1:45 PM - 3:15 PM
[MIS01-P07] Atmospheric and atmospheric-soil hydrothermal extremes
Keywords:atmospheric droughts, atmospheric-soil droughts, extremes, Ped drought index
Study of extreme natural events is actual in the period of modern climatic changes. Droughts and moistening periods are among such events. They bring enormous damage to crop yields in vast areas of the world. Therefore, it is no coincidence that the problem of studying droughts is one of the most important problems in climatology. Until now, there is no generally recognized objective definition of drought. There are many indices for calculating of hydrothermal extremes. , Dmitri Antonovich Ped proposed a drought index S to describe droughts, which takes into account the abnormal weather conditions most important for the formation of drought, such as anomalies in air temperature, precipitation and soil moisture:
S = ΔT/σT - ΔR/σR - ΔE/σE, where ΔT, ΔR, ΔE are the difference between the value for a particular year and the long-term average of temperature, precipitation, and soil moisture, respectively; σT, σR, σE are standard deviations.
The full formula reflects the atmospheric-soil drought (STRE) most dangerous for agriculture. The first two terms from the formula describe only atmospheric drought (STR), and the third term describes the soil drought (SE).
Modern scientific papers usually analyze only an atmospheric drought events. At the same time they study the influence of atmospheric droughts on vegetation productivity, crop yields, etc. But it is not quite correct, because soil moisture conditions is more important for vegetation than atmospheric moisture. The main aim of the present study is to compare the coincidence of identified atmospheric and atmospheric-soil droughts and moistening periods.
Initial data are long-term time series of monthly air temperature and precipitation from weather station Tomsk (Russia) for some months of the warm period (April-October) from 1966 to 2018 (www.meteo.ru). Information on reserves of productive moisture in one meter layer of soil (ten-day values for April-October) refers to agricultural areas near Tomsk.
Calculation results confirm synchronous changes of STRE and STR indices (correlation coefficients for individual months are 0.88-0.92). Further, the years with different intensity of events for atmospheric and atmospheric-soil droughts/periods of overmoistening were considered. In most cases, coincidence of events by STRE and STR values at different intensities was observed. Among the atmospheric events, only one case of extreme intensity (overmoistening) was recorded. Whereas 10 cases of extreme drought and 7 cases of extreme overmoistening were identified in the calculation of atmospheric-soil events. Analysis of the regime of atmospheric-soil extreme events made it possible to identify the years in which three or more consecutive months of droughts. There were 11 of them for the whole study period (1966 - 2018). At the same time, there were only 5 years with prolonged overmoistening period. During the study period, the number and intensity of atmospheric droughts generally increased, while the number of soil droughts decreased. This indicates that despite the decrease in precipitation and increase in monthly temperatures, qualitative reclamation measures to increase moisture content in the soil are carried out.
We compared STRE and STR indices with grain and legume crop yields for 2000-2018 for Tomsk region. A negative correlation at the beginning of the growing season and a positive correlation in August were obtained. This corresponds to an increase in yield with sufficient moisture in the spring and relatively dry conditions at the end of the growing season. However, in most cases, correlation coefficients are not statistically significant. Acknowledgements: project FWRG-2021-0004.
S = ΔT/σT - ΔR/σR - ΔE/σE, where ΔT, ΔR, ΔE are the difference between the value for a particular year and the long-term average of temperature, precipitation, and soil moisture, respectively; σT, σR, σE are standard deviations.
The full formula reflects the atmospheric-soil drought (STRE) most dangerous for agriculture. The first two terms from the formula describe only atmospheric drought (STR), and the third term describes the soil drought (SE).
Modern scientific papers usually analyze only an atmospheric drought events. At the same time they study the influence of atmospheric droughts on vegetation productivity, crop yields, etc. But it is not quite correct, because soil moisture conditions is more important for vegetation than atmospheric moisture. The main aim of the present study is to compare the coincidence of identified atmospheric and atmospheric-soil droughts and moistening periods.
Initial data are long-term time series of monthly air temperature and precipitation from weather station Tomsk (Russia) for some months of the warm period (April-October) from 1966 to 2018 (www.meteo.ru). Information on reserves of productive moisture in one meter layer of soil (ten-day values for April-October) refers to agricultural areas near Tomsk.
Calculation results confirm synchronous changes of STRE and STR indices (correlation coefficients for individual months are 0.88-0.92). Further, the years with different intensity of events for atmospheric and atmospheric-soil droughts/periods of overmoistening were considered. In most cases, coincidence of events by STRE and STR values at different intensities was observed. Among the atmospheric events, only one case of extreme intensity (overmoistening) was recorded. Whereas 10 cases of extreme drought and 7 cases of extreme overmoistening were identified in the calculation of atmospheric-soil events. Analysis of the regime of atmospheric-soil extreme events made it possible to identify the years in which three or more consecutive months of droughts. There were 11 of them for the whole study period (1966 - 2018). At the same time, there were only 5 years with prolonged overmoistening period. During the study period, the number and intensity of atmospheric droughts generally increased, while the number of soil droughts decreased. This indicates that despite the decrease in precipitation and increase in monthly temperatures, qualitative reclamation measures to increase moisture content in the soil are carried out.
We compared STRE and STR indices with grain and legume crop yields for 2000-2018 for Tomsk region. A negative correlation at the beginning of the growing season and a positive correlation in August were obtained. This corresponds to an increase in yield with sufficient moisture in the spring and relatively dry conditions at the end of the growing season. However, in most cases, correlation coefficients are not statistically significant. Acknowledgements: project FWRG-2021-0004.