Overview of US Activities Related to Remote Sensing of Temperatures of Inland Waters

Transcription

1 Overview of US Activities Related to Remote Sensing of Temperatures of Inland Waters Simon J. Hook Philipp Schneider Robert G. Radocinski Robert C. Wilson and many others at other institutions: RIT, UCD Pasadena, California, Contact: Mono Lake, California, October 2009

2 Outline Introduction Global Studies Local Studies Global Lake Temperature Collaboration (GLTC) Summary and Conclusions

3 Global Studies The Idea Temperatures of lakes and reservoirs are good indicators of climate trends Existing in situ data is insufficient in space and time Nearly 30-year record of satellite thermal infrared imagery available Project Objectives Use satellite derived water surface temperatures to characterize the temporal thermal behavior of lakes and inland water bodies worldwide Relate changes in the thermal behavior of the water bodies to global and regional climate change as indicated by surface air temperature data Study sites: 165 large lakes worldwide Case study: 6 lakes in California and Nevada

4 Why is this important? The dataset constructed in the framework of this study will aid in answering questions such as Can the existing archive of satellite thermal infrared imagery deliver stable and accurate time series of lake temperatures? How have temperatures of water bodies worldwide (in particular those without in situ records) changed in the last three decades? Do these changes reflect trends in regional air temperature or do they show different patterns? Do satellite-retrieved temperature time series of lakes and reservoirs have the potential to complement existing air temperature records and improve our understanding of regional climate? The implications of this research can be viewed from two angles: 1. The lake as an indicator of regional climate change ( implications for our understanding of regional climate, complementing air temp. records, lakeatmosphere interactions etc.) 2. The lake as a subject of regional climate change ( implications for limnology, lake ecology, etc.)

5 California/Nevada case study A preliminary case study was carried out for six lakes in California and Nevada. The center panel shows the lake locations and the GISTEMP (Hansen et al., 1999) summertime temperature change between 1991 and In situ measurements at 4 buoys at Lake Tahoe were used to develop algorithms and validate the results

6 Data and Methods Thermal infrared data from two sensor series Moderate Resolution Imaging Spectroradiometer (MODIS) Along-Track Scanning Radiometer (ATSR) Data extraction Cloud masking Atmospheric correction Computation of summer time (JAS) means Weighted linear regression analysis and uncertainty analysis

7 Results: Lake Tahoe Validation Schneider et al. (2009). Satellite observations indicate rapid warming trend for lakes in California and Nevada. Geophysical Research Letters, in print Standard error = 0.2 K

8 Results: Summertime (JAS) trends since 1991 Schneider et al. (2009). Satellite observations indicate rapid warming trend for lakes in California and Nevada. Geophysical Research Letters, in print

9 Global analysis Combine lake temperature retrievals from multiple sensors (ATSR, MODIS, AVHRR) Perform time series analysis to quantify trends in thermal behavior of the lakes Analyze trends and develop metrics to quantify regional and global patterns

10 Great Lakes Validation

11 Global Analysis

12 More on Trends

13 Local Studies Use high spatial resolution data (Landsat and ASTER) Satellite revisit limits types of studies Primarily focused on looking at upwellings, currents and thermal bars Although satellite record is infrequent extends back for almost 30 years

14 Local Studies An Example ASTER 8/04/2000 ASTER 6/03/2001 ASTER 7/22/2001 ASTER 8/22/2001

15 Turning temperatures into circulation MODIS 6/03/2001 ASTER 6/03/2001

16 Turning Temperatures into Currents

17 ASTER-Landsat Current Map Current Tracking with Landsat ETM+ and ASTER Data using Maximum Correlation Method

18 Thermal Bar Spring Progression in Lake Ontario Thermal Bar Late April Density maximum density Mid May Early June Summer Stratification Winter Stratification Temperature (Celsius) Images courtesy of J. Schott RIT Late June

19 LANDSAT: April 23, 1991 Lakes Ontario & Erie Cold center Warm ring True Color Composite Thermal Channel

20 Hydrodynamic Model Used to Predict Thermal Bar Development Thermal Bar at 4 Celsius N S N S vertical cross-section

21 Principal Investigators: Workshop sponsors: Dr. Simon Hook (NASA JPL; California Institute of Technology) Dr. John Lenters (U. Nebraska-Lincoln) Dr. Peter McIntyre (U. Wisconsin-Madison) Dr. Catherine O Reilly (Illinois State University) 40 attendees representing 11 countries

22 Global Lake Temperature Collaboration 2012 Workshop GLTC Goals Utilize in situ and remotely sensed lake temperature data to address: i. Are global and regional patterns of lake warming (or cooling) over the past several decades concordant across space and time? ii. What climatic and geographic factors control these patterns (e.g., air temperature, solar radiation)? iii. How do in situ records compare with satellite data (e.g., mean values, trends, interannual variability)? iv. Do trends in lake surface temperature mimic those in deeper waters, and what does this imply for mixing and stratification? v. What are the ecological consequences of changes in lake temperature? Workshop Hosted in Lincoln, Nebraska; June 1-5, participants from 11 countries Sponsored by NSF, NASA, and the University of Nebraska-Lincoln s Institute of Agriculture and Natural Resources Outcomes Compiled additional datasets; number of lakes with both satellite and in situ measurements more than doubled Found that water temperatures are warming more rapidly than air for many lakes across the world Changes in climatic variables other than air temperature may explain more rapid warming, such as solar dimming/brightening Anomalous warming/cooling rates vary locally depending on lake processes Next Steps Workshop write-up for EOS Global synthesis of in situ and satellite data for high-profile publication Establish process and repository for community data sharing and collaboration among in situ and remote sensing scientists Follow-on workshops at topical meetings Distribution of lake surface temperature trends Lake temperature trends, ( C/decade) Figure 1. Trends in lake surface temperature from (in C/decade), as measured by satellite-based (circles; n = 58) and in situ sensors (squares; n = 31). Figure 2. Both the satellite-based and in situ records show California a large Institute number of Technology of lakes (~95%) that are warming.

23 Summary and Conclusions Nearly 30-year archive of thermal infrared satellite imagery available which can be used to study Temporal changes in lake temperatures worldwide Local scale processes Lakes as well as coastal regions Several groups working on the temperatures of inland waters such as GLTC, International Association for Great Lakes Research (IAGLR), Global Lake Ecologoical Observatory Network (GLEON) Generally a lack of in situ data suitable for use with satellite data. However need better access/organization of in situ data Need thermal infrared satellite data with high temporal and spatial resolution e.g. HyspIRI

24 QUESTIONS? COMMENTS? CONTACT: Lake Gjende, Norway, August 2008, courtesy Philipp Schneider