Work

Evaluation of Surface Conditions from Operational Forecasts Using in situ Saildrone Observations in the Pacific Arctic

Year: 2022
Type: article
Abstract: Observations from uncrewed surface vehicles (saildrones) in the Bering, Chukchi, and Beaufort Seas during June – September 2019 were used to evaluate initial conditions and forecasts with lead times up to 10 days produced by eight operational numerical weather prediction centers. Prediction error behaviors in pressure and wind are found to be different from those in temperature and humidity. For example, errors in surface pressure were small in short-range (<6 days) forecasts, but they grew rapidly with increasing lead time beyond 6 days. Non-weighted multi-model means outperformed all individual models approaching a 10-day forecast lead time. In contrast, errors in surface air temperature and relative humidity could be large in initial conditions and remained large through 10-day forecasts without much growth, and non-weighted multi-model means did not outperform all individual models. These results following the tracks of the mobile platforms are consistent with those at a fixed location. Large errors in initial condition of sea surface temperature (SST) resulted in part from the unusual Arctic surface warming in 2019 not captured by data assimilation systems used for model initialization. These errors in SST led to large initial and prediction errors in surface air temperature. Our results suggest that improving predictions of surface conditions over the Arctic Ocean requires enhanced in situ observations and better data assimilation capability for more accurate initial conditions as well as better model physics. Numerical predictions of Arctic atmospheric conditions may continue to suffer from large errors if they do not fully capture the large SST anomalies related to Arctic warming.
Language: English
Open Access status: green
Awards: PASSIVE MICROWAVE SENSORS PROVIDE A LONG HISTORY OF SEA ICE CONCENTRATION FROM SATELLITE DATA SUITABLE FOR TRACKING CLIMATE CHANGE AND VARIABILITY. SEA ICE EXTENT AND ARU HAVE LONG BEEN CONSIDERED KEY CLIMATE INDICATORS AND HAVE BEEN INCLUDED IN NUMEROUS ASSESSMENT AND CLIMATE INDICATOR REPORTS. HOWEVER THESE TWO PARAMETERS PROVIDE ONLY LIMITED INFORMATION ABOUT THE CHARACTER OF THE SEA ICE; IN ADDITION THEY HAVE LIMITED SKILL AS INDICATORS OF FUTURE SEA ICE CONDITIONS BOTH SEASONAL AND INTERANNUALLY. HERE WE PROPOSE A SUITE OFINTER-RELATED SEA ICE CLIMATE INDICATORS THAT GO BEYOND EXTENT AND AREA TO DESCRIBE THE SEASONAL EVOLUTION OF THE ARCTIC SEA ICE COVER FROM SPRING THROUGH AUTUMN. SPECIFICALLY WE PROPOSE TO DEVELOP THREE INDICATORS: (1) SEA ICE MELT ONSET/FREEZE-UP (2) SEA ICE RETREAT/ADVANCE AND (3) FETCH. AN HISTORICAL TIME SERIES OF THESE FIELDS WILL BE PRODUCED FOR EACH PARAMETER FROM THE START OF THE PASSIVE MICROWAVE RECORD IN 1979 WITH CONTINUING UPDATES. STATISTICS ON TRENDS AND VARIABILITY WILL BE CALCULATED AND VISUALIZATIONS AND METRICS WILL BE DEVELOPED TO EASILY CONVEY THE INFORMATION. THE INDICATORS WILL BE PRODUCED ARCTIC-WIDE BUT REGIONAL BREAKDOWNS WILL ALSO BE PERFORMED WITH A PARTICULAR FOCUS ON THE ALASKAN REGION. THESE THREE PARAMETERS WILL INFORM A VARIETY OF STAKEHOLDERS. FOR EXAMPLE THE TIMING OF MELT ONSET AND THE DATE OF SEA ICE RETREAT CAN PROVIDE USEFUL INFORMATION ON THE EVOLUTION OF THE ICE COVER THROUGH THE REST OF THE SUMMER AND THUS BE USEFUL TO EFFORTS TO IMPROVE SEASONAL SEA ICE FORECASTS. MELT ONSET IS ALSO AN INDICATOR FOR SUMMER MINIMUM EXTENT SINCE IT PLAYS A KEY ROLE IN THE AMOUNT OF SOLAR ENERGY ABSORPTION AND ALONG WITH FREEZE UP THE OVERALL ENERGY BALANCE OF THE ARCTIC CLIMATE SYSTEM. THE LENGTH OF THE OPEN WATER SEASON IS IMPORTANT FOR HUMAN ACTIVITIES AND FOR WILDLIFE. THE LONG TIME SERIES THAT WILL BE PRODUCED WILL INFORM FUTURE PLANNING OF MILITARY CIVILIAN AND COMMERCIAL INFRASTRUCTURE. FETCH THE OPEN WATER DISTANCE BETWEEN THE SHORE AND ICE COVER IS IMPORTANT FOR NAVIGATION AND PLAYS A KEY ROLE IN POTENTIAL COASTAL DAMAGE DUE TO WINDS AND WAVES. INTERACTIVE TOOLS AND VISUALIZATIONS WILL BE DEVELOPED TO DISPLAY AND HELP ANALYZE THE INFORMATION. OUR PROJECT WILL USE PASSIVE MICROWAVE BRIGHTNESS TEMPERATURES AND SEA ICE CONCENTRATION FIELDS DERIVED FROM THEM TO PRODUCE OUR NEW CLIMATE INDICATORS. WE WILL USE CONCENTRATION ALGORITHMS DEVELOPED AT NASA GODDARD. HOWEVER THERE ARE A VARIETY OF DIFFERENT ALGORITHMS AND THE RESULTING CONCENTRATION FIELDS DO NOT INCLUDE AN UNCERTAINTY ESTIMATE AND DO NOT TYPICALLY HAVE A QUANTIFIABLE BASIS TO DERIVE EXTENT UNCERTAINTY. THIS LEADS TO CONFUSION AND INCONSISTENCY IN THE ESTIMATES. THE NOAA/NSIDC SEA ICE CLIMATE DATA RECORD CREATED FROM THE NASA SATELLITE PRODUCTS PROVIDES THE MEANS TO PROVIDE A SINGLE AUTHORITATIVE SEA ICE CONCENTRATION ESTIMATE; ALSO ALL PROCESSING METHODS ARE FULLY DOCUMENTED REPRODUCIBLE AND PUBLICALLY AVAILABLE. THIS IS ESSENTIAL FOR PUBLIC CONFIDENCE IN THE INDICATORS. THUS IN THIS PROPOSAL WE PLAN TO USE THE NASA PRODUCTS AS DISTRIBUTED THROUGH THE CLIMATE DATA RECORD FRAMEWORK AS THE SOURCE OF SEA ICE CONCENTRATION FOR THE RETREAT/ADVANCE AND FETCH INDICATORS. MELT ONSET AND FREEZE-UP ARE CALCULATED DIRECTLY FROM BRIGHTNESS TEMPERATURES THE SAME SOURCE DATA USED FOR THE SEA ICE CONCENTRATIONS WHICH PROVIDES CONSISTENCY ACROSS THE INDICATORS., G3153789621, G316620673, G450852192, NSFGEO-NERC Collaborative Research: Advancing Predictability of Sea Ice: Phase 2 of the Sea Ice Prediction Network (SIPN2), Collaborative Research: Forum for Arctic Modeling and Observational Synthesis (FAMOS) phase 2: focus on high and very high resolution modeling, G6367438762, G6843095815, G968142726
OpenAlex ID: W4220877458
FWCI: 0.629
Cites: 78
Cited by: 12
Related to: 10