ISCCP at 30, April 2013 Concurrent Study of a) 22 – year reanalysis and extension of global water vapor over both land and ocean (NVAP–M) and b) the matching ISCCP data set Thomas H. Vonder Haar John M. Forsythe John Haynes Cooperative Institute for Research in the Atmosphere (CIRA) Colorado State University Fort Collins, CO 1 NVAP-M (NVAP (NASA Water Vapor Project) – MEaSUREs) NASA MEaSUREs Program: Making Earth System Data Records for Use in Research Environments STC - METSAT Science and Technology Corporation - Metsat Division, Fort Collins CO

ISCCP at 30, April Reanalysis and extension ( ) of the heritage NVAP ( ) dataset Total (TPW) and layered (LPW) precipitable water Removes time-dependent biases caused by dataset and algorithm changes incurred during multi-phase processing. – Focus on consistent data inputs and peer reviewed processing algorithms through time. Back-propagation of modern observations through the entire data period. – Collaboration with AIRS water vapor project at NASA JPL. (E. Fetzer et al.) Global (land and ocean) data with vertical structure information. Multiple data products to fit varying user needs. Highly model-independent Now Available at NASA Langley Atmospheric Science Data Center (ASDC). /project/nvap/nvap-m_table /project/nvap/nvap-m_table NASA Water Vapor Project – MEaSUREs “NVAP-M” refers to the new NVAP-MEaSUREs data set. “Heritage NVAP” refers to the existing dataset described by Randel et al., 1996 Vonder Haar et al. 2012: Weather and climate analyses using improved global water vapor observations. Geophys. Res. Lett., 39, L doi: /2012GL Similar in concept to GPCP, ISCCP…

ISCCP at 30, April 2013 NVAP-M: Input Datasets SSM/I Average TPW September 10, 2004 Retrieved from microwave Tbs intercalibrated by Sapiano et al 75 mm 0 AIRS Version 5 Level 3 Average TPW September 10, mm 75 HIRS Average PW September 10, mb layer Retrieved from clear-sky radiances 20 mm 0 GPS TPW Data Points (beginning 1997) (Wang et al. 2007) SSM/I AIRS Sonde HIRS GPS Sapiano et al. (TGRS; 2012) intercalibration; Elsaesser et al retrieval. (IGRA) (Wang et al.) Jackson and Bates radiances; Engelen and Stephens (1999) retrieval 3

ISCCP at 30, April More confidence in later period due to increased observations 4

ISCCP at 30, April 2013 NVAP-M: A Three-Tiered Product Approach NVAP-Weather Used for weather case studies on timescales of days to weeks SSM/I Level 1 C intercalibrated radiances HIRS cloud cleared radiances Radiosonde, GPS since 1997 AIRS Level 3 TPW and Layered PW Maximizes spatial and temporal coverage Not driven by reduction of time- dependent biases 4x daily ½ degree resolution TPW and layered precipitable water surface to 700 hPa 700 to 500 hPa 500 to 300 hPa < 300 hPa. NVAP-Climate Used for studies of climate change and interannual variability SSM/I Level 1 C intercalibrated radiances HIRS cloud cleared radiances, + AIRS since 2002 Radiosonde Consistent inputs through time. Consistent, high quality retrievals. Less emphasis on spatial and temporal coverage Daily 1-degree resolution TPW layered precipitable water surface to 700 hPa 700 to 500 hPa 500 to 300 hPa < 300 hPa NVAP-Ocean SSM/I-only. Supplemental Fields Data source code (DSC) map, indicating the sources used in each grid box. Heritage NVAP begun in early 1990’s was “one size fits all” approach. 5

ISCCP at 30, April 2013 NVAP-M Weather vs. Climate Product 0-6Z Z 18-24Z 6-12Z 0 mm 75 Weather Product Climate Product 10 September,

ISCCP at 30, April 2013 Heritage NVAP NVAP-M Climate Global Mean TPW Dotted lines : Known time- dependent biases due to processing changes -90° 90° -90° 90° Heritage: 24.5 mm NVAP-M: 25.3 mm Monthly Zonal TPW Anomaly Over Land and Ocean 7

ISCCP at 30, April 2013 ISCCP zonal mean cloud amount anomaly (%) (Raschke and Kinne (2008)) NVAP-M Climate TPW anomaly (mm) 8

ISCCP at 30, April 2013 Correlation Coefficient Correlation of ISCCP total cloud and NVAP-M total precipitable water vapor monthly anomalies ( ) NVAP-M Ocean (SSM/I only) NVAP-M Climate (SSM/I, AIRS, HIRS, Sondes) Blue areas indicate cloud amount decreases as TPW increases Subtropical ocean regions show increasing low-level stratus coupled with dry subsidence aloft Low correlation or negative correlation over land under study 9

ISCCP at 30, April NVAP-M-Climate Preliminary - Significance testing in progress Trend (mm / decade) ISCCP Monthly Mean Cloud 50 – 100% only ISCCP Monthly Mean Cloud 0 – 50% only Insufficient data 10

ISCCP at 30, April 2013 At this time, we can neither prove nor disprove a robust trend in the global water vapor data from the NVAP-M Climate data set 11

ISCCP at 30, April Monthly Mean TPW (mm) from NVAP-M Climate 12

ISCCP at 30, April 2013 Summary NVAP-MEaSUREs represents the first reanalysis of the heritage NVAP global water vapor data over both land and ocean. NVAP-M features intercalibrated radiances, time-consistent retrieval algorithms, climate / weather / ocean processing paths and use of the first 7.5 years of AIRS data Data fusion and study with companion climate records such as ISCCP allows increased insight into each data set and natural processes. Trend analysis must consider: a)Time-dependent bias due to instruments, calibration, algorithm and ancillary data b)Changing time/space sampling of observations 13

ISCCP at 30, April 2013 Data now available from NASA Langley Atmospheric Science Data Center: (netCDF format) For further information see Vonder Haar, Bytheway, Forsythe, 2012: "Weather and climate analyses using improved global water vapor observations." Geophys. Res. Lett., 39, L16802, doi: /2012GL052094doi: /2012GL