Torrential Rain in Central Karakorum, 9-10 September 1992:

Simulations With the WRF Model

A. Parodi (1), J. von Hardenberg (2), A. Provenzale (2), F. Viterbo (1)

(1) CIMA Research Foundation, Savona, Italy, (2) Istituto di Scienze dell’Atmosfera e del Clima (ISAC), Consiglio Nazionale delle

Ricerche, Torino, Italy

The case study:The case study:

Severe Rains in Central Karakoram, 9-10 September 1992Severe Rains in Central Karakoram, 9-10 September 1992

ImpactsImpacts

Torrential Rains in Central Karakoram, 9-10 September 1992. Geomorphological Impacts and Implications for Climatic, Kenneth Hewitt, Mountain Research and Development, Vol. 13, No. 4 (Nov., 1993), pp. 371-375.

WRF model 3.3.1 which is a fully compressible, nonhydrostatic, scalar variable-conservings, mesoscale model.

Two domains, two-way nesting (IC and BC from ERA-Interim, 08-12 september 1992):

Vertical domain size: until to 20 km [~ 60 m near the bottom boundary, ~ 600m near the top one]

Initial and boundary conditions: ERA-Interim

Turbulent parameterization: Mesoscale 1D, Yonsei University (YSU) Planetary boundary layer scheme

Convection parameterization: Kain-Fritsch scheme

Microphysical parameterizations: WSM 6-class scheme and Thompson scheme

NUMERICAL MODEL SETTING NUMERICAL MODEL SETTING

d01: x =y = 15 km

d02: x =y = 5 km

Cumulus parameterizationCumulus parameterization

Microphysics parameterization:Microphysics parameterization:

9 September 1992:9 September 1992:

Observed vs predicted (d02, cu1, mp6) daily rainfall depthObserved vs predicted (d02, cu1, mp6) daily rainfall depth

9 September 1992:9 September 1992:

Observed vs predicted (d02, cu2, mp6) daily rainfall depthObserved vs predicted (d02, cu2, mp6) daily rainfall depth

9 September 1992:9 September 1992:

Observed vs predicted (d02, cu1, mp8) daily rainfall depthObserved vs predicted (d02, cu1, mp8) daily rainfall depth

9 September 1992:9 September 1992:

Observed vs predicted (d02, cu2, mp8) daily rainfall depthObserved vs predicted (d02, cu2, mp8) daily rainfall depth

10 September 1992:10 September 1992:

Observed vs predicted (d02, cu1, mp6) daily rainfall depthObserved vs predicted (d02, cu1, mp6) daily rainfall depth

10 September 1992:10 September 1992:

Observed vs predicted (d02, cu2, mp6) daily rainfall depthObserved vs predicted (d02, cu2, mp6) daily rainfall depth

10 September 1992:10 September 1992:

Observed vs predicted (d02, cu1, mp8) daily rainfall depthObserved vs predicted (d02, cu1, mp8) daily rainfall depth

10 September 1992:10 September 1992:

Observed vs predicted (d02, cu2, mp8) daily rainfall depthObserved vs predicted (d02, cu2, mp8) daily rainfall depth

Initial conditions uncertainty: water vapor columnar Initial conditions uncertainty: water vapor columnar content, content, 8 september 19928 september 1992

Observed vs predicted: water vapor columnar content, Observed vs predicted: water vapor columnar content,

8 - 11 september 1992 (cu2, mp6, 5 km)8 - 11 september 1992 (cu2, mp6, 5 km)

Other observational data: radiosoundingsOther observational data: radiosoundings

H_DIABATIC cross section (lon=72.9, d02, cu2, mp6):H_DIABATIC cross section (lon=72.9, d02, cu2, mp6):

9 september 1992, 15 UTC9 september 1992, 15 UTC

W cross section (lon=72.9, d02, cu2, mp6):W cross section (lon=72.9, d02, cu2, mp6):

9 september 1992, 15 UTC9 september 1992, 15 UTC

We are thinking about adding d03 at 1 km, upper limit of the so-called cloud-permitting range:

•Most of the assumptions of radiative schemes are breaking-down at this resolution over such very complex-orography regions;

•1 km is also the “gate” for the “terra-incognita” region for the turbulence closure: unclear if we may want to use 1D or 3D/LES approaches

•But certainly at 1 km over complex orography the 1D closure scheme fails

•Serious impact on the computing time step!

Single-event case, next steps: finer resolutions?Single-event case, next steps: finer resolutions?

1 km vs 5 km: Karakorum area1 km vs 5 km: Karakorum area

STATION Local (m)

Moving to seasonal-scale simulationsMoving to seasonal-scale simulations

The goal of the project is to characterize the precipitation climatology and potential hydrologic impacts in these areas at very high spatial resolution (up to about 4 Km, corresponding to the “cloud-permitting” range, representing a leading-edge limit for climate change research), for three future time-slices in the periods 2046-2050, 2071-2075 and 2096-2100.We will characterize changes in the amplitude of the probability distribution of precipitation intensities, of the length of dry periods and of the duration of precipitation events. In particular in the framework of the project we will characterize changes in the amplitude probability distribution of precipitation intensities, of the length of dry periods and of the duration of precipitation events.

Thanks