Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
2009
Volume 12
Issue 4
Topic:
Agronomy
ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Chabior M. , Michalska B. 2009. VARIABILITY OF SENSIBLE TEMPERATURE (STI) IN NORTH-EAST POLAND, EJPAU 12(4), #22.
Available Online: http://www.ejpau.media.pl/volume12/issue4/art-22.html

VARIABILITY OF SENSIBLE TEMPERATURE (STI) IN NORTH-EAST POLAND

Marek Chabior1, Bożena Michalska2
1 Department of Marine Ecology and Environmental Protection, West Pomeranian University of Technology in Szczecin, Poland
2 Department of Meteorology and Climatology, West Pomeranian University of Technology in Szczecin, Poland

 

ABSTRACT

In order to estimate the biothermic conditions of north-east Poland, Błażejczyk's sensible temperature index STI was applied, which is based on the analysis of human heat balance. STI value was determined using the simplified version of the model based on the following term data from 12 o'clock UTC: air temperature, relative air humidity, steam pressure, wind speed, and cloudiness by low (CL) and middle (CM) clouds. Data were taken from 10 meteorological stations in north-east Poland, and the period of the study was years 1966–2000. Sensible temperature index STI fell within the range of below -38°C to over 55°C. To the particular values of the STI index, Błażejczyk attributed heat sensations in a seven-degree scale of subjective heat sensations – from "very cold" to "very hot". Mean STI values and the frequency of the occurrence of the particular heat sensations were presented for months, seasons, and a year. Time trends of sensible temperature STI were determined for four seasons and a year, and a spatial diversification of this index in north-east Poland was carried out. Sensible temperature STI showed a statistically significant increase in the period of 35 years in all seasons only in Suwałki, and at the remaining stations, a significant increasing trend of this temperature occurs during spring and winter. The highest sensible temperature increase, from 0.57°C in Płock to 1.99°C in Suwałki fell in the spring, except the station in Ostrołęka where in that season, a negative and statistically insignificant tendency was noted. Spatial picture of the distribution of sensible temperature STI shows an increase in its values from the north towards the south of the studied area in all the seasons of the year except winter, in which a decrease in STI values takes a direction from SW to NE.

Key words: heat sensations, time trends, spatial diversification.

INTRODUCTION

Recreation and tourism in a given region is conditioned by many factors, and in the case of spending time in the open air, some of the most important, next to landscape qualities, are weather conditions, first of all the course of air temperature in connection with solar radiation and wind speed.

Increasing popularity, even fashion for tourism, including agrotourism, makes the evaluation of biothermal conditions of the region important. Qualities of the landscape of north-east Poland make it very touristically attractive. What influences the features of the bioclimate of this region are: geographic factors, such as relief, kind of ground, plant cover, water relations, area use, and weather conditions, which constantly affect our organisms with various stimulation and intensity [8]. Until now, the climate and bioclimate of this region has been the subject of studies of many authors, among others: Olszewski [14], Stopa-Boryczka et al. [17], Kozłowska-Szczęsna [7], Błażejczyk [1,2], Krawczyk [12], Krawczyk and Błażejczyk [13], Górniak [6], Szwejkowski et al. [18], Dragańska et al. [5], and Panfil [16]. Majority of the enumerated works were conducted on relatively short observation material from earlier years or concerned single locations situated in different parts of the region. In their most recent work [4], the authors evaluated the biothermic conditions of north-east Poland on the basis of the effective radiation temperature TRE. As the study methods were becoming more sophisticated, new possibilities appeared of elaboration on the basis of indexes based on the analysis of human heat balance. One of them is sensible temperature STI, which was used in the present study.

The aim of the work was an attempt of space and time presentation of the diversification of sensible temperature in north-east Poland and the determination of the direction of its changes in the last 35 years, as well as answering questions in what periods the most profitable conditions for tourism and agrotourism occur and whether there exist a possibility of prolonging the resting period beyond the summer vacation season.

MATERIAL AND METHODS

In the study, the following meteorological term data were used from 12 o'clock UTC: air temperature, relative air humidity, steam pressure, wind speed, and cloudiness by low (CL) and middle (CM) clouds. Data originated from 10 meteorological stations form north-east Poland, and the period of study included years 1966-2000. Additionally, three stations from beyond the region were taken into account (Warszawa, Siedlce, and Terespol), which were used during the evaluation of the spatial diversification of sensible temperature. Wind speed was brought to the height of 2 m above the ground and the terrain of the roughness class "3", which allowed to a significant degree to eliminate the influence of local factors on wind speed, and consequently on the evaluation of human heat perception.

STI value was determined using a simplified version of the model on the basis of the above mentioned data, since for the calculation of the STI index, a relatively high amount of meteorological data is needed.

To sensible temperature STI values correspond heat sensations according to the following scale:

Weather type

STI

Subjective heat sensation

-3

< -38.0°C

very cold

-2

-38.0 to -0.5°C

cold

-1

-0.6 to 22.5°C

cool

0

22.6 to 32.0°C

comfortably

+1

32.1 to 46.0°C

warm

+2

46.1 to 55.0°C

hot

+3

> 55°C

very hot

Values of the STI index scale also inform about the weather type in the Błażejczyk's biothermal-meteorological weather classification [2]. To the particular values of the STI index, heat sensations are assigned in a seven-degree scale of subjective heat sensations – from "very cold" – weather type -3 to "very hot" – weather type +3 [2].

Spatial distribution of the mean STI index values and the trends of the changes are shown in the system of months, seasons, and a year, and the frequency of the occurrence of particular heat sensations – in decades and during a year.

In order to study the tendency of changes in biothermal conditions from year to year, the linear regression method was applied.

RESULTS AND DISCUSSION

In the spring, in the whole region the average STI temperatures fall within the heat sensation range of "cool" (Fig. 1). Highest sensible temperature – over 21°C occurs in the south part of the region, and the lowest – below 18°C in the Suwałki Lake District.

Fig. 1. Average sensible temperature values STI (°C) in seasons and in January and August in the 35-year period of 1966–2000

In the summer, the average STI temperature – over 38°C occurs in the south part of the region, and the lowest – below 36°C in the Suwałki Lake District and falls within the heat sensation range of "warm". The highest average sensible temperature STI in this season occurs in August, and the isarithms take a clear parallel course. Even in the warmest month, the long-term average sensible temperature in no part of the region exceeds weather type +1.

Course of isarithms in the autumn is similar to the one form the spring, although the diversification of the STI temperature is higher and ranges from 11°C in the north-east part of the region to 15°C in the south part. In spite of the fact that the values of the temperature in the autumn are from 6 to 7°C lower than in the spring, the average heat sensation in this season is "cool".

In the winter, the STI values change from -8°C in the most north-east part of the region to -4°C in the south-west part, and the coldest month in this season of the year is January (Fig. 1). Course of isarithms on both maps is nearly the same, although the average STI temperature is lower in January by 2°C from the temperature in the whole winter period (December – February).

Values of the lowest sensible temperatures STI oscillated between -37.8°C in Ostrołęka to -41.3°C in Kętrzyn, which corresponded to weather type "very cold", and at almost all the stations such a low value of the temperature index occurred in December 1978. On the other hand, the highest value of the sensible temperature index occurred in August and was from 69.3°C in Mikołajki to 77.5°C in Toruń, exceeding the value of 70°C, which makes it possible to call such a day torrid [2]. Owczarek [15] in her studies on the biothermal conditions in Gdynia in years 1951–2005 stated the occurrence of days with the heat sensation “torrid” but did not note any "very cold" days. December in north-east Poland turned out to be the month with the lowest sensible temperature variability – standard deviation was within the range of 2.2 – 2.8, and July with the highest – even three times in relation to December – from 6.3 to 7.6. Suwałki stood out with the highest year variability of the STI index, (2.6), and Ostrołęka with the lowest (1.6); no clear spatial diversification of the monthly variability of this temperature expressed by standard deviation was stated.

Fig. 2. Course of average sensible temperature STI (°C) at 12 o'clock UTC with trends in the seasons in years 1966–2000
Statistically significant trend at the level of *α = 0.05; **α = 0.01

Table 1 presents the values of the correlation indexes of the linear trend of sensible temperature STI according to months and a year and the values of the changes in that temperature per 10 years. It results from the data analysis that a significant or highly significant positive trend of the sensible temperature at all the studied stations occurred in January. The highest temperature increase (2.2°C) is noted in Suwałki, and the smallest (1.1°C) in Ostrołęka. Another month in which the sensible temperature trend is significant is April, and like in January, the temperature increases most noticeably in Suwałki – as much as 3.2°C per 10 years, and the least in Ostrołęka and Płock (statistically insignificant trend) – 1.0°C. In the remaining months, except February, there were no clear change tendencies, only in June at most of the stations a temperature decrease was noted – the highest (statistically significant) in Ostrołęka (-2.1°C/10 years) and Olsztyn (-1.8°C/10 years). In the whole studied area of north-east Poland, sensible temperature increased, above all, in January and April (1.6 and 1.7°C, respectively), and in February (1.0°C) and October (1.2°C) the relation of this temperature to years is weaker but also positive.

Table 1. Correlation and linear trend indexes of the changes in sensible temperature STI (°C/10 years) in months and a year in the 1966–2000 period

Place

 

I

II

III

IV

V

VI

VII

VIII

IX

X

XI

XII

Year

Elbląg

trend

1.83

1.17

0.57

1.99

1.43

-1.03

0.88

0.41

0.55

1.39

0.21

0.51

0.8

r

0.46**

0.36*

0.14

0.40*

0.26

-0.23

0.13

0.08

0.10

0.32

0.08

0.24

0.46**

Kętrzyn

trend

1.4

0.8

-0.2

1.9

0.4

-1.0

0.4

0.0

-0.5

1.0

0.0

0.2

0.4

r

0.41*

0.26

-0.05

0.38*

0.07

-0.21

0.06

0.00

-0.10

0.22

-0.01

0.08

0.20

Suwałki

trend

2.2

1.4

1.0

3.2

2.6

1.2

2.3

2.1

1.2

2.3

0.7

0.9

1.8

r

0.57**

0.42*

0.23

0.54**

0.44**

0.23

0.30

0.35*

0.19

0.46**

0.28

0.33

0.70**

Toruń

trend

1.3

0.8

0.4

2.2

1.3

-1.1

0.9

0.4

-0.6

0.5

-0.1

0.6

0.6

r

0.36*

0.23

0.10

0.42*

0.25

-0.21

0.12

0.08

-0.10

0.11

-0.02

0.21

0.30

Mława

trend

1.8

1.4

0.2

1.9

2.0

0.3

1.7

1.2

0.7

1.5

0.1

0.7

1.1

r

0.46**

0.43*

0.04

0.39*

0.35*

0.05

0.24

0.21

0.11

0.32

0.02

0.31

0.54**

Olsztyn

trend

1.5

0.8

-0.3

1.7

0.7

-1.8

0.5

-0.1

-0.5

0.8

-0.3

0.4

0.3

r

0.42*

0.30

-0.07

0.37*

0.12

-0.36*

0.08

-0.02

-0.10

0.17

-0.10

0.16

0.16

Mikołajki

trend

1.7

1.3

0.3

2.4

1.1

-0.2

1.0

1.2

0.4

1.5

0.5

0.5

0.7

r

0.47**

0.41*

0.07

0.50**

0.24

-0.05

0.17

0.24

0.08

0.37*

0.21

0.19

0.27

Ostrołęka

trend

1.1

0.2

-0.9

1.0

-0.3

-2.1

0.1

-1.0

-1.6

-0.2

-0.8

0.0

-0.4

r

0.31

0.07

-0.20

0.20

-0.06

-0.38*

0.01

-0.18

-0.25

-0.04

-0.23

0.01

-0.25

Białystok

trend

1.6

0.8

0.5

2.1

1.6

0.2

0.7

0.9

-0.1

1.6

0.3

0.4

0.9

r

0.47**

0.25

0.11

0.42*

0.31

0.04

0.11

0.17

-0.01

0.31

0.11

0.18

0.49**

Płock

trend

1.7

0.9

-0.4

1.0

1.2

-1.6

0.3

0.0

-1.1

0.1

-0.6

0.2

0.1

r

0.42*

0.24

-0.09

0.22

0.23

-0.30

0.05

0.00

-0.17

0.03

-0.17

0.08

0.07

Masuria

trend

1.6

1.0

0.0

1.7

1.1

-0.9

0.5

0.4

-0.3

1.2

0.2

0.5

0.6

r

0.46**

0.32

-0.01

0.37*

0.23

-0.19

0.08

0.08

-0.05

0.27

0.06

0.22

0.33

Statistically significant trend at the level of *α = 0.05; **α = 0.01

From the presented in Fig. 2 course of the average sensible temperature STI in years 1966-2000 at chosen stations in the four seasons of the year it results that it increases significantly in winter and spring, whilst in the summer, a slight negative tendency can be found, which was influenced by colder and colder June.

Dominant heat sensations throughout the year at all the analysed stations were "cool" – from 32.9% days in Białystok to 37.0% in Elbląg (Fig. 3). Equally high participation had days with the sensation of "cold" – ranging from 26% in Płock to 33% in Suwałki. The highest number of days with the heat sensation of "comfort" and "warm" was in Białystok – 24.2% of the year, and the lowest in Ostrołęka – 21.6%. Days with the heat sensation of "very cold" (STI below -38°C) occurred only sporadically, mainly in December and January, and according to Ustrnul and Czekierda [19], very low negative temperatures are related to high pressure anti-cyclone circulation and the lingering of the wedge of high pressure over Central Europe. On the other hand, days sensed as "very hot" (STI over 55°C, type +3) were noted more frequently – from 3.6 in Suwałki to 6.1% in Płock (Fig. 3). In this weather type, also days with the sensation of torrid (STI > 70°C) occurred, which happened at all the stations except Mikołajki in the period of June-August. Ustrnul and Czekierda [19] state that maximally high temperatures (over 35°C), which occurred in north-east Poland in years 1959, 1992, and 1994, were most often related to the influx of very warm air from the south sector.

Fig. 3. Frequency (%) of the occurrence of heat sensations according to STI during a year, in the 1966–2000 period
(Heat sensations: +3 "very hot"; +2 "hot"; +1 "warm"; 0 "comfort"; -1 "cool"; -2 "cold"; -3 "very cold")

It results from the course of the frequency of the occurrence of heat sensations for 10-day periods (Fig. 4) that the most profitable biothermal conditions – defined as a period when heat sensations are from "comfort" to "warm", started already at the end of February and could still appear at the beginning of November but the frequency of the occurrence in those periods was small. On the other hand, with the highest repeatability – 40% on average, these heat sensations occurred from the first decade of May to the first decade of October. "Hot" weather type appeared in the studied area in mid-April, and disappeared in early October, whereas "very hot" weather appeared in the spring a decade later, and in the autumn disappeared on average two decades earlier than hot weather type. The highest frequency of the occurrence of both weather types falls in the first decade of August – from ca. 45% in the north part of the region to 50% in the south and west parts. Heat sensation of "cool" as the only weather type occurred in all the decades of the year. It was the most characteristic in October and in the first decade of November, since at the majority of the stations it made up 50% of the days, only in Suwałki did cool sensation occur with over 50% frequency already in the last decade of September, and in the first decade of November, the sensation of "cold" started to prevail. That last weather type dominated from the second decade of November to the end of February, and the highest frequency – over 80% fell in the first decade of January. In Gdynia [15], cold weather type showed a negative, statistically significant trend in the months from December to March, and in Świnoujście [10], a negative in the first three months of the year but statistically significant only in March. Authors found an increasing number of days with cool sensations at the cost of cold days, which causes mildening of the sensible conditions in winter. However, in the months from April to September, in Świnoujście the number of cool days decreases, and in July and August also of comfortable days, and the number of warm and hot days increases.

Fig. 4. Frequency (%) of the occurrence in following decades of heat sensations according to STI in the 1966-2000 period

Days sensed as "hot" and "very hot", namely heat discomfort, occurred in north-east Poland more often than on the Baltic coast, as in the studied area there were on average 40 of them in Suwałki to 55 in Płock, and on the coast from 38 w Łeba and 43 in Ustka to 46 days in Świnoujście [11], whereas in the Szczecin Lowland, there are on average 44 days with heat discomfort [9]. It results from the studies by Chabior [3] that the coast is characterised by a significantly higher insolation than the remaining part of Pomerania, and the Pomeranian Lake District has a higher temperature than the coast. Therefore, the number of days with the heat sensation of "hot" and "very hot" is in the Pomeranian Lake District more similar to the number of days with these heat sensations in north-east Poland.

CONCLUSIONS

  1. In all the analysed periods, the lowest sensible temperature STI occurred in the Suwałki Lake District, and the highest in the west and south parts of the region. Spatial picture of the distribution of sensible temperature STI shows an increase in its value from the north to the south of the studied area in all the seasons except winter, when a decrease in the STI value takes a direction from south-west to north-east.

  2. It results from the course of the mean values of sensible temperature STI in north-east Poland that the average heat sensation in the spring and autumn fell within the range of "cool", and in winter and summer – "cold" and "warm", respectively. In the spring, sensible temperature STI was from 6 in the south of the studied region to 7°C in the Suwałki Lake District higher than in the autumn, with very similar spatial distribution in both seasons.

  3. Statistically significant increase in sensible temperature STI in the winter and spring influenced the mildening of the biothermal conditions, especially in April when this temperature increases in the whole region by 1.7°C per 10 years.

  4. In the annual distribution of heat sensations, cool weather type had the highest participation and occurred on average in the studied region in 34.5%, and then cold weather type – 28.4%. Burdening organism with heat – weather type hot and very hot occurred in 13.1% of the total number of days in the year – with the highest intensification in the first decade of August. Thermoneutral weather – warm and comfort occurred in north-east Poland on nearly one fourth days of the year – 24%, and those days had the highest participation (except the Suwałki Lake District) in the period from early May to the first decade of October.

  5. Taking into account the time and spatial distribution of sensible temperature STI and also its changeability in the studied years and the participation of subjective heat sensations on different days of the year, it can be stated that conditions favourable for resting and mild forms of tourism occur from May to mid-September, whereas for moderate forms of tourism – from April to mid-October.


REFERENCES

  1. Błażejczyk K., 1992. Bioclimatic analysis of weather conditions in Poland [Bioklimatyczna analiza warunków pogodowych w Polsce]. Zesz. IGiPZ PAN 8, 24 [in Polish].

  2. Błażejczyk K., 2004. Bioclimatic conditions for recreation and tourism in Poland [Bioklimatyczne uwarunkowania rekreacji i turystyki w Polsce]. Pr. Geogr. IGiPZ PAN 192, 291 [in Polish].

  3. Chabior M., 2006. Chosen aspects of the bioclimate of Pomerania [Wybrane aspekty bioklimatu Pomorza]. Balneol. Pol. 2, 128–132 [in Polish].

  4. Chabior M., Michalska B., 2007. Evaluation of the sensible climate of north-east Poland on the basis of the effective radiation temperature (TRE) [Ocena klimatu odczuwalnego w Polsce północno-wschodniej na podstawie temperatury radiacyjno-efektywnej (TRE)]. Acta Agrophys. 10, 19-30 [in Polish].

  5. Dragańska E., Szwejkowski Z., Cymes I., Sałacki M., 2005. Frequency of the occurrence of certain thermal sensibility situations in Olsztyn in years 1998-2000 [Częstość występowania określonych sytuacji odczuwalności termicznej w Olsztynie w latach 1998-2000]. Zesz. Probl. Post. Nauk Rol. 505, 101–106 [in Polish].

  6. Górniak A., 2000. Climate of Podlaskie Province [Klimat województwa podlaskiego]. IMGW Białymstok [in Polish].

  7. Kozłowska-Szczęsna T., 1991 Anthropoclimate of Poland [Synthesis attempt] [Antropoklimat Polski [Próba syntezy)]. Zesz. IGiPZ PAN 1, 64 [in Polish].

  8. Kozłowska-Szczęsna T., Błażejczyk K., Krawczyk B., 1997. Human bioclimatology. Methods of its use in research on the bioclimate of Poland [Bioklimatologia człowieka. Metody ich zastosowania w badaniach bioklimatu Polski]. IGiPZ PAN Warszawa, Monografie 1, 200 [in Polish].

  9. Koźmiński Cz., Mąkosza A., Michalska B., 2007. Bioclimatic conditions for resting in the region of Lake Miedwie in the warm half-year [Bioklimatyczne warunki wypoczynku w rejonie jeziora Miedwie w półroczu ciepłym]. Przegl. Nauk. Inż. Kształt. Środ. 3, 3–13 [in Polish].

  10. Koźmiński Cz., Michalska B., 2008. Assessment of weather conditions for recreation and tourism in the Świnoujście region [Ocena warunków pogodowych dla rekreacji i turystyki w rejonie Świnoujścia]. [In:] Problems of tourism and recreation [Problemy turystyki i rekreacji], M. Dutkowski (red.), US OFICYNA 1, 31–41 [in Polish].

  11. Koźmiński Cz., Michalska B., 2009. Changeability of cool, hot and torrid days and heat sensations in the zone of Polish Baltic coast [Zmienność dni chłodnych, gorących i upalnych oraz odczucia cieplne w strefie polskiego wybrzeża Bałtyku] (w druku) [in Polish].

  12. Krawczyk B., 1995. Bioclimate of Poland and the possibility of climatherapy, recreation, and work in the open air [Bioklimat Polski a możliwości klimatoterapii, rekreacji i pracy na wolnym powietrzu]. Przegl. Geogr. 67(1–2), 29–44 [in Polish].

  13. Krawczyk B., Błażejczyk K., 1999. Climatic and bioclimatic characteristics of north-east Poland [Klimatyczna i bioklimatyczna charakterystyka Polski północno-wschodniej]. Zesz. IGiPZ PAN 58, 33 [in Polish]

  14. Olszewski J.L., 1973. Complex formulation of the climate of north-east Poland [Klimat północno-wschodniej Polski w ujęciu kompleksowym]. Prace i Studia IG UW, Klimatologia 11(6), 135–161 [in Polish].

  15. Owczarek M., 2007. Changeability of biothermal conditions in Gdynia [Zmienność warunków biotermicznych w Gdyni (1951–2005)]. [In:] Climate fluctuation in different spatial and time scales [Wahania klimatu w różnych skalach przestrzennych i czasowych], K. Piotrowicz,
    R. Twardosz (red.), 297–305 [in Polish].

  16. Panfil M., 2005. Thermal extrema in north-east Poland in years 1951–2000 [Ekstrema termiczne w północno-wschodniej Polsce w latach 1951–2000]. Woda – Środowisko – Obszary Wiejskie 5, Zesz. spec. 14, 237–242 [in Polish].

  17. Stopa-Boryczka M.(red), 1986. Atlas of interdependencies of meteorological and geographical parameters in Poland. IV. Climate of north-east Poland [Atlas współzależności parametrów meteorologicznych i geograficznych w Polsce. IV. Klimat północno-wschodniej Polski]. Wyd. UW [in Polish].

  18. Szwejkowski Z., Nowicka A., Dragańska E., 2002. Climate of the Masurian Lake District. Part I, temperature and precipitation in the 45-year period of 1951–1995 [Klimat Pojezierza Mazurskiego. Cz. I. Temperatura i opady atmosferyczne w okresie 45-lecia 1951–1995]. Fragm. Agron. 2(74), 285–295 [in Polish].

  19. Ustrnul Z., Czekierda D., 2002. Extreme air temperature values in Poland in the second half of the 20th century against the background of circulatory conditions [Ekstremalne wartości temperatury powietrza w Polsce w drugiej połowie XX wieku na tle warunków cyrkulacyjnych]. Wiad. IMGW XXVI (XLVI), 4, 3–8 [in Polish].

 

Accepted for print: 11.12.2009


Marek Chabior
Department of Marine Ecology and Environmental Protection,
West Pomeranian University of Technology in Szczecin, Poland
Papieża Pawła VI 3, 71-459 Szczecin, Poland
email: marek.chabior@zut.edu.pl

Bożena Michalska
Department of Meteorology and Climatology,
West Pomeranian University of Technology in Szczecin, Poland
Kazimierza Królewicza 4, 71-550 Szczecin, Poland
email: bozena.michalska@zut.edu.pl

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.