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Land surface models (LSMs) are useful for estimating land surface states and fluxes such as snow water equivalent, soil moisture content, vegetation, and river discharge. Although estimates are continuous in time and space, LSMs are flawed since they lack comprehensive representation of process physics and are dependent on uncertain boundary conditions. One way to improve LSM performance is by conditioning model states on space-borne retrievals using an ensemble Kalman filter framework. In this study, the Noah-MP version 4.0.1 LSM without conditioning (a.k.a., Open Loop; OL) is compared against the same model with conditioning (a.k.a., Data Assimilation; DA). Two different univariate DA experiments are conducted: 1) assimilation using terrestrial water storage (TWS) anomalies from GRACE / GRACE-FO, and 2) assimilation using leaf area index (LAI) retrievals from MODIS. Not only do the experiments assimilate different types of retrievals (i.e., TWS versus LAI), but also, they assimilate products of different spatial (~3° versus ~0.005°) and temporal (~monthly versus ~weekly) resolutions. Experiments are conducted across different watersheds in North America with a particular focus on basins with irrigated agriculture. Modeled states and fluxes from the OL and DA are then compared against independent, ground-based measurement networks including U.S. SNOTEL, Canadian CanSWE product, U.S. SCAN for soil moisture, and USGS measurement gauges for river discharge. Statistical analyses, including bias, RMSE, and normalized information content (NIC) are computed to quantify the marginal improvements via each assimilation experiment. Results provide a basis to better understand the coupling between different state variables (i.e., snow mass, soil moisture, and groundwater) as well as the utility of using coarse-scale and fine-scale retrievals in land data assimilation.

To compare the accuracy of three devices (Pentacam, Sirius and OPD-Scan III) to differentiate subclinical keratoconus from normal corneas by wavefront parameters. Two hundred and seventeen patients were enrolled in three groups [68 normal, 79 subclinical keratoconus (SKCN) and 70 KCN eyes] in this prospective diagnostic test study. Wavefront indices were evaluated between the groups using Pentacam, Sirius and OPD-Scan III. The accuracy of the parameters was determined by measuring the area under the receiver operating characteristic curve (AUC) for each group. Front Baiocchi-Calossi-Versaci (BCV) index with Sirius (sensitivity = 87.7%, specificity = 83%, AUC = 0.887), front Vertical Coma (Z3−1) with Pentacam (sensitivity = 75%, specificity = 100%, AUC = 0.857) and Corneal Z3−1 with OPD-Scan III (sensitivity = 100%, specificity = 78.6%, AUC = 0.857) had the highest AUC values for the diagnosis of subclinical KCN. In the KCN group, the highest AUC values were obtained for front higher-order aberration (HOA), front/back Z3−1 and front Secondary Vertical Coma (Z5−1) with Pentacam (sensitivity = 100%, specificity = 100%, AUC = 1.00 for all three), front root mean square values per unit area (RMS/A), HOA, Residual HOA, BCV, RMS Trefoil and RMS Coma with Sirius (sensitivity = 100%, specificity = 100%, AUC = 1.00 for all) and Corneal HOA, RMS total Coma and Z3−1 with OPD-Scan III (sensitivity = 100%, specificity = 93%, AUC = 0.96 for all three). Corneal wavefront indices generated from different devices have acceptable validity for differentiating normal cornea from the early form of KCN, and this can be very useful for preoperative screening before refractive surgery. The front BCV with Sirius was the most accurate parameter for diagnosis of SKCN followed by Z3−1 with Pentacam and OPD-Scan III.

PurposeTo determine the two-year results of small incision lenticule extraction (SMILE) for correcting post-keratoplasty myopia and myopic astigmatism.MethodsIn this case-series study, 10 eyes of 10 patients with a 6-10-year history of successful deep lamellar keratoplasty (DALK) underwent SMILE using VisuMax laser platform. Ophthalmologic examinations and visual acuity and refraction measurement were done pre- and 1, 3, 6, 12, and 24 months postoperatively. Pentacam and Sirius imaging was done in the first and last follow-up session.ResultsThe mean age of the patients was 39.60±7.86 years. Six subjects were male. After two years, uncorrected distance visual acuity did not change in one eye and improved 1-6 lines in other eyes. Corrected distance visual acuity decreased in one eye, did not change in four eyes, and improved 1-8 lines in other eyes. The mean decrease of spherical equivalent, spherical error, and cylinder power was 1.92±1.96 diopter (D) (P=0.013), 0.70±3.05D (P=0.213), and 2.42±2.91D (P=0.024), respectively. The vector mean target induced astigmatism, surgical induced astigmatism, and difference vector was 1.30D@44˚, 1.11D@24˚, and 0.86D@73˚, respectively. Two years after surgery, vertical coma, horizontal coma, and spherical aberration increased by 0.44±0.51, 0.23±0.32, and 0.02±0.16µm respectively (all P>0.05) while trefoil reduced by 0.29±0.75µm (P=0.428).ConclusionSMILE is a successful procedure for reducing refraction and astigmatism after DALK in patients with moderate myopia and moderate to severe astigmatism and improves the visual acuity in these patients. Axis rotation during surgery may result in under-correction of astigmatism. Refinement of SMILE treatment nomogram for post-DALK cases seems necessary.

Purpose: To evaluate the ray tracing method's accuracy employing Okulix ray tracing software and thin-lens formulas to calculate intraocular lens (IOL) power using a swept-source optical coherence tomography (SS-OCT) biometer (OA2000). Methods: A total of 188 eyes from 180 patients were included in this study. An OA-2000 optical biometer was used to collect biometric data. The predicted postoperative refraction based on thin-lens formulas including SRK/T, Hoffer Q, Holladay 1, and Haigis formulas and the ray tracing method utilizing the OKULIX software was determined for each patient. To compare the accuracy of approaches, the prediction error and the absolute prediction error were determined. Results: The mean axial length (AL) was 23.66 mm (range: 19–35). In subgroup analysis based on AL, in all ranges of ALs the ray tracing method had the lowest mean absolute error (0.56), the lowest standard deviation (SD; 0.55), and the greatest proportion of patients within 1 diopter of predicted refraction (87.43%) and the lowest absolute prediction error compared to the other formulas (except to SRK/T) in the AL range between 22 and 24 mm (all P < 0.05). In addition, the OKULIX and Haigis formulas had the least variance (variability) in the prediction error in different ranges of AL. Conclusion: The ray tracing method had the lowest mean absolute error, the lowest standard deviation, and the greatest proportion of patients within 1 diopter of predicted refraction. So, the OKULIX software in combination with SS-OCT biometry (OA2000) performed on par with the third-generation and Haigis formulas, notwithstanding the potential for increased accuracy in the normal range and more consistent results in different ranges of AL.

Submerged breakwaters are used to prevent shore line erosion and sediment transportation. One of their advantages is low visual impact. In this paper, the effects of discontinuous submerged breakwaters over water surface elevation was numerically studied considering the extended Boussinesq equations as governing equations using MIKE21 software. The result of discontinuous breakwater was compared with a beach without breakwater. The results showed that the gap dramatically effects on surface elevation from shore line to offshore. It is also evident from results that with approaching the center of the gap, fluctuation of surface elevation is generated. It is because of passing longshore currents towards offshore through the gap which leads to an increase in sediment transportation rate. Nevertheless, transferring water mass from breakwater gap results in powerful rip currents leading to high changes on longshore wave profile. As waves propagate towards shore line the transformation phenomena occurs related to sea bottom bathymetry changes. The length and the height of waves moving from deep water to shallow water change and as the wave slope goes over the critical limit and waves reach the breaking line they break and most of the wave energy releases. When high waves approaching the shoreline, water fluctuations occurs leading to beach erosion and sediment transportation. Therefore, preventing land erosion by wave attacks and decreasing the impact of inducing waves on shore structures are important subjects in coastal engineering. Breakwater is a structure which is mainly used to protect the area in its lee from wave attack. In reality, the purpose of building breakwaters is providing a sheltered area for loading and offloading of the ships; as well as to manipulate the littoral transport conditions by trapping the moving sand particles. There are different types of breakwaters like detached breakwater that is completely isolated from shore and attached breakwater that is connected to the shoreline. Both of these types of breakwaters can be floating, emerged and submerged structures. Today the use of detached low-crested or submerged breakwaters in conjunction with beach nourishment is advised for stabilization of beaches. This is mainly related to their small