Analysis of the Observed Trends in Rainfall and Temperature Patterns in North-Eastern Nigeria
, Emmanuel Tanko Umaru 1,3, Abel Aderemi Adebayo 4, Ralf Löwner 5 and Appollonia Aimiosino Okhimamhe 1,6
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe content of the manuscript is important and the manuscript contains the new information. Currently, these articles are very demand and used. Moreover, the authors used many references which are less than five years old. However, there are minor errors in the manuscript that reduce its quality. Therefore, I recommend for printing after these corrections (see below).
In introduction – the authors are concerned with the decrease / increase of precipitation, but their different distribution during the year is also assumed - could the authors add information regarding the distribution of precipitation during the year?
Figures – the figures were artificially expanded (please, it would have been better to insert the figures in the original format - height, width)
L46 – remove the second “in”
L58 – in a study by [26] – correct is „study by Praveen et al. [26]“
L59 – more spaces between „studied. and Few“
L59, L73, L82, L94, L337, L349, L351 (2x) and the others – similarly as L58
L68 – recent Studies – correct is „recent studies“ – with lowercase letter
L107 – is missing dot in the end of sentence „.“
„2. Material and methods“ – is missing title of chapter
L121 – 2042m – divide it
L122 – The Maximum – maximum with lowercase letter
L125 – between 35°C – 40°C – correct is „between 35°C and 40°C
L126 – 647mm and 2280m – divide it (similarly as L121)
L110 and L111 – latitudes and longitudes X L127 – Latitudes and Longitudes (unify it)
L129 – 38° C and 25° C – together (without space between ° and C)
L149 – [54; 34] – correct it [34, 54]
L252 + L253 and L256 + L257 - for numbers, only four digits after the dot are sufficient
L307 – 2021in – divide it
L321 – 2021(Figure – divide it
L355 – [65, 43] – correct it [43, 65]
L367 – [64, 79, 71] – correct it [64, 71, 79]
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe present study offers a comprehensive evaluation of monthly rainfall and temperature patterns across nine stations and fifty-nine points in North-eastern Nigeria, spanning four decades (1981-2021) using NASA’s Prediction of Worldwide Energy Resources data. By employing the Mann-Kendall (MK) test and Inverse Distance Weighting (IDW) interpolation, the researchers effectively detected and visualized trends in climate variables. The MK test results indicated contrasting rainfall trends, with notable decreases in Akko, Billiri, Maiduguri, Numan, and Yola, and increases in Gombe, Abadam, Biu, and Mubi. The trend in maximum temperature was found to be statistically significant across all stations, showing a consistent increase, whereas minimum temperature trends exhibited a slight but insignificant decrease. The application of the Theil-Sen slope estimator quantified these trends, providing nuanced insights into the magnitudes of changes in climate variables. The IDW results further corroborated the general trend of decreasing rainfall (z = -0.442), modest increases in maximum temperature (z = 0.046), and a marginal decline in minimum temperature (z = -0.005).
This study makes an important contribution by advocating for the proactive dissemination of climate information. Given the evident climate shifts, particularly the increasing temperatures and fluctuating rainfall patterns, timely access to such information is crucial to enhancing climate resilience in the region. The rigorous statistical methods applied and the detailed spatial analysis strengthens the validity of the findings, making this study a valuable resource for both researchers and policymakers aiming to address climate variability in North-eastern Nigeria and these research results might be useful to understand the climate variabilities in different parts of the world, as well.
Major issues:
However, there are a few issues that need to be commented/dealt with by the authors, which include:
a) The study uses monthly data, which might overlook shorter-term variations such as daily or seasonal fluctuations. This could lead to underestimation of extreme weather events, such as short but intense rainfall periods or heatwaves.
b) While IDW (Inverse Distance Weighting) is a widely used interpolation method, it has limitations in accurately representing complex spatial patterns, especially in regions with sharp gradients or varying terrain. More advanced geostatistical methods such as kriging could potentially offer better accuracy in such cases.
Regarding statistical models used in this study:
a) The Mann-Kendall test is commonly used for trend analysis, but it does not account for potential autocorrelation in the data. If the time series data exhibits significant autocorrelation (e.g., due to persistence in weather patterns), the test may lead to biased results, particularly with regard to the significance of trends.
b) While robust, the Theil-Sen estimator assumes a linear trend over time. Climate variables, however, may follow nonlinear or cyclical trends, which this method cannot fully capture. The study may benefit from exploring nonlinear trend analysis techniques, especially given the long period of study (1981–2021).
Minor Issues:
a) The font sizes associated with all figures are so small and the sizes shall be enhanced.
b) The word ‘North-Eastern’ has written in different ways in different parts of the text. Kindly maintain consistency.
c) Page 4, Section 2.2. Data Sources and Analysis need to be explained further
d) A few grammatical and typos are present here and there. Correct them all with maximum efforts.
Comments for author File: Comments.pdf
A few grammar and typos are present here and there. Correct them all with maximum effort.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsIt needs to say directly. I am not like the presented material and that's why It is a paper from the mainstream, one of the great many number of such ones which supported the modern global warming and the present one is only one of them - to find upward temperature trend in data series for any region and/or downward trend for rainfalls in the same one. Too routine and boring!
.However on the other side I am not like to reject papers for review. That's why the following improvements in the text should be made:
1. The results are presented mainly in tables as values of "p" and "z" parameters for the separate stations as well as maps about rainfalls and temperature changes. There are not plots of rainfalls or temperature time series (original or smoothed data). This leads to suspicion that the discussed there trends are not so good expressed (very probably!). A figure, containing such plots is strongly necessary. In contrary it remain to suspices that author tries something to obscured - for example if the trends are not so good expressed. Or (maybe) there are statistically significant cyclic oscillations?!
2. The maps in Fig2 support such assumption.The redistribution maps for rainfalls and temperatures seems to show a wave-type behavior during the investigated 40-year interval . This could be traced the influence of ~20yr solar-climatic cycle (in relation to the solar 20-22yr magnetic cycle, most probable ) and/or with tidal forces cycles by Moon and Sun. There are many evidences, which are described in literature. These studies are not in PRESENT mainstream of climatology, but the last one make them not many valid. However for such study the authors need search no only for trends but also for statistically significant cycles. This is no possible in this study however the problem could be considered shortly in the Section "Discussion".
3. It should also strongly taken into account that "trends" are only mathematical models of time series for relative short time intervals. They are results of too limited time intervals as in this case. 40 years is too short interval for the climate time scale changes! Please, mark this statement in Discussion.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsComments and suggestions
This study examined long-term trends of precipitation and temperature in north-eastern Nigeria using data from NASA's Prediction of Worldwide Energy Resources between 1981 and 2021. Based on statistical analysis methods, the authors found decreasing rainfall trend in Akko, Billiri, Maiduguri, Numan, and Yola, and increasing trend in Gombe, Abadam, Biu, and Mubi. In addition, maximum temperature trends show significant increasing trend across all stations, while the trend of minimum temperature is insignificantly. This manuscript fits the scope of this Journal (Climate). However, it needs a major revision before it can be accepted.
[1] The writing of this study should be further revised and polished.
[2] Title: Temperature should be revised. It should specify temperature in which level. Do you mean surface temperature?
[3] Introduction: The authors should also review the factors for the variation of rainfall and temperature in north-Eastern Nigeria in the introduction.
[4] The abstract should be refined. For instance, in Line 19, you needn't introduce the statistical analysis and the IDW interpolation methods in the abstract. You should describe the main findings of this study.
[5] Introduction: As introduced by the authors, many studies have examined long-term trends of surface temperature and precipitation over Africa. Hence, the authors should describe the innovation of this study in more details.
[6] Data: This study only used the data from the NASA's Prediction of Worldwide Energy Resources. The authors should also used other data from different sources to confirm the robustness of the results.
[7] This study only examines long-term trends of precipitation and temperature in Northeastern Nigeria via statistical analysis. However, the factors responsible for these trends were not examined and discussed. In particular, the authors should discuss the possible role of global warming and internal climate variability. The following articles are good for the discussions.
Strengthened impact of boreal winter North Pacific Oscillation on ENSO development in warming climate. npj Climate and Atmospheric Science, 7, 69.
Recent pronounced warming on the Mongolian Plateau boosted by internal climate variability. Nature Geoscience, 17, 181-188.
Comments on the Quality of English Languagesee review report.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThank you for your changes. Your manuscript is very successful.
Reviewer 2 Report
Comments and Suggestions for AuthorsMost of my concerns were properly dealt with by the authors. I am satisfied with their answers and the way they responded.
Reviewer 3 Report
Comments and Suggestions for Authors...It should be noted that researchers have observed that solar activity affectsprecipitation patterns and temperature cycles through mechanisms like the Sun's magnetic field and its influence on Earth's atmosphere. These interactions appear to contribute to variations in climate over decadal timescales, resembling cyclic patterns similar to the ~20-year oscillations seen in temperature and rainfall distribution maps [81]. The limitation of this study is that the observed "trends" are based on a relatively short 41-year period, which is insufficient to fully capture long-term climate changes. This brief timeframe may not adequately reflect true climate-scale variations, as climate trends typically require longer intervals for reliable analysis....
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By my opinion it is too difficult to made better improvement of the text on base of this limited in time observation data (41 years). That's why I accept that that the added by authors above mentioned (italic) text is enough essential and important in the case of this study. I agree that the paper could be publish in this form.
Reviewer 4 Report
Comments and Suggestions for AuthorsI have no further comments.
