地元の背景気候が都市熱島に大きく貢献している
Lei Zhao1, Xuhui Lee1, Ronald B Smith2
11] Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science and Technology, Nanjing 210044, China [2] School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA.
Nature
|July 11, 2014
まとめ
都市熱島 (UHI) は,都市の熱を大気中に効率的に転送する程度によって,冷却の減少だけでなく,強化されます. このコンベクション効果は気候によって変化し,都市温暖化と熱ストレスに影響を与えます.
科学分野:
- 気候科学 気候科学
- 都市気候学 都市気候学
- 環境科学 環境科学
背景:
- 都市熱島 (UHI) は,世界の人口に大きな影響を与えるが,その要因は十分に理解されていない.
- UHIの強度 (ΔT) の定量的帰属は,効果的な緩和戦略の障壁です.
- 共通の,しかし潜在的に不完全な知覚は,UHIを減少した蒸発冷却に起因する.
研究 の 目的:
- 北米の都市における昼間の都市熱島強度 (ΔT) の要因を定量的に分類する.
- ΔTの地理的変動を説明するコンベクティブ熱伝送効率の役割を調査する.
- 都市部と農村部における熱伝導の関係に対する地元の背景気候の影響を評価する.
主な方法:
- 都市部と農村部間の温度差 (ΔT) をシミュレートし分析するために気候モデルを使用した.
- エアロダイナミック特性 (表面の粗さ) とコンベクティブ熱伝送効率の関係を調べた.
- 背景気候 (湿気と乾燥) が昼間 ΔT に与える影響を分析した.
主要な成果:
- 昼間のΔTの地理的変動は,主に都市部と農村部間のコンベクティブ熱伝送効率の違いによって説明されます.
- 空力学的に滑らかな都市表面は,効率の悪い散熱につながり,都市温暖化が増加します.
- コンベクション効果は,昼間の ΔT を大きく変化させ,湿気のある気候では 3.0 ± 0.3 K 増加させ,乾燥した気候では 1.5 ± 0.2 K 減少させます.
- 湿気のある米国東部では,より乾燥した年により高いΔTが観察され,降水-気温フィードバックを示唆しました.
結論:
- 都市表面の空気力学の影響を受けるコンベクティブ熱伝導効率は,都市熱島強度の主要な要因です.
- UHIは,湿気のある気候や乾燥した年間における熱波のストレスを悪化させ,人間の健康に悪影響を及ぼします.
- アルベド管理は,都市熱島強度の大規模な削減のための実行可能な戦略を提示します.
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