Analysis of Projected Temperature Changes in Aceh Province

The objective is to analyse temperature changes and their future projection in Aceh. The activities consist of collecting past and future temperature data, preparing materials for processing, and analyzing past and future temperature data (climate change projections). The data used are monthly average temperature data from data global climate model, e.g., csiromk3.6-hist-1986-2005-tas, csiromk3.6-rcp45-2016-2035-tas, csiromk3.6-rcp45-2046-2065-tas, csiromk3.6-rcp45-2081-2100-tas, csiromk3.6-rcp85-2016-2035-tas, csiromk3.6-rcp85-2046-2065-tas, and csiromk3.6-rcp85-2081-2100-tas. The study began with reading climate data in NetCDF format using GRADS software, data processing using CDO software, providing a coordinate system using QGIS software, making climate change projection maps using ArcGIS software, and making climate change graphs using spreadsheet program. Two scenarios, i.e., RCP4.5 and RCP8.5 are used to analyse the projected temperature changes in the short-term (2016 – 2035), medium-term (2046-2065), and long-term (2081-2100). The results show that the RCP4.5 projection shows a lower change in temperature rise than the RCP 8.5. A change in a temperature rise of up to 5°C was found in the RCP8.5 scenario.


Background
Climate change has an impact on human health and the agriculture economy.The distribution or pattern of rainfall is highly reliant on temperature increases.It is projected that wetter areas will become wetter and drier areas will become drier, causing water resources to be disrupted [1,18].High latitudes receive the largest increase in air temperature, which has an impact on global environmental changes such as biodiversity, vegetation distribution, and ice melting at the poles [2,19,20].Meanwhile, low latitudes show a slight change in annual temperature.The altitude of a location also influences the temperature over a certain regional surface.The lower the position of a region, the higher the air temperature, and vice versa, the higher the position of a region, the lower the air temperature [3,4].Heat transport anomalies carry heat from the land to the oceans where the climate is stressed by growing CO2 concentrations in the atmosphere, causing the sea surface to warm.Heat transport anomalies compensate for the "lost" radiation pressure over land when the climate is stressed by variations in sea surface heat by moving heat from the oceans to the land, which heats the land surface [5].The lowest and highest temperatures in numerous years are caused by the inverse comparison between land surface temperature and ocean surface temperature.
Climate scenarios try to track changes in climate conditions in a given area over time and compare them to baseline circumstances.This forecast was created to better comprehend the repercussions of anthropogenic climate change based on the output of climate impact models [6].The Representative Concentration Pathways (RCP) scenario was employed in this study.Climate change is defined as a shift in the distribution of weather events relative to average conditions.Climate change occurs over decades or longer and can usually be detected using statistical tests to examine the variability of its features or changes in its average temperature [7].Climate change has a significant impact on the frequency and intensity of severe events or natural disasters, as well as the extent to which these occurrences affect ecosystems and socioeconomic elements that cause environmental and societal damage [8,9].
Aceh Province has a mountainous to flat topography.About 32% of Aceh's area has flat and sloping topography and around 68% has hilly to mountainous topography.The central part of Aceh has a mountainous topography which is a part of Bukit Barisan mountains.The northern and eastern parts of Aceh have hilly and sloping topography [10].
Besides its high rainfall variability [11], differences in temperature are also noticeable in both the west and the east of Aceh Province.The objective is to analyze temperature changes and their future projection in Aceh.This research is expected to be able to provide education and information regarding climate change projections for Aceh Province, in this case, the temperature changes.

Methodology
The data used in this processing are monthly average temperature data from global climate atmospheric model (GCAM) outputs, e.The RCP scenarios considered in this study were RCP8.5 and RCP 4.5.RCP 8.5 is a scenario that results in ongoing increases in greenhouse gas emissions.The MESSAGE model and IIASA, Austria were used to creating this scenario.RCP4.5 is a scenario for stabilizing radiative forcing beyond 2100 without surpassing the long-term radiative forcing target limit [12,13].The GCAM modeling adapted to this scenario is from the US Pacific Northwest National Laboratory JGRCI.
In this study, temperature spatial projection data were interpolated using the Inversion Distance Weighted (IDW) approach.The IDW method is a type of interpolation that produces results that are limited to the values in the sample data.This approach employs the sample data's average, therefore the value cannot be less than the minimum or more than the sample data.As a result, the interpolation results of this model cannot represent the highest summits of hills or the deepest valleys.The IDW method outperforms the Kriging method in terms of interpolation accuracy.This is because all of the IDW method's results give values near to the minimum and maximum values of the data samples.While the Kriging method occasionally produces interpolation results with a narrow range.The power settings and sample count have no discernible effect on the interpolation results.
Temperature changes are projected in order to detect temperature anomalies or fluctuations in values in the future.Temperature change is projected by subtracting the projected temperature value from the base temperature value from 1986 to 2005.This projection produces spatial data that has been interpolated using IDW.
Reading climate data in NetCDF format using GRADS software, data processing using CDO software, providing a coordinate system to data using QGIS software [14], making climate change projection maps using ArcGIS software, and making climate change graphs using spreadsheet program are the work steps of this research.Figure 1 depicts the flow chart of this study.

Results and Discussion
The csiromk3.6-hist-1986-2005-tasdata shows that the lowest average monthly temperature from 1986 to 2005 occurred in February, i.e., 20.9 °C, and the highest average monthly temperature occurred in October, i.e., 28. 6 °C.Seasonal average temperatures from 1986 to 2005 show that the lowest monsoon temperatures are in the DJF (December January February) months which is 28.1 °C and the highest temperatures are in the SON (September, October, November) months which is 28.5 °C, whereas in the transition months MAM (March, April, May) and JJA (June, July, August) the temperature is 28.3 °C.The monthly average temperature pattern from 1986 to 2005 can be seen in Figure 2. Figure 3 where Gayo Lues area which has a higher altitude than other Aceh regions, i.e., around 3448 meters, is the area that has the lowest temperature ranging from 15.9-18 ℃.In contrast, the lowest areas which are generally on the coast have temperatures ranging from 28-30 ℃.Hence, we could notice that topography is a local factor that influences temperature variations in Aceh Province.In addition, the areas in the back of the mountains which encounter leeward condition, for instance on the north and east coasts of Aceh may have high temperatures, particularly during the southwest monsoon which lasts from May to September.Those could be the examples of local factor that may affect temperature variations in Aceh Province.The annual average temperature trend from 1986 to 2005 in Aceh Province is shown in Figure 4 where the lowest annual average temperature was in 1994, i.e., 27.4 °C, and the highest temperature was in 1998,1999,2003,2004, and 2005 which is 28.6 °C.The trend of the seasonal average DJF temperature in Figure 5 shows that the highest temperature occurred in 2003, i.e., 28.5 °C, and the lowest temperature occurred in 1994, i.e., 27.3°C, a change in temperature this season was 0.026°C.It is due to a positive IOD event that occurred in 2003 which then affected climate variability in the province of Aceh.A study by [15] showed the annual IOD time-series where it is shown that at the end of 2003 a positive IOD signal appeared which further cause the air temperature on December remains high.This condition emerges as a result of the cold sea surface temperature around Aceh Waters which cause a low rate of evaporation so that the cloud cover in the sky becomes less.Hence the exposure of direct sunlight on the ground may lead the air temperature to rise.Meanwhile in 1994 there was no climate anomaly.As shown by work done by [15], IOD signal was still within the normal range, thus, the temperature remains in average condition ranging between 26-27°C.The trend of the MAM seasonal average temperature in Figure 5 shows that the highest temperature occurred in 2003, i.e., 28.5°C, and the lowest temperature occurred in 1995, i.e., 27.2°C, a change in temperature this season was 0.033°C.The seasonal average temperature trend JJA in Figure 5 shows that the highest temperature occurred in 1991, i.e., 29 °C, and the lowest temperature occurred in 1994, i.e., 27.1 °C, the temperature change in this season is 0.021 °C.The seasonal average temperature trend SON in Figure 5 shows that the highest temperature occurred in 1997, i.e., 28.9 °C, and the lowest temperature occurred in 1994, i.e., 27.4 °C with a temperature change this season of 0.013°C.On March, Aceh Province is situated in the Inter-Tropical Convergence Zone (ITCZ) zone, which is the path on the Earth surface with the highest average temperature where the sun is directly above Aceh Province.However, the maximum temperature does not occur when the sun is directly above Aceh Province.There is a lag between the moment of maximum irradiation and the moment of maximum temperature increase.Although the sun is right on the Equator on March 21, the annual maximum temperature in Indonesian is not precisely rise on March, but there is a delay of about one month [16].It is also happening in Aceh.Therefore, the air becomes uncomfortable in Aceh Province is on April.Lack of wind and high humidity on April lead the air temperature to feel hotter and exhausting from April to May in Aceh Province.Temperatures in 1994-1995 were the lowest of all temperature data from 1986 to 2005, possibly because the El Niño event occurred in 1994-1995, causing sea surface temperatures to rise, and land surface temperatures to fall.The temperature in 1999-1998 became the highest in the annual average temperature from 1986 to 2005, presumably because another incident occurred this year in which the sea surface temperature declined, causing the land surface temperature to rise.A study by [17] showed a moderate correlation between ENSO and rainfall variability in Greater Aceh district.It is revealed that ENSO might influence the fluctuations of air temperature in Aceh where during El Niño temperature is rising while rainfall is reducing leading to prolonged drought in Aceh Province.7 depicts the anticipated maximum temperature in the long-term RCP 8.5 scenario, which is around 30 °C, as well as the expected minimum temperature in the short-term RCP 4.5 scenario, which is less than 18 °C.Figure 4.5 depicts a projection diagram of the monthly average temperature at a longitude of 95.3723 and a latitude of 5.3747.RCP4.5 is a scenario of greenhouse gas concentrations where there is a mitigation effort to cope with it.RCP4.5 represents a stable scenario.Although there is an increase in temperature due to the increased concentrations of greenhouse gases, with proper implementation of mitigation, the temperature is expected to stabilize in the future.Meanwhile, RCP8.5 represents a worse scenario where there is no act on mitigation to combat the changing climate.Consequently, hot temperatures hit the world which at last threaten our food security.
The monthly average temperature in Aceh Province is projected from csiro data mk3.6 RCP4.5 and RCP8.5 throughout three time periods: shortterm (2016-2035), medium-term (2046-2065), and long-term (2081-2100).Figure 8 depicts a projection diagram of the yearly average temperature at a longitude of 95.3723 and latitude of 5.3747.Figure 4.7 depicts the anticipated maximum temperature in the long-term RCP 8.5 scenario, which is around 31.55 °C, and the estimated minimum temperature in the short-term RCP 4.5 scenario, which is less than 28.89 °C.16 for JJA.The classification of temperature changes in Aceh Province is divided into 11 classifications.The seasonal average temperature projection is divided into four periods, i.e., months of DJF, months of MAM, months of JJA, and months of SON.The results of the spatial projection of seasonal average temperature changes show that the highest increase in temperature values is in the months of JJA (Figure 16) and the months of MAM.While the lowest temperature increase is in the months of DJF and followed by the months of SON.

Conclusion
The RCP 4.5 scenario and the RCP 8.This analysis of Aceh Province's temperature change forecasts can be updated using the most recent scenarios and data.The expected outcomes of this temperature rise can serve as a guideline for avoiding a substantial increase in temperature by enacting legislation to minimize greenhouse gas emissions.

Figure 3 .
Figure 3.The annual average temperature for the period 1986-2005 and the topography of Aceh Province.

Figure 4 .
Figure 4.The annual average temperature trend from 1986 to 2005 in Aceh Province.

Figure 5 .
Figure 5. Annual average temperature trends and seasonal average temperature trends.

Figure 6 .
Figure 6.Projected Changes in Monthly Average Temperatures for the Period 1986-2005.

Figure 7 .
Figure 7. Spatial projection of monthly average temperature in Aceh Province.

Figure 7
Figure 7 depicts spatial projections of monthly average temperatures in Aceh Province derived from csiro mk3.6 RCP 4.5 and RCP 8.5 data and interpolated using IDW.The monthly average temperature projection is separated into three time periods: short-term (2016-2035), medium-term (2046-2065), and long-term (beyond 2065), (2081-2100).Figure 7 depicts the anticipated maximum temperature in the long-term RCP 8.5 scenario, which is around 30 °C, as well as the expected minimum temperature in the short-term RCP 4.5

Figure
Figure 7 depicts spatial projections of monthly average temperatures in Aceh Province derived from csiro mk3.6 RCP 4.5 and RCP 8.5 data and interpolated using IDW.The monthly average temperature projection is separated into three time periods: short-term (2016-2035), medium-term (2046-2065), and long-term (beyond 2065), (2081-2100).Figure 7 depicts the anticipated maximum temperature in the long-term RCP 8.5 scenario, which is around 30 °C, as well as the expected minimum temperature in the short-term RCP 4.5

Figure 8 .
Figure 8. Annual average temperature projection diagram.Figures 9 to 12 show spatial predictions of seasonal average temperatures in Aceh Province using csiro data mk3.6 RCP 4.5 and RCP 8.5 interpolated using IDW.The seasonal average temperature projection is separated into three time periods: short-term (2016-2035), medium-term (2046-2065), and long-term (beyond 2065).(2081-2100).The anticipated seasonal average temperature is further separated into four periods: to 4.11 shows that the maximum temperature projected in the long-term period RCP 8.5 scenario is around 30 °C and the minimum temperature is projected in the shortterm RCP 4.5 scenario, which is less than 18 °C.As Aceh is located in Equatorial region, no fluctuation of air temperature is found in the warming of the Earth's surface.The intensity of daily heating is relatively similar throughout the year.Even if it is found a difference in warming in each season, it does not have any significant impact.

Figure 9 .
Figure 9.The projected spatial seasonal mean temperature for the DJF period.The results of spatial projections of average seasonal temperatures show that the temperature distribution has the highest values in the months of JJA and the months of MAM.While the lowest temperature distribution is in the months of DJF and followed by the months of SON.

Figure 10 .
Figure 10.Projection of the spatial seasonal mean temperature of the MAM period.

Figure 11 .
Figure 11.Projection of spatial seasonal mean temperature for the JJA period.

Figure 12 .
Figure 12.Projection of the spatial seasonal mean temperature of the SON period.The projection diagram of the monthly average temperature change at the point of longitude 95.3723 and latitude 5.3747 is shown in Figure 15 that the highest change in temperature increase occurs in the RCP 8.5 scenario for the period 2081-2100, where the highest increase occurs in July, which is 4°C.The lowest temperature increase occurs in the projected RPP 4.5 scenario for the 2016-2035 period, i.e., in December at 0.554°C.

Figure 13 .
Figure 13.Projected Changes in Monthly Average Temperature for the period 1986-2005.

Figure 14 .
Figure 14.Projected changes in monthly average temperature in Aceh Province.The spatial projection of changes in the monthly average temperature in Aceh Province is shown in Figure 14.The classification of temperature changes in Aceh Province is divided into 11 classifications.The highest temperature increase is shown by the projection of the RCP 8.5 scenario for the period 2081-2100, i.e., in Subulussalam region.The lowest temperature increase is shown by the projection of the RCP 4.5 and 8.5 scenarios for the period 2016 to 2035.

Figure 15 .
Figure 15.Projected annual average temperature change.The projected diagram of the annual average temperature change is shown in Figure 15.Projected changes in the annual average temperature are carried out using scenarios RCP 4.5 and 8.5.The projected period for changes in average temperature is divided into three periods, i.e., 2016-2035, 2046-2065, and 2081-2100.

Figure 16 .
Figure 16.Projected changes in the seasonal average temperature for the JJA month Spatial projections of seasonal average temperature changes in Aceh Province are shown in Figure16for JJA.The classification of temperature changes in Aceh Province is divided into 11 classifications.The seasonal average temperature projection is divided into four periods, i.e., months of DJF, months of MAM, months of JJA, and months of SON.The results of the spatial projection of seasonal average temperature changes show that the highest increase in temperature values is in the months of JJA (Figure16) and the months of MAM.While the lowest temperature increase is in the months of DJF and followed by the months of SON.
5 scenario are used to analyze expected temperature changes in the near term (2016-2035), medium term (2046-2065), and long term (2081-2100).The forecast using the RCP 4.5 scenario indicates less change in temperature rise than the projection using the RCP 8.5 scenario, which shows a temperature rise of up to 5°C.