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Spatial contribution of one-day precipitations variability to rainy days and rainfall amounts in Iran
Nazaripour, H. & Mansouri Daneshvar, M R.
Abstract
Rainfalls with short persistency are the tangible
characteristics of arid and semiarid regions such as
Iran. Iran is an arid and semiarid region with dramatic
tempo-spatial changes of rainfall. In this regard, the short
persistency of rainfall is approximately observed from 1 to
7 days in whole parts, while the greater ones are only
separated in eastern parts of Iran. According to the results,
the rainfall persistency is ranged from 1 to 45 days, but the
maximum amount and rainy days are generated by rainfalls
with short persistency. So, the rainfall events with long
persistency are considered as an extreme event with
extreme variability. One-day precipitations generate the
maximum rainy days and rainfall amounts, especially in
eastern parts of Iran. Decrease in the one-day precipitations
contribution to eastern parts may indicate to decrease in
regional precipitation. However, decrease in contribution
in western parts may indicate to increased amounts of
rainfall at other persistency rates. Our results revealed that
the contribution of the one-day precipitation to general
rainfall has reductive trends in almost 17.5 % of the whole
Iran. The most integrated and significant reductive trend of
one-day precipitation contribution to rainfall spreads
northeastern and eastern parts of Iran. However, in the
western parts of Iran, decreasing one-day precipitation
contribution to rainy days affects to increase in the diurnal
rainfall. The mentioned variability can be considered as the
climate change signals in respect of one-day precipitation.
Keywords
One-day precipitations; Persistency; Rainfall amounts; Spatial contribution; Trend analysis
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