Among these models, the small-slope approximation/small perturbation model (SSA / SPM) [18,19,20,21], two scale model (TSM) [22,23,24] and empirical/semi-empirical models [25,26] have been widely used by the research community and implemented in different satellite data processing systems.
1	Among	among	ADP	IN	_	3	case	3:case	Discourse=elaboration-additional:67->65:1
2	these	this	DET	DT	Number=Plur|PronType=Dem	3	det	3:det	Entity=(128-abstract-giv:act-cf1*-2-coref
3	models	model	NOUN	NNS	Number=Plur	55	obl	55:obl:among	Entity=128)|SpaceAfter=No
4	,	,	PUNCT	,	_	3	punct	3:punct	_
5	the	the	DET	DT	Definite=Def|PronType=Art	13	det	13:det	Entity=(132-abstract-new-cf2-9-coref
6	small	small	ADJ	JJ	Degree=Pos	8	amod	8:amod	Entity=(133-abstract-new-cf3-4-coref(134-abstract-new-cf18-3-sgl|SpaceAfter=No|XML=<w>
7	-	-	PUNCT	HYPH	_	6	punct	6:punct	SpaceAfter=No
8	slope	slope	NOUN	NN	Number=Sing	9	compound	9:compound	Entity=134)|XML=</w>
9	approximation	approximation	NOUN	NN	Number=Sing	13	compound	13:compound	Entity=133)|SpaceAfter=No|XML=<w>
10	/	/	SYM	SYM	_	12	cc	12:cc	SpaceAfter=No
11	small	small	ADJ	JJ	Degree=Pos	12	amod	12:amod	Entity=(135-abstract-new-cf4-2-coref|XML=</w>
12	perturbation	perturbation	NOUN	NN	Number=Sing	9	conj	9:conj:slash|13:compound	Entity=135)
13	model	model	NOUN	NN	Number=Sing	55	nsubj:pass	55:nsubj:pass|61:nsubj:pass	Entity=132)
14	(	(	PUNCT	-LRB-	_	15	punct	15:punct	Discourse=restatement-partial:68->67:0|SpaceAfter=No
15	SSA	SSA	PROPN	NNP	Number=Sing	13	appos	13:appos	Entity=(132-abstract-giv:act-cf2-1,3-appos(133-abstract-giv:act-cf3-1-coref)
16	/	/	SYM	SYM	_	17	cc	17:cc	_
17	SPM	SPM	PROPN	NNP	Number=Sing	15	conj	13:appos|15:conj:slash	Entity=(135-abstract-giv:act-cf4-1-coref)132)|SpaceAfter=No
18	)	)	PUNCT	-RRB-	_	15	punct	15:punct	_
19	[	[	PUNCT	-LRB-	_	20	punct	20:punct	Discourse=explanation-evidence:69->67:1|SpaceAfter=No|XML=<w>
20	18	18	NUM	CD	NumForm=Digit|NumType=Card	13	dep	13:dep	Entity=(136-abstract-new-cf9-1-sgl)|SpaceAfter=No|XML=<ref></ref>
21	,	,	PUNCT	,	_	22	punct	22:punct	SpaceAfter=No
22	19	19	NUM	CD	NumForm=Digit|NumType=Card	20	conj	13:dep|20:conj	Entity=(137-abstract-new-cf10-1-sgl)|SpaceAfter=No|XML=<ref></ref>
23	,	,	PUNCT	,	_	24	punct	24:punct	SpaceAfter=No
24	20	20	NUM	CD	NumForm=Digit|NumType=Card	20	conj	13:dep|20:conj	Entity=(138-abstract-new-cf11-1-sgl)|SpaceAfter=No|XML=<ref></ref>
25	,	,	PUNCT	,	_	26	punct	26:punct	SpaceAfter=No
26	21	21	NUM	CD	NumForm=Digit|NumType=Card	20	conj	13:dep|20:conj	Entity=(139-abstract-new-cf12-1-sgl)|SpaceAfter=No|XML=<ref></ref>
27	]	]	PUNCT	-RRB-	_	20	punct	20:punct	SpaceAfter=No|XML=</w>
28	,	,	PUNCT	,	_	31	punct	31:punct	_
29	two	two	NUM	CD	NumForm=Word|NumType=Card	30	nummod	30:nummod	Discourse=same-unit_m:70->67:2|Entity=(140-abstract-new-cf5-3-coref(141-abstract-new-cf19-2-sgl
30	scale	scale	NOUN	NN	Number=Sing	31	compound	31:compound	Entity=141)
31	model	model	NOUN	NN	Number=Sing	13	conj	13:conj:slash|55:nsubj:pass	Entity=140)
32	(	(	PUNCT	-LRB-	_	33	punct	33:punct	Discourse=restatement-partial:71->70:0|SpaceAfter=No
33	TSM	TSM	PROPN	NNP	Number=Sing	31	appos	31:appos	Entity=(140-abstract-giv:act-cf5-1-appos)|SpaceAfter=No
34	)	)	PUNCT	-RRB-	_	33	punct	33:punct	_
35	[	[	PUNCT	-LRB-	_	36	punct	36:punct	Discourse=explanation-evidence:72->70:1|SpaceAfter=No|XML=<w>
36	22	22	NUM	CD	NumForm=Digit|NumType=Card	31	dep	31:dep	Entity=(142-abstract-new-cf13-1-sgl)|SpaceAfter=No|XML=<ref></ref>
37	,	,	PUNCT	,	_	38	punct	38:punct	SpaceAfter=No
38	23	23	NUM	CD	NumForm=Digit|NumType=Card	36	conj	31:dep|36:conj	Entity=(143-abstract-new-cf14-1-sgl)|SpaceAfter=No|XML=<ref></ref>
39	,	,	PUNCT	,	_	40	punct	40:punct	SpaceAfter=No
40	24	24	NUM	CD	NumForm=Digit|NumType=Card	36	conj	31:dep|36:conj	Entity=(144-abstract-new-cf15-1-sgl)|SpaceAfter=No|XML=<ref></ref>
41	]	]	PUNCT	-RRB-	_	36	punct	36:punct	XML=</w>
42	and	and	CCONJ	CC	_	46	cc	46:cc	Discourse=same-unit_m:73->67:2
43	empirical	empirical	ADJ	JJ	Degree=Pos	46	amod	46:amod	Entity=(145-abstract-new-cf7-4-sgl|SpaceAfter=No|XML=<w>
44	/	/	SYM	SYM	_	45	cc	45:cc	SpaceAfter=No
45	semi-empirical	semi-empirical	ADJ	JJ	Degree=Pos	43	conj	43:conj:slash|46:amod	XML=</w>
46	models	model	NOUN	NNS	Number=Plur	13	conj	13:conj:and|55:nsubj:pass	Entity=145)
47	[	[	PUNCT	-LRB-	_	48	punct	48:punct	Discourse=explanation-evidence:74->73:0|SpaceAfter=No|XML=<w>
48	25	25	NUM	CD	NumForm=Digit|NumType=Card	46	dep	46:dep	Entity=(146-abstract-new-cf16-1-sgl)|SpaceAfter=No|XML=<ref></ref>
49	,	,	PUNCT	,	_	50	punct	50:punct	SpaceAfter=No
50	26	26	NUM	CD	NumForm=Digit|NumType=Card	48	conj	46:dep|48:conj	Entity=(147-abstract-new-cf17-1-sgl)|SpaceAfter=No|XML=<ref></ref>
51	]	]	PUNCT	-RRB-	_	48	punct	48:punct	XML=</w>
52	have	have	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	55	aux	55:aux|61:aux	Discourse=same-unit_m:75->67:2
53	been	be	AUX	VBN	Tense=Past|VerbForm=Part	55	aux:pass	55:aux:pass|61:aux:pass	_
54	widely	widely	ADV	RB	Degree=Pos	55	advmod	55:advmod	_
55	used	use	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	0:root	_
56	by	by	ADP	IN	_	59	case	59:case	_
57	the	the	DET	DT	Definite=Def|PronType=Art	59	det	59:det	Entity=(148-organization-new-cf6-3-sgl
58	research	research	NOUN	NN	Number=Sing	59	compound	59:compound	_
59	community	community	NOUN	NN	Number=Sing	55	obl:agent	55:obl:agent	Entity=148)
60	and	and	CCONJ	CC	_	61	cc	61:cc	Discourse=joint-list_m:76->67:3
61	implemented	implement	VERB	VBN	Tense=Past|VerbForm=Part	55	conj	55:conj:and	_
62	in	in	ADP	IN	_	67	case	67:case	_
63	different	different	ADJ	JJ	Degree=Pos	67	amod	67:amod	Entity=(149-abstract-new-cf8-5-sgl
64	satellite	satellite	NOUN	NN	Number=Sing	65	compound	65:compound	Entity=(150-abstract-new-cf20-3-sgl(151-abstract-new-cf21-2-sgl(152-object-new-cf22-1-sgl)
65	data	datum	NOUN	NNS	Number=Plur	66	compound	66:compound	Entity=151)
66	processing	processing	NOUN	NN	Number=Sing	67	compound	67:compound	Entity=150)
67	systems	system	NOUN	NNS	Number=Plur	61	obl	61:obl:in	Entity=149)|SpaceAfter=No
68	.	.	PUNCT	.	_	55	punct	55:punct	_
