3.1. LCZ in Balneário Camboriú
World Urban Database and Access Portal Tools (WUDAPT) technique [
21,
30] was used in this research to determine the Local Climate Zones for Balneário Camboriú. The following LCZs were found by the authors in the research area: LCZ 1, LCZ 2, LCZ 3, LCZ 4, LCZ 5, LCZ 6, LCZ 8, LCZ A, LCZ B, LCZ D, LCZ E, LCZ F, and LCZ G. As indicated in
Figure 3, the data collecting locations are located in five of these LCZs: LCZ 1, LCZ 3, LCZ 6, LCZ 8, and LCZ 9.
LCZ 1 is defined as an area with a high density of tall structures [
21] (more than 10 stories), few or no trees, and is located near the beach sand strip (LCZ F) and the Atlantic Ocean (LCZ G). LCZ 3 is located in the furthest part of the Atlantic Ocean and is defined as a region with a high density of low structures with up to three stories, few or no trees, and heavily paved land. LCZ 1 and LCZ 3 best depict Balneário Camboriú, urbanized areas with few or no trees and heavy traffic [
30].
LCZ 6 is located in the northern portion of the municipality and is distinguished by a spaced layout of medium-sized buildings (between 3 and 9 stories) and permeable soil covering. LCZ 08 is the class that includes single-story low-rise structures. LCZ 09, on the other hand, is one of the least urbanized classes in this study, with fewer buildings, more permeable soil covering, and a larger prevalence of trees. LCZ A is made up of heavily forested vegetation that is mostly permeable.
Point 00, as indicated in
Figure 3, is located in LCZ 9, which is distinguished by low-rise building designs and permeable soil. Point 01 lies near LCZ A (thick vegetation), on the Camboriú River’s right bank, LCZ 8 (big low-rise structures and impermeable soil), and LCZ 9, whereas Point 02 is completely immersed in LCZ 3, in an area of low, compact buildings with impermeable soil.
Points 03 and 04 are in LCZ 1 (skyscraper, compact, and waterproof). What distinguishes the two is that Point 04 is influenced by LCZ F, which is characterized by exposed soil, which does not occur with Point 03 because it is inserted in LCZ 1 and under its influence only. Point 05, on the other hand, is in an LCZ 3, near to LCZ 1, and point 06 is in both LCZ 1 and LCZ A. Point 07 sits at the bank of a creek (LCZ A) and in an LCZ 6 with medium-sized structures. Point 08 is in an LCZ 8 and point 09 and 10 in LCZ 3.
3.2. Ta data from Collection Points
Using Point 00 as the reference point for this study, the average Ta recorded at this position for the data collecting period was 16.1°C. During the investigated time period, the absolute maximum and lowest Ta recorded at the reference site were 23.6°C and 8.9°C, respectively, resulting in a thermal amplitude of 14.7°C.
Table 3 displays the average temperature data, absolute maximum and lowest temperatures, and thermal amplitude of the 11-research area representative locations.
During this study, the lowest average Ta reported in Balneário Camboriú was 15.9°C, recorded at Point 01, a location impacted by three separate local climate zones, LCZ 8, LCZ 9, and LCZ A. The highest average Ta for the data collecting period, 17.2°C, was recorded at Point 09, as was the absolute maximum temperature, 28.8°C. Point 09 is situated inside LCZ 3. Point 03 in LCZ 1 had the lowest absolute maximum temperature and the greatest absolute minimum temperature (22.3°C and 9.5°C, respectively), as well as the lowest thermal amplitude measured throughout the examined time. Point 01 had the lowest absolute minimum temperature in the study region, at 7.8°C.
3.3. Magnitudes of UHI and UCI in Balneário Camboriú
Figure 4 depicts the absolute maximum and lowest magnitudes of daily UHI and UCI (7am to 6pm) for each Ta recording station.
Maximum UHI magnitudes reached moderate intensity throughout the day in Points 01, 06, 07, 08, and 10. The UHI achieved their peak magnitude throughout the analysis period at points 02 and 04, respectively. Points 03, 05, and 09 recorded extremely intense heat islands.
During the day, the UCI were detected with moderate intensity at the greatest number of collection places (01, 02, 04, 06, 07, 08, 09, and 10). The magnitudes of the UCI were greatest at Points 03 and 05, with very strong and strong intensities, respectively. The intensity of both Ta islands was found to be lower at night, between 6:30 p.m. and 6 a.m., compared to the daylight period.
Figure 5 depicts the magnitudes of the nighttime UHI and UCI.
Moderately intense nocturnal UHI were detected at locations 01, 02, 06, 08, 09, and 10. UHI of high intensity were reported at points 03, 04, and 05. Point 07 was the only one with a high UHI intensity. Five of these places had the same UHI intensities as during the day. Another four places had lesser UHI magnitudes, with just one showing an increase in heat intensity when compared to daylight.
During the night, points 03, 04, 06, 07, and 08 recorded islands of low intensity coolness. UCI of moderate intensity was found at locations 02, 05, 09, and 10. During the night period, Point 01 reported an UCI with a high intensity. When the magnitudes of the UCI were compared during the day and at night, it was discovered that the intensity of the UCI remained constant in three spots. During the night, five points reported a drop in the intensity of the UCI, while two places recorded an increase in the intensity of the coolness.
When monitoring UHI and UCI hourly, fluctuations in the incidence of phenomena can be observed throughout the day.
Figure 6,
Figure 7 and
Figure 8 depict the hourly evolution (between 00:00 and 23:00) of the magnitudes of UHI and UCI recorded at the 10 places examined between June 1st and 14th, 2022. For better visualization, the points were separated into three groups.
Except for Point 01, all sites in
Figure 6 displayed UHI of weak, moderate, or strong intensity, and in a time span that began at 4 p.m. and ended around 6 a.m. At each place, UCI appear at various periods. Point 01, for example, had negative magnitudes in practically all of the period’s recordings. Points 03, 05, 06, 07, 08, and 09 all displayed negative magnitudes between the early morning and early afternoon. Only at night and on specified days did points 02 and 09 record negative magnitudes.
In the case of UHI, heat bubbles display increased intensity at the end of the day (5/6pm) and the early hours of the night (till 11pm) at points 01, 03, 04, 05, 06, 07, 08, and 10. The most significant UHI at point 02 occurred between 1pm to 3pm The most extreme UHI was observed during the morning and early afternoon (between 8:30am and 2pm) at Point 09, which had the highest UHI magnitude value of the time (8.4°C). According to
Figure 6, the heat at Point 09 was the most substantial over the time.
The UCI observed during the analysis period do not follow an hourly trend. Points 01, 02, and 09 in
Figure 8 recorded the lowest negative magnitudes at 8pm and remained on the UCI until the early morning hours of the following day, but with less intensity. During the day, the other places reported the lowest magnitudes of UCI. The most powerful of them occurred in the morning at points 03 and 06, while points 04, 05, 07, 08, and 10 reported more substantial UCI between 12pm and 2pm.
Figure 6,
Figure 7 and
Figure 8 further reveal that the maximum intensities of the UHI and UCI phenomena found in this investigation occurred between June 11th and 14th.
The era’s synoptic analysis revealed that two distinct synoptic conditions occurred throughout the data collecting period, which were classified as cyclonic and anticyclonic. The passage of polar frontal systems and frontal cyclones affected or influenced the city during the cyclonic days. Overcast sky, air instability with rainfall, and minimum temperatures over 15.0°C define this period. Clear skies and no cloud cover were seen during the anticyclonic period, resulting in surface heating by direct solar radiation during the day and adiabatic cooling during the night. Minimum Ta were below 15.0°C throughout this time period.
The cyclonic phase is between the 1st to 3rd of June 2022, and the 6th to 10th of June 2022, with a preponderance of atmospheric instability, cloudiness, and low-intensity rain. The city was under the authority of the Atlantic Polar Migratory Anticyclone and the Polar Air Mass during June 4th and 5th, as well as the 11th to 14th. The existing thermal disparity between these two anticyclonic period temporal slices is attributable to the loss of intensity of the Atlantic polar air mass as a result of fast warming and thermal increase. Otherwise, the Polar Air Mass that reached Balneário Camboriú was vigorous between June 11th to 14th, lowering temperatures and sustaining atmospheric stability, promoting dry days without clouds and contributing to the balance of daytime and evening energy.
3.4. Relation of LCZs, Average Ta and Day and Night Magnitudes of the UHI/UCI at Each Point
Table 4 shows how distinct metropolitan areas and their local climatic zones (as well as the affects of other neighboring zones) affect daytime and nighttime temperatures, as well as how these temperatures vary during the investigated period.
The highest average daily Ta recorded was 19.3°C at Point 9 (LCZ 3), while the lowest was 17.4°C at Point 1 (LCZ 9). Point 7 (LCZ 6) had the greatest average overnight Ta of 15.8°C, while Point 1 (LCZ 9) had the lowest average nighttime temperature of 4.5°C.
The magnitudes of the UHI discovered during the investigated period reveal that the maximum magnitude discovered during the day was 1.6°C at Point 9 (LCZ 3), while the lowest magnitude discovered during the day was -0.3°C at Point 1 (LCZ 9). The maximum magnitude during the night period was 1.1°C at Point 7 (LCZ 6). Point 1 (LCZ 9) had the lowest nighttime magnitude of -0.2°C.
Ta at LCZ 1 range from 17.5°C to 18.1°C during the day and from 15.4°C to 15.7°C at night. Magnitudes range from -0.1°C and 1.0°C during the day and 0.7°C and 1.0°C at night. Ta at LCZ 3 range from 17.6°C to 19.3°C during the day and 15.1°C to 15.6°C at night, with magnitudes ranging from 0.3°C to 1.6°C during the day and 0.4°C to 0.9°C at night.
The average Ta in LCZs 6 and 8 ranges from 17.6°C to 19.3°C during the day and from 15.1°C to 15.6°C at night. Variations in magnitude were found from 0.1°C to 0.8°C during the day and from 0.7°C to 1.1°C at night. LCZ 9 had the lowest Ta fluctuation, with -0.3°C magnitude during the day and -0.2°C magnitude at night.
Regarding the third column of
Table 4, which concerns the LCZ influence, it was observed that the magnitudes presented at these points are related to the LCZ with the greatest vertical density, as points 01, 04, 05, 06 and 07 are located in areas of contact between different LCZs (
Figure 3), with the LCZ mentioned in the third column being the one that had the most impact on the values mentioned.