Chairman
"Accuracy is the lifeline of flood and weather forecast. The hydrometeorological sector should forecast flood and weather accurately and enhance the level of promptness and scientific character of the hydrometeorological data by furnishing itself with modern weather observation equipment."
A significant urbanization effect in the observed surface air temperature data series have been found in study area. In this paper, we analyzed the possible impact of urbanization on long-term SAT trends in the Pyongyang region of the Democratic People's Republic of Korea by using data of SAT, wind data and Landsat TM images. This paper assessed the urbanization effect on SAT trends in Pyongyang region. The main conclusions were drawn as follows:
(1) To improve estimation of urbanization effect, an approach with considering the direction and frequency of prevailing wind was applied to classify 13 stations over Pyongyang region. All stations were divided into 4 groups (large city, medium city, small city/town and rural stations) based on the new method and satellite images.
(2) Remarkable urbanization effects existed in the SAT data series of urban stations in Pyongyang region during 1961–2019 (1969–2019). For the period 1961–2019, the annual mean urbanization contributions to the overall warming reached 11.3% for Pyongyang station. Since 1969, Pyongyang station had experienced somewhat strengthened urbanization effect, and they were 0.051°C/decade (13.1%) for stations of big city (Pyongyang), 0.031°C/decade (8.4%) for stations of medium-size cities, and 0.019°C/decade (5.3%) for stations of small cities and towns.
(3) By season, the urbanization contributions were 8.6% in spring, 10.5% in summer, 9.3% in autumn, and 21.3% in winter, respectively, since 1969. Winter witnessed the largest urbanization contributions for all the stations and for the two periods analyzed.
(4) Urban area, especially, Pyongyang city experienced more extreme temperature events than the surrounding rural areas, urbanization contribution to increasing trends of representative temperature indices ranged nearly one-quarter or one-fifth, with accounting for nearly 30% of TNn and TN10p as cold(cool) weather-related indices, while some hot (warm) weather-related indices have relatively weaker intensifying uptrends.
It was worth noting that the estimates of urbanization effect and contribution as reported in this paper, as those given in any other studies, were conservative due to the difficulty of identifying real rural stations with observational records long enough for the comparative analysis.
Our result was published with the title of "A detectable urbanization effect in observed surface air temperature data series in Pyongyang region, Democratic People's Republic of Korea" (https://doi.org/10.1016/j.uclim.2021.100907) in the journal "Urban Climate" (38 (2021) 100907).
