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Snow cover and Ole Humlum


Snow cover and Ole Humlum21-06-2021 21:24
kfl
★★★★★
(2165)
Snow cover and Ole Humlum

På side 36 i The State of the Climate 2020 af Ole Humlum står der:

The Northern Hemisphere snow cover extent is subject to large local and regional variations from year to year. However, the overall tendency (since 1972) is towards stable Northern Hemisphere snow conditions, as illustrated in Figure 41.


Dette er ikke en retvisende beskrivelse i henhold til følgende resume:

Snow cover extent in the Northern Hemisphere has declined significantly over the past 90 years, with most of the reductions occurring since 1980. Over the period 1967–2015, snow cover extent in the Northern Hemisphere has decreased by 7 % on average in March and April and by 47 % in June; the observed reductions in Europe are even larger, at 13 % for March and April and 76 % for June.

Snow mass in the Northern Hemisphere is estimated to have decreased by 7 % in March from 1982 to 2009; snow mass in Europe has decreased more rapidly than the average for the Northern Hemisphere, but with large interannual variation.

Model simulations project widespread reductions in the extent and duration of snow cover in the Northern Hemisphere and in Europe over the 21st century.

Changes in snow cover affect the Earth's surface reflectivity, water resources, flora and fauna and their ecology, agriculture, forestry, tourism, snow sports, transport and power generation.


alt sammen ifølge: EEA Snowcover

Past trends
Satellite observations of monthly snow cover extent in the Northern Hemisphere are available from 1967 onwards [i]. A detailed analysis based on multiple sources shows there have been significant decreases in Northern Hemisphere snow cover extent during the spring melt season since about 1980 (March to June; Figure 1, left) [ii]; in other seasons, the snow cover extent has remained stable or even slightly increased. A separate analysis for Europe (EEA-39 region) shows even larger reductions of 13 % for March and April, and 76 % for June between 1980 and 2015 (Figure 1, right).

Decreases in snow cover extent are caused by an earlier onset of melting and a shorter duration of the snow season. Since 1972, the duration of the snow season averaged over the Northern Hemisphere declined by five days per decade, but with substantial regional variation. The duration of the snow season has decreased by up to 25 days in western, northern and eastern Europe due to earlier spring melt, whereas it has increased by up to 15 days in south-eastern Europe due to an earlier onset of the snow season [iii].

The snow mass (i.e. the amount of water that the snow contains) is an important variable, as it affects the role of snow in the hydrological cycle. For the whole of the Northern Hemisphere, a 7 % decrease in March snow mass was observed between 1982 and 2009 [iv]. An extension of this data focusing on EEA member countries demonstrates a stronger average decline of 30 % for the period 1980–2015, although the year-to-year variation is large (Figure 2). Winter increases in precipitation have also led to an increase in snow mass at higher altitudes in Norway.


Hvorfor skriver Ole Humlum, som han gør, når det forholder sig stik modsat ?

Ole Humlum er, som udnævnt professor, i stand til at læse og skrive, men mangler han en forståelse for det han læser ?

Jeg tror det næppe. Det er bevidst ond vilje.



KFL
Vær skeptisk over for skeptikerne.... Det er der grund til.
Redigeret d. 21-06-2021 21:32
22-06-2021 00:38
delphiProfilbillede★★★★★
(6959)
Citat:

Satellite observations of monthly snow cover extent in the Northern Hemisphere are available from 1967 onwards [i]. A detailed analysis based on multiple sources shows there have been significant decreases in Northern Hemisphere snow cover extent during the spring melt season since about 1980 (March to June; Figure 1, left) [ii]; in other seasons, the snow cover extent has remained stable or even slightly increased. A separate analysis for Europe (EEA-39 region) shows even larger reductions of 13 % for March and April, and 76 % for June between 1980 and 2015 (Figure 1, right).

Decreases in snow cover extent are caused by an earlier onset of melting and a shorter duration of the snow season. Since 1972, the duration of the snow season averaged over the Northern Hemisphere declined by five days per decade, but with substantial regional variation. The duration of the snow season has decreased by up to 25 days in western, northern and eastern Europe due to earlier spring melt, whereas it has increased by up to 15 days in south-eastern Europe due to an earlier onset of the snow season [iii].

The snow mass (i.e. the amount of water that the snow contains) is an important variable, as it affects the role of snow in the hydrological cycle. For the whole of the Northern Hemisphere, a 7 % decrease in March snow mass was observed between 1982 and 2009 [iv]. An extension of this data focusing on EEA member countries demonstrates a stronger average decline of 30 % for the period 1980–2015, although the year-to-year variation is large (Figure 2). Winter increases in precipitation have also led to an increase in snow mass at higher altitudes in Norway.


De data der ligger til grund for Humlums analyse er disse se http://climate.rutgers.edu/snowcover/table_area.php?ui_set=0&ui_sort=0

Det er dataene i kolonnen N. Hemisphere der bearbejdes i det efterfølgende.

Dataene i Excel kan downloades her se http://xqw.dk/y21/Sne.xlsx

Hver ugentlig sneareal (km2) alle årlige uger siden 1970 (x-aksen er ugenumre startende med uge 22, 2021 fra venstre)



Her ugerne 9 til og med 13' areal lagt sammen for hvert år (marts måned) se



Her ugerne 15 til 28' areal lagt sammen (sommermåneder)



Og ugerne 43 til og med uge 8 for hvert år lagt sammen (vinter) se



Og endelig sommerugerne 22 og 5 frem (juni) se



Konklusionen kan kun følge Humlums: der er ikke nogen reduktion i det årlige snedække. Måske en svag stigning når man ser på vintersnedækket, hvor der er tale om store arealer, som mere end rigelig opvejer de minimale udsving der er i sommersnedækket se


Redigeret d. 22-06-2021 00:39
22-06-2021 00:50
delphiProfilbillede★★★★★
(6959)
Det ugentlige sneareal for den nordlige halvkugle se



Her alle årets ugers sneareal lagt sammen se



Fuldstændig ingen ændring overhovedet i snedækkets årlige udbredelse, måske bortset fra en svag stigende tendens!

Hvorfor skriver man som man gør hvorfor stirre man sig blind på en sommermåned og glemmer helt at se på hele årets snedække for når man ser på hele året (som humlum gør) så forholder det sig stik modsat.

Hvordan kan man tillade sig at fremføre sådan en gang løgn, eller det kan kun være bevist ond vilje:

Satellite observations of monthly snow cover extent in the Northern Hemisphere are available from 1967 onwards [i]. A detailed analysis based on multiple sources shows there have been significant decreases in Northern Hemisphere snow cover extent during the spring melt season since about 1980 (March to June; Figure 1, left) [ii]; in other seasons, the snow cover extent has remained stable or even slightly increased. A separate analysis for Europe (EEA-39 region) shows even larger reductions of 13 % for March and April, and 76 % for June between 1980 and 2015 (Figure 1, right).

Decreases in snow cover extent are caused by an earlier onset of melting and a shorter duration of the snow season. Since 1972, the duration of the snow season averaged over the Northern Hemisphere declined by five days per decade, but with substantial regional variation. The duration of the snow season has decreased by up to 25 days in western, northern and eastern Europe due to earlier spring melt, whereas it has increased by up to 15 days in south-eastern Europe due to an earlier onset of the snow season [iii].

The snow mass (i.e. the amount of water that the snow contains) is an important variable, as it affects the role of snow in the hydrological cycle. For the whole of the Northern Hemisphere, a 7 % decrease in March snow mass was observed between 1982 and 2009 [iv]. An extension of this data focusing on EEA member countries demonstrates a stronger average decline of 30 % for the period 1980–2015, although the year-to-year variation is large (Figure 2). Winter increases in precipitation have also led to an increase in snow mass at higher altitudes in Norway.

Redigeret d. 22-06-2021 01:03
22-06-2021 15:09
Robert Wagner
★★★☆☆
(638)
Og så kan man spørge sig, om en lille fremgang om vinteren eller en tydelig tilbagegang om sommeren har mere betydning ift. albedo...
22-06-2021 17:52
delphiProfilbillede★★★★★
(6959)
Fra https://www.eea.europa.eu/data-and-maps/indicators/snow-cover-3/assessment sommersnedækket er faldet med op til 47 % de seneste år.

Fra Humlums papir se



Jo sørme der er et betydeligt fald om sommeren af et næsten mikroskopisk snedække for den nordlige halvkugle.

Nedbør, sommer og vinterdækket er intakt måske endda stigende.
Redigeret d. 22-06-2021 17:53
22-06-2021 20:47
Robert Wagner
★★★☆☆
(638)
Jo sørme der er et betydeligt fald om sommeren af et næsten mikroskopisk snedække for den nordlige halvkugle.


Så Grønland er af mikroskopisk størrelse?




Deltag aktivt i debatten Snow cover and Ole Humlum:

Husk mig

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