String based sea ice mass balance array (SIMBA) buoy is a good data source to figure out the temporal variations of sea ice freeboard or thickness over the polar oceans. In particular, SIMBA buoys operated as a part of MOSAiC expedition provide relatively homogeneous measurements of snow depth and ice thickness nearby MOSAiC distributed regional network. Therefore, by using 10 SIMBA buoys from MOSAiC expedition, we assess the ability of CryoSat-2 and ICESat-2 in estimating the temporal variations of the sea ice freeboard over the freezing season. We first calculate the ice freeboard and total freeboard at each SIMBA buoy from the temperature profiles of the buoy. Then the mean, median, and lognormal mode of the CryoSat-2 ice freeboard and ICESat-2 total freeboard are calculated within 20 km buffer from the buoy. CryoSat-2 ice freeboard shows a good correspondence with the buoy ice freeboard: increase rate of ~2 cm/month, correlation coefficient (R) greater than 0.7 (P < 0.001), and RMSE of 3-4 cm. Meanwhile, ICESat-2 also shows a significant correlation: increase rate of 2-4 cm/month, R > 0.7, and RMSE of 8-12 cm. CryoSat-2 generally overestimates the ice freeboard and the lognormal estimations show the least biases. On the contrary, ICESat-2 underestimates the total freeboard and the mean estimations show the least biases. This result should be associated with various sources of uncertainties: formation of snow ice at the buoys, variations of snow/ice density, freeboard retrieval algorithms of the satellite altimeters, and spatial/temporal variations between buoy and satellite data.