Draft plan about lunar calibration for FY-3 MWHS Gu Songyan, Guo Yang, Wu Ronghua, Sun Fenglin, Wu Qiong and Dou Fangli. National Satellite Meteorological Center, China Meteorological Administration (NSMC/CMA)

1 Background OUTLINE 2 Moon glint in MWHS 3 Microwave Moon—MicM 4 Draft plan

1 Backgroud ok Microwave Temperature Sounder (MWTS) 13 channels (AMSU-A) Microwave Radiation Imager 10 channels Microwave Humidity Sounder (MWHS) 15channels with channels at 118 GHz (MHS) We have launched 4 fy-3 satellites, fy-3/a/b/c, and d. There are 3 microwave instruments board on fy-3 satellites, they are MWRI, MWTS, and MWHS.All of them have the two points calibration system of space view and warm target view on orbit. Just like optical instruments, they all make an inclusive of non-lineary system response.

Atmospheric Transmission at Microwave Wavelengths MWHS2

Central Frequency (GHz) WMHSⅡ Parameter Specification Scan Angle ±53.35° Pixels Per Scan Line 98 Quantization 14 bits Ch No. Central Frequency (GHz) Polarization Bandwidth (MHz) Freq. Stability (MHz) Dynamic Range (K) NEΔT(K) Cal. Acc. Main Beam Width Main Beam Eff. Purpose 1 89.0 V 1500 50 3－340 1.0 1.3 2.0° >92% Surface and Precipitation 2 118.750.08 H 20 30 3.6 2.0 Atmospheric Temperature Profile 3 118.750.2 100 4 118.750.3 165 1.6 5 118.750.8 200 6 118.751.1 7 118.752.5 8 118.753.0 1000 9 118.755.0 2000 10 150.0 1.1° >95% 11 183.31±1 500 Atmospheric Moisture Profile 12 183.31±1.8 700 13 183.31±3 14 183.31±4.5 15 183.31±7 2018/12/10

The NEdT from FY3A to FY3C is improved much FY-3C Specification FY-3C On-orbit FY-3B On-orbit FY-3A On-orbit Channels Peak nonlinearity /K Channels

FY-3C/MWHS CALIBRATION RESULTS Cross-compare with ATMS （O-B） Site calibration at Puer FY3C MWHS（II）   Soumi/NPP ATMS 通道号 标准差 （K） CH1 4.03 CH16 3.49 CH2 0.43 -- CH3 0.23 CH4 0.29 CH5 0.27 CH6 0.48 CH7 1.8 CH8 2.26 CH9 3.6 CH10 3.06 CH17 3.45 CH11 1.36 CH22 1.33 CH12 1.47 CH21 1.34 CH13 1.7 CH20 1.57 CH14 2.08 CH19 1.93 CH15 2.39 CH18 2.44 通道 标准差 （K） 11 0.947 12 0.8183 13 0.8603 14 0.9516 15 0.9361

2 Moon glint in MWHS 9 MOON 3 warm target views 黑体 MWHS 3 space views 98 earth views 3 space views 黑体 MWHS MOON 3 warm target views 9

2 Moon glint in MWHS Space view Space view Scan line number

2 Moon glint in MWHS SPACE VIEW SP COUNT Ch1 Ch2 Ch3 LINE NUMBER

Lunar glint identification

From Yang Hu

NESDIS interpolation using Smooth Curve

Before correction After correction Sub-point BT Space view DN

150GHz 89GHz 118GHz-8 183GHz-4

FY-3C/MWHS CALIBRATION RESULTS Cross-compare with ATMS （O-B） Site calibration at Puer FY3C MWHS（II）   Soumi/NPP ATMS 通道号 标准差 （K） CH1 4.03 CH16 3.49 CH2 0.43 -- CH3 0.23 CH4 0.29 CH5 0.27 CH6 0.48 CH7 1.8 CH8 2.26 CH9 3.6 CH10 3.06 CH17 3.45 CH11 1.36 CH22 1.33 CH12 1.47 CH21 1.34 CH13 1.7 CH20 1.57 CH14 2.08 CH19 1.93 CH15 2.39 CH18 2.44 通道 标准差 （K） 11 0.947 12 0.8183 13 0.8603 14 0.9516 15 0.9361

3 Microwave Moon Ground-based microwave measurements of the Moon have been studied at wavelengths of 1–500 cm since 1960s (Battaglia, 2003; Hirth et al., 1976; Keihm and Gary, 1979; Morabito et al., 2008; Schloerb et al., 1976). However, such observations have a number of drawbacks as: (i) they cannot observe the far side of the Moon; (ii) the spatial resolution is much lower than what can be done by a lunar satellite; (iii) due to the presence of limb effects, interpretation of off-center data are much more difficult. TB of the Moon and its characteristics were investigated theoretically and predicted by a number of authors (Fa and Jin, 2007a; Gary and Keihm, 1978; Hagfors, 1971; Keihm, 1982; Keihm and Gary, 1979; Muhleman, 1972). Interpretations of ground-based lunar microwave measurements were done based on different lunar regolith models (Feng et al., 2010; Keihm and Cutts, 1981; Schloerb et al., 1976). Passive orbital microwave measurements at different frequencies were proposed since the 1980s (Keihm, 1984), with the expectation that they could lead to the knowledge of global lunar heat flow and average regolith thickness. This thermal information, which is not available through active radar images of the Moon obtained by recent lunar orbiters Kaguya (Ono et al., 2009) and Chandrayaan-1 (Spudis et al., 2010), could provide important clues to understand the thermal evolution of the Moon and provide reliable estimation of valuable lunar resources, such as helium-3, due to their dependence on the thickness of regolith (Fa and Jin, 2007b). Passive microwave observation can sense emission from below the lunar surface (possibly down to 10 m, depending on the dielectric properties of the lunar regolith), and is able to “see” the permanently shadow region in the poles and the Moon at night regardless of solar illumination.

Chinese Chang’E-1 (CE-1) Among recent lunar orbiters, only the Chinese Chang’E-1 (CE-1) was equipped with a passive microwave radiometer (MRM) to measure the natural microwave emission from the lunar surface. The microwave emission, characterized by a frequency-dependent brightness temperature (TB), is related to the physical temperature and dielectric properties of the lunar surface. By measuring the brightness temperature at different frequencies, detailed thermal behavior and properties of the lunar surface can be retrieved. Using CE-1’s microwave data, we present here a set of microwave maps of the Moon constructed through a rescaling of TB to noontime or midnight CE-1 launched in 2007-10-24.

Information about MRM Frequencies (GHz) 3.0 (±1%) 7.8 (±1%) 19.35 (±1%) 37 (±1%) Bandwidth (MHz) 100 (±15%) 200 (±15%) 500 (±15%) Integration time (ms) Temperature sensitivity (K) ⩽0.5 Linearity ⩾0.99 3 dB beam width E:15 ± 2° E:9 ± 2° E:10 ± 2° H:12 ± 2° H:9 ± 2° H:10 ± 2° Footprint (from 200 km orbital altitude) (km) 56 30

3 Microwave Moon---MicM

3 Microwave Moon---MicM

Central Frequency (GHz) 4 Draft plan Inter-channel calibration for oxygen absorption channels at 118GHz Ch No. Central Frequency (GHz) Polarization Bandwidth (MHz) Freq. Stability (MHz) Dynamic Range (K) NEΔT(K) Cal. Acc. Main Beam Width Main Beam Eff. Purpose 1 89.0 V 1500 50 3－340 1.0 1.3 2.0° >92% Surface and Precipitation 2 118.750.08 H 20 30 3.6 2.0 Atmospheric Temperature Profile 3 118.750.2 100 4 118.750.3 165 1.6 5 118.750.8 200 6 118.751.1 7 118.752.5 8 118.753.0 1000 9 118.755.0 2000 10 150.0 1.1° >95% 11 183.31±1 500 Atmospheric Moisture Profile 12 183.31±1.8 700 13 183.31±3 14 183.31±4.5 15 183.31±7

Put the ch (3) as a reference channel, and transfer the ref Put the ch (3) as a reference channel, and transfer the ref. to others by lunar views, to optimize the calibration results. FY-3C Specification FY-3C On-orbit FY-3B On-orbit FY-3A On-orbit Channels

SV DN during the Moon appearing in the field of space view Deep Space view DN SV DN during the Moon appearing in the field of space view Reference DSV DN Scan line Rsp(moon,ch1), ……,Rsp(moon,chn) ----------------Rsp(moon,reference) Rsp(moon,chm)=Rsp(moon,reference) +△R(chm) (m=1,2,…,n)

Central Frequency (GHz) Ch No. Central Frequency (GHz) Main Beam Width Main Beam Eff. Purpose 1 89.0 2.0° >92% Surface and Precipitation 2 118.750.08 Atmospheric Temperature Profile 3 118.750.2 4 118.750.3 5 118.750.8 6 118.751.1 7 118.752.5 8 118.753.0 9 118.755.0 10 150.0 1.1° >95% 11 183.31±1 Atmospheric Moisture Profile 12 183.31±1.8 13 183.31±3 14 183.31±4.5 15 183.31±7 Bandwidth (MHz) 1500 20 100 165 200 1000 2000 500 700 MWHS: total power radiometer

Brightness tem./K Warm target Moon target C DSV 0º 90º 180±2º 270º 53.35º 287±2º DSV 306.65º earth scene Brightness tem./K DN Warm target B A Space point 282K 2.73K moon Moon target C DN(space view) DN(moon view) DN(warm view)  

---- antennas mismatch 4 Draft plan (2) Lifetime stability checks of MWHS (3) Pointing bias evaluation for two antenna systems of 118GHz and 183GHz. ---- antennas mismatch

Bridge the lunar BT (2.730K,150K) to the T/V test results over (80K,310K) and then getting the system respond over whole dynamic range of (2.73K,310K). Extrapolate the T/V test results of(80K,310K) to (2.73K,310K)

谢谢! Thank you!

f0-df f0 f+df

SNO ( FY3/MWHS and NPP/ATMS at 183GHz)