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我国水文地理研究领域的主要开拓者,著名地理学家、中科院院士刘昌明提出:“研究尺度不一样,分析结果就不一样。地理现象在一定比例尺上表现的信息量是不一样的”
我国生态学、自然地理学家,中科院院士傅伯杰指出:“地理现象在时间、空间尺度的表征,随着观测时空分辨率的变化,获得的信息也在变化;不同的研究对象有其对应的时间空间尺度,需要研究与发现其时空尺度特征;观测尺度与地理现象的时空尺度要匹配。“
尺度问题,有空间尺度和时间尺度;下图是Sturman and Tapper (1996,2006)The weather and climate of Australia and New Zealand, 2nd edition书中关于尺度的划分。
一、空间尺度
空间尺度是术语尺度的特定应用,用于描述或分类(例如,按数量级)空间的大小(因此是空间的),或现象或过程发生的程度。
例如,在物理学中,如果物体或现象太小而无法看到,则可以将其称为微观。在气候学中,微气候是可能发生在山区、山谷或湖岸附近的气候。在统计学中,大趋势是一种政治、社会、经济、环境或技术趋势,它涉及整个地球或应该持续很长时间。这个概念也用于地理、天文学和气象学。
1、Micro-微观 :
Microscale meteorology or micrometeorology is the study of short-lived atmospheric phenomena smaller than mesoscale, about 1 kilometre (0.6 mi) or less.
2、Meso-中观:
Mesoscale meteorology is the study of weather systems smaller than synoptic scale systems but larger than microscale and storm-scale cumulus systems. Horizontal dimensions generally range from around 5 kilometers to several hundred kilometers.
Meso-alpha 200–2000 km scale of phenomena like fronts, squall lines, mesoscale convective systems (MCS), tropical cyclones at the edge of synoptic scale
Meso-beta 20–200 km scale of phenomena like sea breezes, lake effect snow storms
Meso-gamma 2–20 km scale of phenomena like thunderstorm convection, complex terrain flows (at the edge to microscale, also known as storm-scale)
3、Macro-宏观/Synoptic-综观:
The synoptic scale in meteorology (also known as large scale or cyclonic scale) is a horizontal length scale of the order of 1000 kilometers (about 620 miles) or more.
synoptic scale:The scale of the migratory high and low pressure systems (or cyclone waves) of the troposphere with wave lengths of 1000–4000 km.
4、Local-regional区别
Local is a small area around some place while regional is a larger area. For example, if you live in Tokyo, the Local name is Tokyo, Regional name might be the Kanto Area. Local is a small area around some place while regional is a larger area.
二、时间尺度
https://www.zhihu.com/question/63779947/answer/220348561
https://www.nature.com/articles/s43017-021-00155-x
Gerald A. Meehl 2021 figure 1
1、时间尺度划分
时间尺度上从秒(second),分钟(miniute),小时(hour),到天(day),周(week),这些小于2周(14天)的时间尺度一般都和天气(weather)密切相关。
月(month),季节(season/seasonal),年(year/annual),年际(interannual, multi-year),年代际(decadal),多年代际(multi-decadal, inter-decadal),再往上还有世纪尺度的(secular),这些时间尺度就是常说的气候(climate)。
2、annual、inter-annual和decadal说明
annual一般指季节以上一年以下的年变率;annual这里的意思应该是要指period小于一年的变化,可以包括seasonal cycle,subseasonal,seasonal variability,气候学上常见的有自然的季节变化,热带季节内振荡Madden Julian Oscillation,etc.
inter-annual,multi-year,这些年际变率主要是指时间尺度大于一年小于9到10年的变率,multi-year在有些文献中指5-8年,一般大于1年小于9到10年的变率都可以称作inter-annual,主要也是因为很多变率表现出了跨时间尺度的特征(multi time scales),所以inter-annual,multi-year这些名词囊括了众多变率。如果细分还有Biennial(两年一次的),quasi-biennial(准两年一次的),等等。常见的interannual的变率有El Nino-Southern Oscillation (ENSO),AO/NAO等等。
decadal,年代际一般指周期10年左右,往上甚至可以形容到20-30年周期的变率,如果细分也有quasi-decadal(准年代际),就是为那些周期介于8、9年到15年的变率提供的。decadal常常和multi-decadal,inter-decadal一起出现,通常文献中会这么写decedal/multi-decadal variability,其实就是笼统地说年代际/多年代际变率,它们的特征周期都在10年以上。
3、时间前缀含义
sub-:来源拉介词sub,意为“under,from under”等,表示“在下”的位置或“自下而上”的运动。
inter-:意思是“在…之间(between 或 among)”
intra-:意思是“在…之内(inside 或 within)”
multi-:来源于拉丁语的multus,意为“many,much”
举例说明:
Inter-annual:interannual is occurring between years, or from one year to the next while annual is happening once every year.
Intra- and Inter-annual Variation of Soil Microbial and Enzymatic Response to Water and Nitrogen Addition in a Chinese Semi-arid Steppe
multi-year:多年 for more than one year
The 2018–2020 Multi-Year Drought Sets a New Benchmark in Europe
subseasonal:次季的,表示与上一年的这个季节比
intraseasonal:季内的,表示这个季节内部的时间
Intra-annual and intra-seasonal flow dynamics of a High Arctic polythermal valley glacier
4、关于seasonal和subseasonal
https://www.ibm.com/blogs/internet-of-things/what-is-seasonal-and-subseasonal-forecasting/
seasonal:最多 7 个月的时间间隔
Seasonal forecasts predict weather anomalies at monthly intervals up to 7 months out.
subseasonal:每周生成一次,最长可达 5 周
Subseasonal forecasts are generated at weekly intervals up to 5 weeks out.
5、Adusumilli 2019 GRL
From the joint GPS-GRACE inversions, we derived weekly TWSA on a uniform 0.5° grid in units of equivalent water height (EWH). To better understand the hydrologic and climate drivers of observed changes in TWSA, we partitioned the TWSA time series into seasonal (annually repeating), interannual (>1-year), and subseasonal (<1-year) components.
如何由等效水高计算一个区域内的总水量变化呢?
答:等效水高一般单位是mm(或者cm),比如上面表格中EWH(cm),下面就以cm为基准来计算:
因为,总质量=面密度*面积=等效水高*水密度*面积
所以,面密度=水密度*等效水高
因为,水的密度是1000 kg/m3
所以,单位面质量密度 1 kg/m2 = 1 mm w.e.
基于上面,表格中New England流域的面积171,083km2,等效水高17.4±5.0cm
面密度=((17.4)/100)*1000 =174±50kg/m2
总质量=面密度*面积=(174)*171,083*1,000,000=2.9768*1013 kg
因为,1 Gt = 1012 kg
所以,总质量=29.768 Gt ≈ 30 Gt
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