Temporal and spatial variation of the zenith tropospheric delay : case study of Egyptian territory

الملخص EN

Space geodesy techniques can determine baseline lengths up to 1000km with accuracy better than 10-8.

However, mismodeling of the tropospheric delay experienced through the electrically neutral atmosphere is a serious error source.

This propagation delay can be divided into two parts according to their origins.

The first is hydrostatic (dry) and the second is the wet delay.

Both the dry and wet delay can be described as a product of the delay at the zenith and a mapping function Dry delay is in the range of 2.2-2.4 meters at the zenith and constitutes about 90% of the total tropospheric delay.

The current paper studies the temporal and spatial variation of the dry delay in the Egyptian territory.

To study this phenomenon, ray tracing based on MSIS dry model is used at nine well distributed sites over Egypt for one year.

It was found that Aswan shows the minimum value of zenith dry delay with a value of 2.24 meters.

The zenith dry delay varies through the year, such that it assumes its minimum value during spring and autumn months, especially April and May.

The maximum value of the zenith dry delay happens during summer months, especially June and July.