Mean Minimum Temperature Research Articles

Spatiotemporal impacts of climate change on food production: case study of Shaanxi Province, China.

The climate change on the impact of grain production potential has significant regional differences. Researchers have studied the grain production potential of various crop combinations or focused on single crop types in a typical area; however, the regional differences of the climate change on the impact of grain production potential were neglected. This paper used the Global Agro-Ecological Zone (GAEZ 3.0) model to focus on the analysis what is the climate change on the impact of grain production potential in different geographic units (Northern Shaanxi Plateau, Guanzhong Basin, Qinba Mountain) in Shaanxi Province of China. The case showed that the precipitation (Pre) what made changes of grain production potential was the most important factor in different geographic units. The increase of Pre had a positive impact on the grain production potential in Northern Shaanxi Plateau and Guanzhong Basin. However, in Qinba Mountain, due to excessive Pre in the Qinba Mountains, the decrease of Pre had a certain positive impact on the grain production potential. The precipitation was less in the Northern Shaanxi Plateau; therefore, its major factors leading to changes of crop production were precipitation and rainfall days. The increase of the mean maximum temperature (Tmx) and the mean minimum temperature (Tmn) had a positive impact of the grain production potential in the Northern Shaanxi Plateau and Guanzhong Basin. The higher temperature had a negative impact on the grain production potential. In Qinba Mountain, the increase of the temperature has a certain negative impact on the grain production potential. It has more influence of Tmx in the Guanzhong Basin and Qinba Mountain rather than that in the Northern Shaanxi Plateau. Generally speaking, the major climatic factors leading grain production potential were Pre and Tmx in Guanzhong Basin and Qinba Mountain.

Temperature Tolerance and Thermal Environment of European Seed Bugs.

Heteroptera, or true bugs populate many climate zones, coping with different environmental conditions. The aim of this study was the evaluation of their thermal limits and derived traits, as well as climatological parameters which might influence their distribution. We assessed the thermal limits (critical thermal maxima, CTmax, and minima, CTmin) of eight seed bug species (Lygaeidae, Pyrrhocoridae) distributed over four Köppen–Geiger climate classification types (KCC), approximately 6° of latitude, and four European countries (Austria, Italy, Croatia, Bulgaria). In test tubes, a temperature ramp was driven down to −5 °C for CTmin and up to 50 °C for CTmax (0.25 °C/min) until the bugs’ voluntary, coordinated movement stopped. In contrast to CTmin, CTmax depended significantly on KCC, species, and body mass. CTmax showed high correlation with bioclimatic parameters such as annual mean temperature and mean maximum temperature of warmest month (BIO5), as well as three parameters representing temperature variability. CTmin correlated with mean annual temperature, mean minimum temperature of coldest month (BIO6), and two parameters representing variability. Although the derived trait cold tolerance (TC = BIO6 − CTmin) depended on several bioclimatic variables, heat tolerance (TH = CTmax − BIO5) showed no correlation. Seed bugs seem to have potential for further range shifts in the face of global warming.

Variations in extreme temperature and precipitation for a Caribbean island: Barbados (1969–2017)

Changes in temperature and precipitation can have direct effects on a country’s economic and sustainable development. This study presents the historical trends in daily extreme temperature and precipitation indices for Barbados, a Caribbean island, for the period 1969–2017. Linear trends were determined on monthly, seasonal, and annual indices derived from daily rainfall, and daily maximum and minimum temperatures collected at Husbands using the Mann-Kendall trend test and the Sen slope estimator. Annual precipitation total, the simple daily rainfall intensity index (SDII), and the total precipitation when daily rainfall was greater than the 95th percentile (R95P) changed significantly by 3.9% per decade, 0.38 mm day−1 per decade, and 2.9% per decade, respectively. Annual trends in mean maximum (TXmean) and mean minimum temperatures (TNmean), 0.06 °C decade−1 and 0.34 °C decade−1, respectively, mask stronger monthly warming trends: TXmean for September and October both warmed at a rate of approximately 0.17 °C decade−1 while TNmean for April warmed at 0.40 °C decade−1. In addition, warming manifests in the frequency of warm nights and cool days at rates of 4.23% per decade and − 2.34% per decade, respectively. Of the extreme temperature indices, the percentage of warm nights (TN90P), cool nights (TN10P), the maximum of the daily minimum temperature (TNX), and the minimum of the daily minimum temperature (TNn) show trends in their monthly indices. These trends indicate warming at Husbands, Barbados, to a greater degree in increasing nighttime temperatures than daytime temperatures.

Evaluation of a New Statistical Method—TIN-Copula–for the Bias Correction of Climate Models’ Extreme Parameters

During the last decades, global and regional climate models have been widely used for the estimation of future climate conditions. Unfortunately, the models’ estimated values present important biases relative to the observed values, especially when the estimations refer to extremes. Consequently, several researchers have studied several statistical methods that are able to minimize the biases between climate models and observed values. The present study evaluates a new statistical method for bias correction: The triangular irregular network (TIN)-copula method. This method is a combination of the triangular irregular networks and the copula theory. In the present research, the new method is applied to ten Mediterranean stations and its results are compared with the bias-corrected values of three other widely used methods: The delta, the scaling, and the empirical quantile mapping methods. The analysis was made for maximum mean temperature (TMX) and minimum mean temperature (TMN) as well as for extreme precipitation (R99). According to the results, the TIN-copula method is able to correct extreme temperature and precipitation values, estimated by regional climate models, with high accuracy. Additionally, it is proven that the TIN-copula method is a useful tool for bias correction as it presents several advantages compared with the other methods, and it is recommended for future works.

MOTEDAS century: A new high‐resolution secular monthly maximum and minimum temperature grid for the Spanish mainland (1916–2015)

AbstractInformation was retrieved from the Annual Climate Summaries (ACS) on average monthly temperatures in Spain for the period 1916–1949, and combined with the digitalized data from the National Climate Data Bank of the Spanish meteorological service (AEMET) to create the new MOTEDAS_century (MOnthly Temperature Dataset of Spain) database of mean monthly maximums (Tmax) and minimums (Tmin). This database was used to calculate a high‐resolution (10 × 10 km) grid that allowed to make a detailed analysis of the temporal evolution of temperature in Spain during the period 1916–2015. Over the period, mean Tmax increased by 1.2°C, while Tmin increased by 1.0°C (this ratio is reversed in the second half of the century). In the last 30 years, however, mean annual Tmax and Tmin trends have not been significant. There are some differences between the new mean annual maximum and minimum temperature series and previous versions, which seem to arise from the much higher number of weather stations analysed, their location and the processing used. There is a discussion on the improved spatial representativeness of the new MOTEDAS_century that provides a more detailed representation of the spatial variability of temperatures in continental Spain.

Assessment of environmental variability on malaria transmission in a malaria-endemic rural dry zone locality of Sri Lanka: The wavelet approach.

Malaria is a global public health concern and its dynamic transmission is still a complex process. Malaria transmission largely depends on various factors, including demography, geography, vector dynamics, parasite reservoir, and climate. The dynamic behaviour of malaria transmission has been explained using various statistical and mathematical methods. Of them, wavelet analysis is a powerful mathematical technique used in analysing rapidly changing time-series to understand disease processes in a more holistic way. The current study is aimed at identifying the pattern of malaria transmission and its variability with environmental factors in Kataragama, a malaria-endemic dry zone locality of Sri Lanka, using a wavelet approach. Monthly environmental data including total rainfall and mean water flow of the "Menik Ganga" river; mean temperature, mean minimum and maximum temperatures and mean relative humidity; and malaria cases in the Kataragama Medical Officer of Health (MOH) area were obtained from the Department of Irrigation, Department of Meteorology and Malaria Research Unit (MRU) of University of Colombo, respectively, for the period 1990 to 2005. Wavelet theory was applied to analyze these monthly time series data. There were two significant periodicities in malaria cases during the period of 1992-1995 and 1999-2000. The cross-wavelet power spectrums revealed an anti-phase correlation of malaria cases with mean temperature, minimum temperature, and water flow of "Menik Ganga" river during the period 1991-1995, while the in-phase correlation with rainfall is noticeable only during 1991-1992. Relative humidity was similarly associated with malaria cases between 1991-1992. It appears that environmental variables have contributed to a higher incidence of malaria cases in Kataragama in different time periods between 1990 and 2005.

Long-term temperature and precipitation trends in the Luquillo Mountains, and their relationships to global atmospheric indices used in climate change predictions

Most climate models for the Caribbean predict drying trends, increased temperature, and precipitation variability. We used regression analyses to evaluate how global predictions translated into local temporal patterns of climatic variation within the Luquillo Mountains in Puerto Rico, and which variables were more useful for expressing precipitation and temperature variability trends there. We used cross-correlation analyses to evaluate how local precipitation and temperature data related to regional atmosphere-ocean teleconnections indices (ENSO, NAO, TNA, and AMO). Contrary to regional climate predictions, we found an increase in mean annual precipitation during the dry season, and no trends in annual and wet season precipitation data sets were observed. Precipitation variance increased after 1995, but only when considering dry season data, which showed a decrease in the total number and consecutive days without rain after 1995. In agreement with regional predictions, maximum and minimum annual mean temperatures increased between 1975 and 2015. We found strong positive associations between maximum and minimum temperatures and rainfall distribution (i.e. more wet days, less dry intervals). Precipitation and temperature were more strongly associated to changes in the Tropical Atlantic than to changes in the North Atlantic or the Eastern Pacific. Our downscaling analysis (one station data) shows the relevance of evaluating global climate predictions in specific areas where landscape features can modify the patterns observed at bigger scales. The combination of downscaling analysis and the inclusion of long-term climate trends can facilitate the development of better future scenarios of climate variability and evaluate their importance to local forest ecosystems.

Ambient temperature correlates with geographic variation in body size of least horseshoe bats.

Geographic variation in body size is common within many animal species. The causes of this pattern, however, remain largely unexplored in most vertebrate groups. Bats are widely distributed globally owing to their ability of powered flight. Most bat species encounter a variety of climatic conditions across their distribution range, making them an ideal taxon for the study of ecogeographic patterns in body size. Here, we used adult least horseshoe bats, Rhinolophus pusillus, to test whether geographic variation in body size was determined by heat conservation, heat dissipation, climatic seasonality, or primary productivity. We measured body mass and head-body length for 246 adult bats from 12 allopatric colonies in China. We quantified the ecological conditions inhabited by each colony, including mean maximum temperature of the warmest month, mean minimum temperature of the coldest month, temperature seasonality, precipitation seasonality, and annual net primary productivity (ANPP). Body mass and head-body length, 2 of the most reliable indicators of body size, exhibited marked differences between colonies. After controlling for spatial autocorrelation, the mean minimum temperature of the coldest month explained most of the variation in body size among colonies, regardless of sex. The mean maximum temperature, climatic seasonality, and ANPP had limited power in predicting body size of males or females in comparison with mean minimum temperature. These results support the heat conservation hypothesis and suggest adaptive responses of body size to cold climates in cave-dwelling bats.

Trend analysis of climatic variables and their relation to snow cover and water availability in the Central Himalayas: a case study of Langtang Basin, Nepal

This paper investigates the long-term monthly, seasonal, and annual trends of climatic variables, snow cover extent, and discharge in Langtang Basin, Central Himalayas. The Mann-Kendall test with variance corrections is used to detect the trend, and Sen’s slope estimator is calculated to quantify the trend. The innovative trend analysis, a graphical method for trend detection, is applied, and the results are compared. The snow cover extent for the study area was derived from moderate resolution imaging spectroradiometer (MODIS) satellite images. The result suggests that there is a significant increasing trend for mean temperature and minimum temperature, while no remarkable trend is identified for maximum temperature. Similarly, precipitation shows a rising trend for all seasons except winter. Snow cover is a major source of fresh water for the region and is depleting at an alarming rate. River discharge, augmented by snowmelt and high rainfall, is upsurging. In summary, this study portrays the links of climatic variables with snow cover and river discharge. The outcome of this study will be useful for understanding the climate change status in the Central Himalayas and sustainably managing the watershed.

Changes of Tree Species Composition and Distribution Patterns in Mts. Jiri and Baegun, Republic of Korea over 15 Years

Long-term changes in the abundance and distribution of tree species in the temperate forests of South Korea remain poorly understood. We investigated the changes in tree species composition in temperate mountainous forests using survey data from 130 permanent plots (0.1 ha) from the past 15 years (1998–2012) distributed across Mts. Jiri and Baegun, South Korea. The tree communities showed positive net changes in terms of stand density, richness, diversity, and evenness. At the species level, the change in relative species composition has been mainly driven by species such as Quercus mongolica, Carpinus laxiflora, Quercus serrata, Quercus variabilis, Styrax japonicus, Lindera erythrocarpa, and Pinus densiflora. These changes were categorized into five groups representing gradual increase or decrease, establishment, extinction, or fluctuation in species populations. At the community level, the changes in species composition showed consistent and directional increases in the annual rate of change for the mean species traits, including stand prevalence, pole growth rate, adult growth rate, and adult stature. Based on additive models, topographic variables (elevation, latitude, longitude, slope, topographic wetness index, and curvature) were more strongly associated with the distribution of species diversity than climate variables (annual mean minimum and maximum temperatures, temperature seasonality, annual rainfall, rainfall seasonality). Elevation was the most significant driver, followed by latitude and longitude. This study reveals the dynamics of change in tree species composition and distribution along topographical and climate gradients in South Korea and contributes to a broader understanding of temperate forest ecosystems for the purpose of better forest management.

Temperature change and urbanisation in a multi-nucleated megacity: China's Pearl River Delta

This paper investigates urbanisation and temperature indices, over four decades in a multi-nucleated megacity, China's Pearl River Delta (PRD). Daily mean minimum, maximum and mean temperatures (Tmin, Tmax and Tmean) have increased considerably above background warming rates. However, only weak to moderate relationships are observed between trends in local urban surface area surrounding climatic stations, and Tmin used as a proxy for UHI development. While 5 out of 21 stations with high increase in both Tmin and degree of urbanisation, showed moderate relationship (R = 0.51), another 8 stations with low urbanisation showed significant increase in Tmin. This suggests warming from factors other than local urban development on Tmin. Since PRD contains eight cities over 4 million population, and a semi-continuous urbanised area due to merging of urban centres, a regional heat island circulation, or heat dome model is invoked. The observed increase in Tmax above background warming rates for 14 stations, is more difficult to explain as Tmax is not generally affected by urbanisation. This is attributed to high surface energy flux in the afternoon, and anthropogenic energy use in dense urban districts. The regional heat dome circulation over PRD suggests local temperatures will increase further, even without further local developments.

KONYA KAPALI HAVZASI (TÜRKİYE) YILLIK SICAKLIK VERİLERİNİN TREND ANALİZİ VE DEĞİŞİM NOKTALARININ BELİRLENMESİ

Climate change is expressed as major changes in the average climate which exist for many years. Although climate change occurs on a global scale, the impact of climate change varies from region to region. Therefore, the analysis of the variations in meteorological variables is a very vital issue in monitoring of climate change. In this study, assignment of the change points and trends of annual mean temperature, maximum temperature and minimum temperature data of the Konya Closed Basin in Turkey is examined. For this aim, air temperature data of 11 meteorology station were used. The change point of temperature time series data was examined using the Pettitt test, Standard Normal Homogeneity test and Buishand Range test. The Mann-Kendall, Spearman Rho and Innovative Şen Trend methods were used to determine trends of air temperature.

First adaptation of quinoa in the Bhutanese mountain agriculture systems.

Bhutan represents typical mountain agriculture farming systems with unique challenges. The agriculture production systems under environmental constraints are typical of small-scale agricultural subsistence systems related to family farming in the Himalayan Mountains with very low level of mechanization, numerous abiotic stresses influenced by climate and other socio-economic constraints. Quinoa was first introduced in 2015 through FAO’s support to Bhutan as a new crop to enhance the food and nutritional security of the Bhutanese people. The main objective was to adapt this versatile crop to the local mountain agriculture conditions as a climate resilient crop for diversifying the farmer’s traditional potato and maize based cropping systems. Ten quinoa varieties were evaluated at two different sites representing contrasted mountain agroecologies in Bhutan and were tested during the two agricultural campaigns 2016 and 2017. Yusipang (2600 masl) represents the cool temperate agroecological zone, and Lingmethang (640 masl) the dry subtropical agroecological zone. The sowing time differed depending on the growing season and elevation of the sites. Results indicate that quinoa can be successfully grown in Bhutan for the two different agroecological zones. The grain yields varied from 0.61 to 2.68 t.ha-1 in the high altitude areas where quinoa was seeded in spring and harvested in autumn season. The grain yield in the lower elevation ranged from 1.59 to 2.98 t.ha-1 where the crop was sown in autumn and harvested in winter season. Depending on genotypes’ characteristics and agroecological zones, crop maturity significantly varied from 92 to 197 days with all genotypes maturing much earlier in the lower elevations where mean minimum and maximum temperatures during the growing season were higher. Quinoa is rapidly promoted across different agroecological contexts in the country as a new climate resilient and nutrient dense pseudo cereal to diversify the traditional existing cropping system with some necessary adjustments in sowing time, suitable varieties and crop management practices. To fast track the rapid promotion of this new crop in Bhutan, four varieties have been released in 2018. In just over three years, the cultivation of quinoa as a new cereal has been demonstrated and partially adapted to the maize and potato based traditional cropping systems under the Himalayan mountain agriculture. Quinoa is also being adapted to the rice based cropping system and rapidly promoted as an alternative food security crop in the current 12th Five Year national development plan of Bhutan. To rapidly promote quinoa cultivation, the Royal Government of Bhutan is supporting the supply of free quinoa seeds, cultivation technologies and milling machines to the rural communities. To promote the consumption and utilization of quinoa at national level, consumer awareness are created by preparing and serving local Bhutanese dishes from quinoa during local food fairs and farmer’s field days. In addition, the Royal Government of Bhutan has included quinoa in the school feeding programme recognizing the high nutrient value of the crop for enhancing and securing the nutritional needs of the young children.

Spatio-temporal behaviour of Nehnar Glacier from 1962 to 2017, Jhelum basin, Kashmir Himalayas, India

ABSTRACT Nehnar glacier is located in the Sindh sub-basin of the Jhelum River in the Kashmir Himalayas. We studied the dynamic response of the glacier (area, snout, Equilibrium Line Altitude (ELA), specific mass balance, volume) using Survey of India (SOI) toposheets and Landsat imagery series from 1962 to 2017. The results show that this glacier has lost an area of 1.4 km2 (50.35%) during this period of 55 years. The snout position and ELA have risen significantly, with varying rates at different time intervals. The specific mass balance of the glacier changed from −2.3 cm water equivalent (w.e.) to −35.1 cm w.e. during this period, with a loss of glacier volume from 0.17 km3 to 0.07 km3. Annual mean maximum (Tmax) and mean minimum (Tmin) temperatures show significant increases, whereas an insignificant decrease in precipitation has been recorded from 1980 to 2016. The continuous glacier retreat will have a significant impact on streamflow, agriculture, and other sectors of the Kashmir Himalayas.

Forecasting the Future Temperature Using a Downscaling Method by LARS-WG Stochastic Weather Generator at the Local Site of Phitsanulok Province, Thailand

The study evaluates the effect of climate change on temperature, which is one of the most important variables in water resources management and irrigation scheduling. Climate prediction is necessary in the agricultural and hydrological analysis. This study proposed an approach to the application of the Long Ashton Research Station Weather Generator (LARS-WG) in Coupled Model Inter-comparison Project Phase 5 (CMIP5) under EC-Earth and MPI-ESM-MR. The first step is model calibration, where the observed dataset is analyzed statistically. In the second stage, the synthetic data and observed data are checked for Kolmogorov-Smirnov and the means and standard deviations. In order to evaluate the response of temperature under future warmer climate trends, the approach was assessed using data series. These parameters consisted of the minimum and maximum temperature at the Phitsanulok Meteorological Station (WMO Index 48378) and RCP4.5 climate change scenario for the base period as well as for 2021-2040 (the near future), 2041-2060 (the medium future) and 2061-2080 (the far future). The results of the numerical applications indicated that the linkage between the observed data spatially downscaled from LARS-WG simulations with the historical one of the locations during the baseline period had a very good accuracy. It was also found that the future climate change of temperature contributed to higher change. The mean of minimum temperature in the baseline year was 23.13°C while the mean of minimum temperature in the projection period for 2021-2040, 2041-2060 and 2061-2080 is expected to be 24.09 (+4.18%), 24.49 (+5.94%) and 24.82 (+7.36%)°C, and 24.12 (+4.32%), 24.82 (+7.36%) and 25.08 (+8.48%)°C for the EC-Earth and MPI-ESM-MR, respectively. While, the mean of maximum temperature in the baseline year was 33.41°C, the maximum temperatures are projected to increase at 34.47 (+3.19%), 34.88 (+4.43%) and 35.21 (+5.40%)°C, and 34.53 (+3.36%), 35.19 (+5.34%) and 35.30 (+5.67%)°C, respectively. Furthermore, the future local surface temperatures from the MPI-ESM-MR project tended to be higher than EC-Earth. In conclusion, the study results indicate that in coming three time periods, the minimum and maximum temperature increase is expected in Phitsanulok province, Thailand.

Potential implications of land use/land cover change and climate variability on ungauged watershed hydrology

In Farta watershed, the impact of land use/land cover (LULC) change and climate variability on hydrological processes was simulated using the soil and water assessment tool (SWAT). The values of R2, NSE, RSR and PBIAS were 0.79, 0.67, 0.82 and 4.8% throughout calibration and 0.61, 0.69, 0.69, and 5.2% throughout validation respectively. Climate trend were analysed in the study area by using Mann-Kendall (MK) test. Percentage change of 10.94%, 8.13% and 16.09% for average annual temperature, mean maximum temperature and mean minimum temperature were observed respectively. The four Landsat images (2000, 2005, 2010 and 2017) were classified into five major LULC classes and areal extent of each LULC were 9.2 Km2 urban, 8.5 Km2 plantations, 5.7 Km2 waterbody, −22.3 Km2 agricultural land and −1.0 Km2 pastureland. The combined effects of LULC and climate variability in the study area should be taken into consideration for the water resources planning and management.

Projected temperature changes in Kolašin (Montenegro) up to 2100 according to EBU-POM and ALADIN regional climate models

This paper deals with the temperature projections of two regonal climate models, actually three scenarios by 2100: the A2 scenario of the EBU-POM model and the RCP4.5 and RCP8.5 scenarios, the latest projections of the ALADIN model. Kolasin was chosen, because the altitude of the place is the average height of the northern region of Montenegro (about 1000 m). A total of 22 temperature parameters for the period 2011–2100 were analyzed. The upward trend of projected seasonal and annual (TY, TYx, and TYn) mean, mean maximum, and mean minimum temperatures by 2100 is very significant. According to the RCP4.5 and RCP8.5 scenarios, in 2011-2100, the trend of projected mean winter (TW) temperatures will be from 0.2 to 0.37 °C per decade, and the trend of projected mean summer (TSu) temperatures will be from 0.24 to 0.54 °C per decade. Compared to the base period (1981–2010), the average annual temperature in 2071–2100 is expected to be higher than 2.2 (RCP4.5) to 3.6 °C (A2 and RCP8.5). Also, by the end of the 21st century, a significant increase in the number of summer and tropical days (SD and TD) together with a decrease in the number of frost and ice days (FD and ID) are expected. During the instrumental period, a temperature higher than 37 °C was not recorded. According to projections, in the late 21st century, in summer, maximum temperatures of 40 °C are possible, even in the milder variant (RCP4.5) scenario. According to projections of the used models, Kolasin and the northern region of Montenegro expect a warmer future with more frequent extreme temperatures in a positive direction.

Potential implications of land use/land cover change and climate variability on ungauged watershed hydrology

In Farta watershed, the impact of land use/land cover (LULC) change and climate variability on hydrological processes was simulated using the soil and water assessment tool (SWAT). The values of R2, NSE, RSR and PBIAS were 0.79, 0.67, 0.82 and 4.8% throughout calibration and 0.61, 0.69, 0.69, and 5.2% throughout validation respectively. Climate trend were analysed in the study area by using Mann-Kendall (MK) test. Percentage change of 10.94%, 8.13% and 16.09% for average annual temperature, mean maximum temperature and mean minimum temperature were observed respectively. The four Landsat images (2000, 2005, 2010 and 2017) were classified into five major LULC classes and areal extent of each LULC were 9.2 Km2 urban, 8.5 Km2 plantations, 5.7 Km2 waterbody, −22.3 Km2 agricultural land and −1.0 Km2 pastureland. The combined effects of LULC and climate variability in the study area should be taken into consideration for the water resources planning and management.

The m-delay Autoregressive Model with Application

The classical autoregressive (AR) model has been widely applied to predict future data using m past observations over five decades. As the classical AR model required m unknown parameters, this paper implements the AR model by reducing m parameters to two parameters to obtain a new model with an optimal delay called as the m-delay AR model. We derive the m-delay AR formula for approximating two unknown parameters based on the least squares method and develop an algorithm to determine optimal delay based on a brute-force technique. The performance of the m-delay AR model was tested by comparing with the classical AR model. The results, obtained from Monte Carlo simulation using the monthly mean minimum temperature in Perth Western Australia from the Bureau of Meteorology, are no significant difference compared to those obtained from the classical AR model. This confirms that the m-delay AR model is an effective model for time series analysis.

Statistical analyses of climate change (case study of rivers east Senatorial District of Rivers State Nigeria)

The formation of settlement mainly depends on the climatic conditions of that location, Variation in temperature has been a challenge to scientist because of its direct and indirect effect on meteorological phenomena. The temperature trends globally revealed a continuous variability that is seasonally dependent within any particular year considered. Data's for Rivers east Senatorial district were taken for a period of 5 years (2008–2013) and evaluated for possibility of climate change. Including the concentration of carbon dioxide over the senatorial district around the same time as temperature was assessed from Nigeria metrological center. The highest minimum temperature of 17.9oc was recorded in okrika in 2009. The highest maximum temperature mean temperature of 42.1oc was recorded in port Harcourt in 2012. The mean minimum and maximum temperature showed a reducing and increasing temperature respectively, occasioned by natural and manmade activities such as gas flaring, bush burning, illegal refining of crude oil and other activities.the concentration of carbon dioxide over the Rivers East Senatorial district has been one of the contributing factor of rising temperatures in the senatorial district. This investigation examination the inconstancy of temperature (day by day, month to month and annual).the study uncovered expanding occasions of extraordinary temperature in wide territories in the senatorial region aside from in Ogu/Bolu of and Okrika nearby government zones of the area. In coming down season, expanding temperature of the atmosphere state and debilitating temperature limits are seen in Port Harcourt. All in all, expanding temperature of the atmosphere and upgrading temperature limits were normally watched Obio/Akpor, Port Harcourt and Ikwerre Nearby Government Territories.