51 Juan L. Minetti: Continentality Indices BERICHTE UND MITTEILUNGEN CONTINENTALITY INDICES METHODOLOGICAL REVISION AND PROPOSITION With 9 figures and 1 table Juan L. Minetti Zusammenfassung: Kontinentalitatsindizes: Methodologische into the atmosphere for a given latitude and the Revisionen und Vorschlage annual amplitude of themonthly average of temper ature. Latitude is included in Brunt's index in the Kontinentalitatsindizes wurden schon in der Vergangen radiation coming into the atmosphere. The mathe heit behandelt, aber die mathematische Behand eingehend matical has a now. lung der jahreszeitlich bedingten thermischen Wellen hat algorithm physical meaning neue Berg used a new of the in der Gegenwart eine Bewertung der Indizes erlaubt. concept continentality: pre continental air masses in a in relation Die jahrliche thermische Welle irgendeiner im aufier vailing region to mass a tropischen Gebiet liegenden Station weist einen Amplitu the total present during year. deneffekt auf, der dem Kontinentalitatsgrad zuzuschreiben Because of the difficulty to identify the types of air aber sie auch eine und masses as come sources ist, zeigt Verschiebung Asymmetrie they out from their and the in zur an der Beziehung Sonneneinstrahlung Obergrenze lack of information concerning the altitude for a der Atmosphare. three-dimensional in these Berg's In dieser Arbeit wird dafi der Phasen winkel study regions, dargestellt, is not to der ersten Harmonischen einer Fourierschen Reihe der methodology easily apply. The indices, which are based on thermal Temperatur-Monatsmittel nicht nur in Verbindung mit previous von and are difficult to in low der Verzogerung Maxima und Minima einer Welle amplitude latitude, apply er to steht, sondern dafi auch einen Index der Asymmetrie latitudes (Conrad and Pollak 1950) due the low wird Phasen darstellt. Abschliefiend gezeigt, dafi dieser temperature amplitudes of tropical humid continen winkel als Indikator des Kontinentalitats- oder Maritimi tal climates. Ratisbona (1976) says that with these zu tatsgrades eines Ortes interpretieren ist, und es wird indices the basin of Amazonas River seems to be a eine Qualifikationsskala vorgeschlagen. large ocean. This disturbing effectcaused by themen tioned variable spreads from the humid Tucumano to 1. Introduction Oranense forest, in the northwest of Argentine, the Sierras de Cordoba and the Sierras de San Luis. oceans masses not The effects of continents and upon the Oceanic only regulate the annual tem a are a wave climate of region well known in climatologi perature of region but also the phase and cal literature. Gorczynski (1920), Brunt (1924), asymmetry with regard to the external radiative Berry et wave which force the land-ocean Johansson (1926), Berg (mentioned by al. atmosphere system. 1945), Conrad (1946) and Barry and Chorley Johansson (1926) introduced an index which some account (1972) suggested indices to quantify those takes into the asymmetry of the seasonal ther effects. mal wave, the thermal amplitude and the latitude of a Due to the dependence between temperature and place. Afterwards, Prohaska (1976) discussing the Gorczynski to estimate the conti seasonal of latitude, suggested change the temperature in extratropical of a account South a or ocean nentality region by taking into the ampli America, introduced continentality tude of the annual temperature oscillation and the ity classification based upon the difference between latitude of the Later the of autumn place. on, Johansson proposed average temperatures and spring tomodify these variables and Conrad mapped them (asymmetry synonym). (Conrad and Pollak 1950). This paper will show that some of the indices which Conrad and Pollak carried on the are methodologi used to identify continental ormaritime effects in an are not cal study of the proposed indices. They regard extratropical place effective, and therefore Brunt's as a index promising one, because itworked suggests an improved classification based upon the to according the average radiation amplitude coming phase and asymmetry of the seasonal thermal wave. 43/1989 52_Erdkunde_Band 2. Materials andMethods 3. Results and Discussion means ocean as a Monthly of 30-year temperature records in In this paper the is regarded reservoir of 356 places of the Southern Hemisphere (176 belong energy, large enough to regulate the amplitude of were to sea to Argentine) computed in this analysis. The annual temperature, delay and change the sources were wave the Climatological Statistics published sonal thermal in large regions. by the ServicioMeteoroldgico Nacional (1944, 1958, It is useful to remember that the local variation of 1969, 1974, 1981), theUSA Department ofCommerce temperature T? may be represented by themodel: (1959, 1966) and Prohaska (1976). _ dT? = dT? _> The following indicators of continentality were (4) used in the -r-_?H.VHT? analysis: with: a) Index of Johansson (1926), used by Conrad Sometimes it is mentioned as Conrad's ar (1946). ?-= local variation of a fixed index. * temperature (in geographical station) ???dT? with: = individual variation of * temperature (mov K: index of able to the continentality (%) * according parcel) T? = horizontal advection A: range of annual temperature vH Vh temperature = = a and b: constants, (a 1.7; b 14) Moreover, <p:latitude 1 ~= dT? dW _ b) Prohaska (1976, p. 43) classifies extratropical (5) South American into continental and mari cF"""ir-w" places with: time ones, on the base of the of the asymmetry = at constant Cp specific heat of air pressure seasonal change of temperature (difference between the of autumn and average temperatures spring). = variation of the received and emitted The criteria are: energy Continental climates: w = vertical of air - velocity = May average temperature September average g gravity acceleration <0 = temperature q air density Maritime climates: - or term - wg q air compression expansion (it repre May average temperature September average sents the adiabatic variations of parcel temperature) temperature >0 In this case the limit between continental and mari The variation of energy with time is a function of time climates is given by the same temperature the energy balance. The balance of energy may be autumn reached in and spring. represented by: c) This work is based upon the following hypothesis. = W (Q+q)(l-a) + Ii-It (6) It is supposed that the phase angle as well as the wave = asymmetry of the seasonal thermal could be W H + LE +AF (7) the of the first har properly represented by phase where the three terms of show the balance of short from a Fourier's for discrete series (6) monic, analysis and wave radiation or net radiation and to N = so that the wave for the most long (Rn), according 12, shows the flow of sensible and latent heat and the of the be as: (7) part variability may represented one acts balance surface net energy. The last only over ocean Afterwards: T,= T + (2) the (Sellers 1972). A,si?(ifl,)+B,cos(Jfl?) dw aw _ = = (8) with Tt monthy average temperature, T annual ir=ir+VH,vw average temperature and It is supposed by the aforesaid that the variation of = = temperature of a place is a function of energy balance A1 2/N I N P=12 Ttsin(^-t)V 7 fluctuation, adiabatic processes and energy advec (3) tion. This situationmay be represented by themodel: = = = Bj 2/N E Tt cos (?? N P 12 - xj ar /aw - \ =f vh VHw, (9) = "37" \~^~' wge) 0 arc tgBj/Aj, called phase angle. some Land and sea features different answers to the Later on, adjustments between variables give because of their different (containing simple or logarithmically transformed balance of local energy spe 1 an of for two values) are made, using the least square method cific heats. Fig. shows example "Q" America. So it is seen that the (Brooks and Carruthers 1953). places of South easily Juan L. Minetti: Continentality Indices 53 2 calcm dia0 I Riode Janeiro (Brazil) I ?Cr30 11001 asymmetry of the wave, changing the sine-shaped iooo- '28 y^y\ ^^^V I type. On thewhole, the thermal wave shiftsfrom 15 days Insolation900- / (Argentine) -26 | f j to one '^-^Rivadavia month in the continental regions and from "800- 15 to twomonths in the oceanic ones with y/S\s | jj -24. days respect to the incoming radiation wave. In order to delimit how effective the advection of the "inland" sea -S600- -20 to accurate a / / ?l vL I energy is thermal control, quantifica tion of the 0" is necessary. This hori 500- / I \ -18 "phase angle j movement sea zontal zonal takes place from the to I 400-I -16 continent and vice versa. I I tem -I-.-.-,-1-r-J-1-.-1-,-,-r-J-V14300 Fig. 2 shows the seasonal variation of average JASONOJ FMAMJ J some M o n t h s perature for places in Australia and South a America and oceanic zones and western Fig. 1: Annual distributions of temperature for maritime (continental - a and eastern city (Rio de Janeiro Brazil) and continental city (Riva coasts). - davia of In order to waves to Argentine). Quantities (by cal/cm2 day) compare thermal with regard are received energy indicated by uninterrupted line. phase and distortion and to eliminate amplitude, of with to the insolation Delays temperatures respect Fig. 3 shows the same graphics in terms of the relative curve are represented by arrows temperature with respect to the annual thermal Jahrliche Temperaturverteilung fiir eine maritime Stadt - amplitude. de und Stadt (Rio Janeiro Brasilien) eine kontinentale to - According Prohaska's criteria, temperatures (Rivadavia Argentinien). Die Energiemengen der Inso are higher in autumn than in spring in places located lation (in cal/cm2 und Tag) sind mit einer durchgezoge in the oceans and on the coasts; the seasonal wave nen Linie dargestellt. Verzogerungen der Temperatur in on zur delay the Southeastern Pacific Ocean is lower Bezug Insolationskurve sind durch Pfeile gekenn zeichnet than on the Southwestern one; there is a three month mild winter maximum in South America compared with a short minimum in Australia.