mpact of River Discharge on Arctic Atmosphere: Coupling a River Routing Model

The Korea Institute of Atmospheric Prediction Systems (KIAPS) is committed to enhancing the accuracy and reliability of weather forecasts, especially for periods extending beyond the conventional two-week timeframe. To support this goal, we are developing an innovative and comprehensive model that seamlessly integrates various components of the Earth system, including oceans, sea ice, waves, and river systems. This integrated approach is crucial because, while short-term weather predictions typically focus on atmospheric variables, they often overlook the significant role that rivers play in the global hydrological cycle. However, as the forecasting window extends into extended-medium range, the contribution of rivers to the Earth’s water balance becomes increasingly important. To address this, the project employs a specialized model designed to accurately estimate the volume of freshwater that rivers discharge into the oceans, which in turn influences a range of oceanic and atmospheric processes.

In this study, we have integrated the Catchment-based Macro-scale Floodplain (CaMa-Flood) model with the Korean Integrated Model (KIM) Numerical Weather Prediction (NWP) system. The CaMa-Flood model is specifically designed to simulate river discharge and floodplain dynamics on a global scale, making it a valuable tool for enhancing the realism of hydrological processes in weather prediction models. By coupling CaMa-Flood with the KIM, we aim to improve the representation of riverine processes within the broader context of Earth system modeling.

To evaluate the effectiveness of this integration, we conducted a series of validation analysis. These involved comparing river discharge data generated by the coupled KIM/CaMa-Flood model with observational data from various sources, as well as reanalysis datasets. The objective is to assess the model’s ability to accurately reproduce the spatial distribution and seasonal variability of river discharge across different regions. Additionally, the study explores the impact of freshwater influx from rivers on key oceanographic parameters such as sea surface temperature, salinity, and sea ice concentration, particularly in the Arctic region. A significant focus of the research is the Arctic, where the interactions between river discharge, sea ice, and atmospheric conditions are especially complex and influential on global climate variabilities. We are conducting an in-depth analysis of the relationships among sea ice extent, surface air temperatures, and upper atmospheric dynamics in the Kara-Barents Sea region of the Arctic. The findings from this study are expected to provide valuable insights into the role of riverine processes in Arctic climate dynamics and contribute to the development of more accurate and reliable long-term forecasts.