Category Archives: Uncategorized

Snow cover

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Sector Essential climate variable (ECV)
Description Snow cover calculated as snow water equivalent
Calculation method Title Period Processing Unit Comment
Hourly Hourly The hourly time series from HYPE mm  
Monthly min Monthly The monthly minimum snow cover mm Not available for Bologna
Monthly mean Monthly The monthly mean snow cover mm Not available for Bologna
Monthly max Monthly The monthly maximum snow cover mm Not available for Bologna
Yearly min Yearly The yearly minimum snow cover mm Not available for Bologna
Yearly mean Yearly The yearly mean snow cover mm Not available for Bologna
Yearly max Yearly The yearly maximum snow cover mm Not available for Bologna
Mean over period Five years Total mean for the full period mm Not available for Bologna
Provenance The hydrology downscaling was performed with tailored setups of the HYPE model. 
Validation The downscaling made by MATCH in Urban SIS has been validated against observations in Urban SIS deliverable 5.3. Section 4.1 gives a validation of how precipitation data from the HARMONIE-AROME used as forcing for HYPE which can be used for further understanding of validity of the results.

Zero crossings

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Sector Infrastructure and transport
Description Number of days with 2 m air temperatures on both sides of 0 °C.
End User Nordic road administrations
Calculation method ID Title Period Statistical processing Unit Threshold Comment
zerocrossings Number of days on both sides of 0 °C yearly Days with temperatures on both side of zero (requires daily max and daily min temp). days  

Only evaluated during winter months.

Not available yet
Provenance Theese indicators are based on output from the Harmonie meteorological modell.
Calculation caveats Spatial representation: S1
Other caveats: 
Could be compared to:
Could be used with:
Motivation

When temperature often changes around 0 °C, it has consequences for winter road maintenance. Examples are thaw/freezing cycles affecting the road icing conditions, increasing the deterioration of road surfaces.
Experience user  
References  

Universal Thermal Climate Index

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tor Health, human comfort
Description The UTCI is a thermal comfort indicator based on human heat balance models and designed to be applicable in all seasons and climates and for all spatial and temporal scales (Bröde et al. 2012). There are 10 UTCI stress categories describing conditions ranging from extreme cold stress to extreme heat stress.
End User General public, health authorities Bologna
Calculation method UTCI is calculated in the Town Energy Balance (TEB) model used during the downscaling of regional climate data in this project (Masson 2000).
ID Title Period Statistical processing Unit Threshold Comment
utcindex Universal Thermal Climate Index yearly Number of days in each UTCI stress category days  

Not available yet
Provenance Theese indicators are based on output from the Harmonie meteorological modell.
Calculation caveats Spatial representation: S1
Other caveats: 
Could be compared to:
Could be used with:
Motivation

The UTCI is selected for this work (in addition to the Thom Discomfort Index) because it uses a human energy balance approach to account for heat exchange between humans and the surrounding atmosphere. This physiologically-based method is also incorporated and used in operational urban climate canopy models such as TEB (Masson, 2000).
Experience user  
References

 Bröde P et al. 2012: Deriving the operational procedure for the Universal Thermal Climate Index (UTCI). International journal of biometeorology 56:3, 481-494.

Masson V 2000: A physically-based scheme for the urban energy budget in atmospheric models. Boundary-layer meteorology 94:3, 357-397. 
 

Tropical nights

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Sector Heat stress and human comfort
Description Tropical nights are nights when minimum 2 m air temperature remains greater than 20° C (e.g. Fischer and Schär 2010).
End User General public
Calculation method
ID Title Period Statistical processing Unit Threshold Comment
tropicalnights Tropical Nights yearly Number of days with daily minimum temperature greater than 20°C. nights  20°C Not available yet
Provenance Computed by the HARMONIE model.
Calculation caveats

Spatial representation: S1
Other caveats:
Could be compared to: 
Could be used with: 
Motivation

This indicator has been shown, in combination with hot days (indicator id: hotdays), to explain temporal and spatial variance of excess mortality during recent European heatwaves (e.g. Fischer and Schär 2010). The temperature threshold used to identify a tropical night that is used follows EEA (2009).

The indicator “Tropical nights” is meant as an intuitive way to present high temperatures occurrences for the public.
Experience user  
References

EEA Report No 5/2009. Ensuring quality of life in Europe’s cities and towns – tackling the environmental challenges driven by European and global change. ISSN 1725-9177

Fischer EM, C Schär 2010: Consistent geographical patterns of changes in high-impact European heatwaves. Nature Geoscience 3.6: 398-403.

Heat wave duration

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Sector Heat stress and human discomfort
Description Heat waves are characterized as periods of sustained, extreme heat, although there is no universal definition of a heat wave. For this application, a heat wave is defined according to Meehl and Tebaldi (2004) based on daily maximum air temperature (Tmax) and two percentile thresholds (T1 and T2) from the distribution of daily Tmax during the reference scenario period.
End User General public, health authorities, urban planners
Calculation method

A heat wave is defined as a period of consecutive days that satisfy the following conditions: i) Daily Tmax is above T1 for at least three days, ii) the average Tmax is above T1 over the entire period, and iii) the daily Tmax must be above T2 every day of the period (the total heat wave period must be greater than or equal to 3 days). Here, T1=97.5th percentile and T2=81st percentile, following Meehl and Tebaldi (2004).
ID Title Period Statistical processing Unit Threshold Comment
heatwaveduration Hot period duration yearly Maximum number of consecutive days when: i) Daily Tmax is above T1 for at least three days, ii) the average Tmax is above T1 over the entire period, and iii) the daily Tmax must be above T2 every day of the period (the total heat wave period may be longer than three days). days T1 = 97.5th percentile T2 = 81st percentile 

Not available yet
Provenance Theese indicators are based on output from the Harmonie meteorological modell.
Calculation caveats Spatial representation:
Other caveats: O3, O4
Could be compared to:
Could be used with:
Motivation

Both duration and frequency of heat waves may increase in Europe (Perkins et al. 2011). The provided indicator can give planners a hint of changes to expect in their city. The selected method (Meehl and Tebaldi 2004) provides information about heat wave duration.
Experience user Many methods to define a heatwave (Souch and Grimmond 2004, Perkins 2015).
References

Meehl GA, C Tebaldi 2004: More intense, more frequent, and longer lasting heat waves in the 21st century. Science 305.5686, 994-997.

Perkins SE, Alexander LV, Nairn JR 2012: Increasing frequency, intensity and duration of observed global heatwaves and warm spells. Geophysical research letters. 39:20

Perkins SE 2015: A review on the scientific understanding of heatwaves—their measurement, driving mechanisms, and changes at the global scale. Atmospheric Research, 164, 242-267.

Souch C, CSB Grimmond 2004: Applied Climatology: Heat Waves. Progress in Physical Geography, 28, 599-606. doi: 10.1191/0309133304pp428pr