Application of field spectrometry and remote sensing data for permafrost surface studies in the Laptev Sea coastal low land (Lena River Delta)
Introduction
The monitoring of permafrost c oas tal l andscapes is a cor nerstone of t he quantificati on of f uture environmental changes and their impacts on Arctic coast al lowl ands of the Lena River Delta, which link t he Arctic continental region to t he Laptev S ea. Thawi ng per mafros t might c ause massi ve landsc ape changes due to thermokarst and enhanced rel ease of greenhouse gas es from t he large c arbon storage of fr ozen deposits . In additi on, current quantities of c arbon and ot her nutrients in s edi ments, li kel y to be mobilized by ever increasing erosion, are onl y crudel y known.
Remote s ensing and s pati al data analysis are ideal t ools t o detec t, st udy, and quantif y c hanges in t he Arctic t undra landsca pes. F or a succ essful interpret ation of s uch data, consider able basic knowledge on t he properties of these l andsc apes is required. T his includes t he c haract erization of vegetation, s oils, geomorphol ogy, and s pectral s urfac e properties .
Main objectives
Development of general met hods for t he c haract erization and classific ation of t ypical periglacial landsc apes in t he Arctic c oast al lowland of t he Lena Ri ver D elta, and t heir applicability f or remot e s ensi ng based anal ys es.
Development of a spectral dat abase for periglacial / tundra surfac es in the Lena River Delta.
Development of a det ailed Lands at 7 ETM+ land c over classification and a pedol ogical map based on CHRIS Proba data s hall provide the basis f or detecti ng long ter m changes
Results
A variet y of field investigations and lab anal yses (image and spectra processing, terrain modelling, spatial data analysis) were carried out for the assessment of periglacial surface properties in the Lena River Delta.
More than 500 field spectra were acquired from 19 sites in the delta. 12 different surface classes were extracted from these spectra. The classification indicates significant differences in surface properties between the delta main t erraces, and thus their good spectral separability.
Remote sensing based image classification was s uccessfully applied for the detailed characterization of land cover units in t he study sites.
CHRIS-Proba data was used for the classification of soils in a t haw depression.
A multi-temporal image stoc k for change detection analysis was compiled.
Conclusion
The combination of a variet y of field and lab studies provides an excellent ground truth dataset for the analysis of multispectral remote sensing imagery and the classification of periglacial surfaces.
The first step for the development and maintenance of a spectral database f or Arctic periglacial regions is done.
The unique dataset acquired provides t he base for further anal ysis of multi- and hyperspectral imagery (e.g. Chris-Proba) in the Lena River Delta tundra.
Study areas
Location: Lena Ri ver Delt a, Laptev Sea coast, N orth Si beria Coverage: 29. 000 km2(largest Arctic delta)
Study sites: A: Turakh (wester n delta);
B: S amoylov and Kur ungnakh (central delta) Vegetation zone: Lowland t undra
Geomorpholog y: 1s tterrac e: Rec ent floodplains and Holoc ene sandy deposits (the modern “ac tive“ delta) (ca: 1 – 12 m a.s.l.)
2ndterrace: Characterized by sandy deposits, probabl y of Lat e Pleistocene fluvial genesis (ca: 11 – 30 m a.s.l.)
3rdterrace: Late Pleist ocene accu mulation plai n of ice- and organic-rich deposits (“Ice C omplex”) (ca: 30 – 60 m a.s .l.) Speci al conditions: Situat ed in t he z one of continuous permafrost (sediments are
perenniall y froz en); dominated by fluvial-deltaic and periglacial processes ; large portions are wetlands wit h strong het erogeneit y in micro-relief, veget ation patter ns, and soil moistur e distribution
(Contact: Mathias.Ulrich@awi.de)
Mathias Ulrich
a, Guido Grosse
b, Sabine Chabrillat
c, Lutz Schirrmeister
aa - Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany b - Geophysical Institute, Universtity of Alaska, Fairbanks, USA
c - German Research Center for Geoscience, GFZ, Potsdam, Germany
Acquired multi-temporal and multi- sensoral remote sensing data Long-term change detection
10-J ul- 0 6 15-J ul- 0 5 13-J un -0 6 CH RIS-Pr ob a
29-J un -0 5 4-Ju l-0 5 30-J un -0 1
28-J ul- 0 1 5-Au g- 00 La nds at-7 ETM+
26-J ul- 0 1 27-J ul- 0 0 26-J ul- 7 3 La nds at-1 M SS
16-J ul- 7 5 29-S ep -6 8 1-Oct-6 5 Cor on a
9-Au g- 80 18-J ul- 6 4
22-J un -6 4 22-J un -6 4
T urakh Samoylov Sensor
Outlook
Multi-temporal, hyperspectral CHRIS-Proba satellite data and optical ALOS PRISM/AVNIRR2 satellite data will be used for further analysis and classification of the Lena River Delta coastal lowlands and comparison of t he results with existing classifications.
The field s pectra datasets will be used f or comparison with satellite derived spectra from CHRIS-Proba and other sensors.
Field spectrometry with an ASD FieldSpec Pro FR (Summer 05)
Corona 22-Jun-64
CHRIS-Proba 04-Jul-05 Samoylov Island Maximum-likelhood classification of a Landsat 7 ETM+ subset
We produced a detailed land cover classification of each geomorphological terrace at the T urakh study site based on ou r field investigations and a Landsat-7 image subset.
T he diagrams show exemplar y classification results for the a rea of the thermoka rst depressions on the 2nd ter race (see geomorphological analysis above).
Characterization of vegetation, soils, and active layer depth
Example: Surface pa rameters of a slope and basin association in a typical thaw depression (thermo ka rst) on the 2ndLena Delta terr ace (T urakh stud y site; soil map based on CHRIS- Proba data fr om June 05).
Drya s sp., lic he n, dry m oss Active l ay er d epth: 8 0 cm Typic Ps amm otur be l
Base d o n fluv ia l fin e to med iu m gr ai ne d sa nds Typic Fi brist il
Base d o n l ake an d flo od- pla in s ed im ents, p eat
Sed ge s an d mo ss Active l ay er d epth: 3 0 cm
(b) Wel l dr ai ne d sl op e (a)
(a)
(b) (b)
(a) Po orl y dra in e d ba sin
Wav el en g th (nm ) Wav el en g th (nm ) Wav el en g th (nm ) Wav el en g th (nm ) Wav el en g th (nm )
Reflectance(%)
Flat of alluv ial wood H igher non flooded areas H igher floodplains Seasonal floodplains Arc tophilas p. dominated s easonal floodplains
Wav el en g th (nm ) Wav el en g th (nm ) Wav el en g th (nm ) Wav el en g th (nm ) Wav el en g th (nm )
Reflectance(%)
Poly gonal tundra Sand bank , v egetated Thaw depress ion s lope Thaw depress ion Vegetated, mars hy lak e
Wav el en g th (nm ) Wav el en g th (nm )
Reflectance(%)
Surfac e 3rd terrac e Thaw depress ion
A B C D E
K L
F G H I J
Spectral properties of various surface types on the 1st terrace of the Lena Delta
Spectral properties of various surface types on 2nd terrace of the Lena Delta (Turakh)
3r d terrace of the Lena Delta
T he water absorption center ed at ~1160 nm (f rom 1120 – 1240 nm ) applying continuum re moval
technique on the ASD reflectance spectra.
Related Publication
Ulrich, M., Grosse, G., Chabrill at, S. & Schirrmeister, L. (in revision). Arctic perig laci al surface featur es as enviro nmenta l ind icators usi ng fiel d spectrometry an d remote sens ing d ata. Remote Sens ing of Envir onme nt.
Geomorphological analysis at study site level (example: Turakh)
