Frequent cloud cover in Taiwan’s subtropical monsoon climate often limits optical remote sensing, while slope hazards, land subsidence, and maritime surveillance demand all-weather, day-and-night synthetic aperture radar (SAR) observation. SAR is an active microwave imaging system. Its range resolution is governed by signal bandwidth, and its azimuth resolution is determined by the synthetic aperture, independent of range. The retained phase further enables interferometric (InSAR), polarimetric (PolSAR), and tomographic (TomoSAR) applications. However, Taiwan’s first indigenous SAR mission, FORMOSAT-9, comprises two X-band active phased-array satellites (best resolution ≤ 1 m, maximum swath > 50 km), and its first launch is not scheduled until 2028, one year later than previously planned. Until then, domestic users remain reliant on foreign commercial SAR data.

This talk begins with a review of SAR imaging geometry, resolution, and processing workflows, followed by a systematic overview of Taiwan’s SAR research and development capabilities across industry, government, academia and domestic industry. The assessment indicates that domestic InSAR applications are internationally competitive, but it also identifies three structural gaps: (1) the absence of an indigenous data source before 2028; (2) the concentration of spaceborne payload integration in a single supplier, with transmit/receive (T/R) modules and GaN power amplifiers not yet space-qualified domestically; and (3) the lack of a shared validation infrastructure among the hardware, data, and algorithm communities. Accordingly, a three-phase roadmap toward indigenous capability is proposed, with the two FORMOSAT-9 launches as milestones. The first phase emphasizes pooled procurement of commercial data, calibration-site establishment, and airborne pathfinder validation. The second focuses on in-orbit calibration and a second payload supplier. The third targets a small SAR constellation and multi-baseline tomographic missions.

Our group addresses these gaps from both the simulation and the system perspectives. On the simulation side, a GPU-accelerated, fully polarimetric shooting-and-bouncing-ray/physical-optics (SBR/PO) echo simulator has been developed. It models the polarimetric calibration chain using TerraSAR-X orbit and imaging geometry and incorporates a spherical-wave PO kernel for near-field airborne echoes. This enables imaging algorithms, radiometric calibration, and calibrator designs to be verified before measured data become available. On the system side, a dual-mode X-band (9.65 GHz) unmanned aerial vehicle (UAV) SAR has been designed for an operating altitude of 110 m. The High and Low modes use range bandwidths of 424 MHz and 212 MHz and provide ground swaths of approximately 100 m and 495 m, respectively. Under conservative assumptions, including an antenna efficiency of 0.4 and a system loss of 6 dB, the worst-case noise-equivalent sigma zero (NESZ) is −34.2 dB, exceeding the −30 dB requirement by about 4 dB. In the processing architecture, an RFSoC performs waveform generation, sampling, digital down-conversion, and range compression. An embedded system  executes backprojection imaging, motion compensation, and phase gradient autofocus, with an estimated compute margin of 20–80×. Future work will complete hardware integration and conduct flight tests over a corner-reflector calibration site for cross-validation against simulation. Together, the simulator and the UAV SAR provide an airborne pathfinder for FORMOSAT-9 and help close the validation gap in Taiwan’s pursuit of indigenous SAR capability.

Keywords: synthetic aperture radar (SAR); polarimetric simulation; SBR/PO; UAV SAR; noise-equivalent sigma zero (NESZ); FORMOSAT-9

20min (incl. Q&A) per talk

1.大屯火山群蒸氣噴發產物之礦物學研究 Mineralogical study of phreatic eruption products from the Tatun Volcano Group

李恆毅 / 師大地科系 LEE, Harry Heng-Yi / NTNUES

Supervisor： 賴昱銘教授 Prof. Yu-Ming Lai

2. 熔積岩的產狀與構造：以海岸山脈與澎湖為例 Occurrence and textures of peperites: examples from the Coastal Range and Penghu Islands

周哲宇 / 師大地科系 JHOU, Jhe-Yu / NTNUES

Supervisor： 賴昱銘教授 Prof. Yu-Ming Lai

3. 裂隙碎形幾何分析及其對岩體滲流特性之意涵探討 Fractal Characterization of Rock Fracture Networks and Its Implications for Permeability Anisotropy

王姿茵 / 師大地科系 WANG, Zi-Yin / NTNUES

Supervisor： 葉恩肇教授 Prof. En-Chao Yeh

4. 現地應力非彈性應變回復法之精度分析與改進 Improvement of Anelastic Strain Recovery Method for In-Situ Stress Assessment

洪振益 / 師大地科系 ANG, Kim Joo / NTNUES

Supervisor： 葉恩肇教授 Prof. En-Chao Yeh

Falling ice particles — including ice crystals, snow, and other frozen hydrometeors — exert significant but long-underappreciated radiative effects on Earth’s energy budget. In contemporary general circulation models (GCMs), the treatment of ice-phase microphysics and their associated radiative properties remains a leading source of systematic bias, with downstream consequences for simulated tropical circulation, sea surface temperature (SST) variability, sea surface height (SSH) anomalies, and El Niño–Southern Oscillation (ENSO). This talk synthesizes findings from a series of studies that used complementary satellite observations — including CloudSat, CALIPSO, MODIS, AIRS, Jason-1/2, QuikSCAT, and CERES — alongside CMIP5 and CMIP6 multi-model ensembles to diagnose how falling ice radiative effects (FIRE) propagate through the coupled climate system. We demonstrate that FIRE warm the lower troposphere and cool the surface in the tropics, modulating surface wind stress, influence thermocline depth, and SSH anomalies in ways that bias the representation of Central-Pacific (CP) El Niño in models. We further show that CMIP3/CMIP5/CMIP6 models exhibit systematic shortwave and longwave radiation biases over tropical and subtropical oceans attributable to the parameterization of frozen hydrometeor optical properties, and that correcting or constraining these biases substantially alters projected Southern Ocean sea ice trajectories and CP-ENSO statistics under global warming. Taken together, these results highlight FIRE as a critical but underexplored physical mechanism linking cloud microphysics to large-scale ocean–atmosphere variability, with implications for climate projection fidelity.