P92 WRF absolute humidity profile simulations: Sensitivity studies and comparisons against scanning water vapor DIAL measurements

Milovac, Jospia, Florian Späth, Kirsten Warrach-Sagi, Andreas Behrendt, Volker Wulfmeyer, Thomas Schwitalla, University of Hohenheim

In this case study WRF model is utilized to examine the sensitivity of absolute humidity profile simulations to boundary-layer (BL) and land-surface (LS) parameterization options available within the model. Simulations were run using four different BL schemes, and two LS schemes at convection-permitting scales over Germany. The results are compared against available water vapor measurements performed with the differential absorption lidar (DIAL). Comparing to single radiosonde profiles, DIAL provides continuous data set in higher resolution, which allows better distinction of the structures within the BL and the lower troposphere. The results show that BL schemes and LS schemes have great impacts on the simulated absolute humidity profiles. However, the model appears to be much more sensitive to LS schemes than to BL schemes; moreover, this is not only the case for the lower, but also for the upper BL often including the whole of the lower troposphere. Furthermore, we found Mellor-Yamad-Janic (MYJ) scheme to be more sensitive to the LS scheme choices than the other three BL options deployed. Also, regarding the structure of the simulated BL flow, MYJ exhibits different performance comparing to the other BL schemes, esspecially in the residual layer and in the entrainment zone.