COSMIC Data Analysis and Archive Center CDAAC https://cdaac-www.cosmic.ucar.edu/

ERA5 monthly averaged data on pressure levels from 1979 to present H. Hersbach, B. Bell, P. Berrisford, G. Biavati, A. Horányi, J. Muñoz Sabater, J. Nicolas, C. Peubey, R. Radu, I. Rozum, D. Schepers, A. Simmons, C. Soci, D. Dee, and J.-N. Thépaut https://doi.org/10.24381/cds.6860a573

ERA5 monthly averaged data on single levels from 1979 to present H. Hersbach, B. Bell, P. Berrisford, G. Biavati, A. Horányi, J. Muñoz Sabater, J. Nicolas, C. Peubey, R. Radu, I. Rozum, D. Schepers, A. Simmons, C. Soci, D. Dee, and J.-N. Thépaut https://doi.org/10.24381/cds.f17050d7

MERRA-2 instM_2d_asm_Nx: 2d, Monthly mean, Single-Level, Assimilation, Single-Level Diagnostics V5.12.4 GMAO (Global Modeling and Assimilation Office) https://doi.org/10.5067/5ESKGQTZG7FO

Aqua/AIRS L3 Monthly Standard Physical Retrieval (AIRS-only) 1 ◦ ×1 ◦ V7.0 AIRS project https://doi.org/10.5067/UBENJB9D3T2H

Aqua/AIRS L3 Monthly Standard Physical Retrieval (AIRS+AMSU) 1 ◦ ×1 ◦ V7.0 AIRS project https://doi.org/10.5067/KUC55JEVO1SR

Carbon-Tracker CT2019B A. R. Jacobson, K. N. Schuldt, J. B. Miller, T. Oda, P. Tans, A. Andrews, J. Mund, L. Ott, G. J. Collatz, T. Aalto, S. Afshar, K. Aikin, S. Aoki, F. Apadula, B. Baier, P. Bergamaschi, A. Beyersdorf, S. C. Biraud, A. Bollenbacher, D. Bowling, G. Brailsford, J. B. Abshire, G. Chen, H. Chen, L. Chmura, Sites Climadat., A. Colomb, S. Conil, A. Cox, P. Cristofanelli, E. Cuevas, R. Curcoll, C. D. Sloop, K. Davis, S. D. Wekker, M. Delmotte, J. P. DiGangi, E. Dlugokencky, J. Ehleringer, J. W. Elkins, L. Emmenegger, M. L. Fischer, G. Forster, A. Frumau, M. Galkowski, L. V. Gatti, E. Gloor, T. Griffis, S. Hammer, L. Haszpra, J. Hatakka, M. Heliasz, A. Hensen, O. Hermanssen, E. Hintsa, J. Holst, D. Jaffe, A. Karion, S. R. Kawa, R. Keeling, P. Keronen, P. Kolari, K. Kominkova, E. Kort, P. Krummel, D. Kubistin, C. Labuschagne, R. Langenfelds, O. Laurent, T. Laurila, T. Lauvaux, B. Law, J. Lee, I. Lehner, M. Leuenberger, I. Levin, J. Levula, J. Lin, M. Lindauer, Z. Loh, M. Lopez, I. T. Luijkx, C. Lund Myhre, T. Machida, I. Mammarella, G. Manca, A. Manning, A. Manning, M. V. Marek, P. Marklund, M. Y. Martin, H. Matsueda, K. McKain, H. Meijer, F. Meinhardt, N. Miles, C. E. Miller, M. Molder, S. Montzka, F. Moore, J.-A. Morgui, S. Morimoto, B. Munger, J. Necki, S. Newman, S. Nichol, Y. Niwa, S. ODoherty, M. Ottosson-Lofvenius, B. Paplawsky, J. Peischl, O. Peltola, J.-M. Pichon, S. Piper, C. Plass-Dolmer, M. Ramonet, E. Reyes-Sanchez, S. Richardson, H. Riris, T. Ryerson, K. Saito, M. Sargent, M. Sasakawa, Y. Sawa, D. Say, B. Scheeren, M. Schmidt, A. Schmidt, M. Schumacher, P. Shepson, M. Shook, K. Stanley, M. Steinbacher, B. Stephens, C. Sweeney, K. Thoning, M. Torn, J. Turnbull, K. Tørseth, P. V. D. Bulk, D. V. Dinther, A. Vermeulen, B. Viner, G. Vitkova, S. Walker, D. Weyrauch, S. Wofsy, D. Worthy, D. Young, and M. Zimnoch https://doi.org/10.25925/20201008

Global Precipitation Climatology Project (GPCP) Climate Data Record (CDR), Version 2.3 (Monthly) R. Adler, J. Wang, M. Sapiano, G. Huffman, L. Chiu, P. Xie, R. Ferraro, U. Schneider, A. Becker, D. Bolvin, E. Nelkin, G. Gu, and NOAA CDR Program https://doi.org/10.7289/V56971M6

Version 4 of the CRU TS monthly high-resolution gridded multivariate climate dataset (https://crudata.uea.ac.uk/cru/data/hrg/) I. Harris, T. J. Osborn, P. Jones, and D. Lister https://doi.org/10.1038/s41597-020-0453-3

A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index (https://cran.r-project.org/web/packages/SPEI) S. M. Vicente-Serrano, S. Beguería, and J. I. López-Moreno https://doi.org/10.1175/2009jcli2909.1

Standardized precipitation evapotranspiration index (SPEI) revisited: parameter fitting, evapotranspiration models, tools, datasets and drought monitoring (https://cran.r-project.org/web/packages/SPEI) S. Beguería, S. M. Vicente-Serrano, F. Reig, and B. Latorre https://doi.org/10.1002/joc.3887