地図は地理学の生命であり,地図作成は地理学者が最も精魂を傾ける側面の1つである.地図は「地理学の言語」である.地理学者は1枚の白紙を地図という言語(記号系)に転化し,それを媒体として自己の主張を表現し伝達する.この転化過程は,次の2つの要件を満足しているはずである.第1に,その過程は無矛盾な記号系への転化過程でなければならない.さもなくば,地図は最も基本的な機能ですら果たすことができない.第2に,その過程は同時に地図が研究手段としての有効性を獲得していく過程でなければならない.さもなくば,地図は単なる表現・伝達の道具に終始する.しかし,この転化過程の真相,すなわち「地図を描く」ことの本質は,具体的作業の裏に隠蔽されている.もしその本質が解明できるならば,研究手段としての地図の能力は高まるであろう.本稿はその転化過程の掘り起こしを試みたものである.このような議論は,「カルトグラフィ」を超えた「メタカルトグラフィ」とみなされよう.

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まず,月日別にまとめた気圧配置型の出現頻度の統計値を使って,日本の季節区分を行なった.すなわち次の14季節である.初春3月1日～3月17日,春3月18日～5月4日,晩春5月5日～5月21日,初夏5月22日～6月10日,梅雨6月11日～7月16日,夏7月17日～8月7日,晩夏8月8日～8月20日,初秋8月21日～9月11日,秋雨9月12日～10月9日,秋10月10日～11月3日,晩秋11月4日～11月25日,初冬11月26日～12月25日,冬12月26日～1月31日,晩冬2月1日～3月28日.次に各季節について,次の項目を計算した. (1) 各気圧配置型の出現頻度, (2) 札幌・新潟・東京・鹿児島の4地点における種々の気象要素(海面気圧・平均気温,日最高気温,日最低気温,水蒸気圧,相対湿度・雲量・風速・日降水量・日照時間)の平均値, (3) 4日間の気圧配置型の組み合わせの出現回数これらによって各季節の特徴を記述した.

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An attempt was made to clarify the atmospheric conditions associated with high SO₂ pollution, and the diurnal changes of the relation between atmospheric conditions and air pollution were discussed regarding its regional difference in a multiple-source situation. Mean hourly SO₂ measurements at nine stations in Sendai (Fig. 1) were analyzed by a statistical method.
In order to evaluate not only the factors having effects upon the day-to-day variation in concentration but also the diurnal and regional change patterns of the factors, daily SO₂ data were examined at each hour by using Factor Analysis. Contributions of main factors, that is, “first-factor” and “second-factor”, are shown in Fig. 3. Because of high contribution throughout the day, the day-to-day variation in the suburban area is generally explained by the “first-factor”. On the other hand, in the built-up area, a major source area, the variation in the daytime is mainly connected with the “second-factor”, though the night-time variation is caused by the “first-factor”. In the built-up area, therefore, the atmospheric condition which causes air pollution at night is considered to be different from that which causes it in the daytime.
High concentrations resulting from the “first-factor” occur in the suburban area through-out the day and in the built-up area at night under a migratory anticyclone, whereas those from the “second-factor” occur in the daytime in the built-up area under windy conditions when winter-monsoon prevails (Fig. 4).
Fig. 5 shows mean concentrations classified by wind speed at two selected stations. When it is windy, the concentration at Station-4 in the built-up area increases extremely by day, but it decreases by night. On the other hand, the concentration at Station-1 in the suburban area increases with decreasing wind speed throughout the day. According to Fig. 6, showing the high-pollution appearance classified both by wind speed and lapse rate (between Station-A (H: 38m) and Station-B (H: 220m)), high concentrations at night tend to occur under calm and stable conditions at the both stations.
Therefore, the “first-factor” corresponds to the meteorological conditions for stagnation of pollutants, while the “second-factor” corresponds to conditions for “gale-pollution”. Pollutants are generally much diluted by the strong wind, and concentration decreases with the distance from the sources. However, strong wind tends to be accompanied with extraodinary high concentrations due to exposure of undiluted plume in the vicinity of active sources, where the effect of strong wind is in opposition to its diluting action.
Thus, the relationship between concentration and meteorological condition not only varies from place to place in a small area but also changes diurnally.

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