آب وهواشناسي آب بارش پذير درسرزمين عراق

All condensed water in a column of the atmosphere that can rain is called precipitable water. Knowing the amount of precipitable water in the atmosphere is very important for predicting the amount of rainfall. The purpose of this research is to analyze the tempo spatial of precipitable water in the Iraq.For this purpose, the data of precipitable water for the period of 1979 to 2022 for 44 years was extracted from the website of the National Center for Atmospheric Prediction of the United States (NCEP/DOE).The process of data preparation was done with two approaches of temporal analysis and spatial analysis in four time frames: hourly, daily, monthly and yearly.In order to eva‎luate temporal and spatial trends, linear regression trend tests and the Mann-Kendall test using the Senʹs slope estimator method were used.In addition to the trend test, frequency analysis was also used to identify time changes.For the regionalization of Iraq by precipitable water, a hierarchical cluster analysis method and Wardʹs method was used.The annual average of precipitable water in Iraq is about 14 mm, which has decreased over a period of 44 years, but it is not statistically significant.The monthly regime of precipitable water follows the temperature regime so that it decreases in the cold period of the year and increases in the warm period of the year.The eva‎luation of the monthly trend showed that the slope of the trend line is negative in all months and it indicates the existence of a slight decreasing trend in some months.But only the decreasing trend for the two months of January and April is significant at the 90% level.The temporal changes of precipitable water during different hours of the day and night follow a similar pattern and its regime is similar to the monthly regime.Investigations showed that from November to May, for seven months, the amount of precipitable water during the day is more than during the night.While in the warm months of the year from June to October, this difference is reduced and even in July and August, the amount of precipitable water at night is more than the amount of precipitable water that during the day.The amount of precipitable water in Iraq increases from the northeast to the south.But in the months of June to September, the curves take an east-west arrangement and the precipitable water decreases from west to east.The spatial distribution map of annual precipitable water trends showed that decreasing trends are observed in the north of the 32 degree latitude.Examining the decadal changes in the abundance of precipitable water showed that the precipitable water decreased in the third decade compared to the first decade and moved to lower value.While in the fourth decade, the distribution of the abundance of precipitable water has shifted to the right and towards higher amounts of precipitable water.The pattern of temporal changes of precipitable water in Iraq includes four time periods: the period of minimum (January, February and December), the period of maximum (July and August), the period of transitional (March and November) and the period of intermediate (April, May, June, September and October).The spatial distribution pattern of precipitable water in Iraq can be divided into four areas.The Euphrates River is the boundary between the minimum and maximum precipitable water areas in Iraq.The difference in the amounts of precipitable water between the four sub-regions increases in the cold period and decreases in the warm period, especially in May, June and July.

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