. Hegge, J. Gould, and I. Eliot, 1997: Impact of sea-breeze activity on nearshore and foreshore processes in southwestern Australia. Cont. Shelf Res., 17, 15391560, https://doi.org/10.1016/S0278-4343(97)00016-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pazandeh Masouleh, Z., 2015: Identification of sea breezes, their climatic trends and causation, with application to the Adelaide coast. Ph.D. thesis, University of Adelaide, 200 pp., https://hdl.handle.net/2440/95317.

  • Pazandeh Masouleh, Z., D. Walker, and J. M. Crowther, 2016: Sea breeze characteristics on two sides of a shallow gulf: Study of the Gulf St Vincent in South Australia. Meteor. Appl., 23, 222229, https://doi.org/10.1002/met.1547.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Perez, G. M. P., and M. A. F. Silva Diaz, 2017: Long-term study of the occurrence and time of passage of sea breeze in São Paulo, 1960–2009. Int. J. Climatol., 37, 12101220, https://doi.org/10.1002/joc.5077.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Physick, W. L., and R. A. D. Byron-Scott, 1977: Observations of the sea breeze in the vicinity of a gulf. Weather, 32, 373381, https://doi.org/10.1002/j.1477-8696.1977.tb04481.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Psuty, N. P., 2005: Coastal foredune development under a diurnal wind regime, Paracas, Peru. J. Coastal Res., Special Issue 42, 68–73, available from .

    • Search Google Scholar
    • Export Citation
  • Steyn, D. G., and D. A. Faulkner, 1986: The climatology of sea breezes in the lower Fraser Valley, B.C. Climatol. Bull., 20, 2139.

  • Sumner, G. N., 1977: Sea breeze occurrence in hilly terrain. Weather, 32, 200208, https://doi.org/10.1002/j.1477-8696.1977.tb04556.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tijm, A. B. C., A. A. M. Holtslag, and A. J. Van Delden, 1999: Observations and modeling of the sea breeze with the return current. Mon. Wea. Rev., 127, 625640, https://doi.org/10.1175/1520-0493(1999)127<0625:OAMOTS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Townshend, J. R. G., 1994: Global data sets for land applications from the Advanced Very High Resolution Radiometer. Int. J. Remote Sens., 15, 33193332, https://doi.org/10.1080/01431169408954333.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Williams, A. A., and R. C. Stone, 2009: An assessment of relationships between the Australian subtropical ridge, rainfall variability, and high-latitude circulation patterns. Int. J. Climatol., 29, 691709, https://doi.org/10.1002/joc.1732.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yoshikado, H., 1992: Numerical study of the daytime urban effect and its interaction with the sea breeze. J. Appl. Meteor., 31, 11461164, https://doi.org/10.1175/1520-0450(1992)031<1146:NSOTDU>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yoshikado, H., 1994: Interaction of the sea breeze with urban heat islands of different sizes and locations. J. Meteor. Soc. Japan, 72B, 139143, https://doi.org/10.2151/jmsj1965.72.1_139.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fig. 1.

    Map of the study area showing the two measurement stations of Adelaide Airport and Edithburgh. The two components of the sea breeze and the resultant are also shown. (Source: Google Earth.)

  • Fig. 2.

    Summer sea-breeze, average U component at 1500 local time for (a) the entire period and (b) excluding 1972–84 when observation times were changed by an hour for daylight saving.

  • Fig. 3.

    Summer average U component at (left) 1200 and (right) 2100 local time for (a),(c) the entire period and (b),(d) excluding 1972–84, when observation times were changed by an hour for daylight saving.

  • Fig. 4.

    Summer average V component of (a) 1800 and (b) 2100 ACST wind for sea-breeze days and (c) 2100 ACST wind for non-sea-breeze days.

  • Fig. 5.

    Autumn average U component of (a) 1500 and (b) 2100 ACST wind for sea-breeze days and (c) 2100 ACST wind for non-sea-breeze days. The 5-yr moving averages are also plotted.

  • Fig. 6.

    Autumn average V component of (left) sea breeze and (right) non–sea breeze at (a),(b) 1500, (c),(d) 1800, and (e),(f) 2100 ACST. The 5-yr moving averages are also plotted.

  • Fig. 7.

    Spring average U component of wind on sea-breeze days at (a) 1200, (b) 1500, (c) 1800, and (d) 2100 ACST.

  • Fig. 8.

    Spring average V component of wind on sea-breeze days at (a) 1500, (b) 1800, and (c) 2100 ACST.

  • Fig. 9.

    Maximum speed of sea breeze averaged (a) annually and seasonally over (b) summer, (c) autumn, and (d) spring.

  • Fig. 10.

    Annual frequency of sea-breeze events for the period of 1956–2007, with the line showing the 5-yr moving average.

  • Fig. 11.

    The 1800 ACST wind component (X axes) against 1500 ACST wind component (Y axes) for (top) sea-breeze and (bottom) non-sea-breeze days for the (a),(b) U and (c),(d) V components (m s−1).

  • Fig. 12.

    Anomalies (bars), 5-yr moving average (thick curve), and linear-trend line of 1.2-m (a) maximum and (b) minimum temperatures at Adelaide Airport.

  • Fig. 13.

    Plots of monthly averaged detrended V component of wind against detrended maximum temperature on (left) sea-breeze and (right) non-sea-breeze days at (a),(c) 1800 and (b),(d) 2100 ACST.

  • Fig. 14.

    Plot of monthly averaged maximum temperature (°C) vs the percentage of selected sea-breeze days.

  • Fig. 15.

    Annually averaged time of (top) sea-breeze onset, (middle) time of sea-breeze maximum, and (bottom) sea-breeze duration for the two periods of 1985–95 (black) and 1996–2007 (gray).

  • Fig. 16.

    Seasonally averaged sea-breeze duration for the period of 1985–2007.

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