A new approach for bias adjustment of IMERG remotely sensed snowfall product

• Published in: Theoretical and applied climatology Vol. 143; no. 1-2; pp. 675 - 690
• Main Authors: Sadeghi, Leili, Saghafian, Bahram, Moazami, Saber
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 2021; Springer; Springer Nature B.V
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Bias; Boxes; Calibration; Climate science; Climatology; Distribution (Probability theory); Distribution functions; Earth and Environmental Science; Earth Sciences; Global precipitation; Ground stations; Longitude; Lower bounds; Original Paper; Pixels; Precipitation; Remote sensing; Resolution; Satellites; Snow; Snow accumulation; Snowfall; Snowpack; Spatial discrimination; Spatial resolution; Telemetry; Temporal resolution; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-020-03420-z

Due to uncertainty in the nature of indirect remotely sensed precipitation products, bias adjustment is a crucial step. In this research, bias adjustment of Integrated Multi-satellitE Retrievals for GPM (Global Precipitation Measurement) (IMERG) snowfall estimates with 0.1° spatial resolution and half-hour temporal resolution was performed over a basin located in the Western United States based on Snowpack Telemetry (SNOTEL) ground station snow accumulation (SA) observations using the Gridded based Bias Adjustment using Copula (GBAC) approach. After dividing the study area into several boxes, usual and unusual pairs of cumulative distribution functions (CDFs) were separated in station pixels. Then, simulated biases were obtained using multivariate copula functions in station boxes. Next, based on the T copula function, bias adjustment bands were generated during the calibration period in station pixels. This step was followed by the validation stage. Also, bias adjustment bands were generated in pixels with no station. Based on calibration results, in boxes located west of 120° W, the range between the lower bound and the 10th percentile of the band had the most impact on satellite SA adjustment. Conversely, in boxes located east of 120° W, the middle range of the band (between 10th and 90th percentiles) was more effective. Thus, longitude was an effective factor in satellite SA bias adjustment. The validation results showed that in station boxes with a longitude over 120° west, the adjustment band was narrower. This is while in station boxes with longitude less than 120° west, the bias adjustment band better encompassed the ground SA data.