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<p>This study emulates dropsondes to elucidate the extent to which sporadic airborne sondes adequately represent divergence of moisture transport in Arctic atmospheric rivers (ARs). The convergence of vertically integrated moisture transport (<span class="inline-formula">IVT</span>) plays a crucial role as it favours precipitation that significantly affects Arctic sea ice properties. Long-range research aircraft can transect ARs and drop sondes to determine their <span class="inline-formula">IVT</span> divergence. In order to assess the representativeness of future sonde-based <span class="inline-formula">IVT</span> divergence in Arctic ARs, we disentangle the sonde-based deviations from an ideal instantaneous <span class="inline-formula">IVT</span> divergence, which result from undersampling by a limited number of sondes and from the flight duration.</p> <p>Our synthetic study uses C3S Arctic Regional Reanalysis (CARRA) reanalyses to set up an idealised scenario for airborne AR observations. For nine Arctic spring ARs, we mimic flights transecting each AR in CARRA and emulate sonde-based <span class="inline-formula">IVT</span> representation by picking single vertical profiles. The emulation quantifies <span class="inline-formula">IVT</span> divergence observability by two approaches. First, sonde-based <span class="inline-formula">IVT</span> and its divergence are compared to the continuous <span class="inline-formula">IVT</span> interpolated onto the flight cross-section. The comparison specifies uncertainties of discrete sonde-based <span class="inline-formula">IVT</span> variability and divergence. Second, we determine how temporal AR evolution affects <span class="inline-formula">IVT</span> divergence values by contrasting time-propagating sonde-based values with the divergence based on instantaneous snapshots.</p> <p>For our Arctic AR cross-sections, we find that coherent wind and moisture variabilities contribute less than 10 % to the total transport. Both quantities are uncorrelated to a great extent. Moisture turns out to be the more variable quantity. We show that sounding spacing greater than 100 km results in errors greater than 10 % of the total <span class="inline-formula">IVT</span> along AR cross-sections. For <span class="inline-formula">IVT</span> divergence, the Arctic ARs exhibit similar differences in moisture advection and mass convergence across the embedded front as mid-latitude ARs, but we identify moisture advection as being dominant. Overall, we confirm the observability of <span class="inline-formula">IVT</span> divergence with an uncertainty of around 25 %–50 % using a sequence of at least seven sondes per cross-section. Rather than sonde undersampling, it is the temporal AR evolution over the flight duration that leads to high deviations in divergence components. In order to realise the estimation of <span class="inline-formula">IVT</span> divergence from dropsondes, flight planning should consider not only the sonde positioning, but also the minimisation of the flight duration. Our benchmarks quantify sonde-based uncertainties as essential preparatory work for the upcoming airborne closure of the moisture budget in Arctic ARs.</p>