Bonne, Jean-Louis

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ISOARC	project		Samoylov	water	vapour	isotopes	analyser	raw	data		Within	the	ISOARC	project,	the	water	vapour	analyser	on	Samoylov		is	dedicated	to	the	continuous	measurements	 in	 ambient	 air	 of	 humidity	 level	 (in	 ppm),	 δ18O	 and	 δD	 (in	permil,	‰).			The	raw	dataset	archived	 in	PANGAEA	consists	of	 two	 types	of	 files,	which	have	 to	be	combined	for	a	correct	use	of	the	observations.	The	description	of	the	files	structure	is	provided	thereafter,	following	explanations	about	the	calibration	protocol.			Calibration	protocol			Figure	 1:	 Schematic	 of	 the	water	 vapour	 isotopes	 analyser	 calibrations	 and	 ambient	 air	injection	system.			A	 schematic	 of	 the	 analyser	 setup	 is	 presented	 in	 Figure	 1.	 The	 analyser	 is	 a	 Picarro	brand	 L2140i	 Cavity	 Ring	 Down	 Spectrometer,	 operating	 with	 a	 custom-made	calibration	system.	Ambient	air	is	continuously	pumped	through	a	heated	tube,	with	an	inlet	located	at	about	5	meters	height	above	ground	level.	The	analyser	is	continuously	measuring	and	recording	data	at	a	frequency	of	about	1Hz.	An	injection	and	calibration	system	controlled	by	a	Labview	program	running	on	an	independent	computer	switches	automatically	 the	humidity	air	 sources	analysed	by	 the	 instrument:	either	ambient	air	sampled	 from	 the	 inlet	 or	 air	 coming	 from	 the	 calibration	 unit.	 The	 calibration	 of	 the	instrument	consists	of	 the	successive	 injection	of	water	vapour	samples	with	different	isotopic	 compositions	 independently	 known.	 For	 a	 better	 stability	 of	 the	 instrument,	two	 independent	 calibration	 systems	 have	 been	 installed	 on	 the	 instrument	 and	 are	presented	hereafter.			The	 first	 calibration	 system,	 later	 named	 vaporizer,	 consists	 in	 vaporizing	 the	 water	standards	at	high	temperature	and	mixing	them	with	dry	air.	It	corresponds	to	the	green	shadow	zone	of	Fig.	1.	Four	different	standards	can	be	delivered	by	eight	 independent	lines,	 two	 lines	being	dedicated	 to	each	 standard	 for	a	better	 resilience	of	 the	 system.	The	names	of	the	8	lines	of	the	vaporizer	are	successively	1A,	2A,	3A,	4A,	1B,	2B,	3B,	and	4B.	 	 Each	 standard	 should	 be	 used	 both	 on	 A	 and	 B	 lines	 of	 the	 same	 number.	 	 The	calibration	standards	are	in	liquid	form,	stored	in	glass	bottles,	and	have	to	be	vaporized	before	 being	 injected	 into	 the	 analyser.	 The	 liquid	 water	 is	 injected	 through	 glass	capillaries	into	a	tee	piece	heated	at	170,0°C	and	mixed	with	dry	air	coming	from	a	high-pressure	 gas	 bottle.	 Increasing	 the	 pressure	 in	 the	 bottles	 containing	 the	 liquid	standards	(using	the	air	pressure	from	the	gas	bottle)	allows	the	standard	water	to	be	pushed	into	the	glass	capillaries.			The	 second	 calibration	 system,	 later	 named	 bubbler,	 consists	 of	 custom	 dew	 point	generator	 providing	 a	 humid	 air	 of	 theoretically	 known	 isotopic	 composition.	 It	corresponds	 to	 the	orange	shadow	zone	of	Fig.	1.	 It	 allows	measurements	of	only	one	standard.	Dry	air	is	injected	under	the	form	of	small	bubbles	through	a	large	amount	of	this	liquid	standard	under	a	controlled	environment:	temperature	probes	T1	and	T2	are	respectively	recording	the	water	and	air	temperature	inside	this	bubbler	system.		Both	calibration	systems	use	dry	air,	which	can	be	provided	either	by	a	dry	air	generator	or	by	a	dry	air	gas	bottle.	The	instrument	is	routinely	operated	with	dry	air	from	the	dry	air	 generator,	 but	 some	 tests	 were	 performed	 with	 dry	 air	 from	 a	 gas	 bottle.	 An	operating	checklist	contains	the	necessary	information	about	the	dry	air	source	used.			The	different	 valves	 shown	on	 fig.	 1.,	 controlled	by	 the	Labview	program,	 are	used	 to	control	the	injection	in	the	analyser.		The	inlet	injection	part	of	the	system,	in	purple	on	fig.	1,	determines	the	humidity	sources:	ambient	air	inlet,	air	from	the	room	or	air	from	one	of	the	calibration	systems.	A	pump	continuously	flushes	the	air	inlet,	as	long	as	valve	V9	 is	 opened.	When	 the	 valve	V10	 is	 opened,	 all	 the	 vales	V4	 (V4.1	 to	V4.8)	 from	 the	vaporizer	 and	 the	 valve	 V5	 from	 the	 bubbler	 system	 should	 be	 closed,	 and	 the	 flow	comes	from	the	ambient	air	inlet.	If	both	V10	and	all	the	valves	V4	and	V5	are	closed,	the	air	 comes	 from	 the	open	 split	 of	 valve	V10,	 in	other	words	 from	 the	 room,	where	 the	analyser	 is	 installed.	When	 one	 or	 several	 of	 the	 valves	V4	 or	V5	 are	 opened	 and	 the	valve	 V10	 is	 closed,	 the	 flow	 goes	 from	 the	 corresponding	 calibration	 systems	 to	 the	analyser,	and	the	over-pressure	is	released	through	the	open	split.			The	 vaporizer	 system	 is	 controlled	by	 all	 the	V1	 (V1.1	 to	V1.8),	 V2	 (V2.1	 to	V2.8),	 V3	(V3.1	to	V3.8)	and	V4	(V4.1	to	V4.8)	valves.	To	inject	dry	air	through	the	vaporizer,	the	V5	valve	should	not	be	activated.	Opening	both	valves	V3	and	V4	on	one	line	allows	dry	air	 from	 the	 gas	 bottle	 to	 be	 pushed	 into	 the	 system	 and	 measured	 by	 the	 Picarro.	Opening	 the	 valve	 V1	will	 pressurize	 the	 glass	 bottle	 and	 push	 liquid	 standard	water	through	 the	 capillaries	 towards	 the	 oven.	 On	 the	 other	 hand,	 opening	 valve	 V2	 will	release	the	pressure	 in	the	bottle.	 If	valves	V3	and	V2	are	opened	at	the	same	time	on	one	line,	liquid	water	and	then	dry	air	will	be	pushed	back	into	the	bottles	(this	purge	is	more	 efficient	when	 V4	 is	 closed).	 This	 last	 combination	 is	 used	 to	 dry	 the	 lines	 and	avoid	accumulation	of	water	after	the	injection	of	water.			The	bubbler	system	is	controlled	by	all	the	valves	V5,	V6,	V7	and	V8.	A	heating	wire	can	also	be	activated	while	using	the	bubbler	 to	warm	the	 incoming	and	out	coming	air	 to	prevent	condensation	in	the	calibration	system.	Activating	V5	and	V8	will	allow	dry	air	to	be	directed	through	the	outlet	of	the	bubbler	system	towards	the	analyser.		Activating	V7	will	allow	the	dilution	of	wet	air	coming	from	the	bubbler	by	dry	air.	Activating	V6	will	inject	dry	air	through	the	bubbler	itself	and	thus	provide	wet	air.	Three	temperature	values	are	measured:	T1,	T2	and	T3,	which	respectively	correspond	to	the	temperatures	from	the	liquid	water	standard,	from	the	air	inside	the	bubbler	and	from	the	cooling	box	in	which	the	bubbler	is	placed.		Here	 is	 a	 summary	 of	 the	 main	 open	 valves	 combinations	 used	 for	 the	 different	injections	(assuming	that	all	other	valves	are	closed):		#	Vaporizer	control:	-	V1,	V3,	V4:	Injection	of	vaporized	standard	in	the	system	and	measurement.		-	V3,	V4:	Injection	of	dry	air	in	the	system	and	the	Picarro	analyser.	Used	to	dry	the	lines	-	V2,	V3:	Push	back	water	and	dry	air	into	the	bottles.	-	V2,	V3,	V4:	Push	back	water	and	dry	air	into	the	bottles	and	the	Picarro	analyser.	-	V2:	Release	pressure	in	the	bottles	#	Bubbler	control:	-	V5,	V6,	V7,	V8:	Injection	of	wet	air	from	the	bubbler	in	the	system	and	measurement.		-	V5,	V8	or	V5,	V7,	V8:	Injection	of	dry	air	in	the	bubbler	outlet	and	the	Picarro	analyser.	Used	to	dry	the	line	#	Choice	of	air	source:		-	V9,	V10:	ambient	air	measured	-	V9,	V4:	air	from	the	vaporizer	measured,	over-pressure	released	through	open	split	-	V9:	room	air	through	open	split			The	humidity	 level	 of	 the	 calibration	 can	be	 regulated	by	 two	mains:	 (i)	 changing	 the	dilution	with	 dry	 air	 by	 adjusting	 the	 flow	 of	 dry	 air	 via	 the	Mass	 Flow	Meter	 (MFC)	controlled	 by	 the	 Labview	 program	 (an	 higher	 dry	 air	 flow	 giving	 lower	 humidity	levels),	or	(ii)	adjusting	one	of	the	manual	manometers	to	regulate	either	the	pressure	applied	into	the	bottles	containing	the	liquid	water	standards	for	the	vaporizer	(a	higher	pressure	giving	a	larger	water	flow	and	thus	higher	humidity	levels)	or	the	flow	of	dry	air	pushed	into	the	bubbler	for	the	bubbler	system.		Typical	 valve	 control	 sequences	used	during	 routine	measurements	 last	25	hours	 and	consist	 of	 the	 successive	 injections	 of	 each	 calibration	 standard	 during	 30	 minutes,	surrounded	 by	 a	 purge	 of	 the	 lines	 with	 dry	 air	 for	 2	 minutes,	 and	 followed	 by	 the	injection	of	ambient	air	from	the	inlet	system.	Either	both	calibration	systems	are	used	successively,	or	only	one	is	used	for	the	normal	calibration	sequence.	A	manual	control	of	the	system	is	also	possible	with	the	Labview	program,	and	is	mainly	used	during	the	maintenance	periods	of	the	analyser.			To	calibrate	the	instrument	regarding	its	dependency	to	humidity	level,	experiments	are	performed	approximately	 twice	a	year:	each	standard	 is	 injected	at	different	humidity	levels	 covering	 the	 range	 of	 humidity	 values	 expected	 for	 ambient	 air	 observations.	During	 those	 experiments,	 the	 standards	 are	 injected	 several	 hours,	 and	 the	humidity	levels	are	changed	every	30	minutes	by	adjusting	the	MFC	command	voltage.		To	cover	the	full	range	of	expected	humidity	values,	both	adjustments	of	the	MFC	and	the	manual	manometers	 are	 needed.	 Thus,	 several	 sequences	 covering	 the	 full	 MFC	 range	 are	usually	performed	with	different	pressures	in	the	water	samples	bottles.			Data	files	structure		The	dataset	generated	by	the	analyser	setup	is	composed	of	two	different	types	of	files,	which	must	be	 combined	 for	 a	 correct	use	of	 the	data:	 files	 from	 the	Picarro	analyser	containing	the	raw	measurements	of	humidity	and	its	isotopes,	described	in	subsection	a,	 and	 files	 from	 the	 Labview	 program	 containing	 the	 information	 on	 the	 applied	different	valve	settings,	described	in	subsection	b.			The	 computers	 clocks	 are	 normally	 synchronised	 automatically	 via	 the	 network	 since	mid-April	2016.	The	time	zone	used	is	always		UTC+00.			a)	The	names	of	the	Picarro	data	files	follow	this	nomenclature:			HKDS2021-YYYYMMDD-HHMMSSZ-DataLog_User.dat.gz		The	date	and	time	in	the	filenames	correspond	to	the	moment	of	creation	of	the	file.	A	new	file	is	created	every	day	at	midnight	and	also	each	time	the	instrument	is	restarted	(one	can	also	create	a	new	file	manually	on	the	Picarro	analyser	program).		Those	 files	 have	 been	 compressed	 using	 gzip	 on	 a	 Windows	 computer.	 When	uncompressed,	the	file	extension	is	*.dat.	These	are	simple	text	files,	containing	a	header	with	explicit	 labels	at	the	first	line	and	65	columns	separated	by	tabulations.	After	this	label,	each	line	corresponds	to	one	measurement,	at	a	frequency	close	to	1Hz.				Among	other	instrumental	parameters,	the	DATE,	TIME	give	the	date	and	time	of	each	recorded	 data,	 under	 the	 format	 YYYY-MM-DD	HH:MM:SS.sss.	 The	H2O,	Delta_18_16,	Delta_D_H,	 D_Excess,	 Delta_17_16	 and	 Excess_17	 respectively	 give	 the	 specific	humidity	(in	ppm)	and	the	δ18O,	δD,	d-excess,	δ17O	and	17O-excess	values	in	permil.			b)	The	names	of	the	files	created	by	the	Labview	program,	named	logfiles,	are	under	the	form:		LogFile-YYYYMMDD.txt	There	is	one	file	by	day,	which	contains	all	the	daily	available	data.	The	date	in	the	file	name	corresponds	to	the	date	of	the	data	contained	in	the	file.	The	data	are	stored	at	a	minute	frequency.	The	columns	are	separated	by	tabulations.			The	comprehensive	labels	and	descriptions	of	each	column	are	given	thereafter:	Date;	 time;	 cal_sys;	 l1_a_b;	 l2_a_b;	 l3_a_b;	 l4_a_b;	 l1_v1;	 l1_v2;	 1_v3;	 l1_v4;	 l2_v1;	l2_v2;	l2_v3;	l2_v4;	l3_v1;	l3_v2;	l3_v3;	l3_v4;	l4_v1;	l4_v2;	l4_v3;	l4_v4;	l5_v1;	l5_v2;	5_v3;	l5_v4;	l6_v1;	l6_v2;	l6_v3;	l6_v4;	l7_v1;	l7_v2;	l7_v3;	l7_v4;	l8_v1;	l8_v2;	l8_v3;	l8_v4;	s_1;	s_2;	s_3;	s_4;	s_5;	s_6;	in_v9;	in_v10;	t1;	t2;	t3;	p_date;	p_time;	h2o;	d18o;	dhdo	After		20160414	at	00:50:49,	it	has	been	a	little	modified	to:		Date;	 time;	 vaporizer;	 bubbler;	 l1_a_b;	 l2_a_b;	 l3_a_b;	 l4_a_b;	 l1_v1;	 l1_v2;	 1_v3;	l1_v4;	l2_v1;	l2_v2;	l2_v3;	l2_v4;	l3_v1;	l3_v2;	l3_v3;	l3_v4;	l4_v1;	l4_v2;	l4_v3;	l4_v4;	l5_v1;	l5_v2;	5_v3;	l5_v4;	l6_v1;	l6_v2;	l6_v3;	l6_v4;	l7_v1;	l7_v2;	l7_v3;	l7_v4;	l8_v1;	l8_v2;	l8_v3;	l8_v4;	v5;	v6;	v7;	v8;	s_5;	heat;	in_v9;	in_v10;	t1;	t2;	t3;	p_date;	p_time;	h2o;	d18o;	dhdo		-	 The	 columns	 Date	 and	 time	 correspond	 to	 the	 date	 and	 time	 from	 the	 computer	running	 the	 Labview	program	 controlling	 the	 instrument,	which	 is	 the	 reference	 time	for	the	valves	switching.			-	The	cal_sys	column	informs	of	which	calibration	system	is	used:	either	V	for	vaporizer	or	B	for	bubbler.	The	vaporizer	and	bubbler	column	which	replace	it	after	20160414	at	00:50:49	describe	if	respectively	the	vaporizer	or	the	bubbler	are	activated.	The	values	are	respectively	V	or	B	if	the	systems		are	activated,	or	X	if	they	are	not.		-	 The	 next	 44	 columns	 correspond	 to	 the	 state	 of	 the	 calibration	 and	 inlet	 injection	system.		The	four	columns	l1_a_b,	l2_a_b,	l3_a_b	and	l4_a_b	indicate	which	of	the	A	or	B	lines	 from	the	vaporizer	are	used	 for	each	standard,	respectively	 from	line	1	 to	4.	The	possible	values	are:	-1	for	line	A,	1	for	line	B,	or	0	if	none	of	the	lines	are	used.	The	next	32	columns	give	the	state	of	the	4	valves	from	V1	to	V4	on	the	8	different	lines,	with	the	nomenclature	li_vj,	where	i	is	the	line	number	and	j	is	the	valve	number.	The	values	are	0	for	a	closed	valve,	and	1	for	an	opened	valve.	The	columns	v5,	v6,	v7	and	v8	indicate	respectively	if	the	valves	V5,	V6,	V7	and	V8	from	the	bubbler	system	are	activated.	The	values	are	0	for	a	closed	valve,	and	1	for	an	opened	valve.	The	columns	s_5	give	the	sate	of	 an	 additional	 switch.	Those	 switches	have	been	 implemented	 for	 a	potential	 future	enhancement	of	the	instrument,	but	they	have	not	been	used	within	the	system,	so	far.	The	column	heat	indicates	if	the	heating	wire	from	the	bubbler	system	is	activated.	The	values	are	0	 if	 	and	1	 if	active.	The	columns	in_v9	and	in_v10	give	the	state	of	the	two	inlet	valves	respectively	V9	and	V10,	shown	in	fig.	1.		The	values	are	0	for	a	closed	valve,	and	1	for	an	opened	valve.			-	 The	 next	 3	 columns	 t1,	 t2	 and	 t3	 give	 the	 3	 temperature	 values	 measured	 in	 the	bubbler	system,	respectively	the	temperatures	from	the	liquid	water	standard,	from	the	air	inside	the	bubbler	and	from	the	cooling	box.			-	 The	 Labview	program	 imports	 the	 last	 Picarro	 analyser	 data	 every	minute	 from	 the	network	 connection,	 and	 some	 of	 those	 data	 are	 saved	 in	 the	 logfile	 for	 the	synchronisation	 of	 both	 data	 files.	 This	 constitutes	 the	 next	 5	 columns:	 p_date	 and	p_time	correspond	to	the	Picarro	analyser	date	and	time,	whereas	h2o,	d18o	and	dhdo	respectively	 correspond	 to	 the	 recorded	 H2O	 in	 ppm	 and	 δ18O	 and	 δD	 values,	 both	expressed	in	permil.	If	for	some	reason,	the	Picarro	data	are	not	imported	(for	example	if	 the	 instrument	 is	 not	 recording,	 if	 a	 new	 Picarro	 file	 has	 just	 been	 created	 after	midnight,	 or	 if	 there	 is	 a	 trouble	 on	 the	 network	 communication	 between	 both	computers),	 the	 corresponding	 columns	 will	 contain	 the	 following	 values:		XXXXXXXXXX	XXXXXXXX	 		-9999.99	 		-9999.99	 		-9999.99		Complementary	data		The	real	values	of	the	standards	used	on	the	instrument	are	measured	independently	in	the	 laboratory	 twice	 a	 year.	 These	 values	 and	 the	 positions	 of	 each	 standard	 on	 the	different	lines	are	stored	in	separate	files	available	on	https://sensor.awi.de/.		Scientists	 on-board	 fill	 in	 a	 checking	 list	 (in	 form	 of	 an	 Excel	 sheet)	 on	 a	 daily	 basis,	containing	 a	 list	 of	 parameters	 checked	 manually	 and	 potential	 comments	 during	maintenance	of	the	system.	This	file	is	also	available	on	https://sensor.awi.de/.	

Manual for raw data Samoylov water vapour isotopes analyser

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