Tecnical Report 11-18 QASITEEX 2011 Te Qaanaaq sea ice termal emission experiment Field report Copenagen 2011 www.dmi.dk/dmi/tr11-18 page 1 of 27
Tecnical Report Colopon Serial title: Tecnical Report Title: QASITEEX - 2011 Subtitle: Te Qaanaaq Sea Ice Termal Emission EXperiment Field and data report Autor(s): Gorm Dybkjær (DMI), Jacob Høyer (DMI), Rasmus Tonboe (DMI), Steffen Olsen (DMI), Sane Rodwell (SAMS), Werenfried Wimmer (NOCS), Sten Søbjærg (DTU-space). Oter contributors: Leif Toudal Petersen (DMI), Jeremy Wilkinson (SAMS), Henriette Skourup (DTU-space). Responsible institution: Danis Meteorological Institute and Greenland Climate and Researc Centre Language: Englis Keywords: Sea ice temperature, brigtness temperature, microwae, termal infra red, ocean, ocean salinity, ocean current, ice tickness, Qaanaaq, Inglefield Bredning. Url: www.dmi.dk/dmi/tr11-18.pdf ISSN: 1399-1388 Version: 1.00 Website: www.dmi.dk and ocean.dmi.dk Copyrigt: DMI and Greenland Climate and Researc Centre Application and reference is allowed wit proper reference. www.dmi.dk/dmi/tr11-18 page 2 of 27
Tecnical Report Content: Abstract... 4 Resumé... 4 Introduction... 5 Motiation... 7 Set-up, instrumentation and data... 8 TIR radiometers... 10 Program... 10 Procedure... 10 Data - temperaturs... 11 Data - emissiity experiment... 12 MW radiometers... 14 Program... 14 Data... 15 THICK... 17 Program... 17 Procedure... 17 Data - EM31... 19 Data air borne... 19 OCEAN... 21 Program... 21 Procedures... 22 Data - CTD... 23 Data ADCP/Current mooring... 24 Contacts... 26 References... 27 Preious reports... 27 www.dmi.dk/dmi/tr11-18 page 3 of 27
Tecnical Report Abstract Te Qasiteex 2011 field work took place in April, at Inglefield Bredning by Qaanaaq in Nort West Greenland. Te oerall goal of QASITEEX was to inestigate termal properties of te fiord system, to improe and alidate satellite based sea ice temperature algoritms and to collect data for subsequent modelling of eat transports between ocean, sea ice and atmospere. Te field work included measurements of water temperatures, salinity, ocean dynamics, sea ice surface and integrated snow/ice temperatures, ice tickness, ice growt and ice salinity and air temperatures. Finally, a range of tecnical and logistical issues were tested during te fieldwork. Tis report is a full record of te collected data during Qasiteex 2011. Resumé www.dmi.dk/dmi/tr11-18 page 4 of 27
Tecnical Report Introduction QAanaaq Sea Ice Termal Emission EXperiment (QASITEEX) took place at Inglefield Bredning fjord system by Qaanaaq from Marc 30 to April 6t, 2011. Te oerall goal of QASITEEX was to inestigate termal properties of te fiord system, to improe and alidate satellite based sea ice temperature algoritms and to collect data for subsequent modelling of eat transports between ocean, sea ice and atmospere. Te field work included measurements of water temperature and salinity, ocean dynamics, sea ice surface and integrated snow/ice temperatures, ice tickness, ice growt, ice salinity and air temperatures. Te field campaign actiities were diided into 4 temes. 1) A microwae teme (MW) using semi stationary radiometers to measure integrated surface and subsurface brigtness temperatures. 2) A termal infra red teme (TIR) wit 1 semi stationary and 2 mobile radiometers to measure ice/snow/water skin temperatures and angular dependencies tereof. 3) An ice tickness teme (THICK) using a mobile EM-31 unit to measure transects of ice tickness and a termistor string to measure te termodynamic temperature profile trougout te field work 4) An oceanograpic teme (OCEAN) equipped wit CTD and ADCP instruments for temperature and salinity profiling and ocean current profiling, respectiely. Te OCEAN teme also included water sampling for cemical analysis. QASITEEX was a joint field campaign between te main contributor Greenland Climate and Researc Centre (GCRC) and Te Scottis Association for Marine Science (SAMS), National Oceanograpy Centre, Soutampton (NOCS), National Space Institute at te Danis Tecnical Uniersity (DTU-space) and te leading partner Center for Ocean and Ice at Danis Meteorological Institute (DMI). Figure 1 SAR cart of Inglefield Bredning from Marc 2011 wit Qasiteex actiities indicated by dots and lines. Dots named Qxx sow positions of oceanograpic stations and dots named BC1 and BC2 are BaseCamps 1 and 2, used for miscellaneous TIR and MW measurements. Lines are collocated TIR and ice tickness pats. Beside te GCRC 'Satellite remote sensing of Greenland waters' project, also oter researc and www.dmi.dk/dmi/tr11-18 page 5 of 27
Tecnical Report deelopment project will benefit from te experiment. Seeral national and international projects suc as te Danis NAACOS, te EU MyOcean, te EUMETSAT OSI SAF, te ESA CCI SST and Sea-Ice project and te INUIT CLIMATE EXPERIMENT (Nordic Council of Ministers) ae actiities were te QASITEEX data are releant. Tis report is organised in tree sections, a section briefly describing te motiation for te experiment, followed by a section were instruments and field set-up are described along wit te pysical, geograpical and temporal sampling properties of te collected data. Finally, a list of contact details, were questions and requests for data can be posted. Te study receied financial support from te Danis Agency for Science, Tecnology and Innoation and is a part of te Greenland Climate Researc Centre www.dmi.dk/dmi/tr11-18 page 6 of 27
Tecnical Report Motiation A future perspectie of te QASITEEX field work, and possible upcoming field works in te Inglefield Bredning fjord system, is to collect a compreensie data set for termodynamically modelling of te fjord. Te data collected during tis field work constitute central pysical parameters responsible for te eat transport between ocean, ice and air and te integrated data are essential for model tuning and alidation. Howeer, eac of te participating scientific teams also ae immediate and indiidual purposes for teir data and associated results. Te microwae (MW) emission from sea ice is a function of surface and subsurface properties and te MW experiment proided data for alidation of models and for deelopment of new models, for e.g. estimation of sea ice concentrations. Te instruments are identical to past, present and future sensors on satellites like te SSM/I series and te objectie is to exploit te satellite measurements better troug and increased understanding of te emission processes. Te termal infrared (TIR) instruments measure te termal emission from te skin surface of sea ice, te Ice Surface Temperature (IST). Te TIR experiment ad 3 focus areas, one was to matc te ground data to coincided satellite measurements, a second focus was on more tecnical aspects, namely to inestigate te sensitiity/response of different sensors to band widt and scan angle and estimation of emissiity. Te tird focus area was to inestigate spatial ariations of sea ice skin temperatures, to better understand distributed IST data from satellites. Finally, a fourt focus was to inestigate te performance of te state of te art SST IR radiometer (ISAR) in extreme cold conditions. Te perspectie of te ice tickness program was to obtain full seasonal ice tickness transects oer dog sledge pats trougout te winter season or as long as te ice is safe for dog sledge transport. Tis information can be used for sea ice growt modelling and for direct use by te unters and illagers tat use te ice for transportation. Tis teme is still in its deeloping pase and it is presently focusing on finding practical and tecnical solutions to ensure te instrumentation autonomously operates trougout te winter. Te applications of te ocean field program were many fold but focussed on documenting te winter ydrograpy of te fjord supplying insigt to te possible upper estuarine and intermediate circulation loops connecting te fjord wit te open waters of te Baffin Bay. Tis also yields an important estimate of te upper layer stratification and ertical ocean eat flux across te sea-ice interface. Obserations along te lengt of te fjord also allow an assessment of te aailable eat for glacier melt at te ead of te fjord. Finally, tracer samples will be used to gie direct eidence for subsurface glacier melt in te winter season. www.dmi.dk/dmi/tr11-18 page 7 of 27
Tecnical Report Set-up, instrumentation and data Tis section briefly describes te applied instruments along wit te set-up in wic tey were working. An oeriew of recorded data is gien and data samples are plotted. Detailed instrument description, field set-up and data access can be gien by te responsible persons (see 'contacts', below). Te field program consisted partly of collocated measurements and partly of indiidual measurements. Te science teams were grouped into two working groups, for bot conenience and because of synergy of collocated measurement. One working group was formed by te oceanograpic and te ice tickness teams. Tis working group was conenient as bot measuring programmes were scientifically strengtened by large geograpical spread. Tis group jointly conducted 3 dog sledge trips, as indicated on figure 1 by coloured dots and lines. Tis group also brougt a TIR instrument for collocating ice tickness and IST measurements. Table 1 Approximate time line (UTC) for MW and TIR records. Grey fields represent continuous measurements of snow and ice surface and subsurface measurement, te red fields represent instrument failure of any kind (like te Ku instrument tat broke down on day 3), blue fields is te period angular TIR dependency program and green fields represent te sea water freeze-up experiment. Instrum. site Tursday Marc 31 st Friday April 1 st Saturday April 2 nd Sunday April 3 rd Monday April 4 t Tuesday April 5 t Wed.day April 6 t Ku BC1 BC2 Ka BC1 BC2 IR100 MIX TRIP - END OF FJORD IR120 BC1 BC2 ISAR BC1 BC2 Te oter group was formed by te MW and te TIR teams. All measurements performed by tis group took place at two 'base-camps' in te icinity of Qaanaaq, at te positions BC1 and BC2 on www.dmi.dk/dmi/tr11-18 page 8 of 27
Tecnical Report figure 1. Te MW and TIR radiometers were more or less deployed on full time at te 2 base-camp positions. A time table of all MW and TIR data tat were collected is gien in table 1. Figure 2 Plot of all collected IR data from te IR100, IR120 and ISAR sensors. Data are not calibrated. Grey and blue data refer to surface brigtness temperatures from te IR100 and IR120 instruments, respectiely and te black dots refer to te air temperature measured by te IR120 data logger. Te red data dots are ISAR surface temperature estimated wit sea water emissiity. Black circles are mean IST estimates based on te infrared AVHRR instrument on te Metop satellite. Figure 3 Water and ice skin temperatures from freeze-up experiment in red (roug calibration to termodynamic temperature). Air temperatures are plotted in green. www.dmi.dk/dmi/tr11-18 page 9 of 27
Tecnical Report TIR radiometers Te TIR experiments included measurements wit 3 different TIR sensors, 2 broad band radiometers and a narrow band radiometer. Te TIR sensors are: ISAR narrow band sensor (9.6-11.5 microns, iew angle ~12 degrees), deeloped at NOCS. IR100 broad band sensor (7 14 microns, iew angle ~9 degrees), manufactured by Campbell Science. IR120, broad band sensor (8 14 microns, iew angle ~40 degrees), manufactured by Campbell Science. Te ISAR instrument is a scanning self-calibration radiometer, wit a eated and ambient black body, a sky and a target iew (see Donlon et. al, 2008). Te emissiity used to calculate ice surface temperatures were te sea water emissiity for te corresponding target angle (25 degrees for BC 1 and BC2 emissiity of 0.9916, 55 for te refreezing experiment emissiity of 0.985). Beside te TIR measurements corresponding termodynamic measurement of snow/ice skin temperatures and air temperatures are recorded. Program 1) Spatial ariability measurements. IR100 wit GPS mounted on dog sledge along wit te ocean and ice tickness working group on 3 day journey along te fjord and back. See route on figure 1 and sample data in figures 2 and 5. 2) Temporal ariability measurements. IR 120 mounted at BC1 and BC2 during most of te duration of te field campaign. ISAR was mounted at BC1 and BC2, respectiely, for te duration of te campaign. See table 1 and figure 2. 3) Freeze up measurement. ISAR and IR100 ice surface measurements coincided wit IR120 measurements in freeze up experiment. See Freeze up procedure and data in figure 3. 4) Angular dependency measurements. IR120 used as mobile radiometer for measuring temperature dependency of obseration angle. See angular measurement in figure 4 and procedure description below. 5) Snow in situ measurements. For all stationary positions of te IR100/120 instruments snow parameters were measured. Measured parameters are grain size, salt content and termodynamic temperature (te data logger of te in situ termometer broke down and ence only few in situ temperatures are logged). Procedure Spatial ariability: Te IR100 was performed 'en-route' during te 3 day OCEAN-THICK-TIR programme to te bottom of te fjord (figure 1, 5 and 10). Te IR radiometer was mounted on te same dog sledge as te EM31 ice tickness instrument to obtain optimal coincident measurements of tickness and IST temperatures. Te IR100 dog sledge set-up (joint wit te EM31) is seen on te poto in figure 9. Te temperature transects from te dog sledge trips are plotted in figures 2 and 5 Temporal ariability: Te IR120 sensor was mounted on a tripod close to te ISAR sensor to test te broad/narrow band sensitiity to skin temperature ariations. Tis procedure was followed at bot BC1 and BC2. Occasionally te IR120 was used for angular dependency measurements. Te IR120 and ISAR set-up is seen in figure 7 and all temperature profiles are plotted in figure 2, as brigtness temperatures. www.dmi.dk/dmi/tr11-18 page 10 of 27
Tecnical Report Freeze up: Te freeze up experiment was of joint interest to te TIR and te MW measurement programmes. All TIR and MW radiometers were arranged around te constructed open water basin before te ole was inundated. An oeriew poto (figure 7) illustrates tis set-up. Te ole was drilled using a Ø 25 cm ice drill to create an approximately 1 by 1 meter basin. Te basin was cleaned for ice and snow and eentually inundated troug a ole to te sea water below. Angular measurements: Te angular IR radiation pattern was mapped by using te IR120 instrument as a and eld radiometer. View angles between 0 and 60 degrees were recorded in 10 degree interals. At appropriate interals te sky temperature is recorded to andle te reflectance term for calculation of emissiity. In situ measurements: Snow grain size, salinity and termodynamic temperatures were recorded during all stationary IR measurements. Data - temperaturs An oeriew of te full TIR radiometer deployment record is sown in table 1, and all brigtness temperature records from te ISAR, IR100 and IR120 instruments are plotted in figure 2. Tus te table sow in wic configuration te temperature data from figure 2 is recorded. Te IR100 data (bot air and surface brigtness) are sifted approximately +8K relatie to te oter IR data, i.e. we seem to ae an offset error. Te reason for tis offset problem is not yet found, but under inestigation. Te spatial ariability data (IR100) are clearly affected by day warming and large spatial ariability and te nigt time data are more constant (figure 2). Extreme large fluctuations in te temporal ariability data (IR120) during day time are caused by te angular measuring program, wit sky measurements and moing te radiometer around in general. Data from te satellite based IST production, tat is set up for te Inglefield Bredning and oter Greenland fjords, are also plotted on figure 2. Tese data sow fine agreement wit te land based IR measurements during te first 3-4 days, ereafter te satellite and land based measurements dierge. Tis diergence is caused by clouds obstructing te measurements of te ice surface from satellite. A colour plot of te IR100 data on route to te bottom of te fjord wit te ocean and tickness teams is plotted on top of te coinciding SAR image in figure 5. Te 'freeze up' sections of te temperature records is zoomed into and plotted in figure 3. Here time of inundation and selected ice tickness data are superimposed. Te freeze up data is coarsely calibrated to termodynamic temperatures. www.dmi.dk/dmi/tr11-18 page 11 of 27
Tecnical Report Figure 4 Angular measurements from IR120 and estimated emissiity. Data - emissiity experiment A series of experiments were carried out wit te IR 120 radiometer to examine te angular dependence of te IR emissiity for te snow and ice (see table 1 for time of obserations). In total, 12 angular measurements profiles (from 0 degrees zenit angle to 70 wit step of 10 degrees) were performed at base camp 1 and 2, measuring te IR temperature, in situ air and snow temperature. Te eigt of te radiometer was 130 cm and te last 8 profiles also included 0 zenit angle obserations at 1 cm aboe te ice. 4 sites were used for te last eigt angular profiles (two sites at BC1 and two sites at BC2). At eac base camp, a site was cosen wit a smoot snow surface and one wit a more textured snow surface. Samples were taken of te snow on top of te ice and te snow grain size and te salinity were measured. Clear sky was present for all obserations wit te solar eleation angles being about 15 degrees and mostly perpendicular to te line of sigt of te IR instrument. It was attempted to measure two angular profiles of te IR sky temperature, oweer, te sky temperature was too cold (colder tan -100C) for te IR instrument to obsere and no obserations came out of tis. www.dmi.dk/dmi/tr11-18 page 12 of 27
Tecnical Report Figure 5 Measurement from dog sledge mounted IR120 radiometer. Data are superimposed a SAR image. Te colour code is: blue is colder tan red. Tese obserations were used to calculate te snow and ice emissiity for angles wit an interal of 10 degrees and te results are sown in figure 4, indicating a clear angular dependence for all te angular profiles tat were made, irrespectiely of te surface conditions and te actual temperature. www.dmi.dk/dmi/tr11-18 page 13 of 27
Tecnical Report MW radiometers Te microwae radiometer experiment measured te termal emission from snow and sea ice in te Ku and Ka microwae bands, frequencies around 16 and 34 GHz, respectiely. Te Ku and Ka band radiometers measured at bot ertical and orizontal polarisation. Te Ku band radiometer operated only te first day, April 1 st, due to a problem wit te local oscillator. Figure 6 Te Ka-band radiometer digital counts for cannel 1 and cannel 2 during te freeze-up experiment on 5. April 2011. Program Te diurnal microwae emission cycle was measured on tick snow coered first-year ice at base camp 1. Te temperature profile witin te ice at BC1 was measured wit a termistor string from air to water during all 6 days. Te upper 15-20cm of te string was aboe te ice and te termistor spacing was 2 cm. Te radiometer measurements were repeated at base camp 2 on a ticker snow pack. Te freeze up experiment was conducted at base camp 2 witout relocating te radiometers. Te microwae radiometer set-up from site BC2 at te beginning of te freeze-up experiment is illustrated in figure 7. Snow and ice properties were measured near te target including: Snow dept and stratigrapy using a ruler. Ice tickness using a drill or measuring samples in te freeze-up experiment. Snow grain size estimated wit magnifying glass on mm- grid. Snow density measured wit density soel and scale. Salinity of snow and ice measuring te conductiity of melted samples Snow and ice temperature using a termometer. www.dmi.dk/dmi/tr11-18 page 14 of 27
Tecnical Report Figure 7 Open water/freeze-up experiment sortly before letting water into te ole. ISAR on te box on te rigt, IR120 on te tripod on te left and MW instruments on te scaffold Data Te full deployment oeriew of te microwae (and TIR) data records is sown in table 1. Due to a defect power generator te microwae radiometer record is not complete. Te following periods were coered by te Ka-band radiometer: 14.00 1. April to 6.00 2. April 15.00 2. April to 14.00 3. April 17.00 3. April to 8.00 4. April 14.00 4. April to 24.00 5. April 16.00 5. April to 9.00 6. April Te Ku-band radiometer operated only from 14.00 1. April to 6.00 2. April due to a problem wit te local oscillator. Sample data (as digital counts) from te Ka radiometer are plotted in figure 6. Te temperature profile data from te termistor string is plotted in figure 8. www.dmi.dk/dmi/tr11-18 page 15 of 27
Tecnical Report Figure 8 Temperature profile data from termistor string frozen in at BC1. Te approximately top 20 cm are in open air, and dept resolution (termistor spacing) is 2 cm. Te first axis of te top plot is ours from deployment, in 6 ours resolution. www.dmi.dk/dmi/tr11-18 page 16 of 27
Tecnical Report THICK Te ice tickness program uses a mobile autonomous sea-ice tickness monitoring deice tat is currently under deelopment by te Marine Tecnology group at SAMS. Te deice utilizes te commonly used EM31 conductiity probe by Geonics Ltd. In tis instance we use te new sorter ersion, wic is more easily mountable on a dog sled. Tis new prototype deice includes a range of sensors, including a GPS to proide precise measurements wit ig spatio-temporal accuracy. A potograp of te sledge set-up is sow in figure 9. An oer-fligt wit laser scanner and radar altimeter was completed approximately 2 weeks after te Qasiteex period to matc up te EM31 data wit airborne data. Figure 9 Em-31 wrapped up on a dog sledge and ready to go. Te IR100 radiometer is seen by te rigt andle at te back of te sledge. Program Te goal of te THICK program was to test te new prototype EM-31 deice in autonomous operation mounted on te unter s sled. Tis is in anticipation of future deployments, wen te system will be mounted on a sled for a full season. By accompanying te OCEAN team, it was possible to surey a large area of te fjord. Te instrument was continuously sampling during periods of sled trael. As well recording conductiity and GPS position we were also logging a range of pysical parameters suc as inclination, acceleration and temperature. Tis additional data will elp us during te data analysis in identifying ow te dynamics of dog-sled trael affect te conductiity signal quality, and ultimately improe te accuracy of te data. Procedure Te deice was mounted on te unter s sled during eac of te trips carried out by te OCEAN team. It was important to distribute te loading of eac sled so tat te EM31 deice was not cluttered wit metallic (conductie) objects. Ideally te EM31 sled carried minimal personnel (drier + 1 passenger) and articles suc as cloting and camping gear. Oceanograpic equipment (winces, generators, CTD etc.) was carried on a separate sled, altoug tis was not always possi- www.dmi.dk/dmi/tr11-18 page 17 of 27
Tecnical Report ble and is reflected in te data. Te sled track runs can be seen in figure 10. Te first day was a sort trip out and back across te mout of te fjord. Te purpose of tis first day was to test te set-up and erify te operation of te prototype logger. Tis test proed successful and te deice was setup for autonomous logging for subsequent trips. Stops were made at 2km interals for manual ice tickness measurements, as well as te two stops made by te OCEAN team. Calibration of te EM31 instrument was also carried out during te OCEAN stops. On days 2, 3 and 4 te trip went to te ead of te fjord, oernigt at Qeqertat and back. Stops were made for manual ice-tickness measurements only at te OCEAN team stops. Te first day some damage was noticed on te instrument, altoug a repair was possible. As a result tere is a gap in te data, as seen in te figure. Day 5 was a run out to te centre of te Olrik fjord and back, again stopping only at te OCEAN team sites for manual ice tickness measurements, instrument calibrations were also carried out during tese stops. Test run Fjord Run: Run up te centre of te fjord. Instrument stopped responding near te ead of te fjord Head run: Run around te ead of te fjord Fjord run2: Run along side of te fjord www.dmi.dk/dmi/tr11-18 page 18 of 27
Tecnical Report Across run: Run across fjord. Figure 10 Pats of te fie separate runs of te EM mounted sled system Data - EM31 Data was collected from eac of te sled runs on eac day from te routes sown in figures 1 and 10. Te data are currently being processed so tat a full ice tickness data set can be determined for te entire trip. Te system data is also being analysed to identify possible errors in te conductiity data, and correct for sled dynamics. An example of one calibrated data set of sea-ice tickness from te return journey from Qeqertat to Qaanaaq can be seen in figure 11. Figure 11 Ice tickness sample data from fjord run2. Te colour bar indicate tickness in cm. Data air borne Te airborne CryoSat Cal/Val team was operating around Qaanaaq coincident wit tis field work. Te Cal/Val team made an oer-fligt along te EM31 route along te fjord. Te original plan was to fly te Qasiteex surey line, on April 9-10. Howeer, te laser scanner was too cold and did not www.dmi.dk/dmi/tr11-18 page 19 of 27
Tecnical Report operate. A successful fligt was completed on April 19, see green fligt track in figure 12. During te surey fligts ig-resolution laser scanner data and 13.5 GHz radar altimetry data supported by ertical potograpy were obtained. Te airborne laser and radar data are not yet processed or calibrated, but are expected aailable from beginning of 2012. Figure 12 Fligt pats on April 19t 2011, wit laser scanner and 13.5 GHz radar altimeter. Blue dots on te fjord correspond to oceanograpic and ice tickness surey route to te end of te fjord. Te 2 dots on te glacier are way-points added for fligt naigation. www.dmi.dk/dmi/tr11-18 page 20 of 27
Tecnical Report OCEAN Hydrograpic data are obtained from a sledge based surey from te ice coered outer fjord region towards te ead of te fjord wit its caling glacier fronts (figure 13). Obserations document te dominance of warmer intermediate waters from te Baffin Bay trougout te lengt of te fjord and in direct contact wit te glacier fronts (figure 14). Obserations sow no sign of a cold alocline structure of Arctic origin below te winter mixed layer but, reacing a dept of 80-100m, te cold mixed layer does limit te melting rates at sallower depts trougout te year. Te ertical water mass distribution resembles te conditions in te Baffin Bay toug modified at te mixedlayer interface. Consequently only te deep reacing floating glaciers contribute to te obsered melting and are ulnerable to warming of te Atlantic layer. Figure 13 Oceanograpic measurements in te bottom of Inglefield Bredning. Te CTD is lowered into te water from te tripod on te left and te EM-31 is idden on te sledge in te background. Program Te program is planned as tree section sureys supported by two to tree Inuit unters wit dog sledges: A two-day surey across te Inglefield Bredning, A one-day surey to te entrance of te Olrik Fjord and A tree-day journey along te Inglefield Bredning to te ead of te fjord. www.dmi.dk/dmi/tr11-18 page 21 of 27
Tecnical Report It was possible to occupy te cross fjord section and te Olrik Fjord opening on one-day journeys returning to te DMI facility in Qaanaaq oernigt. During te longer journey along te fjord we planned to camp on te ice off te small settlement Qeqertat on te Harard Øer. Howeer, we were kindly offered use te combined scool and Sunday curc for sleeping. Tis also made it possible to download data and ceck instrument functionality in warm conditions. Figure 14 Water mass properties on te oceanograpic surey sections off Qaanaaq across Inglefield Bredning and towards te ead of te fjord. Procedures Measurements of water mass distribution were done at full dept at te defined sections, along and across te fjord making use of a portable CTD system. Tis system consists of a SBE19plusV2 pumped Seacat unit, a portable electric winc wit 2000m syntetic rope and Niskin type water samplers attaced to te line and triggered by drop messenger. Sensors include te built in Temperature-Conductiity package and an additional SBE43 oxygen membrane sensor. Te ice was in general 80-120 cm tick, relatiely flat and wit no open water leads except ery near te glacier front. On station, te dog sledges were unloaded and te Honda EU20i (2kW) generator was powered up to eat te CTD box wit te underwater unit. We used a 1.2kW air dryer yielding good entilation and tempered outlet temperature. Hereafter we drilled a 10 inc ole using a gas powered ice auger. Slus was remoed from te ole by pulling up te auger fast frequently during te drilling. Tis was also necessary in order to aoid te drill from fastening. After assembling te portable winc, a weigt was attaced to te line and te dept logged using te digital meter weel. Wit knowledge of te station dept, te eated CTD was deployed troug te wole in a swift procedure to aoid cooling of te unit. After deployment, te CTD rested in te subsurface layer for approximately 5 minutes waiting for te pump to turn on and allowing any slus ice from te drill ole to melt and in turn stabilizing sensor readings before te actual cast. Hereafter te CTD were raised to te base of te ice from www.dmi.dk/dmi/tr11-18 page 22 of 27
Tecnical Report were te profiling of te water column was started. Profiles were retrieed wit a descent rate of approximately 30 m/min in te upper 200m, rougly troug te mixed layer and across te strongly stratified interface. Away from strong gradients, a descent rate of 50m/min was used. Water samples were taken at predefined depts, 5m and 100m after te termination of te up-cast part of te profile using te 2.5 l Niskin water sampler. Samples were drawn for isotopic composition (d18o) and nutrients; see Table 2 for a complete list of te distribution of samples at indiidual stations. Nutrient samples were frozen immediately wile te d18o samples were stored warm inside te eay Parkas. All samples collected will be analyzed after return to Copenagen. In total 13 full dept profiles were obtained during te field campaign (Table 2). SBE43 data are only aailable for station Q02. Te oxygen membrane sensor failed after te first deployment due to te cold working conditions near or below -20 o C. Figure 15 Lower mixed layer current ariability at station Q01 (50-80m aerage) from te upward looking ADCP mooring. Upper stick plot sows te current components wit te primary flow direction into te fjord directed upward. Below is sown te current magnitude, components and direction, respectiely. Te current direction is rotated so tat zero degrees is eastward along te aerage flow direction Data - CTD No bottle data were drawn for salinity calibration and we rely on te ery recent instrument calibration. After downloading te raw data from te CTD (HEX format), profile readings were conerted to engineering units including pressure, in situ temperature, conductiity and oxygen concentration. Pressure readings are initially ig pass filtered two ways in order to smoot ig frequency data and to obtain a uniform descent istory of te cast. Te applied cut-off period for te SBE19plusV2 is 1.0 seconds. Inerent misalignment time delay in sensor responses and transit time delay in te www.dmi.dk/dmi/tr11-18 page 23 of 27
Tecnical Report pumped pluming line are corrected by adancing conductiity 0.5 sec relatie to pressure for te SBE19plus. By tis alignment, measurements refer to same parcel of water and te procedure eliminated artificial spikes in te calculated salinity wic is dependent on temperature, pressure and conductiity. A recursie filter was ereafter applied to remoe cell termal mass effects from te measured conductiity according to te specifications for te indiidual sensors of te CTD system. Tis correction of salinity is significant in te upper layers wit steep temperature gradients, but oterwise negligible. Te last modification of te data remoes scans wit slow descent rate or reersals in pressure. Post processed data is aeraged into 1m bins and includes deried parameters; salinity and oxygen concentration. Data ADCP/Current mooring Te current structure and tidal ariability in te mixed layer under te sea ice was monitored on station Q02 (BC1) off te city of Qaanaaq (see table 2 and figure 15) on te section crossing te Inglefield Bredning. We used a 300 khz RD-Sentinel Workorse Broadband Acoustic Doppler Current Profiler (ADCP) moored at a dept of 92m below te surface looking upward. Te ADCP was deployed 14:30 31-03-2011 and recoered again on 15:30 06-04-2011 yielding six days of obserations. Te ADCP was configured in moored profiling mode witout bottom track. Using RD software (PlanADCP) te dept range was set to 110m, 2m cell size yielding 54 dept cells, 50 pings per ensemble and 2 min between measurements. Measured elocities were generally less tat 10cm/sec oriented rougly along te direction of te fjord wen taking into account te negatie magnetic declination of 52.50 o W. Te field strengt in te region is weak (5400 nt) and near te tresold of te internal flux gate compass. Tus, te aerage direction of te currents is associated wit significant uncertainty. Measured currents sow a mixed (weak diurnal and stronger semidiurnal) tidal current signal associated wit reersals in current direction. Obsered tilt and role of te instrument was negligible een toug te unit was anging freely in te water by its own weigt. Interestingly, obsered magnitudes of tidal currents are comparable to geostropic estimates based on te cross fjord ydrograpy (not sown). Positioned near te mixed layer interface, te temperature time series from te mooring yields additional insigt to te ertical moement associated wit tides and internal waes. Amplitudes of 0.8 o C is obsered and may be translated into isopycnal migration of up to 15m. A reduced ertical coerage is obsered during day time due to a low abundance of acoustic scatters in te water column. Only during nigttime, migration of zooplankton allows full profiling from te mooring dept te base of te sea-ice. Considering te tides and te duration of te mooring tis makes it difficult retriee a robust estimate of te aerage profile in te upper part of te mixed layer. Table 2 CTD stations and bottle samples Station Cast Latitude Longitude Bottle samples Date ID # Nort East d18o Nutrients yyyymmdd Q01 2 77.428 290.864 5m 5m 20110331 Q03 4 77.377 290.943 5m/5m 5m 20110401 Q02 5 77.330 291.013 5m/5m none 20110401 Q04 6 77.444 290.840 5m/5m 5m 20110401 Q06 7 77.439 291.678 none none 20110402 Q07 8 77.464 292.442 none none 20110402 Q11 9 77.604 293.595 5m/100m 5m/100m 20110403 Q12 10 77.657 293.462 5m/100m 5m/100m 20110403 Q13 11 77.639 293.679 5m/100m 5m/100m 20110403 Q14 12 77.548 293.105 5m/100m 5m/100m 20110404 www.dmi.dk/dmi/tr11-18 page 24 of 27
Tecnical Report Q15 13 77.593 292.960 5m 5m 20110404 OL01 14 77.266 290.905 5m/5m 5m 20110405 OL02 15 77.244 290.875 5m/5m 5m 20110405 www.dmi.dk/dmi/tr11-18 page 25 of 27
Tecnical Report Contacts Following persons participated in te QAASITEEX field campaign. For information about te data, te fieldwork in general and access to data, please contact a person connected to te data you are interested in. Table 3 Contact details and affiliations for all Qasiteex participants. Name Teme Institution mail Jacob L Høyer TIR DMI jl@dmi.dk Rasmus T Tonboe MW + TIR DMI rtt@dmi.dk Steffen M Olsen OCEAN DMI smo@dmi.dk Gorm Dybkjær TIR DMI gd@dmi.dk Sten Scmidl Søbjærg MW DTU sss@space.dtu.dk Sane Rodwell THICK SAMS sane.rodwell@sams.ac.uk Werenfrid Wimmer TIR NOCS w.wimmer@soton.ac.uk Henriette Skourup THICK (airborne) DTU sk@space.dtu.dk www.dmi.dk/dmi/tr11-18 page 26 of 27
Tecnical Report References Donlon, C., I. S. Robinson, W. Wimmer, G. Fiser, M. Reynolds, R. Edwards, T. J. Nigtingale, 2008: An infrared sea surface temperature autonomous radiometer (isar) for deployment aboard olunteer obsering sips (os). J. Atmos. Oceanic Tecnol., 25, 93 113. Preious reports www.dmi.dk/dmi/tr11-18 page 27 of 27