The climate of Lishui

Survey

Only one source describes the climate of Lishui in words: the study of the Fangshan small watershed states that "the area has a subtropical monsoon climate". All the other sources give figures only, without a description of that kind. This article therefore keeps the two kinds apart — the description and the figures each carry their own source — and sets out every set of figures without choosing one for the reader.

Five sets of climate figures have been found for this site. Two of them agree exactly on mean annual temperature and rainfall, and two share a mean annual temperature of 16.4°C while differing on rainfall and sunshine:

Source	Mean annual temperature	Annual rainfall	Annual sunshine	Other
District Government, Geographical Position page	16.4°C	1204.3 mm	1980.0 hours	Mean annual relative humidity 76%
High-Standard Farmland Construction Plan 2022-2025	16.6°C	1491.5 mm	2205.6 hours	—
Near-Term Implementation Plan of the Territorial Spatial Plan, February 2021	15.5°C	1037 mm	2146 hours	—
Environmental impact report form for the Dongping Subdistrict sewer project, January 2020	15.5°C	1037 mm	—	Wording: "meteorology of the whole district"
Study of the Fangshan small watershed, 2022	16.4°C	1147.0 mm	1969.0 hours	Frost-free period 224 days

Temperature spans 15.5°C to 16.6°C, rainfall 1037 mm to 1491.5 mm, and sunshine 1969.0 hours to 2205.6 hours. The widest gap is in annual rainfall, where 1491.5 mm and 1037 mm differ by 454.5 mm. No source states its period of record or its weather station, and not one says which base period the figures come from.

The only district-wide figure for relative humidity comes from the District Government's Geographical Position page: a mean annual relative humidity of 76%. The only figure for the frost-free period comes from the Fangshan small watershed study: 224 days.

Periods and areas

This article does not divide the climate itself into periods — no comparable long series exists in the sources, so any "periods" could only be groups of sources — and simply groups the five sets by the year they appeared and by the area they cover.

Periods. By year the sources fall into two groups. The 2020-2021 group: the Near-Term Implementation Plan and the environmental impact report form for the Dongping Subdistrict works both give a mean annual temperature of 15.5°C and annual rainfall of 1037 mm, identical to the last decimal, with the former also giving 2146 hours of sunshine. The group around 2022: the High-Standard Farmland Construction Plan gives 16.6°C, 1491.5 mm and 2205.6 hours, while the Fangshan small watershed study, published the same year, gives 16.4°C, 1147.0 mm, 1969.0 hours and a frost-free period of 224 days. The differences between the two groups are not evidence that the climate itself changed: neither group states its period of record, so the figures cannot be aligned.

Areas. By area the sources fall into two classes. Four are district-wide: the District Government's Geographical Position page, the High-Standard Farmland Construction Plan, the Near-Term Implementation Plan, and the Dongping Subdistrict report form, which says in so many words that the figures are the "meteorology of the whole district". One is local: the Fangshan small watershed study, whose figures come from the study area of that watershed and do not stand for the whole district. The distinction has a practical consequence in this article — the frost-free period, and the 1147.0 mm among the rainfall figures, come only from the local source and must not be quoted as district-wide values.

Where two texts corroborate each other, that is set out too: the Dongping Subdistrict report form (compiled January 2020) and the Near-Term Implementation Plan (February 2021) give the same mean annual temperature and annual rainfall, which can be read as one set of figures recurring in two texts. What they corroborate is that two texts used the same figures, not that the figures were verified by measurement.

Open questions

• The five sets differ widely, and none states its period of record or its weather station. Annual rainfall runs from 1037 mm to 1491.5 mm, mean annual temperature from 15.5°C to 16.6°C and annual sunshine from 1969.0 hours to 2205.6 hours, and the differences cannot be explained by "different years", since no source gives a year. This article sets them side by side only: no averaging, no splitting the difference, no choosing one.
• No trend or change in climate may be argued from these five sets. The same year yields different figures in different sources, which shows the differences come chiefly from the basis of compilation and the purpose of each text rather than from the passage of time.
• The frost-free period of 224 days comes only from the Fangshan small watershed study and is a figure for the study area of that watershed, not a district-wide value; it must not be lined up with the district-wide temperature and rainfall figures as one set of climate elements.
• The mean annual relative humidity of 76% appears only on the District Government's Geographical Position page. No second figure for the same element has been found for this site, and no other humidity measure may be derived from it.
• The phrase "subtropical monsoon climate" comes from the text of the Fangshan small watershed study; the other sources give figures only and use no description of that kind. The description and the figures are two different things, each must be quoted from its own source, and a description from a local text must not be turned into a district-wide statement of climate type.
• The qualifier "meteorology of the whole district" appears only in the Dongping Subdistrict report form; the scope of the other four has to be inferred from their wording, and no comparable statement of scope has been found. District-wide and local sources must be told apart when either is quoted.
• Climate statistics and engineering hydrology are not the same use: rainfall figures in water-management and flood-defence texts serve drainage standards and engineering design (polder drainage standards, for instance, are set against rainstorm conditions), and they come from a different basis and serve a different purpose than the figures on a climate statistics page. Figures from the two must not be substituted for one another.