SMOS L2 OS ATBD - ARGANS

More documents

Recommendations

Info

109 ICM-CSIC LOCEAN/SA/CETP IFREMER SMOS L2 OS Algorithm Theoretical Baseline Document Doc: SO-TN-ARG-GS-0007 Issue: 3 Rev: 9 Date: 25 January 2013 Page: 109 with slightly different bandwidths. The "continuum" dataset includes the 2.725K cosmic background. Hydrogen line The Leiden-Argentina-Bonn (LAB) dataset was used here [21]. The LAB survey contains the final data release of observations of 21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey ([10]) of the sky north of –30° with the Instituto Argentino de Radioastronomia Survey ([8]) of the sky south of –25°. The velocity spans a range between -450 km/s and +400 km/s, with a resolution of 1.3km/s. The rms brightness temperature noise of the merged dataset is 0.07-0.09K (for each 1.3 km/s layer). Data are sampled with a 0.5° x 0.5° resolution in latitude longitude (galactic coordinates). This dataset will be referred in the following as the HI map. Integration of HI into the continuum map SMOS measures a bandwidth B SMOS of 19MHz that includes the HI line (1420.4058 MHz) so that the latter has to be integrated into the continuum map in the context of SMOS data processing. The continuum signal is broadband, with almost constant brightness levels, herafter denoted T cont , over SMOS bandwidth. It is understood that the data in (Reich & Testori) includes T cont as well as the 2.725K cosmic background T CMB , while HI data ([21]) does not include T CMB . To derive HI-line contribution over SMOS bandwith from HI line velocity range data, we used a Doppler relation between velocity range and frequency shift. The HI line frequency is f o =1420.4058 MHz. The relation between frequency f and velocity v is given by the Doppler shift = , c v c f fo (1) with c the speed of light and v the speed of the source relative to the observer (positive away from observer). The stopband filter applied to the Reich & Reich measurements is centered on f o and is B HI =2MHz wide. This corresponds to a velocity range of [-211.2 km s 1 , +211.4 km s 1]. Over this bandwidth, the contribution of HI signal is: km s T MHz HI THI( v) dv (211.4 211.2) km s 1 211.4 / 2 = 211.2 / Finally, the resulting sky noise to be taken into account in SMOS measurement is = 2 HI sky CMB cont MHz HI . BSMOS B T T T T (7) Gaps in the continuum survey: use of alternative surveys and source catalogs for missing data integration Some areas of the Reich and Testori continuum survey are void of data; this is for example the case of Cassiopeia A which peculiarities (high power flux) made it impossible to be measured accurately through the standard procedure. Similarly, it may be that some strong (6)
110 ICM-CSIC LOCEAN/SA/CETP IFREMER SMOS L2 OS Algorithm Theoretical Baseline Document Doc: SO-TN-ARG-GS-0007 Issue: 3 Rev: 9 Date: 25 January 2013 Page: 110 punctual sources are not properly taken into account in the continuum survey. Higher resolution surveys are available that can alleviate this problem by providing auxiliary 1.4GHz flux measurements for these problematic areas. These datasets usually come in two forms: • higher resolution local sky maps where for a given area of the sky a radio flux is associated to each [right ascension, declination] cell. This enables to assess the slow variations of the background flux when it results from the combination of minor sources that cannot be individually identified. Once rescaled and converted to the proper geometry, these datasets can be used to patch the continuum map where data is missing. • source catalogues that identify strong sources with small angular extensions and provide their total flux. These datasets can be useful to identify strong sources in otherwise quiet areas of the sky. Unfortunately, these high resolution surveys have still not been compiled into a global map of the radio sources of the sky. Several databases have thus been used here, with the related issues in terms of format / coordinate system / projection / units (main beam or full beam) and homogeneity of the available data. For example, the density of measurements available for the northern sky is larger than for the southern sky. See Appendix A for a discussion on the data from auxiliary surveys / catalogs used to generate the sky map. 1) Cassiopeia A area: In Reich and Testori map, the area around Cassiopeia has been left blank. There are two problems linked with this area: • this remnant of a recent supernova presents a large angular extension, with a complex structure of its flux component, • the measured flux varies in time Effelsberg survey [23], [24] was used here to give an idea of the spatial structure of the radio flux, but the complexity of this area and its temporal variations makes it unsuitable to accurate corrections without spending more effort on the analysis of the properties of this area (data are available on the temporal variation of the emission but are not considered in this algorithm). Consequently, the Reich & Testori map is complemented by the Effelsberg survey of the Cassiopeia area, rescaled (to the Tb for a 35 arcmin beam as in the Reich & Testori survey) and resampled (to the 0.25° pixel size). Moreover, an error Tb fields for the sky map was generated in which the Cassiopeia area is set to the rescaled and resampled value to flag the issue. 2) Other strong sources: One objective here is to check whether strong sources are properly taken into account in the Reich and Testori mapping. The authors mentioned that some strong sources (Orion A, Cygnus A, Taurus A, ...) were not included in the continuum map. In addition, it could be that measurement limitations or processing issues would reduce the intensity of some strong radio sources in the map. To check that the input of strong sources is well quantified, a map of strong sources is generated from L-band source catalogues [25], [26] and the corresponding brightness temperatures that would be collected by the Stockert/IAR radiotelescopes (35 arcmin beamwidth) is computed. These sources were extracted from the NVSS (North) and from the Parkes (South) catalogues. Here, individual sources stronger than 0.3 Jy are selected (such a flux would contribute to around 0.015K error in the Reich and Reich map). It is anyway expected that sources of this strength or fainter are taken into account in the continuum measurement. The resulting brightness temperatures were compared to the combination of the Reich and Testori and HI map. Most sources exhibit a Tb that is equal or smaller to the one of the continuum (as the sources are embedded into a strong emission area which is preponderant in the relatively large beam of the
Page 1 and 2:
ICM-CSIC LOCEAN/SA/CETP IFREMER SMO
Page 3 and 4:
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Table of contents ICM-CSIC LOCEAN/S
Page 13 and 14:
Page 15 and 16:
2 ICM-CSIC LOCEAN/SA/CETP IFREMER S
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
10 ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Presence of ice Applying sea ice ma
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Classification of grid point: g Oce
Page 49 and 50:
36 3.5. Outliers detection ICM-CSIC
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
T T 42 ss ss ICM-CSIC LOCEAN/SA/CET
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
52 4.1. Flat sea ICM-CSIC LOCEAN/SA
Page 67 and 68:
54 SSS ICM-CSIC LOCEAN/SA/CETP IFRE
Page 69 and 70:
Page 71 and 72: 58 ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 121: 108 ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
I(θ_mean)=A1(θx)+A2(θy) where θ
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Tb_i 2 = Tb_meas_i 2 174 ICM-CSIC L
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Uncertainty origin Sea state 4 Sea
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
ICM-CSIC LOCEAN/SA/CETP IFREMER -th
Page 215 and 216:
IV ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 217 and 218:
VI ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 219 and 220:
VIII ICM-CSIC LOCEAN/SA/CETP IFREME
Page 221 and 222:
X ICM-CSIC LOCEAN/SA/CETP IFREMER S
Page 223 and 224:
XII ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 225 and 226:
XIV ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 227 and 228:
XVI ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 229 and 230:
I ICM-CSIC LOCEAN/SA/CETP IFREMER S
Page 231 and 232:
III ICM-CSIC LOCEAN/SA/CETP IFREMER
Page 233 and 234:
V ICM-CSIC LOCEAN/SA/CETP IFREMER S
Page 235 and 236:
VII ICM-CSIC LOCEAN/SA/CETP IFREMER
show all

SMOS L2 OS ATBD - ARGANS

Create successful ePaper yourself

Delete template?

Save as template?