The climatic information recorded by the physician
Francisco Fernández Navarrete in Granada (southern Spain) during the
first third of the 18th century is analyzed in this work. His observations
are included in the book Cielo y suelo granadino ('Sky and soil in
Granada'), and consist of qualitative comments relating climatic conditions
to illness and diseases from 1706 to 1730, as well as instrumental
observations (using an “English barometer” and a “Florentine
thermometer”) from December 1728 to February 1730. To the best of our
knowledge, these are the earliest instrumental observations recorded in
Spain. An alternative methodology to Pfister indices, based on the frequency
of extreme events, was applied to study this new set of documentary data. The
analysis shows that seasonal mean values of temperature and precipitation
during the period 1706–1730 were very similar to those of periods of similar
length at the beginning of the 20th century, such as 1906–1930. However,
some years were especially extreme, such as the dry first half of the 1720s
or the winter of 1728–1729 when a strong cold wave affected the city.
Introduction
Historical climatology offers the possibility of reconstructing climatic
conditions during the pre-instrumental period, that is, before the
establishment of meteorological observation networks around 1850. Documentary
sources are basic data sources for this time period because they record
climatic anomalies and extreme events, making it possible to relate such
events to climatic changes. In recent years a large number of papers on historical
climatology in many areas of the globe have been published (Brázdil et
al., 2005, 2010). In addition, the recovering of the early instrumental
observations is a priority objective in climatic research (Brönnimann et
al., 2018).
There are many example of work on the historical climate in the Iberian Peninsula using
documentary sources and early instrumental observations from Spain and
Portugal (see, for instance, Bullón, 2008; Domínguez-Castro et al.,
2010, 2014; Alcoforado et al., 2012; Barriendos et al., 2014; Fragoso et al.,
2015). The first meteorological measurements in the Iberian Peninsula were
taken in Portugal between 1 November 1724 and 11 January 1725
(Domínguez-Castro et al., 2013). In Spain, the
Ephemerides barométrico-médicas matritenses
('Barometric–medical ephemeris for Madrid') by the physician
Francisco Fernández Navarrete has been considered to be the first meteorological instrumental
series (Anduaga Egaña, 2012). It is a set of daily and sub-daily
meteorological observations taken in Madrid between March and October 1737.
In this work we present a set of observations taken by the same observer in
Granada (in the south of the country) some years before, between
December 1728 and February 1730. These observations are included in a
handwritten book dated to 1732 and kept in the Archive of the Franciscan
Order in Cataluña (Gil Albarracín, 1997). The title of the book is
Cielo y suelo granadino ('Sky and soil in Granada'; Fig. 1),
and it may be regarded as one of the first Spanish medical treatises that
followed the neo-Hippocratic hypothesis concerning the influence of climate
on human health. In the following sections these observations along with
qualitative comments by the author on the climatic conditions from 1706 to
1730 will be analyzed.
Book cover of the handwritten book Cielo y suelo granadino
by Navarrete (1732).
The climatic interest of Granada, in the south of the Iberian Peninsula, is
due not only to its geographic location (37∘10′ N,
3∘36′ W), near the Mediterranean Sea and exposed to Atlantic
disturbances and Mediterranean influences, but also to its height, 660 m
above sea level (a.s.l.) and proximity to the highest mountain ridge in the
Iberian Peninsula, the Sierra Nevada, with some peaks of 3000 m a.s.l.
(Fig. 2). The study period is interesting because it begins at the end of the
cold period called Maunder Minimum (1645–1715; Owens et al., 2017), and
continues during subsequent decades. Therefore, it allows us to explore the
climate behavior in a city located in the Mediterranean area (hot spot of
climatic change; Giorgi, 2006) when natural climatic changes occurred.
Location of Granada and other cities mentioned in the text.
The outline of the paper is as follows: biographical and bibliographical
information on the author and his texts are described in Sect. 2; Sect. 3
studies general conditions during the period 1706–1730, and Sect. 4 is
focused on the instrumental observations from December 1728 to February 1730;
Sect. 5 discusses main results, and some concluding remarks are included in the
last section.
The observer: Francisco Fernández Navarrete
Francisco Fernández Navarrete (born in Granada, 1680; died in Madrid,
1742) studied medicine in
Granada, where he lived until 1734, when he moved to Madrid as doctor of King
Felipe V. He was an active member of the Royal Academy of Medicine (founded
in 1734) and the Royal Academy of History (founded in 1738). He developed his
work following the neo-Hippocratic hypothesis. According to this medical
paradigm, illness, epidemics, and public health are related to environmental
conditions, in particular to the variability of meteorological variables
(Demareé, 1996). This idea was predominant in Spain until at least the
mid-19th century (Rodrigo, 2016). So, it is not surprising that medical
academies and physicians were the prime movers of early meteorological
observations in Spain.
Navarrete was the author of many works, most of them unedited and kept as
manuscripts in the archives of the Spanish academies of Medicine and History.
His attention was focused not only on medicine, but also on physical
observations, cosmography, geography, botany, and, in general, all the fields
considered to be part of “natural history”. His main work was
Ephemérides barométrico-médicas matritenses
('Barometric–medical ephemeris for Madrid'; Navarrete, 1737), published in
Madrid in 1737 (this text is digitized and available at the library of
Seville University: http://fondosdigitales.us.es, last access:
28 March 2019). It is a set of daily meteorological observations (atmospheric
pressure, temperature, wind direction, qualitative comments on rain,
cloudiness, and other meteorological events) taken in Madrid from March to
November 1737. Here, the author establishes the basis of an observational
program dedicated to compiling all the meteorological data potentially useful
to medical studies not only in Madrid, but also in other Spanish cities. This
program was based on the main ideas of the neo-Hippocratic hypothesis, which
was the predominant medical paradigm during the 18th century in Spain.
Unfortunately, this program was not accomplished due to a lack of interest by
the authorities, although it was partially recovered in the last decades of
the century by the medical academies of Seville, Madrid, and Barcelona
(Anduaga Egaña, 2012).
A precursor of the Ephemerides is the book studied in this paper,
Cielo y suelo granadino (`Sky and soil in Granada'). The manuscript
is dated to 1732, and although it was not ultimately published, the book was
finished and prepared for publication. It is kept in the Library and Archive
of the Franciscan Province of Cataluña, Barcelona, and it has been edited
recently (Gil Albarracín, 1997). Among the multiple aspects of natural
history studied by the author, we are interested in the climatological and
meteorological observations. Chapter IV is entitled “Observations of the
atmosphere using the barometer and the thermometer” and includes monthly
summaries (with daily resolution) of these observations from December 1728 to
February 1730. Chapter XVI is entitled “Medical observations for the
knowledge of climate”. Here, the author offers a summary of climatic
conditions (rainfall, dryness, snowfall, frosts, warm or cold weather, winds)
at a monthly and/or seasonal resolution from 1706 to 1730 in Granada as well
as their relationships with the occurrence of illness in the city, following
the neo-Hippocratic paradigm. We place the beginning of the qualitative
series in 1706 because the author, in the description of the cold winter
1729, indicates that this year was the “coldest winter seen in 24 years”, suggesting that he
began to compile his observations that year. These data are available at the
data repository of the University of Almería (Rodrigo, 2018a; file
“NavarreteData.xlsx”, http://hdl.handle.net/10835/6248, last access:
28 March 2019). In next sections we study both chapters separately because
the time resolution and the nature of the data are different in each case.
The period 1706–1730
Chapter XVI of the book by Navarrete (fols. 105–107 of the manuscript) is
dedicated to exposing the “alterations in health due to mutations of the air
and general causes obtained from the long observation and practical knowledge
of the country”. Here, the author establishes relationships between
different diseases and climatic conditions. Qualitative information only
refers to certain years when extreme events occurred. So, for instance, in
paragraph 13 (fol. 106v), he says that “If cold, rain, and snowfall continue
until May: difficult births, chest pains, and dangerous anginas; the year is
1727”. This paragraph allows us to characterize the spring of 1727 as wet
and cold. The analysis of the contents of this chapter yields as a result the
summary shown in Table 1, where the seasons that are unmistakably cold, warm,
wet, or dry are indicated (in the following we designate these seasons as
“extreme seasons”). Seasons are defined as is usual: winter (December,
January, February; winters identified by the year corresponding to January
and February), spring (March, April, May), summer (June, July, August), and
autumn (September, October, November).
Extreme seasons in Granada from 1706 to 1730 (Rodrigo, 2018a,
NavarreteData.xlsx, http://hdl.handle.net/10835/6248, last access:
28 March 2019).
At a first glance, it seems that there is a predominance of cold over warm
conditions in winter and spring, and dry over wet conditions in all the
seasons except spring. Some of these extreme seasons are confirmed by other
data sources. So, for instance, cold winters in 1709, 1729, and 1730 have been
reported in other Spanish cities, such as Tortosa, Seville, and Alicante (Alberola
Romá, 2014) and the drought during the 1720s has been reported for Jerez de
la Frontera (AHVM, 1722), Arcos de la Frontera (ACAF, 1723), and Seville
(Zúñiga, 1747), where pro pluvia rogations were celebrated.
According to Domínguez-Castro et al. (2010), droughts in Spain from the early 18th century to 1730s are very scarce and their extension is very
limited, except precisely in 1724, coinciding with the observations by
Navarrete.
Documentary data normally provide information on extreme events. In a first
step, it is possible to obtain a catalogue of episodes like droughts, intense
rainfall, snowfall, or hailstorms. A preliminary view of this catalogue
may be misleading, the risk is to consider that these events were the
“normal” climatic conditions in the studied period. The question is whether the
historical frequency of extreme seasons is exceptional or, on the contrary,
may be regarded as “normal” according to 20th-century standards. The
usual methodology, based on ordinal indices (Brázdil et al., 2010),
maintains this view if there is no appropriate overlapping period between
documentary and instrumental data to calibrate and validate the index and to
reconstruct long series of a climate variable. In our case, there is no
overlapping period between documentary and instrumental data, so a different methodology must be applied.
Rodrigo (2008) proposed an alternative methodology to indices, trying to
overcome the problem of the lack of an overlapping period. This method was
tested using climate model paleo simulations (Rodrigo et al., 2012). If
p10 and p90 are the percentiles 10 and 90 of a climatic series X
of a mean value u and standard deviation SD, we can find corresponding
normalized values q10 and q90:
qi=pi-uSDi=10,90.
The percentiles qi (i=10, 90) correspond to the standard normal
distribution FX. The normality hypothesis is the simplest choice, and it
is valid for the series of temperature and rainfall in the four seasons of
the year, except in the case of summer rainfall (Rodrigo et al., 2012). We
can obtain the values qi from the number of extreme seasons ni,
with n=25 (number of years of our series), that is,
n10n=ProbX≤q10=FXq10→q10=FX-1n10nn90n=ProbX>q90=1-ProbX≤q902=1-FXq90→q90=FX-11-n90n.
From Eq. (1), we can express the corresponding standard deviation
SD, and mean value u as
SD=p90-p10q90-q10u=p10-SDq10=p90-SDq90.
The basic idea is to accept that threshold values pi (obtained from the
instrumental observations) are also valid for defining extreme values in the
past, that is, we accept that during a past extreme season the value of the
climate variable X was lower (higher) than p10 (p90). Percentiles
10 and 90 are commonly used to define the frequency of extreme indices, such
as cold nights or warm days, and correspond to moderately extreme events
(Zhang et al., 2005). Summarizing, from documentary data analysis, the
numbers of extreme seasons ni (i=10, 90) are obtained (Table 1). These
numbers are used to estimate qi (Eq. 2), and the SD and u
values are calculated considering the values pi corresponding to the
instrumental period (Eq. 3). The hypothesis here is that climatic changes are
revealed not only by changes in the mean value of the variables, but also in
the frequency and intensity of extreme events. Therefore, if we know the
frequency of extremes during a given period, and accepting the normality
hypothesis, we can determine the mean value and standard deviation of the
climate variable corresponding to that period. This methodology does not try
to provide the year-to-year variability but the general characteristics of
the studied period. This is a weakness of the analysis, although it is
possible to reconstruct this interannual variability when documentary and
instrumental periods are consecutive (Rodrigo et al., 2012). However, this
methodology has advantages in comparison with the standard indices
methodology. First, ordinal indices may be skewed by the subjectivity of the
authors in original sources and/or by the interpretation of the researcher of
descriptions in the sources. In addition, ordinal indices are often based on
the impact of the events on the socioeconomic infrastructures (for example,
destruction of bridges during a river flood or loss of harvests), and these
impacts may change in different periods. The risk here is to consider as
heavy extremes certain events that show the vulnerability of the system more
than the extreme character of climate variables. The method followed is not
based on the severity of the phenomena and, in consequence, at least to a
certain degree, avoids these problems. In second place, it does not need an
overlapping period with instrumental data, which are necessary to calibrate
and validate indices and to reconstruct a climate variable. There is a third
problem of a statistical nature: the calibration of indices is normally done
using a regression procedure between proxy data (indices) and instrumental
data during an overlapping period. From a statistical point of view, the
consequence is the loss of variance in the reconstructed series, a problem
that is normally solved using an “inflation factor” to correct the
reconstructed series (Rutherford et al., 2005). With this method, in
principle, it is not necessary to introduce this mathematical artifact.
The reconstruction of SD and u depends on the values pi
previously established as threshold values to define extreme seasons. These
values may be established using the percentiles 10 and 90 corresponding to a
given reference period. Therefore, the reconstruction is strongly dependent
on the chosen reference period. A possible solution is to select as reference
period a period in which there are different climatic situations. Here we use
the period 1895–2005, which contains years characterized by a weak warming
signal (first decades), and years with a clear warming signal (last decades
of the 20th century). Temperature data are extracted from the database
Spanish Daily Adjusted Temperature Series (SDATS; Brunet et al., 2006).
Monthly rainfall data are extracted from the database made by the Spanish
Agency of Meteorology (AEMET; Luna et al., 2012). These databases are
available on the web page of the AEMET (http://www.aemet.es, last
access: 28 March 2019). All the series are homogeneous and do not present
missing data or gaps. Table 2 shows the percentiles 10 and 90 of seasonal
mean temperature and accumulated precipitation in Granada corresponding to
the complete period 1895–2005.
Percentiles 10 and 90 of seasonal mean temperature (SDATS; Brunet
et al., 2006) and total rainfall in Granada from 1895 to 2005 (AEMET; Luna
et al., 2012).
Temperature Rainfall (∘C) (mm) p10p90p10p90Winter6.18.657.7218.0Spring12.014.752.3186.3Summer22.725.12.249.6Autumn14.517.148.0161.0
To calibrate the method, the complete series was divided into 25-year running
periods, the first one being 1895–1919, the second one 1896–1920, and the
last 1981–2005. This procedure was adopted to obtain a large empirical
sample. For each individual period, the mean value u and the standard
deviation SD were calculated and compared with the corresponding
values u and SD estimated from the numbers n10 and n90
of extreme seasons. Correlation coefficients between estimated and observed
values, as well as the root-mean-squared error (RMSE), were calculated. RMSE
is used in forecasts verification and can also be thought as a typical
magnitude for forecast errors (Wilks, 1995). Values of RMSE were used to
provide an estimate of the uncertainties that are associated with the
reconstruction methodology. Table 3 shows the results of this calibration.
All the correlation coefficients were significant at the 95 % confidence
level. According to correlation coefficient values, the method offers better
results for the mean value u (standard deviation SD) of
temperature (rainfall). These differences may be due to deviations from
normality in the case of rainfall, particularly in summer. As an example,
Fig. 3 shows the comparison for the autumn rainfall series.
Calibration of the reconstruction method for autumn rainfall in
Granada from 1805 to 2005. u: mean value; SD: standard
deviation.
Calibration of the reconstruction methodology using 25-year moving
series from 1895 to 2005. u: mean value; SD: standard deviation;
RMSE: root-mean-square error; r: correlation coefficient between observed
and estimated parameters.
The method was applied to the period 1706–1730, using the data of
Table 1 as ni and percentiles pi of the reference period
(Table 2). Figures 4 and 5 and Table 4 show the reconstruction of seasonal
temperature and accumulated rainfall distribution functions, accepting the
normality hypothesis. Only in the case of summer rainfall was the reconstruction not accomplished because of the absence of extreme wet seasons
(Table 1) and the non-normal character of summer rainfall. RMSE values
previously estimated are used as error margins. Results are compared with the
corresponding values of two 25-year periods in the 20th century – 1906–1930
and 1976–2000 – when the warming signal is very different. To obtain a best
view of this comparison, Table 5 shows the statistics corresponding to these
periods. According to these results, seasonal mean temperatures during
1706–1730 were very similar to those during 1906–1930, even slightly
warmer, and lower (except in summer) than temperatures during 1976–2000: around 0.7 ∘C in winter, 0.4 ∘C in spring, and
1 ∘C in autumn. Standard deviations of temperature during 1706–1730
were similar to 1906–1930 and smaller than that of 1976–2000, suggesting
smaller variability in the past. Total rainfall shows values very similar in
autumn for the three periods: slightly wetter conditions in spring during
1706–1730 and 1906–1930 and slightly wetter conditions in winter of
1706–1730 in comparison with 1906–1930. The variability of rainfall in
1706-1730 is similar to that in 1976–2000, except in spring, characterized
during 1976–2000 by drier conditions.
Reconstruction of the period 1706–1730 in Granada. u: mean value;
SD: standard deviation.
Temperature Rainfall u (∘C)SD (∘C)u (mm)SD (mm)Winter7.0±0.10.91±0.08124±1794±6Spring13.2±0.20.86±0.07130±666±4Summer24.0±0.20.8±0.2Autumn15.8±0.20.7±0.5100±652±3
Statistics of the periods 1906–1930 and 1976–2000 in Granada. u:
mean value; Iu: 95 % confidence level interval for mean value;
SD: standard deviation; ISD: 95 % confidence
level interval for standard deviation.
Distribution functions of seasonal temperatures of 1706–1730 and
comparison with 1906–1930 (a) and 1976–2000 (b).
Distribution functions of seasonal rainfall of 1706–1730 and
comparison with 1906–1930 (a, c, e) and 1976–2000 (b, d, f).
From December 1728 to February 1730
Chapter IV of the book (fols. 12–16 of the manuscript) is entitled
“Observations of the atmosphere using the barometer and the thermometer”.
It is the first compilation of early instrumental meteorological data in
Spain, so far as we know. It begins in December 1728 and ends in
February 1730. The author explains that he shows his observations of 1729 as
an example of the effects of atmospheric variability and that these
observations “are broadly in line with the observations that I have taken
during 9 years with these instruments to determine the conditions of the
atmosphere”. Unfortunately, we have not found documentary sources with these
nine years of data, and we have to be content with the available information.
In addition, information is not presented tabulated but as monthly summaries,
indicating characteristic values or corresponding to critical moments, and it
does not cover in detail all the days of the period. Sometimes, he adds
comments on winds and other meteorological events (fog, cloudiness), and he
indicates the number of rainy days of some months. So, for instance, for
August 1729 he indicates that
August began with warm weather; on day 2, the thermometer indicated 34, and there was a southerly wind. On day 8, the
thermometer increased by two lines, from 38 to 40, during the total lunar
eclipse, which was at 1 o'clock. Day 14 seemed to be the warmest day of the year; however
the thermometer indicated 37, and from day 18 onwards there were slight
northerly winds and the temperature decreased to 46.
This information was tabulated for analysis and may be found in
Rodrigo (2018a, NavarreteData.xlsx, p. Gr1728-1730).
Instruments used by Navarrete were an “English barometer” and a
“Florentine thermometer”. There is no information about the installation of
the instruments or the exact time at which readings were taken, and in the
case of temperature, the scale does not correspond to any of the better-known
scales that were introduced later (for instance, the Reamur scale). This
means that any values measured are only important in relative terms
(Brázdil et al., 2008). Nevertheless, we have tried to “calibrate”
these observations using the information provided by the observer.
Navarrete used a Florentine thermometer with “spirit of wine” as
thermometric liquid. After a brief description of the instrument, he explains
how he established the scale used to measure temperatures: he distinguishes
between “maximum cold”, in the extreme cold of winter or when the “little
bottle was buried in snow with salt ammoniac”, and “maximum heat”, in the
extreme warm summer or “at the front of an oven”. Navarrete marks
“maximum cold” with the value T=100, and “maximum heat” with the value
T=1, and divides the length of the thermometer into equal divisions,
calling the intermediate value T=50 an “equilibrium”. The lower defining
point of the Fahrenheit scale (0 ∘F =-17.78∘C) was
established as the temperature of a solution of brine made from equal parts
of ice, water, and ammonium chloride (Fahrenheit, 1724). Note that the
“maximum cold” was established by Navarrete in a similar way, although,
unfortunately, he does not indicate the proportion of salt nor the alcohol
content of the thermometric liquid. In chap. V (“What can be deduced from
these observations?”) Navarrete explains that these limits correspond to “regular
conditions”, but they may be exceeded. Figure 6 shows the measurements
recorded by Navarrete from December 1728 to February 1730. The sensitivity or
resolution of the scale is 0.5 degrees (on 12 July 1729 Navarrete recorded T=38.5 degrees, and from 26 to 28 December 1729, T=87.5 degrees). The
author indicates the appearance of frosts on 25 December 1728 (T=90),
28 December 1728 (T=99), and 19 February 1729 (T=98) and explains
that on 2 February 1729, when the thermometer indicated T=86, “ice
melted”. We estimate the minimum value indicated as T=90 as the
threshold value of the occurrence of frosts. In relation to the
“equilibrium” (T=50), Navarrete indicates that “it is normal that
during the month of May cold and heat equalize, on 29 May the thermometer
reached the exact average value”.
Temperatures measured and scale defined by Navarrete with the
Florentine thermometer.
We do not know the exposure conditions or the time of day at which
measurements were taken. However, some information may be obtained from the
analysis of the text. In particular, when the author describes the month of
July, he explains that “on the first day, the thermometer exposed to the sun
at siesta time increased from 39 to
12”. Given the magnitude of other measurements (for instance, T=34 on
25 July 1729, “the warmest day of the year”), we can infer that
measurements were taken sheltered from the solar radiation (probably indoors)
in the afternoon (“siesta”).
Therefore, these measurements may be regarded as proxies of daily maximum
temperatures (Camuffo, 2002; Wheeler, 1995).
We have tried to calibrate these measurements accepting a linear relationship
between the scale used by Navarrete and the Celsius scale (Vittori and
Mestitz, 1981). For calibration, taking into account the previous comments,
we assign 0.0±0.1∘C to T=90.0±0.5 (frosts) and 23.3±0.1∘C (mean value of daily maximum temperature corresponding
to May during the reference period 1906–1930 and standard error at the
95 % confidence level) to T=50.0±0.5 (“equilibrium”). This last
hypothesis is based on results of the previous section that indicated the
similarity between temperatures of the period 1706–1730 and
1906–1930. The calibration equation is
∘C=aT+b.
Using the law of propagation of uncertainty, the parameters of the equation
are a=-0.58±0.02∘C/T and b=52±2∘C.
Equation (4) was applied to the daily temperatures recorded by Navarrete, and
afterwards the monthly mean values were estimated and compared with the
monthly mean value of daily maximum (mean) temperatures TX (TM) recorded
during the period 1906–1930. Results are showed in Fig. 7. It may be seen
that conditions were colder than modern reference values in winter 1729,
autumn 1729, and winter 1730, even with values lower than reference period TM
values. From May to August, however, reconstructed values and their margin
errors match with modern TX values.
Monthly mean value of daily temperature in 1729 and error margins
estimated and comparison with monthly mean value of daily maximum
temperature (TX) and monthly mean value of daily mean temperature (TM) of
1906–1930.
Winter 1729, “the coldest winter seen in 24 years” according our author,
deserves special attention. Figure 8 summarizes quantitative and qualitative
observations made during this winter: the first days of December 1728 were
dominated by a “cold fog” and high pressures. A sharp decrease in pressure
marked the snowfall on 13 December and three consecutive rainy days from 19
to 21 December. Frosts, rainfall, snowfall, hail, and northern winds
characterized the last days of this month, with T=100.0±0.5 (-6±4∘C, according our calibration) on 29 December. After cloudy days
on 30 and 31 December, 4 snowy days (on 7, 12, 13, and 18 January) were
recorded (in the reference period, the mean value of snowy days is 0). Ice
and snow stayed “in shady places” until 2 February, when it rained. During
February “fog, sun, and frosts continued”. Temperatures indicated by the
author during this winter were colder than T=78.0±0.5 (7±4∘C). Figure 9 shows the monthly average sea level pressure field
(SLP; Fig. 9a, c, e), and anomalies of the SLP field with respect to the
reference period (Fig. 9b, d, f) according to the independent reconstruction
by Luterbacher et al. (2002), available at http://climexp.knmi.nl (last
access: 28 March 2019). Anticyclonic conditions, especially during February,
made possible the appearance of frosts and morning fogs, with northwestern
winds. The negative anomalies corresponding to December and January would
explain the predominance of rainfall and snowfall between mid-December and
mid-January.
Observations during winter 1729. Left axis (dots): temperature
according to Navarrete's scale. Right axis: rainy and snowy days.
Reconstruction of the monthly SLP field in western
Europe (a, c, e) and anomalies of the monthly SLP field with respect
to the reference period 1906–1930 (b, d, f) for
December (a, b), January (c, d), and February (e, f) 1729, according to Luterbacher et al. (2002).
Atmospheric pressure was measured using an English barometer. The observer
was more interested in the fluctuations of this variable than in absolute
values. So, sometimes, he records deviations with respect to a mean value,
which it is not specified (in the 20th-century reference period, the annual
mean value of pressure in Granada is 939 hPa, of an order of 28 English
inches). A deviation of 1 line means changes of an order of 3 hPa.
Barometers usually had a mobile scale with qualitative marks (Guijarro,
2005), from the highest value (“very dry”) to the lowest value (“very
wet”). The number of quantitative measurements is scarce, and we do not know
the exposure conditions nor the temperature of the barometer; in consequence
it is impossible to apply the usual correction to 0 ∘C. Information
on atmospheric pressure is basically qualitative, with references to “very
dry”, “good weather”, “variable”, “windy and/or wet”, and “very wet”
categories. “very dry” conditions are recorded on 12 December 1728, with a
positive deviation of 4 lines above the mean line, that is, around 12 hPa.
On 13 December, according to the author, “the thermometer and the barometer
fell four lines in the morning. I predicted snow. It arrived soon; it was a
lot of snow and persisted all day”. The categories “variable” and “good
weather” are associated with pressure values 1 line above the mean value
(for instance on 25 April 1729 and 17 January 1730). The class “windy and/or
wet” indicated by the barometer is associated with information on snowfall
(27 December 1728), strong rainfall (26 September 1729), or intense rainfall
accompanied by westerly winds (30 November 1729). On 29 December 1728 the
barometer indicated “very wet” conditions (“it rained a lot and hailed”).
Therefore, pressure information is related to other variables (snowfall,
rainfall, winds). Sometimes, the author summarizes the general behavior of a
concrete month, for instance when he indicates that during April 1729
“westerly winds continued, with clouds and water, well-marked by the
barometer”. This month it rained on days 1, 2, 8, 11, 13, 14, and 23; that
is to say, there were 7 rainy days, coinciding with the average value of days
with rain higher than 1 mm during the reference period 1971–2000 (INM,
2004; data on rainy days are not available in the database by Luna et
al. (2012). Therefore, we used the AEMET climate summary of the reference
period 1971–2000). Note that rainfall information is often accompanied by
information on west winds, and cold weather is associated with north winds.
South winds are associated with hot conditions (for instance, on 29 May “a
southeast wind blew, and the afternoon was hot”, and the author indicates
southwest wind on 25 July 1729, “the warmest day of the year”). As we know,
from the analysis of the 20th-century climate in the Iberian Peninsula,
westerly flow in winter is connected with a higher percentage of extreme
precipitation, and cold extremes are associated with the advection of cold
air masses from the north (Fernández-Montes et al., 2012). On the other
hand, a great part of warm days in spring and summer is related to southern
flows (Fernández-Montes et al., 2013). Therefore, although the
information yielded by Navarrete is scarce, it seems coherent with climatic
observations based on instrumental data in the 20th century.
Discussion
In this work we have reconstructed the climatic mean conditions of a poorly
documented period for Spain (the first third of the 18th century) in Granada
(southern Spain) using documentary data. To date, there have been few
attempts to reconstruct temperatures in the Iberian Peninsula, due to the
scarcity of information (Bullón, 2008). Therefore, this work represents a
new contribution to reconstruct historical temperatures in Spain. Results
suggest that during 1706–1730, temperatures were very similar to those of the
first decades of the 20th century, when the warming signal may be considered
very small in comparison with the last decades of the 20th century. This
result contrasts with the analysis by Taborda et al. (2004) on southern
Portugal, where the two first decades of the 18th century were very cold. A
possible explanation may be the variation in climate conditions from west to
east in the southern Iberian Peninsula. The climate of Granada is characterized
by a diminishing of the Atlantic mechanisms that affect the southwestern Iberian
Peninsula and a strengthening influence of the Mediterranean mechanisms. The
convenience of distinguishing between western and eastern stations (particularly
in winter) has been highlighted in a previous work (Rodrigo, 2018b). We must note
that the period 1706–1730 is immediately subsequent to the coldest years of
the Maunder Minimum in central and northern Europe. Luterbacher et al. (2004,
2007) and Xoplaki et al. (2005) found a warming trend in European winter and
spring temperatures from the late Maunder Minimum, culminating in the late
1730s. On the other hand, the mean value of the autumn temperature in central
England between 1729 and 1738 was 10.5 ∘C, equal to that recorded
during 1991–2000 (Jones and Briffa, 2006). Warming from the markedly cold
decade of the 1690s to the 1730s is probably due to the scarcity of major
explosive volcanic eruptions from the early 1700s compared to the previous
two decades (Jones and Briffa, 2006). It is an open question whether there were differences between
southern and northern Europe, but our results suggest
that temperature trends in Granada were similar to those of central and
northern Europe.
In relation to rainfall, there are no clear differences between periods,
except in spring of 1976–2000, when there were drier conditions than in the
past. According to dendroclimatological studies (Manrique and
Fernández-Cancio, 2000), the main phase of the Little Ice Age in Spain
corresponds to the 16th and 17th centuries, with a high variability. This high
variability has also been recorded from dendroclimatological studies covering
the whole Mediterranean Basin (Nicault et al., 2008). According to these
analyses, the 18th century marks the beginning of a period with more stable
conditions. This result has also been found by Spanish climate historians
(Font Tullot, 1988; Alberola Romá, 2014). Therefore, the Little Ice Age
was not a continuous and homogeneous cold and wet period in southern Spain,
but it was characterized by the alternation of different phases, and the
first third of the 18th century would correspond to a more stable phase.
We have retrieved a new early meteorological data series, from December 1728
to February 1730, probably the first instrumental series measured in Spain.
Although the series and metadata are not complete, it has been possible to
calibrate the scale defined by the author and convert temperature values to
Celsius degrees. Applying Eq. (4) we calculate that T=100.0±0.5
(“maximum cold” recorded) is equivalent to -6±4∘C and T=34.0±0.5 (“maximum heat” recorded) to 32±3∘C. The
value T=12.0±0.5 (recorded on 1 July 1729 at the afternoon and with
the thermometer exposed to solar radiation) would be equivalent to 45±2∘C. These values are plausible: “maximum cold” (obtained when
thermometer is in a bath of snow with salt ammoniac) must correspond to a
temperature below 0 ∘C (due to the freezing-point depression of a
salt solution), the mean value of daily maximum temperatures in July is 32.7±0.1∘C, and the absolute daily maximum temperature is 40.9±0.1∘C during the reference period 1906–1930. Additionally, the
estimation of monthly mean values of temperature is in a good agreement with
qualitative comments made by Navarrete in chap. XVI, where he describes
winter 1729, autumn 1729, and winter 1730 as cold seasons and spring 1730 as a warm season, and he does not indicate particular conditions for summer 1730,
which, in consequence, it may be regarded as a “normal” season. Other
variables (surface atmospheric pressure, rainfall, wind direction) are
presented in a qualitative way, but they allow inferences in relation to
atmospheric circulation at certain times within the brief period described by
the author.
Conclusions
As a result of this work, some conclusions can be obtained.
Seasonal temperature and rainfall during the period 1706–1730
were very similar to those in the 1906–1930 period, at the
beginning of the 20th century, when the global warming signal was of less
importance. The first decades of the 18th century can be characterized as a
period of transition to a new phase after the coldest years of the Maunder
Minimum period.
Some important extreme events were detected, such as the drought in the first
half of the 1720s and the cold wave during winter 1729.
The original temperature scale was calibrated and converted to the Celsius
scale, obtaining plausible values, which, at daily and monthly timescales,
allow us to characterize the annual cycle of temperature in 1729.
The reconstruction agrees with independent reconstructions of past
climates, in particular, the sea level pressure field in western Europe.
More research is needed to complete our view on past climate conditions. In
particular, it is hoped that more daily instrumental observations and weather
registers may eventually come to light. The enlargement of databases, and the
study of documentary data and early instrumental data, may contribute to the
knowledge of natural climate variability and, therefore, to the understanding
of climate processes.
Data availability
Data are available at
http://hdl.handle.net/10835/6248 (Rodrigo, 2018a).
Competing interests
The author declares that there is no conflict of
interest.
Acknowledgements
The author wishes to express his gratitude to the anonymous referees for
their useful comments.
Review statement
This paper was edited by Chantal Camenisch and reviewed by
two anonymous referees.
References
ACAF: Archivo Capitular de Arcos de la Frontera, in: Libro Capitular y
Cabildo, Rogativa a Na Sa de las Nieves, Arcos de la Frontera, 1723.
AHVM: Archivo de la Hermandad de la Virgen de la Merced, Rogativas a la
Virgen de la Merced, Jerez de la Frontera, 1722.
Alberola Romá, A.: Los Cambios Climáticos. La Pequeña edad de
Hielo en España, Cátedra, Madrid, España, 341 pp. 2014.Alcoforado, M. J., Vaquero, J. M., Trigo, R. M., and Taborda, J. P.: Early
Portuguese meteorological measurements (18th century), Clim. Past, 8,
353–371, 10.5194/cp-8-353-2012, 2012.
Anduaga Egaña, A.: Meteorología, Ideología y Sociedad en la
España comtemporánea, Consejo Superior de Investigaciones
Científicas, Madrid, España, 450 pp., 2012.Barriendos, M., Ruiz-Bellet, J. L., Tuset, J., Mazón, J., Balasch, J. C.,
Pino, D., and Ayala, J. L.: The “Prediflood” database of historical floods
in Catalonia (NE Iberian Peninsula) AD 1035–2013, and its potential
applications in flood analysis, Hydrol. Earth Syst. Sci., 18, 4807–4823,
10.5194/hess-18-4807-2014, 2014.Brázdil, R., Pfister, C., Wanner, H., von Storch, H., and Luterbacher,
J.: Historical climatology in Europe – the state of the art, Climatic
Change, 70, 363–430, 10.1007/S10584-005-5924-1, 2005.Brázdil, R., Kiss, A., Luterbacher, J., and Valásek, H.: Weather
patterns in eastern Slovakia 1717–1730, based on records from the Breslau
meteorological network, Int. J. Climatol., 28, 1639–1651,
10.1002/joc.1667, 2008.
Brázdil, R., Dobrovolný, P., Luterbacher, J., Moberg, A., Pfister,
C., Wheeler, D., and Zorita, E.: European climate of the past 500 years: new
challenges for historical climatology, Climatic Change, 101, 7–40, 2010.
Brönnimann, S., Brugnara, Y., Allan, R. J., Brunyet, M., Compo, G. P.,
Crouthamel, R. I., Jones, P. D., Jourdain, S., Luterbacher, J., Siegmund, P.,
Valente, M. A., and Wilkinson, C. W.: A roadmap to climate data rescue
services, Geosci. Data J., 5, 28–39, 2018.
Brunet, M., Saladié, O., Jones, P., Sigró, J., Aguilar, E., Moberg,
A., Lister, D., Walther, A, Lopez, D., and Almarza, C.: The development of a
new dataset of Spanish daily adjusted temperature series (SDATS)
(1850–2003), Int. J. Climatol., 26, 1777–1802, 2006.Bullón, T.: Winter temperatures in the second half of the sixteenth
century in the central area of the Iberian Peninsula, Clim. Past, 4,
357–367, 10.5194/cp-4-357-2008, 2008.Camuffo, D.: Calibration and instrumental errors in early measurements of air
temperature, Climatic Change, 53, 297–329, 10.1023/A:1014914707832,
2002.
Demareé, G. R.: The neo-hippocratic hypothesis – an integrated 18th
century view on medicine, climate and environment, Zeszyty Naukowe
Uniwersutetu Jagiellonskiego, MCLXXXVI, Prace Geograficzne, Zeszyt, 102,
515–518, 1996.Domínguez-Castro, F., García-Herrera, R., Ribera, P., and Barriendos,
M.: A shift in the spatial pattern of Iberian droughts during the 17th
century, Clim. Past, 6, 553–563, 10.5194/cp-6-553-2010,
2010.Domínguez-Castro, F., Trigo, R. M., and Vaquero, J. M.: The first
meteorological measurements in the Iberian Peninsula: evaluationg the storm
of November 1724, Climatic Change, 118, 443–455,
10.1007/s10584-012-0628-9, 2013.Domínguez-Castro, F., Vaquero, J. M., Rodrigo, F. S., Farrona, M. M.,
Gallego, M. C., García-Herrera, R., Barriendos, M., and
Sánchez-Lorenzo, A.: Early Spanish Meteorological records (1780–1850),
Int. J. Climatol., 34, 593–603, 10.1002/joc.3709, 2014.
Fahrenheit, D. G.: Experimenta & observationes de congelatione aquæ in
vacuo factæ, Philosophical Transactions, 1724, 78–84, 1724.Fernández-Montes, S., Seubert, S., Rodrigo, F. S., and Hertig, E.:
Wintertime circulation types over the Iberian Peninsula: long-term
variability and relationships with weather extremes, Clim. Res., 53,
205–227, 10.3354/cr01095, 2012.Fernández-Montes, S., Rodrigo, F. S., Seubert, S., and Sousa, P. M.:
Spring and summer extreme temperatures in Iberia during last century in
relation to circulation types, Atmos. Res., 127, 154–177,
10.1016/j.atmosres.2012.07.013, 2013.
Font Tullot, I.: Historia del clima de España, Instituto nacional de
Meteorología, Madrid, España, 297 pp., 1988 (in Spanish).Fragoso, M., Marques, D., Santos, J. A., Alcoforado, M. J., Amorim, I.,
García, J. C., Silva, L., and Nunes, M. F.: Climatic extremes in
Portugal in the 1780s based on documentary and instrumental records, Clim.
Res., 66, 151–159, 10.3354/cr01337, 2015.
Gil Albarracín, A. (Ed.): Francisco Fernández Navarrete 1732. Cielo
y suelo granadino (transcripción, edición, estudio e índices),
GBGeditora, Almería-Barcelona, 1997.
Giorgi, F.: Climate Change hot-spots, Geophys. Res. Lett., 33, 217–222,
2006.
Guijarro, V.: El barómetro y los proyectos meteorológicos de la
Ilustración: el caso español, ENDOXA Series Filosóficas, 19,
159–190, 2005.
INM: Guía resumida del Clima en España 1971–2000, Instituto
Nacional de Meteorología, Madrid, 257 pp., 2004.
Jones, P. D. and Briffa, K. R.: Unsual climate in northwest Europe during the
period 1730 to 1745 based on instrumental and documentary data, Climatic
Change, 79, 361–379, 2006.Luna, M. Y., Guijarro, J. A., and López, J. A.: A monthly precipitation
database for Spain (1851–2008): reconstruction, homogeneity and trends, Adv.
Sci. Res., 8, 1–4, 10.5194/asr-8-1-2012, 2012.Luterbacher, J., Xoplaki, E., Dietrich, D., Rickli, R., Jacobeit, J., Beck,
C., Gyalistras, D., Schmutz, C., and Wanner, H.: Reconstruction of sea level
pressure fields over the Eastern North Atlantic and Europe back to 1500,
Clim. Dynam., 18, 545–561, 10.1007/s00382-001-0196-6, 2002.Luterbacher, J., Dietrich, D., Xoplaki, E., Grosjean, M., and Wanner, H.:
European seasonal and annual temperature variability, trends and extremes
since 1500, Science, 303, 1499–1503, 10.1126/science.1093877, 2004.Luterbacher, J., Liniger, M. A., Menzel, A., Estrella, N., Della-Marta, P.
M., Pfister, C., Rutishauser, T., and Xoplaki, E.: The exceptional European
warmth of autumn 2006 and winter 2007: Historical context, the underlying
dynamics and its phenological impact, Geophys. Res. Lett., 34, L12704,
10.1029/2007GL029951, 2007.
Manrique, E. and Fernández-Cancio, A.: Extreme climatic events in
dendroclimatic reconstructions from Spain, Climatic Change, 44, 123–138,
2000.
Navarrete, F. F.: Cielo y suelo Granadino. Idea de la Historia Natural de
Granada en varias observaciones Físicas, Médicas y Botánicas,
Biblioteca y Archivo de la Provincia Franciscana de Cataluña, Barcelona,
Ms. 1/E/8, 1732.Navarrete, F. F.: Efemérides barométrico-médicas matritenses,
Biblioteca de la Universidad de Sevilla, sgn: 110-57, available at:
http://fondosdigitales.us.es (last access: 28 March 2019), 1737.Nicault, A., Alleaume, S., Brewer, S., Carrer, M., Nola, P., and Guiot, J.:
Mediterranean drought fluctuation during the last 500 years based on
tree-ring data, Clim. Dynam., 31, 227–245, 10.1007/s00382-007-0349-3,
2008.Owens, M. J., Lockwood, M., Hawkins, E., Usoskin, I., Jones, G. S., Barnard,
L., Schurer, A., and Fasullo, J.: The Maunder Minimum and the Little Ice Age:
an update from recent recosntructions and climate simulations, J. Space
Weather Spac., 7, A33, 10.1051/swsc/2017034, 2017.
Rodrigo, F. S.: A new method to reconstruct low-frequency climatic
variability from documentary sources: application to winter rainfall series
in Andalusia (southern Spain) from 1501 to 2000, Climatic Change, 87,
471–487, 2008.Rodrigo, F. S.: Afecciones meteorológicas: Medicina y Meteorología
en Andalucía 1754–1852, Obradoiro de Historia Moderna, 25, 95–113,
10.15304/ohm.25.2944, 2016.Rodrigo, F. S.: Meteorological observations in Granada 1706–1730, Data
Repository, University of Almería, Spain,
http://hdl.handle.net/10835/6248 (last access: 28 March 2019), 2018a.Rodrigo, F. S.: A review of the Little Ice Age in Andalusia (southern Spain):
results and research challengues, Geographical Research Letters, 44,
245–265, 10.18172/cig.3316, 2018b.Rodrigo, F. S., Gómez-Navarro, J. J., and Montávez Gómez, J. P.:
Climate variability in Andalusia (southern Spain) during the period
1701–1850 based on documentary sources: evaluation and comparison with
climate model simulations, Clim. Past, 8, 117–133,
10.5194/cp-8-117-2012, 2012.
Rutherford, S., Mann, M. E., and Osborn, T. J.: Proxy-based Northern
Hemisphere surface temperature reconstructions: sensitivity to method,
predictor network, target season, and target domain, J. Climate, 18,
2308–2329, 2005.
Taborda, J. P., Alcoforado, M. J., and García, J. C.: The climate of
southern Portugal during the 18th century: a reconstruction based on
descriptive and instrumental sources, in: Geoecologia, Rel. 2, Centro de
Estudios Geográficos, Lisboa, 2004.
Vittori, O. and Mestitz, A.: Calibration of the “Florentine Little
Thermometer”, Endeavour, 5, 113–118, 1981.Wheeler, D.: Early instrumental weather data from Cádiz: a study of late
eighteenth and early nineteenth century records, Int. J. Climatol., 15,
801–810, 10.1002/joc.3370150707, 1995.
Wilks, D. S.: Statistical methods in the atmospheric sciences, Academic
Press, San Diego, USA, 464 pp., 1995.Xoplaki, E., Luterbacher, J., Paeth, H., Dietrich, D., Steiner, N., Grosjean,
M., and Wanner, H.: European spring and autumn temperature variability and
change of extremes over the last half millenium, Geophys. Res. Lett., 32,
L15713, 10.1029/2005GL023424, 2005.
Zhang, X., Hegerl, G., Zwiers, F. W., and Kenyon, J.: Avoiding Inhomegeneity
in Percentile-based Indices of Temperature Extremes, J. Climate, 18,
1641–1651, 2005.
Zúñiga, B. L.: Anales eclesiásticos y seglares de la M.N. y M.L.
ciudad de Sevilla: que comprenden la Olimpiada ó Lustro de la Corte en
ella; con dos Apéndices, uno desde el año de 1671 hasta el de 1728, y
otro desde 1734 hasta el de 1746, Biblioteca de Andalucía, Spain, Sgn.:
ANT-XVIII-470, 1747.