EGU2020-19970, updated on 12 Jun 2020
https://doi.org/10.5194/egusphere-egu2020-19970
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Indices for daily temperature and precipitation based on quality controlled and homogenized data in Madagascar

Luc Yannick Andréas Randriamarolaza1, Enric Aguilar1, and Oleg Skrynyk1,2
Luc Yannick Andréas Randriamarolaza et al.
  • 1Universitat Rovira i Virgili, Center for Climate Change (C3) , Spain (lucyannickandreas.randriamarolaza@urv.cat)
  • 2Ukrainian Hydrometeorological Institute, Kyiv, Ukraine

Madagascar is an Island in Western Indian Ocean Region. It is mainly exposed to the easterly trade winds and has a rugged topography, which promote different local climates and biodiversity. Climate change inflicts a challenge on Madagascar socio-economic activities. However, Madagascar has low density station and sparse networks on observational weather stations to detect changes in climate. On average, one station covers more than 20 000 km2 and closer neighbor stations are less correlated. Previous studies have demonstrated the changes on Madagascar climate, but this paper contributes and enhances the approach to assess the quality control and homogeneity of Madagascar daily climate data before developing climate indices over 1950 – 2018 on 28 synoptic stations. Daily climate data of minimum and maximum temperature and precipitation are exploited.

Firstly, the quality of daily climate data is controlled by INQC developed and maintained by Center for Climate Change (C3) of Rovira i Virgili University, Spain. It ascertains and improves error detections by using six flag categories. Most errors detected are due to digitalization and measurement.

Secondly, daily quality controlled data are homogenized by using CLIMATOL. It uses relative homogenization methods, chooses candidate reference series automatically and infills the missing data in the original data. It has ability to manage low density stations and low inter-station correlations and is tolerable for missing data. Monthly break points are detected by CLIMATOL and used to split daily climate data to be homogenized.

Finally, climate indices are calculated by using CLIMIND package which is developed by INDECIS* project. Compared to previous works done, data period is updated to 10 years before and after and 15 new climate indices mostly related to extremes are computed. On temperature, significant increasing and decreasing decade trends of day-to-day and extreme temperature ranges are important in western and eastern areas respectively. On average decade trends of temperature extremes, significant increasing of daily minimum temperature is greater than daily maximum temperature. Many stations indicate significant decreasing in very cold nights than significant increasing in very warm days. Their trends are almost 1 day per decade over 1950 – 2018. Warming is mainly felt during nighttime and daytime in Oriental and Occidental parts respectively. In contrast, central uplands are warming all the time but tropical nights do not appear yet. On rainfall, no major significant findings are found but intense precipitation might be possible at central uplands due to shortening of longest wet period and occurrence of heavy precipitation. However, no influence detected on total precipitation which is still decreasing over 1950 - 2018. Future works focus on merging of relative homogenization methodologies to ameliorate the results.

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*INDECIS is a part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462).

How to cite: Randriamarolaza, L. Y. A., Aguilar, E., and Skrynyk, O.: Indices for daily temperature and precipitation based on quality controlled and homogenized data in Madagascar, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19970, https://doi.org/10.5194/egusphere-egu2020-19970, 2020

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Display material version 2 – uploaded on 05 May 2020, no comments
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  • CC1: Comment on EGU2020-19970, Ny Riavo Voarintsoa, 05 May 2020

    Hello,

    I find your study interesting, but I would also like to ask further explanations:

    - Figure with the Decadal Regional trend, what does the y axis represents (I see  °C/10years) but is it a z-score, std, or something else? 

    -you mentioned to have first studied the daily climate, can you please indicate in which of the figures we could evaluate and understand that?

    - lastly, since each region of Madagascar has different climatic regime (from east to west, and from north to south), are there any difference in the observed trend.

    Thanks very much.

    Voary

    • CC2: Reply to CC1, Luc Yannick Andréas Randriamarolaza, 05 May 2020

      Dear Voary,

      I would like to thank you for your interests on our study. Please find below my answers about your questions.

      Q1: Figure with the Decadal Regional trend, what does the y axis represents (I see  °C/10years) but is it a z-score, std, or something else?

      A1: y axis is the decadal regional trends itself and its limitation. its unit is in brackets (°C/10yrs). It is calculated from annual regional trends. Methods illustrate the applied techniques or tools to calculate it.

      Q2:you mentioned to have first studied the daily climate, can you please indicate in which of the figures we could evaluate and understand that?

      A2: the first step consists to check the quality of daily observational data from 28 synoptic stations (called quality control). The results are not shown here but it will be in full paper. However, the goal of our study is to detect changes in Madagascar climate over 1950-2018. 

      Q3:lastly, since each region of Madagascar has different climatic regime (from east to west, and from north to south), are there any difference in the observed trend.

      A3: Decadal station-by-station trends show these differences. Two examples are shown in the poster related to temperature and precipitation respectively.

      Best regards,

      Luc

      • CC3: Reply to CC2, Ny Riavo Voarintsoa, 05 May 2020

        Thank you Luc!

        I would love to read more about your paper if it is published (voary.voarintsoa@kuleuven.be).

        Best wishes,

        Voary