The measurements will be made from a 65 m tall, small-cross-section tower of the type used to support radio antennas (Rohn 45G, Peoria IL), selected to minimize wind distortion and possible heating artifacts, placing the sensor well above the tallest emergent trees. The data acquisition system and most instruments and will be housed in a climate controlled hut 15-30 m west of the tower base, accessible by a dirt road. The CO2-H2O sensor will be placed close to the sonic anemometer near the top of the tower to keep tubing short.
The site is in a protected primary forest reserve at km 117 south of Santarem (IBAMA station S 03o 21.357′ W 54o 56.959′ in the Floresta Nacional do Tapajos. This site is extremely flat, an extensive planalto that drops about 30m to the level of the Tapajos river 10-15 km to the west. Soils are uniform yellow oxisols similar to soils at the site to be cut, which lies 30 km to the north. The nearest secondary road is 5 km to the east and the nearest urban area is 100 km to the North (Santarem); otherwise the area is quite isolated.
By the beginning of December, writes Columella, the farmer should have finished his autumn planting. Now, at the time of the winter solstice (December 25 in the Julian calendar), Saturnus, the god of seed and sowing, was honored with a festival. The Saturnalia officially was celebrated on December 17 (a.d. XVI Kal. Ian.) and, in Cicero’s time, lasted seven days, from December 17-23. Augustus limited the holiday to three days, so the civil courts would not have to be closed any longer than necessary, and Caligula extended it to five (Suetonius, XVII; Cassius Dio, LIX.6), which Claudius restored after it had been abolished (Dio, LX.25). Still, everyone seems to have continued to celebrate for a full week, extended, says Macrobius (I.10.24), by celebration of the Sigillaria, so named for the small earthenware figurines that were sold then.
Macrobius, in his Saturnalia, creates an imaginary symposium among pagan intellectuals that takes place then. There, he offers an explanation for the varying length of the holiday. Originally, it was celebrated on only one day, the fourteenth before the Kalends of January (December 19). With the Julian reform of the calendar, however, two days were added to December, and the Saturnalia was celebrated sixteen days before the Kalends (December 17), “with the result that, since the exact day was not commonly known–some observing the addition which Caesar had made to the calendar and others following the old usage–the festival came to be regarded as lasting for more days than one” (I.10.2). The original day now was given over to the Opalia, honoring Ops, who personified abundance and the fruits of the earth, and was the consort of Saturn. As the two deities represented the produce of the fields and orchards, so they also were thought to represent heaven and earth. It was for this reason, says Macrobius (I.10.20), that the two festivals were celebrated at the same time, the worshippers of Ops always sitting in prayer so that they touched the earth, mother of all.
In the Roman calendar, the Saturnalia was designated a holy day, or holiday, on which religious rites were performed. Saturn, himself, was identified with Kronos, and sacrificed to according to Greek ritual, with the head uncovered. The Temple of Saturn, the oldest temple recorded by the pontiffs, had been dedicated on the Saturnalia, and the woolen bonds which fettered the feet of the ivory cult statue within were loosened on that day to symbolize the liberation of the god.
It also was a festival day. After sacrifice at the temple, there was a public banquet, which Livy says was introduced in 217 BC (there also may have been a lectisternium, a banquet for the god in which its image is placed in attendance, as if a guest). Afterwards, according to Macrobius (I.10.18), the celebrants shouted “Io, Saturnalia!” at a riotous feast in the temple.
The Saturnalia was the most popular holiday of the Roman year. Catullus (XIV) describes it as “the best of days,” and Seneca complains that the entire city is in a bustle (Epistles, XVIII). Pliny the Younger writes that he retired to his room while the rest of the household celebrated (Epistles, II.17.24). It was an occasion for celebration, visits to friends, and the presentation of gifts, particularly wax candles (cerei), perhaps to signify the returning light after the solstice, and sigillaria. Martial wrote Xenia and Apophoreta for the Saturnalia. Both were published in December and intended to accompany the “guest gifts” which were given at that time of year. Aulus Gellius relates in his Attic Nights (XVIII.2) that he and his Roman compatriots would gather at the baths in Athens, where they were studying, and pose difficult questions to one another on the ancient poets, a crown of laurel being dedicated to Saturn if no-one could answer them.
During the holiday, restrictions were relaxed and the social order inverted. Gambling was allowed in public. Slaves were permitted to use dice and did not have to work. Instead of the toga, less formal dinner clothes (synthesis) were permitted, as was the pileus, a felt cap normally worn by the manumitted slave that symbolized the freedom of the season. Within the family, a Lord of Misrule was chosen. Slaves were treated as equals, allowed to wear their masters’ clothing, and be waited on at meal time in remembrance of an earlier golden age thought to have been ushered in by the god. Lucian relates that “During My week the serious is barred; no business allowed. Drinking, noise and games and dice, appointing of kings and feasting of slaves, singing naked, clapping of frenzied hands, an occasional ducking of corked faces in icy waterââ?¬â?such are the functions over which I preside (Saturnalia, ).
This equality was temporary, of course; and Petronius speaks of an impudent slave being asked at some other time of the year whether it was December yet. Dio writes of Aulus Plautius, who was to lead the conquest of Britain, cajoling his troops. But they hesitated, “indignant at the thought of carrying on a campaign outside the limits of the known world.” Only when they were entreated by a former slave dispatched by Claudius did they relent, shouting “Io, Saturnalia” (LX.19.3).
(If a time of merriment, the season also was an occasion for murder. The Catiline conspirators intended to fire the city and kill the senate on the Saturnalia, when many would be preoccupied with the festivities. Caracalla plotted to murder his brother then, and Commodus was strangled in his bath on New Year’s eve.)
At the end of the first century AD, Statius still could proclaim: “For how many years shall this festival abide! Never shall age destroy so holy a day! While the hills of Latium remain and father Tiber, while thy Rome stands and the Capitol thou hast restored to the world, it shall continue” (Silvae, I.6.98ff). And the Saturnalia did continue to be celebrated as Brumalia (from bruma, winter solstice) down to the Christian era, when, by the middle of the fourth century AD, its rituals had become absorbed in the celebration of Christmas.