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1 Markets I: The Ecosystem and Exchange-Traded Markets市场在线 2 Markets II: Rates, FX and Credit市场在线 3 Markets III: Commodities, Energy and Crypto市场在线 4 Quantitative Methods方法在线 5 Derivatives and Volatility衍生品在线 6 Rates, Credit, XVA and Risk利率、信用与风险在线 7 Research Craft: Predictors, Backtests, Measurement, Portfolios研究在线 8 Strategies I: Equities and Futures策略在线 9 Strategies II: Volatility, Relative Value, Macro and the Bank Desks策略在线 10 Microstructure and Execution交易执行在线 11 Market Making and High-Frequency Trading做市在线 12 Machine Learning for Markets机器学习在线 13 Low-Latency Software技术在线 14 Networks, Hardware and Trading Infrastructure技术在线 15 Research, Data and Risk Platforms技术在线 16 The Desk and the Firm公司运营在线 17 The Industry: Firms, Roles and Careers职业发展在线 18 Interviews I: Maths, Probability and Speed职业发展在线 19 Interviews II: Markets, Trading Games and the Final Round职业发展在线 20 Interviews III: Code职业发展在线

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Earth and Space Sciences · 术语表

什么是 Sea-ice extent？

Definition 24.16 University Earth and Space Sciences — Year 3 · 第 24 章 — Glaciology

The sea-ice extent is the total area of the cells of a satellite map in which sea ice covers more than $15\,\%$ of the surface. It is larger than the sea-ice area, which counts only the ice itself.

Left, the mean Arctic sea-ice extent in March and in September, 1979–2026 (NSIDC Sea Ice Index, version 4), with least-squares trends (dashed): -0.38\, M km2 and -0.74\, M km2 per decade. Right, the growth of sea ice by conduction under a surface 20\, K below freezing, without ocean heat: bare ice by Stefan’s law, and the same ice under 20\, cm of snow. — Left, the mean Arctic sea-ice extent in March and in September, 1979–2026 (NSIDC Sea Ice Index, version 4), with least-squares trends (dashed): $-0.38\,\mathrm{M}\mathrm{km}^{2}$ and $-0.74\,\mathrm{M}\mathrm{km}^{2}$ per decade. Right, the growth of sea ice by conduction under a surface $20\,\mathrm{K}$ below freezing, without ocean heat: bare ice by Stefan’s law, and the same ice under $20\,\mathrm{cm}$ of snow.

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