EMD-WRF On-Demand ICING

NOTE: This dataset and service is currently being integrated with windPRO 3.6 (beta). Please contact our technical specialist Marie Cecilie Pedersen (mcp@emd.dk) for more information and achedule. We will be attending winterwind 2022 in Skellefteå, Sweden, so you are also welcome to meet with us at that event.

Introduction

EMD-WRF OD ICING is the name of EMD’s icing model. The model is driven by an icing configuration of the standard EMD WRF [1] On-Demand service [2]. The model is run with a spatial resolution of 3x3 km with an hourly temporal resolution and using the ERA-5 reanalysis data from ECMWF as global boundary data [3]. The Thompson microphysics scheme is used for parameterization of the cloud physics and the MYJ scheme for the planetary boundary layer physics [4], [5]. The median volume diameter (MVD) by [6] is used, with a constant droplet concentration (Nc) of (default) 100 cm-3 and the liquid water content (LWC) in kg/m3 [7]. The atmospheric data feeds into the standard cylinder-based model [8], [9] including melting and shedding [10]. The WRF grid point (latitude, longitude) closest to the at mast location or site location is used as a default. The grid point holds a certain elevation above sea level and icing is modelled as a default for 15 heights in the vertical direction above ground level (agl.).

The modelled ice load (kg) is used to identify hours of instrumental icing based on the industry standard thresholds of 10 g [11]. And similar from the modelled ice accretion rate (g/h), hours of meteorological icing [12] is found using the threshold of 10 g/h [9]. The final step of EMD’s modelling chain, is an estimate of the expected production loss of a site which is found by using the IEA Ice Classification system seen in Table 1.

TABLE HERE

The complete list of parameters are seen in the Table 2 further below.

The EMD-WRF OD ICING is available as a time-series product, please see more here: Time-Series - On-Demand.
Please also see the technical note and results from recent validation study on EMD-WRF OD ICING for more information. (add link to note)

How to order?

To get pointwise-timeseries data, you need meso-credits (one credit is worth one month of data). Credits can be ordered here: http://www.emd.dk/windpro/online-ordering/ Please note, that a time period of 10 years will include the complete icing analysis, whereas shorter time periods include only raw timeseries. Complete icing analysis includes:

• Icing reports as pdfs at three hub-heights - 100m, 150m and 200m
  • Including predicted AEP loss
• Icing maps at three hub-heights - 100m, 150m and 200m
  • IEA ice class, IEA Ice loss (% AEP) and modelled meteorological icing (icing rate > 10 g/h)
• The possibility to use your icing results and timeseries directly in your windPRO project
• Monthly, yearly and seasonal icing analysis and bin-sector analysis as csv-files
• Timeseries of raw WRF data and modelled icing

Data Availability

All EMD-WRF OD ICING is available with global spatial coverage. The temporal availability and update frequency depends on a number of factors such as availability from the boundary data providers, bandwidth and download times, as well as availability on EMD high-performance computing and storage systems. EMD-WRF OD ICING is availability with the ERA5 only, see table below.

Dataset	First date	Most recent date
EMD-WRF OD (ERA5)	1999.01.01	2-3 months from present day

Set of Standard Dataset Parameters for Icing

A large quantity of useful parameters are available directly in WindPRO to aid in your analysis.
The different parameters in each On-Demand ICING dataset is shown in the list below.

Table: Overview of Standard EMD-WRF On-Demand Dataset Parameters (3 km grid).

Parameter	Unit	Description	Type
time		UTC time stamp
psfc	Pa	Pressure at site	Instantaneous
msl	Pa	Pressure at mean sea level	Instantaneous
wSpeed.x	m/s	Wind speeds at different physical levels (x). Heights for EMD-WRF OD (x): 10m, 25m, 50m, 75m, 100m, 150m, 200m Heights for EMD-WRF Custom Area (x): 10m, 25m, 50m, 75m, 100m, 150m, 200m, 300m, 400m, 500m, 600m, 1000m, 4000m	Instantaneous
wDir.x	deg	Wind speeds at different physical levels (x). Heights for EMD-WRF OD (x): 10m, 25m, 50m, 75m, 100m, 150m, 200m Heights for EMD-WRF Custom Area (x): 10m, 25m, 50m, 75m, 100m, 150m, 200m, 300m, 400m, 500m, 600m, 1000m, 4000m	Instantaneous
wSpeed.0-30mb	m/s	Wind speeds at pressure level 0-30mb.	Instantaneous
wDir.0-30mb	deg	Wind speeds at pressure levels 0-30mb.	Instantaneous
wSpeed.850hpa	m/s	Wind speeds at pressure level 850hPa.	Instantaneous
wDir.850hpa	deg	Wind speeds at pressure levels 850hPa.	Instantaneous
temperature.x	celcius	Temperatures at different heights (x) Heights (x): 2m and 100m	Instantaneous
waterTemp	celcius	Water temperature	Instantaneous
soilTemp.0-10cm	celcius	The temperature in the upper 10 cm of the soil	Instantaneous
relHumidity.2	%	Relative humidity in height 2m above ground level	Instantaneous
snowDepth	m	Snow depth (if present)	Instantaneous
vis.s	m	Visibility at surface	Instantaneous
sensHeatFlux.s	w/m2	Sensible Heat Flux at surface	Instantaneous
totPrecip.s	kg/m^2	Total Precipitation at surface	1h Accumulated
downShortWaveFlux.s	w/m2	Downward shortwave irradiance at surface	1h Average
totalCloudCover.a	%	Total cloud cover in atmosphere	1h Average
convCloudCover.a	%	Convective cloud cover in atmosphere	1h Average
Data below this line are not shown in a default import of EMD-WRF On-Demand data, but can be made available by clicking on the "+" button in the lower left corner of the import table.
4LFTX	K	N/A
rmol	1/m	Inverse Monin-Obukhov-Length
znt	m	Rougnhess length
sqrtTKE.x	m/s	Wind speed given as standard deviation in m/s. Derived from the turbulent kinetic energy (TKE). Results available in different physical levels. Heights (x): 10m, 25m, 50m, 75m, 100m, 150m, 200m	Instantaneous
cloudWater.100	mg/kg	Parameter intended for estimating probability of icing.	Instantaneous
cloudIce.100	mg/kg	Parameter intended for estimating probability of icing.	Instantaneous

Footnotes