Weekly gridded Aquarius L-band radiometer/scatterometer observations and salinity retrievals over the polar regions – Part 2: Initial product analysis

Abstract

Abstract.Following the development and availability of Aquarius weekly polar-gridded products, this study presents the spatial and temporal radiometer and scatterometer observations at L band (frequency ∼ 1.4 GHz) over the cryosphere including the Greenland and Antarctic ice sheets, sea ice in both hemispheres, and over sub-Arctic land for monitoring the soil freeze/thaw state. We provide multiple examples of scientific applications for the L-band data over the cryosphere. For example, we show that over the Greenland Ice Sheet, the unusual 2012 melt event lead to an L-band brightness temperature (TB) sustained decrease of ∼ 5 K at horizontal polarization. Over the Antarctic ice sheet, normalized radar cross section (NRCS) observations recorded during ascending and descending orbits are significantly different, highlighting the anisotropy of the ice cover. Over sub-Arctic land, both passive and active observations show distinct values depending on the soil physical state (freeze/thaw). Aquarius sea surface salinity (SSS) retrievals in the polar waters are also presented. SSS variations could serve as an indicator of fresh water input to the ocean from the cryosphere, however the presence of sea ice often contaminates the SSS retrievals, hindering the analysis. The weekly grided Aquarius L-band products used are distributed by the US Snow and Ice Data Center at http: //nsidc.org/data/aquarius/index.html, and show potential for cryospheric studies.

Weekly gridded Aquarius L-band radiometer/scatterometer observations and salinity retrievals over the polar regions – Part 1: Product description

“…The products also contain ICEF. An initial analysis of these data is provided in the companion paper (Brucker et al, 2014a).…”

“…The distinction for each beam is also needed due to the different incidence angles. The distinction between each orbit type is necessary because of the anisotropy of the ice-covered surfaces (Brucker et al, 2014a). For each week and hemisphere, eighteen NRCS maps are produced and distributed (one for each of the three beams, each of the three polarizations, and each of the two orbit combinations).…”

“…It is anticipated that the products will be updated on a monthly basis following the release schedule of the Level 2 data sets by PO.DAAC. The companion paper by Brucker et al (2014a) focuses on the description of the Aquarius observations and retrievals over the Greenland and Antarctic ice sheets, sea ice in both hemispheres, and polar oceans.…”

Space‐Based Observations for Understanding Changes in the Arctic‐Boreal Zone

“…SSS has been monitored from space since 2010 using L‐band (1.4 GHz) microwave radiometers onboard the SMOS and Aquarius (onboard SAC‐D) missions (Lagerloef et al, ; Kerr et al, ; Brucker et al, ,b; Le Vine et al, ). In June 2015, the Aquarius mission was lost because of a spacecraft failure.…”

Aquarius whole range calibration: Celestial Sky, ocean, and land targets

“…With SMAP's end of life planned for 2018 at the earliest, this makes the L-band continuity extends over about a decade. In order to use L-band data from these various instruments for This research was supported by the NASA grant # NNX10AV23G.. long term scientific studies of oceans and the cryosphere [5], calibration will be of critical importance.…”