Towards a drought early warning system based on a combination of satellite and in situ soil moisture measurements
Climate models predict a combined trend of higher average temperatures and less summer precipitation in the Carpathian Basin. This results in extra vulnerability of the region to droughts. Decreasing soil moisture is a crucial indicator for drought and therefore it is important to develop an operational system that can continuously monitor soil moisture over larger areas.
Currently a framework is being developed that uses a combination of in situ measurements of soil moisture and satellite based soil moisture measurements. The satellite derived daily measurements are calculated using the so-called LST/VI triangle method which is based on land surface temperature and vegetation index data, and provide only information on the soil moisture distribution within the region. This information is relative, which means that soil moisture values at the same location but at consecutive days cannot be compared to each other. The in situ measurements are accurate point measurements taken at a very high temporal interval, but only at a distinct number of locations. Using these point measurements to calibrate the satellite measurements results in spatially continuous daily comparable soil moisture measurements over a large area. These measurements are used to create a database which shows the trend of the development of soil moisture in the study region. Combined with meteorological (e.g. rainfall, potential evapotranspiration) and other data (climate and soil type), this information is essential to predict agricultural drought in the near future.