Field activities of the “Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic” (SIGMA) Project in Greenland in 2011-2013

Aoki, Teruo; Matoba, Sumito; Uetake, Jun; Takeuchi, Nozomu; Motoyama, Hideaki

doi:10.5331/bgr.32.3

Cited by 50 publications

(52 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Measured data were sampled and stored in a data logger (CR1000, Camp- bell, USA) every 1 min. Aoki et al (2014a) have provided a more detailed description of the AWS. In the present study, we used 5 min average values of AWS data, but to highlight important temporal evolution the SEB data reported after Sect.…”

Section: Meteorological Observationsmentioning

confidence: 99%

“…Finally, we used the SMAP model to explore the SEB during the IOP at the SIGMA-A site by diagnosing the turbulent heat fluxes and heat supplied by rainfall. (Aoki et al, 2014a) in northwest Greenland (Fig. 1), and we report the observed meteorological and snow conditions.…”

Section: Introductionmentioning

confidence: 99%

“…For this purpose, we employed data obtained from in situ measurements made at a site named SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic)-A (Aoki et al, 2014a) in northwest Greenland during the 2012 summer intensive observation period (30 June to 14 July, hereafter IOP). During the latter half of the IOP, which coincided with the period of the record near-surface melt event reported by Nghiem et al (2012), we observed remarkable melting of the nearsurface snowpack and encountered continuous rainfall (Aoki et al, 2014b;Yamaguchi et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…1), and we report the observed meteorological and snow conditions. An AWS was newly installed at site SIGMA-A on 29 June 2012 (Aoki et al, 2014a). In the northwest GrIS, two GC-Net AWS sites exist Steffen and Box (2001) presented monthly mean temperatures at these stations and also demonstrated that the mean temperature lapse rate over GrIS in summer was 0.4 • C per 100 m. This information allows us to estimate the average near-surface air temperature during July at the SIGMA-A site, resulting in a value of −6.5 • C. This region of the northwestern GrIS is now being carefully monitored, because since around late 2005 the ice loss over southern portions of the GrIS has been spreading rapidly northward along the northwest coast (Khan et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

et al. 2015

View full text Add to dashboard Cite

Abstract. The surface energy balance (SEB) from 30 June to 14 July 2012 at site SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic)-A, (78 • 03 N, 67 • 38 W; 1490 m a.s.l.) on the northwest Greenland Ice Sheet (GrIS) was investigated by using in situ atmospheric and snow measurements as well as numerical modeling with a one-dimensional multi-layered physical snowpack model called SMAP (Snow Metamorphism and Albedo Process). At SIGMA-A, remarkable near-surface snowmelt and continuous heavy rainfall (accumulated precipitation between 10 and 14 July was estimated to be 100 mm) were observed after 10 July 2012. Application of the SMAP model to the GrIS snowpack was evaluated based on the snow temperature profile, snow surface temperature, surface snow grain size, and shortwave albedo, all of which the model simulated reasonably well. Above all, the fact that the SMAP model successfully reproduced frequently observed rapid increases in snow albedo under cloudy conditions highlights the advantage of the physically based snow albedo model (PBSAM) incorporated in the SMAP model. Using such data and model, we estimated the SEB at SIGMA-A from 30 June to 14 July 2012. Radiation-related fluxes were obtained from in situ measurements, whereas other fluxes were calculated with the SMAP model. By examining the components of the SEB, we determined that low-level clouds accompanied by a significant temperature increase played an important role in the melt event observed at SIGMA-A. These conditions induced a remarkable surface heating via cloud radiative forcing in the polar region.

show abstract

Section: Meteorological Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

et al. 2015

View full text Add to dashboard Cite

show abstract

“…To evaluate snow depth when there are only small amounts of moisture in the snowpack, once the meltwater is refrozen on the snow surface, we used descending data (night scenes), to obtain a temporal resolution of one day. Aoki et al [42] integrated field observation at the QH3 site (Qaanaaq, Greenland) into the framework of the snow impurity and glacial microbe effects on abrupt warming in the Arctic (SIGMA) project. To investigate the microwave characteristics and optimum physical parameters on the GrIS, we used a snow section data set, observed on 30 July 2011 at the QH3 site, which includes the stratigraphic horizon, snow temperature profile, and snow classification of Fierz et al [43].…”

Section: Datamentioning

confidence: 99%

Possibility of Estimating Seasonal Snow Depth Based Solely on Passive Microwave Remote Sensing on the Greenland Ice Sheet in Spring

Tsutsui

Maeda

2017

Remote Sensing

View full text Add to dashboard Cite

Sea level rise related to the melting and thinning of the Greenland Ice Sheet (GrIS), a subject of growing concern in recent years, will eventually affect the global climate. Although the melting of snow on the GrIS is actively monitored by passive microwave remote sensing, very few studies have estimated the seasonal GrIS snow depth using this technique. In this study, to estimate seasonal snowpack on GrIS, we investigated the microwave property and optimum physical parameters. We used our microwave radiative transfer model to create a lookup table and a simple satellite retrieval algorithm to estimate seasonal snow depth on GrIS in spring, based on the microwave satellite brightness temperature from AMSR-E and AMSR2. Our research suggests there is potential for estimating snow depth based solely on GrIS passive microwave remote sensing data. We validated these estimates against in situ snow depths at several sites and compared them with the snow spatial distributions over the entire GrIS of several major products (ERA-interim, MAR ver. 5.3.1 and GLDAS-CLM) that evaluate snow depth.

show abstract

In situ measurements of polarization properties of snow surface under the Brewster geometry in Hokkaido, Japan, and northwest Greenland ice sheet

et al. 2014

Self Cite

View full text Add to dashboard Cite

Ground‐based measurements of spectral degree of linear polarization (DLP) of various snow types were made during intensive field campaigns in a snowfield in Hokkaido, Japan, and on the northwest Greenland ice sheet in 2012. Spectral measurements were conducted under the solar zenith angle of approximately the Brewster angle in order to quantify the polarization properties of light reflected from snow. We obtained spectral DLPs for five different snow types in both field campaigns including precipitation particles, needles, surface hoar, melt forms, and melt freeze crust covering the snow surface. The measurements showed that in the visible region the spectral dependence of the DLP was small while in the near infrared region it increased with increasing snow grain size with some distinct local peaks. The angular dependence indicated that the DLP exhibited small angular dependence in the visible region while in the near‐infrared region it exhibited large and broad peaks in the forward direction. Especially for the melt‐freeze crust, the DLP approached 1.0 at wavelengths close to λ = 1.5 and 2.0 μm. These features can be explained by (1) the relative contribution of surface versus volume scattering to the reflected light, (2) the incident angle (solar zenith angle) of approximately the Brewster angle, and (3) the ratio between direct and diffuse components of the solar radiation incident on the snow surface. The spectral DLP was found to be quiet sensitive to the incident solar radiation and solar elevation as well as snow optical properties. Comparison between the spectral DLP and snow grain size obtained by snow pit work shows that the DLP for λ > 1.5 μm was very sensitive to large snow grains close to the surface. This finding suggests that polarization measurements obtained from airborne/satellite polarimeters will be useful for surface snow grain size retrievals and help improve the accuracy of such retrievals based on the intensity‐only measurements, especially for the large snow grain sizes.

show abstract

Field activities of the “Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic” (SIGMA) Project in Greenland in 2011-2013

Abstract: Introduction

Cited by 50 publications

References 38 publications

Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

Possibility of Estimating Seasonal Snow Depth Based Solely on Passive Microwave Remote Sensing on the Greenland Ice Sheet in Spring

In situ measurements of polarization properties of snow surface under the Brewster geometry in Hokkaido, Japan, and northwest Greenland ice sheet

Contact Info

Product

Resources

About