# A Percentile Method to Determine Cold Days and Spells in Bangladesh
## 4 Discussion
[4] observed when the maximum temperature is less than or equal to 21 \({}^{\circ}\)C, the cold-related mortality is found to be at its maximum, which indicates the dependence on maximum temperature. Therefore, a case study was considered for the period 3-7 January 2023, in winter, to evaluate the SD, 10P, and BMD threshold methods' calculated categories of cold days (see Table 3) with the newspaper's reported intensity of cold conditions. In fact, the daily national newspapers usually publish articles on the intensity of cold conditions in different parts of the country, including the number of cold-related deaths (mortality). According to BMD, mild cold weather was occurring in certain regions of the country during the period 5-7 January 2023. However, it did not reflect the actual cold conditions reported in the newspapers, where felt like cold conditions were much worse in most parts of the country, except for the southern coast and few areas in the hill tracts (see Table 3). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Station Name**} & \multicolumn{3}{c}{**5 January**} & \multicolumn{3}{c}{**6 January**} & \multicolumn{3}{c}{**7 January**} \\ \cline{2-10}  & **SD** & **10P** & **BMD** & **SD** & **10P** & **BMD** & **SD** & **10P** & **BMD** \\ \hline Dinajpur & & & & Mi & & & Mi & & Mi \\ Rangpur & & & & & & & & & \\ Bogura & & Ve & & Mi & Mo & & Ve & Mo & \\ Rajshahi & Mo & Mo & Mi & Ve & Ve & & Ve & Mi \\ Ishurdi & Ve & Ve & Mi & Mo & Mo & & Ve & Ve & Mi \\ Mymensingh & Mi & Mi & & Mo & Mo & & Ve & Ve & Mi \\ Sylhet & & & & & Mi & & & & \\ Sreenmgal & & & & & Mi & & & & \\ Dhaka & & & Mi & & Mo & & Se & Se & \\ Faridpur & Mi & & & Ve & Ve & & Ex & Ex & Mi \\ Madaripur & Ve & Ve & & Se & Se & & Ex & Ex & Mi \\ Jessore & Mo & Mo & Mi & Mi & Mi & Mi & Ex & Ex & Mi \\ Khulna & Mi & & & Mi & Mi & & Se & Se & \\ Sukhira & Mi & Mi & & & Mi & & Se & Se & Mi \\ Barisal & & & & & Mo & Mi & & Mo & Ve & Mi \\ Bhola & & & & Mi & Mi & & Ve & Ve & \\ Patuakhali & & & & & & & & \\ Khepupara & & & & & & & & Ve & \\ Comilla & Mo & Mo & Ve & Ve & & Ve & & \\ Chandpur & Mi & Mi & & Ve & Ve & & Ve & \\ Feni & Mi & Mi & & Mo & Mo & & Mi & \\ M. Court & & & & Mi & Mi & & Mi & \\ Hatiya & & & & & & & & \\ Sandwip & & & & & & & & \\ Sitakunda & & & & & & & & \\ Chattopgar & & & & & & & & \\ Rangamati & & & & & & & & \\ Cox’s Bazaar & & & & & & & & \\ Teknaf & & & & & & & & \\ \hline \hline \end{tabular} SD = standard deviation; 10P = 10 percentile; BMD = Bangladesh Meteorological Department.  
\end{table} 
Table 3: Categories of the estimated cold days in the weather stations during 5–7 January 2023, using SD, 10P, and BMD threshold methods. Cold days were categorized as mild (Mi), moderate (Mo), very (Ve), severe (Se), and extreme (Ex). BMD is considered a cold day when the minimum temperature is less than or equal to 10 \({}^{\circ}\)C. According to BMD, the maximum temperature and or DTR has no effect on a cold day. Our calculation from the 10P method, including the SD method [28], presented stations in those areas with moderate (Mo) to extreme (Ex) cold days, where BMD provided only mild (Mi) cold days, even in fewer stations (see Table 3). Our 10P calculation nearly matched with the newspapers reporting cold conditions in different areas of the country during the case study period. For instance, two leading national daily newspapers published the following articles related to the period of 5-7 January 2023. The intensity of cold conditions increased in Dhaka, and continued. The lowest temperature was recorded 8.4 \({}^{\circ}\)C in Chuadanga (The Daily Ittefaq, 7 January 2023) [54]. Severe cold and dense fog disrupted normal life in most parts of the country, including the capital city, with a temperature of 12.5 \({}^{\circ}\)C (Prothom Alo, 7 January 2023). The number of child patients increased in Khulna Medical College Hospital due to the cold weather severity in Khulna and the surrounding areas (Prothom Alo, 7 January 2023).