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Downscaling an intense precipitation event in complex terrain: the importance of high grid resolution Cover

Downscaling an intense precipitation event in complex terrain: the importance of high grid resolution

Tellus
Volume 69 (2017): Issue 1
By: ,  ,   and    
Open Access
|Jan 2017
Figures & tables

Figures & Tables

Table 1.

Overview of the locations for the HOBO rain gauges (P1–P12) and the meteorological stations (denoted by their national code)

IdentityNameLatitudeLongitudeAltitudeP1Hagavik60.176 ◦ N5.403 ◦ E48 mP2Nesttun60.319 ◦ N5.373 ◦ E58 mP3Hisdalen60.397 ◦ N5.690 ◦ E140 mP4Dale60.590 ◦ N5.829 ◦ E91 mP5Kaldestad60.554 ◦ N6.018 ◦ E521 mP7Steine60.667 ◦ N6.200 ◦ E485 mP8Sandfjellet60.607 ◦ N6.212 ◦ E620 mP9Hodnaberg60.561 ◦ N6.214 ◦ E618 mP10Dyrvedalen60.653 ◦ N6.335 ◦ E355 mP11Flyane60.602 ◦ N6.319 ◦ E436 mP12Vasslii, Voss60.645 ◦ N6.445 ◦ E79 m25830Finsevatn60.592 ◦ N7.524 ◦ E1210 m29400Sandhaug60.183 ◦ N7.481 ◦ E1250 m46430Røldalsfjellet59.832 ◦ N6.733 ◦ E1010 m46450Røldal59.830 ◦ N6.824 ◦ E393 m47450Straumøy59.653 ◦ N5.434 ◦ E36 m47500Etne59.665 ◦ N5.966 ◦ E35 m47600Litledal59.664 ◦ N6.066 ◦ E83 m47610Kritle59.636 ◦ N6.087 ◦ E568 m47820Eikemo59.859 ◦ N6.279 ◦ E178 m47890Opstveit59.858 ◦ N6.017 ◦ E38 m48450Husnes59.864 ◦ N5.770 ◦ E13 m48500Rosendal59.991 ◦ N6.026 ◦ E75 m48780Mauranger60.132 ◦ N6.331 ◦ E33 m49080Øvre Krossdalen60.280 ◦ N6.386 ◦ E342 m49490Ullensvang60.319 ◦ N6.654 ◦ E12 m49631Eidfjord II60.465 ◦ N7.069 ◦ E20 m49800Fet, Eidfjord60.409 ◦ N7.280 ◦ E735 m50070Kvamsøy60.358 ◦ N6.275 ◦ E49 m50080Øystese60.379 ◦ N6.193 ◦ E108 m50110Aksneset, Kvam60.336 ◦ N6.218 ◦ E13 m50120Skulafossen60.275 ◦ N6.039 ◦ E16 m50150Hatlestrand60.042 ◦ N5.906 ◦ E45 m50175Austevoll60.017 ◦ N5.206 ◦ E32 m50310Jonshøgdi60.389 ◦ N5.964 ◦ E455 m50450Stend60.273 ◦ N5.331 ◦ E54 m50480Sandsli60.292 ◦ N5.280 ◦ E45 m50540Florida60.383 ◦ N5.333 ◦ E12 m51010Fossmark60.521 ◦ N5.724 ◦ E10 m51250Øvstedal60.688 ◦ N5.965 ◦ E316 m51440Evanger60.647 ◦ N6.111 ◦ E17 m51470Bulken60.646 ◦ N6.222 ◦ E328 m51530Vossevangen60.625 ◦ N6.426 ◦ E54 m51800Mjølfjell60.702 ◦ N6.937 ◦ E695 m51990Myrkdalen60.866 ◦ N6.473 ◦ E700 m52170Eksingedal60.803 ◦ N6.147 ◦ E450 m52220Gullbrå60.829 ◦ N6.265 ◦ E579 m52310Modalen III60.856 ◦ N5.973 ◦ E125 m52400Eikanger60.623 ◦ N5.381 ◦ E72 m52475Blomvåg60.531 ◦ N4.893 ◦ E30 m52601Haukeland60.835 ◦ N5.583 ◦ E325 m52750Frøyset60.846 ◦ N5.211 ◦ E13 m53160Jordalen60.900 ◦ N6.724 ◦ E614 m53530Midtstova60.656 ◦ N7.276 ◦ E1162 m
Fig. 1.

Map of the experiment area with altitude from the terrain database ASTER GDEM v1 (Tachikawa et al., 2011) contoured in colours. The deployed rain gauges are colour coded and the stations P1–P12 correspond to the line colours in Fig. 5. Black squares are the stations M1–M3 referenced in the text, triangles are the remaining precipitation stations in the area operated by the Norwegian Meteorological Institute (MET Norway). The red line shows the lower edge of the cross sections analysed in Section 3.4.

Fig. 2.

Model domain set up for the WRF simulations. The domains d01, d02 and d03 have horizontal grid resolutions of 9 km, 3 km and 1 km, respectively.

Table 2.

Overview of the physical parametrisation schemes used in the WRF simulations

Category of physicsParametrisation schemesMicrophysicsThompson (Thompson et al., 2004; 2008)Short wave radiationDudhia shortwave (Dudhia, 1989)Long wave radiationRRTM longwave (Mlawer et al., 1997)Planetary boundary layerMYJ (Janjić, 2000)Land surface modelNOAH LSM (Chen and Dudhia, 2001)Cumulus (d01)Kain Fritsch (Kain, 2004)Cumulus (d02 and d03)None
Fig. 3.

Surface analysis chart from UK Meteorological Office, for 28 October 2014 00 UTC. Reproduced with kind permission of the Met Office.

Fig. 4.

Specific humidity (g kg −1) at 850 hPa at 00 UTC on 28 October (coloured contours) and the 850 hPa wind (arrows). Data from the ERA-Interim reanalysis.

Fig. 5.

The observed (a) and simulated (b) accumulated precipitation amounts during the days before the flooding event, from 25 October 06 UTC to 29 October 2014 06 UTC. The observations of the HOBO rain gauges are given as solid coloured lines and the corresponding results from the interpolated 1 km model simulations as dashed lines. Data from the MET Norway stations are indicated by the black diamonds.

Fig. 6.

Comparison of four-day accumulated precipitation from 25 October 06 UTC till 29 October 06 UTC from the WRF 9 km, 3 km and 1 km model output, using the interpolated grid point, and the observations. There is one set of bars for each station and the labels on the horizontal axis show the station id.

Fig. 7.

A Taylor diagram with the 9 km, 3 km and 1 km simulations marked as circles and the observations marked as a black star for reference.

Fig. 8.

Cross sections (above the red line in Fig. 1) of vertical velocities (a–c) with potential temperature contoured in black lines, specific humidity (d–f), liquid water content (g–i) and the sum of liquid and ice water content (j–l) from the 1 km resolution run, at three selected times: 26/18, 27/06 and 28/06 (in the left, middle and right column, respectively).

Fig. 9.

Cross sections (above the red line in Fig. 1) of vertical velocities (a–c), specific humidity (d–f), liquid water content (g–i) and the sum of liquid and ice water content (j–l) at time 28/06 for the 9 km, 3 km and 1 km runs (in the left, middle and right column, respectively.

Fig. 10.

Accumulated precipitation (25/06–29/06 October) in part of the 9 km grid (a). The circles correspond to the HOBO stations, squares are stations from MET Norway. The inner parts of the markers show the observed accumulated precipitation amounts in the period. The other panels show the same for part of the 3 km domain in (b) and for the 1 km domain in (c).

Fig. 11.

The upper panel (a) shows the variance spectrum of the terrain and the specific humidity cross sections (pressure level 850 hPa) shown in Fig. 8 from the 1 km simulations. The middle panel (b) shows the same from the 3 km simulation, and the lower panel (c) for the 9 km simulation.

DOI: https://doi.org/10.1080/16000870.2016.1271561 | Journal eISSN: 3035-9554
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Language: English
Page range: 1271561 - 1271561
Submitted on: Mar 14, 2016
Accepted on: Nov 21, 2016
Published on: Jan 1, 2017
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services
Keywords:
WRF,
resolution,
dynamical downscaling,
extreme precipitation,
flooding,
complex terrain

© 2017 Marie Pontoppidan, Joachim Reuder, Stephanie Mayer, Erik W. Kolstad, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

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