NUMERICAL MODELING OF
POLAR LOWS OVER THE
BARENTS SEA: IMPACT OF
WRF PARAMETRIZATIONS ON
THE QUALITY OF FORECASTRUSSIAN STATE HYDROMETEOROLOGICAL UNIVERSITY

Antonina Polezhayeva

• Over Arctic seas
• From October to May• Short-lived (less 48 hours)• Showers, heavy snow
• Strong winds 18,5–23,5 m/s (35m/s)• Travelling speed of the low ≈ 50–70 (90)km/h

• The problem of forecasting polar low in theirearly stage.
The aims:- to improve polar lows forecast;-to adapt the WRF model for the Barents Sea region-to conduct numerical experiments using WRF model with different

schemes• We used data from AQUA and GCOM-W1 satellites for identification polar lows;• We investigated of the ability of mesoscale numerical WRF model to successfully
simulate evolution;• We tested various WRF schemes to chose valid parameterization for future simulation.

The low under study was over Barents Sea from 1100 UTC 24 March to1400 UTC 25 March 2014.
Integration period0000 UTC 24.03.14 –0000 UTC 26.03.14

integration domain

20⁰ E-26⁰ E
74⁰N-80⁰N.

Projection

Polar stereographic

Spatial step

10 000 m (10 km)

Horizontal gridpoints

120×120

Vertical levels

35

Initial conditions

the reanalysis data ofNCEP FNL (NCAR)AMSR-E, AMSR2Time step

60 seconds

Boundary updating

3 hours

1100 UTC 24 March 1400 UTC 25 March 2014.

11:10 24 March 2014 MODIS

1100 UTC 24 March 1400 UTC 25 March 2014.

05:20 25 March 2014 MODIS

( Eduard I. Lutsenko )•The formation of deep convection in cool air.

•The formation of polar lows occurring preferably in cold air outbreaks, which advect
polar air over relatively warm open oceans with high sea surface temperatures.

•Air-water temperature difference must be about 20⁰.

•The formation of the baroclinic zone along the ice edge or in the cold air flow.

•Polar lows often develop within or close to the field of especially enhanced open-celledcumulonimbus.

•

The presence of latent heat fluxes.

•

The moving cold cyclonic core at 500 hPa over low-level features (negative airtemperature
anomaly in the upper troposphere).

•

When an upper-level jet stream reaches the region of developing polar low.

•

The presence of cyclonic vorticity of the large-scale flow.

We tested various parametrizations within the WRF model. Schemes ofPlanetary Boundary Layer affected the forecast significantly. The mostaccurate schemes revealed were the Yonsei University scheme andthe Mellor-Yamada-Janjic scheme.
1100 UTC 24 March 1400 UTC 25 March 2014.

Yonsei University scheme

Mellor-Yamada-Janjic scheme

Difference between schemes

05:20 25 March 2014, MODISWe compared the Yonsei University scheme and the Mellor-Yamada-Janjic
scheme in water vapor fields. Sufficient difference is in the frontal
moisture location.
1100 UTC 24 March 1400 UTC 25 March 2014.

Yonsei University scheme

Mellor-Yamada-Janjic scheme

Comparison of schemes

05:20 25 March 2014, MODIS

Convection parameter is important. If we compare index CAPE of the twoschemes, the Yonsei University scheme shows more accurate results.
1100 UTC 24 March 1400 UTC 25 March 2014.

Yonsei University scheme

Mellor-Yamada-Janjic scheme

Comparison of schemes

05:20 25 March 2014, MODIS• The main predictors for polar low forecasting are:temperature gradient, latent heat fluxes andconvection.
• The Yonsei University scheme appeared to be themost accurate and suitable for parametrization.

THANKS FOR ATTENTION!